Evaluation of functionalized silver and silica nanoparticles for the removal of deoxyribonucleic acid conveying antibiotics resistance genes from water
- Authors: Ezeuko, Adaora Stella
- Date: 2022
- Subjects: DNA , Silica , Water
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27765 , vital:69414
- Description: Antibiotic resistance genes ARGs are recognized as a serious public health emergency linked to extensive use of antibiotics by humans and animals as a prophylactic agent that treats and prevents infections. The occurrence of high concentrations being identified in wastewater treatment plants, rivers, etc is due to untreated effluents being discharged from households, hospitals, agriculture, and pharmaceutical industries. The application of adequate treatment techniques and material for the removal of bacteria DNA conveying ARGs from the effluents before their release to the environment cannot be overemphasized. Adsorption techniques seem to be effective due to their easy design, operation, and ability to regenerate adsorbents for use without producing toxic by-products. This concept was employed for the removal of bacteria DNA conveying ARGs from simulated aqueous solution, effluents from hospital, river and WWTPs using silver and silica metallic nanoparticles. This thesis investigated the effectiveness of metallic nanoparticles containing silver AgNPs and mesoporous silica nanoparticles MSNPs as well as magnetite Fe3O4 functionalized with 4 4hydroxyphenyl 2 262-terpyridine onto their surface, for the removal of bacteria DNA conveying antibiotic resistance genes from water samples from hospitals, river, and wastewater treatment plants WWTPs. Silver nanoparticles AgNPs of different molar concentrations 0.1M, 0.5M and 1.0 M and mesoporous silica nanoparticles MSNPs adsorbents were successfully synthesized in their original states and surface functionalization achieved by incorporating magnetite Fe3O4 and 4 4 hydroxyphenyl 2 2 6 2 terpyridine on the silver AgNPs Fe3O4 and silica MSNPs TPPY surfaces respectively. Their effectiveness as adsorbent for the removal of bacteria DNA conveying ARGs from aqueous solutions and real water/wastewater samples were investigated. The DNA uptake by the as-synthesized AgNPs and MSNPs were compared to the functionalized AgNPs Fe3O4 and MSNPsTPPY by determining the adsorbents with the highest removal efficiencies. All as synthesized and functionalized adsorbents were characterized by SEM, EDX, FTIR, XRD, UV spectroscopy and PZC before the removal process. The extraction of genomic DNA from antibiotic-resistant Enterococcus faecium and Vibrio parahaemolyticus was successfully achieved via the boiling method. Antibiotic susceptibility test was conducted using the disk diffusion method before the commencement of genomic DNA extraction. Molecular characterization via gel electrophoresis confirmed the presence of resistance genes at different base pairs. Adsorption batch experiment were investigated, and the best optimum parameters were evaluated through the influence of pH, contact time, initial DNA concentration, adsorbent dose, and competitive ions for each sorption process. The rate determining step were determined by fitting kinetic models such as Natarajan and Khalaf first order, pseudo first order, pseudo second order, Elovich model to experimental data. Also, the adsorption mechanisms determining adsorption equilibrium were investigated by fitting Freundlich, Langmuir and Sips model into the experimental data. The application of AgNPsFe3O4 nanocomposite and MSNPsTPPY for the removal of bacteria DNA demonstrated much enhancement for DNA uptake than the as-synthesized AgNPs and MSNPs materials. The incorporation of magnetite and 4 4hydroxyphenyl 2 2 6 2-terpyridine onto AgNPs and MSNPs significantly enhanced the binding affinity towards the removal the bacteria DNA via strong electrostatic attraction between the active sites on the adsorbent and the negative DNA molecules. Finally, high adsorption capacities were recorded with AgNPsFe3O4 nanocomposite and MSNPsTPPY compared to AgNPs and MSNPs with chaotropic salts. The kinetic adsorption models were mostly best fitted by the pseudo-second order and Elovich models while the adsorption equilibrium was best described by Langmuir and Sips isotherm models. MSNPs with different chaotropic salts, AgNPsFe3O4 nanocomposite and MSNPsTPPY also proved its effectiveness in DNA removal not only in the simulated aqueous solution but in three different real life water samples obtained from Cofimvaba hospital, Ndevana river and Uitenhage WWTPs. High adsorption efficiencies above 90 percent were achieved during the removal of DNA in all the three real water samples. Therefore, application of these adsorbents for the removal of bacteria DNA conveying ARGs may be a promising option that would tackle the consequences of consuming ARGs infected water globally. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022
- Authors: Ezeuko, Adaora Stella
- Date: 2022
- Subjects: DNA , Silica , Water
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27765 , vital:69414
- Description: Antibiotic resistance genes ARGs are recognized as a serious public health emergency linked to extensive use of antibiotics by humans and animals as a prophylactic agent that treats and prevents infections. The occurrence of high concentrations being identified in wastewater treatment plants, rivers, etc is due to untreated effluents being discharged from households, hospitals, agriculture, and pharmaceutical industries. The application of adequate treatment techniques and material for the removal of bacteria DNA conveying ARGs from the effluents before their release to the environment cannot be overemphasized. Adsorption techniques seem to be effective due to their easy design, operation, and ability to regenerate adsorbents for use without producing toxic by-products. This concept was employed for the removal of bacteria DNA conveying ARGs from simulated aqueous solution, effluents from hospital, river and WWTPs using silver and silica metallic nanoparticles. This thesis investigated the effectiveness of metallic nanoparticles containing silver AgNPs and mesoporous silica nanoparticles MSNPs as well as magnetite Fe3O4 functionalized with 4 4hydroxyphenyl 2 262-terpyridine onto their surface, for the removal of bacteria DNA conveying antibiotic resistance genes from water samples from hospitals, river, and wastewater treatment plants WWTPs. Silver nanoparticles AgNPs of different molar concentrations 0.1M, 0.5M and 1.0 M and mesoporous silica nanoparticles MSNPs adsorbents were successfully synthesized in their original states and surface functionalization achieved by incorporating magnetite Fe3O4 and 4 4 hydroxyphenyl 2 2 6 2 terpyridine on the silver AgNPs Fe3O4 and silica MSNPs TPPY surfaces respectively. Their effectiveness as adsorbent for the removal of bacteria DNA conveying ARGs from aqueous solutions and real water/wastewater samples were investigated. The DNA uptake by the as-synthesized AgNPs and MSNPs were compared to the functionalized AgNPs Fe3O4 and MSNPsTPPY by determining the adsorbents with the highest removal efficiencies. All as synthesized and functionalized adsorbents were characterized by SEM, EDX, FTIR, XRD, UV spectroscopy and PZC before the removal process. The extraction of genomic DNA from antibiotic-resistant Enterococcus faecium and Vibrio parahaemolyticus was successfully achieved via the boiling method. Antibiotic susceptibility test was conducted using the disk diffusion method before the commencement of genomic DNA extraction. Molecular characterization via gel electrophoresis confirmed the presence of resistance genes at different base pairs. Adsorption batch experiment were investigated, and the best optimum parameters were evaluated through the influence of pH, contact time, initial DNA concentration, adsorbent dose, and competitive ions for each sorption process. The rate determining step were determined by fitting kinetic models such as Natarajan and Khalaf first order, pseudo first order, pseudo second order, Elovich model to experimental data. Also, the adsorption mechanisms determining adsorption equilibrium were investigated by fitting Freundlich, Langmuir and Sips model into the experimental data. The application of AgNPsFe3O4 nanocomposite and MSNPsTPPY for the removal of bacteria DNA demonstrated much enhancement for DNA uptake than the as-synthesized AgNPs and MSNPs materials. The incorporation of magnetite and 4 4hydroxyphenyl 2 2 6 2-terpyridine onto AgNPs and MSNPs significantly enhanced the binding affinity towards the removal the bacteria DNA via strong electrostatic attraction between the active sites on the adsorbent and the negative DNA molecules. Finally, high adsorption capacities were recorded with AgNPsFe3O4 nanocomposite and MSNPsTPPY compared to AgNPs and MSNPs with chaotropic salts. The kinetic adsorption models were mostly best fitted by the pseudo-second order and Elovich models while the adsorption equilibrium was best described by Langmuir and Sips isotherm models. MSNPs with different chaotropic salts, AgNPsFe3O4 nanocomposite and MSNPsTPPY also proved its effectiveness in DNA removal not only in the simulated aqueous solution but in three different real life water samples obtained from Cofimvaba hospital, Ndevana river and Uitenhage WWTPs. High adsorption efficiencies above 90 percent were achieved during the removal of DNA in all the three real water samples. Therefore, application of these adsorbents for the removal of bacteria DNA conveying ARGs may be a promising option that would tackle the consequences of consuming ARGs infected water globally. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022
In Silico analysis of Spermidine, Spermine and Putrescine interaction with selected heat shock proteins from Plasmodium falciparum 3D7 towards malaria drug development
- Authors: Godlo, Sesethu
- Date: 2022
- Subjects: Heat shock proteins , Malaria vaccine , Plasmodium falciparum
- Language: English
- Type: Master'stheses , text
- Identifier: http://hdl.handle.net/10353/27709 , vital:69395
- Description: Malaria is a mosquito-borne disease that affects around half of the world's population. It is one of the most common parasite infections that endangers human life. One of the most serious issues in malaria therapy is the emergence and spread of antimalarial drug-resistant Plasmodium parasites. This is due to the Plasmodium parasite's constant evolution and development of new methods of surviving medication toxicity. Studies of antimalarial drug development have been focused on polyamine biosynthesis by targeting precursors such as ornithine decarboxylase, adenosylmethionine decarboxylase, and spermidine synthase and protein-protein interactions between Plasmodium falciparum chaperones spotting out Hsp90, Hsp70, and Hsp40 as potential targets with little attention being paid to the interaction between polyamines and molecular chaperones. Therefore, this study seeks to identify interactions between polyamines and molecular chaperones present in the malarial parasite Plasmodium falciparum 3D7. The identification of these interactions might lead to the design of effective drugs to treat and eliminate malaria. Using computational analysis, this study aims to find interactions between polyamines and molecular chaperones found in the malarial parasite Plasmodium falciparum 3D7. The sequences of the selected heat proteins retrieved, and the 3D structures predicted and validated. These structures were docked with polyamines retrieved from PubChem and MD simulations on the docked interactions were performed. Docking revealed common amino acid residues with hydrogen bonds and salt bridges between all receptors and ligands, with glutamine and aspartic acid standing out. MD simulations revealed that when HSP20 and HSP40 transport the ligands, they pop up or are released too quickly. However, HSP60, HSP70, and HSP90 provide optimism since the ligands remain attached to the proteins for a specific amount of time. To further understand and confirm these interactions wet laboratory studies may be carried out in future. , Thesis (MSci) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022
- Authors: Godlo, Sesethu
- Date: 2022
- Subjects: Heat shock proteins , Malaria vaccine , Plasmodium falciparum
- Language: English
- Type: Master'stheses , text
- Identifier: http://hdl.handle.net/10353/27709 , vital:69395
- Description: Malaria is a mosquito-borne disease that affects around half of the world's population. It is one of the most common parasite infections that endangers human life. One of the most serious issues in malaria therapy is the emergence and spread of antimalarial drug-resistant Plasmodium parasites. This is due to the Plasmodium parasite's constant evolution and development of new methods of surviving medication toxicity. Studies of antimalarial drug development have been focused on polyamine biosynthesis by targeting precursors such as ornithine decarboxylase, adenosylmethionine decarboxylase, and spermidine synthase and protein-protein interactions between Plasmodium falciparum chaperones spotting out Hsp90, Hsp70, and Hsp40 as potential targets with little attention being paid to the interaction between polyamines and molecular chaperones. Therefore, this study seeks to identify interactions between polyamines and molecular chaperones present in the malarial parasite Plasmodium falciparum 3D7. The identification of these interactions might lead to the design of effective drugs to treat and eliminate malaria. Using computational analysis, this study aims to find interactions between polyamines and molecular chaperones found in the malarial parasite Plasmodium falciparum 3D7. The sequences of the selected heat proteins retrieved, and the 3D structures predicted and validated. These structures were docked with polyamines retrieved from PubChem and MD simulations on the docked interactions were performed. Docking revealed common amino acid residues with hydrogen bonds and salt bridges between all receptors and ligands, with glutamine and aspartic acid standing out. MD simulations revealed that when HSP20 and HSP40 transport the ligands, they pop up or are released too quickly. However, HSP60, HSP70, and HSP90 provide optimism since the ligands remain attached to the proteins for a specific amount of time. To further understand and confirm these interactions wet laboratory studies may be carried out in future. , Thesis (MSci) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022
Preparation, characterization, and in vitro evaluation of polymer-based wound dressings for the management of chronic wounds
- Authors: Alven, Sibusiso
- Date: 2022
- Subjects: Toxicity testing -- In vitro , Wound healing , Chronic diseases
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27992 , vital:71414
- Description: Microbial infections are responsible for the retarded recovery process of chronic wounds. Polymer-based scaffolds possess features suitable for the treatment of chronic injuries. However, these scaffolds are commonly encapsulated with therapeutic agents to enhance their biological activities, including antibacterial efficacy. In this research, two types of polymer-based scaffolds were formulated and evaluated as effective formulations for the treatment of chronic wounds: sponges and topical gels. Sponges were formulated from cross-linking of gelatin and PEG. Ag nanoparticles and metronidazole were incorporated into the sponges to improve their antibacterial activity. Topical gels were loaded with essential oils and Ag nanoparticles and prepared from CMC and poloxamer. The prepared sponges and topical gels were evaluated using various analysis and characterization techniques. SEM/EDX, FTIR, and TGA were employed to characterize gelatin/PEG hybrid sponges followed by porosity, in vitro biodegradability, cytotoxicity, and antibacterial studies. FTIR, SEM/EDX, and TGA confirmed their physicochemical properties and successful fabrication of sponges loaded with metronidazole and Ag nanoparticles. The sponges were biodegradable, indicating their capability to induce skin regeneration. The drug release studies showed a rapid release of metronidazole 28.32-71.97 percent from the sponges over the first hour, followed by a sustained drug release. The Ag nanoparticles were released in a sustained manner, suggesting that these sponges can rapidly destroy bacteria and inhibit persisting bacterial infections as well as protect the lesion bed from further bacteria infections. The in vitro antibacterial studies of sponges displayed superior antibacterial activity against most of the Gram-negative and Gram-positive bacteria strains commonly found in chronic wound infections with a MIC value of 15.625 μg/mL. In vitro cytotoxicity experiments revealed excellent biocompatibility with a percent cell viability of more than 70 percent. The in vitro wound scratch healing assay exhibited that the sponges encapsulated with only metronidazole promoted high cell migration than the dual drug-loaded sponges and untreated cells, suggesting its potential to quicken the wound healing process. CMC/Poloxamer topical gels were also characterized by FTIR, followed by pH, viscosity, spreadability, cytotoxicity, and antibacterial studies. FTIR showed successful preparation of CMC/Poloxamer topical gels loaded with essential oils and Ag nanoparticles. The topical gels exhibited pH in the range of 5.20-6.68, spreadability between 5.4 and 5.9 cm, and viscosity ranged from 216 to 1200 cP at 50 rpm and 210–858 cP at 100 rpm. The in vitro drug release studies demonstrated that Ag nanoparticles were released from the topical gels in a sustained manner. Most formulated topical gels demonstrated superior antimicrobial efficacy against Gram-positive and Gram-negative bacteria strains than the blank gel and controls. The cytotoxicity analysis displayed more than 90.83 percent cell viability for the topical gels, revealing excellent biocompatibility. The outcomes revealed that the topical gels enriched with essential oils lavender and tea tree and Ag nanoparticles and sponges incorporated with metronidazole and Ag nanoparticles are potential wound dressing scaffolds that can be employed for the treatment of chronic infected injuries. The in vitro wound healing experiments showed that the HaCaT cells cultured with gels co-enriched with lavender oil and Ag nanoparticles possessed a higher rate of closure in comparison to the untreated cells for 96 hours. , Thesis (PhD) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022
- Authors: Alven, Sibusiso
- Date: 2022
- Subjects: Toxicity testing -- In vitro , Wound healing , Chronic diseases
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27992 , vital:71414
- Description: Microbial infections are responsible for the retarded recovery process of chronic wounds. Polymer-based scaffolds possess features suitable for the treatment of chronic injuries. However, these scaffolds are commonly encapsulated with therapeutic agents to enhance their biological activities, including antibacterial efficacy. In this research, two types of polymer-based scaffolds were formulated and evaluated as effective formulations for the treatment of chronic wounds: sponges and topical gels. Sponges were formulated from cross-linking of gelatin and PEG. Ag nanoparticles and metronidazole were incorporated into the sponges to improve their antibacterial activity. Topical gels were loaded with essential oils and Ag nanoparticles and prepared from CMC and poloxamer. The prepared sponges and topical gels were evaluated using various analysis and characterization techniques. SEM/EDX, FTIR, and TGA were employed to characterize gelatin/PEG hybrid sponges followed by porosity, in vitro biodegradability, cytotoxicity, and antibacterial studies. FTIR, SEM/EDX, and TGA confirmed their physicochemical properties and successful fabrication of sponges loaded with metronidazole and Ag nanoparticles. The sponges were biodegradable, indicating their capability to induce skin regeneration. The drug release studies showed a rapid release of metronidazole 28.32-71.97 percent from the sponges over the first hour, followed by a sustained drug release. The Ag nanoparticles were released in a sustained manner, suggesting that these sponges can rapidly destroy bacteria and inhibit persisting bacterial infections as well as protect the lesion bed from further bacteria infections. The in vitro antibacterial studies of sponges displayed superior antibacterial activity against most of the Gram-negative and Gram-positive bacteria strains commonly found in chronic wound infections with a MIC value of 15.625 μg/mL. In vitro cytotoxicity experiments revealed excellent biocompatibility with a percent cell viability of more than 70 percent. The in vitro wound scratch healing assay exhibited that the sponges encapsulated with only metronidazole promoted high cell migration than the dual drug-loaded sponges and untreated cells, suggesting its potential to quicken the wound healing process. CMC/Poloxamer topical gels were also characterized by FTIR, followed by pH, viscosity, spreadability, cytotoxicity, and antibacterial studies. FTIR showed successful preparation of CMC/Poloxamer topical gels loaded with essential oils and Ag nanoparticles. The topical gels exhibited pH in the range of 5.20-6.68, spreadability between 5.4 and 5.9 cm, and viscosity ranged from 216 to 1200 cP at 50 rpm and 210–858 cP at 100 rpm. The in vitro drug release studies demonstrated that Ag nanoparticles were released from the topical gels in a sustained manner. Most formulated topical gels demonstrated superior antimicrobial efficacy against Gram-positive and Gram-negative bacteria strains than the blank gel and controls. The cytotoxicity analysis displayed more than 90.83 percent cell viability for the topical gels, revealing excellent biocompatibility. The outcomes revealed that the topical gels enriched with essential oils lavender and tea tree and Ag nanoparticles and sponges incorporated with metronidazole and Ag nanoparticles are potential wound dressing scaffolds that can be employed for the treatment of chronic infected injuries. The in vitro wound healing experiments showed that the HaCaT cells cultured with gels co-enriched with lavender oil and Ag nanoparticles possessed a higher rate of closure in comparison to the untreated cells for 96 hours. , Thesis (PhD) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022
Synthesis and in vitro biological studies of ursolic acid-based hybrid compounds
- Authors: Khwaza, Vuyolwethu
- Date: 2022
- Subjects: Herbal medicine , Herbs -- Therapeutic use , Antineoplastic antibiotics
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27797 , vital:69689
- Description: Ursolic acid UA, a pentacyclic triterpenoid that is commonly found in many medicinal herbs and fruits, has been identified as a potential source of therapeutic agents because of its potent biological effects, which include its potential anticancer and antimicrobial activities. However, its limited solubility, rapid metabolism and poor bioavailability inhibit its clinical applications. Numerous UA derivatives have been prepared over the past years in an effort to mitigate the drawbacks associated with UA, as new chemical entities for the treatment of various infections. There is very little progress in the discovery of efficient UA derivatives. In this study, a class of ester and amide-linked ursolic acid-based hybrid compounds fused with selected pharmaceutical scaffolds were successfully synthesized using amidation and esterification reactions and tested for antibacterial and cytotoxicity activities. Hybridizing UA with other known pharmaceutical scaffolds has the potential of overcoming its drawbacks. FT-IR, Mass Spectroscopy, and 1H13C-NMR spectroscopy were used to confirm the structures of the synthesized hybrid compounds. Among the tested ester-linked hybrid compounds in Chapter three, compounds 3.14-3.19,3.21, 3.34, 3.31, and 3.30 demonstrated significant antibacterial activities against some tested bacteria, with MIC values of 15.625 μgml. Furthermore, the in vitro cytotoxicity of these hybrids was determined using the MTT assay against three human tumor cell lines MCF7, MDA-MB-231, and HeLa cells. Compounds 3.19 and 3.34 were found to have better cytotoxic activity when compared to ursolic acid, with IC50 values of 46.99 and 48.18 μg ml respectively. Both compounds revealed more promising docking results, presenting favourable binding interactions as well as better docking energy against the MCF 7 protein target compared to the parent compound ursolic acid. In Chapter Four, among the tested amide-linked hybrid compounds, Compounds 4.17 and 4.24 demonstrated significant antibacterial activity against the majority of bacterial strains with MIC values of 15.625 gml. Compound 4.24 exhibited a MIC value of 15.625gmL against BS, SA, PV, KO, PM, and EC. Compound 4.23 was more cytotoxic to HeLa cells than ursolic acid. Furthermore, molecular docking calculations revealed that compound 4.16 strongly binds to the protein epidermal growth factor receptor while e compounds 4.17 and 4.24 showed a strong binding affinity for the methionyl-tRNA synthetase. In both cases, the hybrid compounds showed better conformational fittings in the active site of the targeted proteins as compared to the parent ursolic acid. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022
- Authors: Khwaza, Vuyolwethu
- Date: 2022
- Subjects: Herbal medicine , Herbs -- Therapeutic use , Antineoplastic antibiotics
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27797 , vital:69689
- Description: Ursolic acid UA, a pentacyclic triterpenoid that is commonly found in many medicinal herbs and fruits, has been identified as a potential source of therapeutic agents because of its potent biological effects, which include its potential anticancer and antimicrobial activities. However, its limited solubility, rapid metabolism and poor bioavailability inhibit its clinical applications. Numerous UA derivatives have been prepared over the past years in an effort to mitigate the drawbacks associated with UA, as new chemical entities for the treatment of various infections. There is very little progress in the discovery of efficient UA derivatives. In this study, a class of ester and amide-linked ursolic acid-based hybrid compounds fused with selected pharmaceutical scaffolds were successfully synthesized using amidation and esterification reactions and tested for antibacterial and cytotoxicity activities. Hybridizing UA with other known pharmaceutical scaffolds has the potential of overcoming its drawbacks. FT-IR, Mass Spectroscopy, and 1H13C-NMR spectroscopy were used to confirm the structures of the synthesized hybrid compounds. Among the tested ester-linked hybrid compounds in Chapter three, compounds 3.14-3.19,3.21, 3.34, 3.31, and 3.30 demonstrated significant antibacterial activities against some tested bacteria, with MIC values of 15.625 μgml. Furthermore, the in vitro cytotoxicity of these hybrids was determined using the MTT assay against three human tumor cell lines MCF7, MDA-MB-231, and HeLa cells. Compounds 3.19 and 3.34 were found to have better cytotoxic activity when compared to ursolic acid, with IC50 values of 46.99 and 48.18 μg ml respectively. Both compounds revealed more promising docking results, presenting favourable binding interactions as well as better docking energy against the MCF 7 protein target compared to the parent compound ursolic acid. In Chapter Four, among the tested amide-linked hybrid compounds, Compounds 4.17 and 4.24 demonstrated significant antibacterial activity against the majority of bacterial strains with MIC values of 15.625 gml. Compound 4.24 exhibited a MIC value of 15.625gmL against BS, SA, PV, KO, PM, and EC. Compound 4.23 was more cytotoxic to HeLa cells than ursolic acid. Furthermore, molecular docking calculations revealed that compound 4.16 strongly binds to the protein epidermal growth factor receptor while e compounds 4.17 and 4.24 showed a strong binding affinity for the methionyl-tRNA synthetase. In both cases, the hybrid compounds showed better conformational fittings in the active site of the targeted proteins as compared to the parent ursolic acid. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022
Soil erodibility indices affecting the development of gully erosion in highly erodible soils of the Tsitsa Catchment in T35D and T35E, Eastern Cape, South Africa
- Kanuka, Gcobisa https://orcid.org/0000-0003-4736-7136
- Authors: Kanuka, Gcobisa https://orcid.org/0000-0003-4736-7136
- Date: 2022-01
- Subjects: Soil erosion , River sediments
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22677 , vital:52642
- Description: This study evaluated soil inherent properties for the development of gullies and their erodibility potential using the holistic field and laboratory sample investigation approach. The potential of negative impact of sedimentation on dam and water infrastructure performance has raised the need to evaluate the factors promoting soil erosion leading to land degradation. The study aimed to assess the relationship among the selected properties of soil and variability among various soil groups. A case study design approach was adopted at the T35D and T35E areas of Tsitsa hydrologic Basin, Eastern Cape, South Africa. The task was accomplished through detailed random soil sampling in the field, soil chemical analysis and comparative analysis of soil variables. Based on the scope of the study soil laboratory analysis included the following: particle size distribution, soil textural analysis, physicochemical parameters analysis, macro-and-micronutrient analysis, and micro-porosity analysis. Further spatial and scenario analysis of soil erodibility was done using selected erodibility indices such as Sodium Adsorption Ratio (SAR), Exchangeable Sodium Percentage (ESP), Dispersivity Ratio (DR), Clay Dispersion Ratio (CDR), Clay Flocculation Index (CFI), Water-Stable Aggregate analysis (WSA), and Soil Erodibility factor analysis (KEF). The findings of the study showed that the catchment hosts sixteen distinct soil forms categorized into seven unique soil groups. The results further indicated that the Katspruit soil form of the gleyic soil group has the highest clay-size particles and a considerably high clay dispersion attribute among others soil forms. It was further deduced that gleyic soil type exhibited the highest soil pH (6.36), a considerably low Ca:Mg ratio (1.43), a substantially high sodium ion (0.50 mg/kg), the highest SAR (0.5), lowest WSA (0.018percent) and a substantially high KEF (0.018ab). Similarly, saprolite soils exhibited the nature of the lixisol with a virtually equal amount of clay (43.63percent) and fine sands (41.68percent), the lowest amount of Ca:Mg ratio (1.35), the highest acid saturation (50.59), the highest ESP (8.39), and a considerably high WSA (38.75). Other remarkable problematic soils identified in the study include the lithic soil and the duplex soil. For instance, the Lithic soil is characterized by the highest fine sand-size texture (61.38percent), considerably low organic carbon (2.63percent), low cation exchange capacity (3.55 cmol(+)/kg), much high DR (0.75), very low WSA (0.027percent), and the highest KEF (0.027a). Whereas, the duplex soil is characterized by the highest DR (0.81), critically high CDR (38.19percent), very low WSA (0.019percent), and a considerably high KEF (0.019a). The relatively stable soils within the catchment are the oxidic, and melanic, where the WSA is highest in oxidic (38.19percent) and relatively high for melanic (36.6percent), CFI is highest in melanic (85.02percent), and oxidic (74.32percent), and KEF is relatively low (0.016b) for both. Correlation of the selected soil erodibility indices shows that CFI shares a perfect inverse relationship with CDR while maintaining a strong significant relationship with DR (R = -0.504). Findings also show that the SAR expectedly produced a robust significant relationship with ESP (R = 0.644), while KEF exhibited a solid inverse relationship with WSA (R = 0.913). The correlation across the physical and chemical properties suggests that DR and CDR can be firmly and positively influenced by dispersive clay. At the same time, the two factors maintain a significantly negative relationship with dispersive sand. Also, clay-sized particles depicted a significant relationship with WSA. Physicochemical and chemical parameters influence only the ESP and SAR. A remarkable finding is the influence of iron and its presence on SAR. On the other hand, ESP was distinguished from SAR due to the inverse influence of potassium. The lithic soils identify as members of the collapsible soil of South Africa, while the gleyic soils identify with duplex and saprolite soils in the class of dispersive soils. The vertic soils characterize as expansive soil, while the Duplex soil also exhibits a soft soil attribute. In general, the study suggests that T35D and T35E areas of Tsitsa catchment vary spatially in soil erodibility potential. T35D area is characterized by dominant oxidic soil cover of relatively stable aggregate whose iron oxide enrichment could be attributed to inculcation of dolerite debris. Overall, the soil erodibility indices showed that the development of gully erosion in Tsitsa catchment is driven by high clay dispersivity ratio of the soil (mean = 0.70; 24percent CV), and poor soil structure relative to the low WSA range (18.1 – 34.0). Erodibility due to high sodicity are associated with saprolite (ESP = 8.02) and gleyic soils (ESP = 7.43) while the high soil dispersion was due to the vertic (46percent), duplex (38percent), cumulic (30percent), and lithic (27percent) soil components. The poor soil aggregates (WSA) were mainly controlled by the lithic (10percent), vertic (27percent), duplex (28percent), cumulic (31percent), and gleyic (34percent) soil components. Meanwhile, the T35E area is dominated by the dispersive and collapsible soils dominated by saprolites and lithic soils. Therefore, the environmental stakeholders are advised to adopt the best management practices within the dam area considering the vulnerability of the catchment to the development of gullies and the potential impact of sedimentation on the adequate performance of Tsitsa dam and its water infrastructures. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-01
- Authors: Kanuka, Gcobisa https://orcid.org/0000-0003-4736-7136
- Date: 2022-01
- Subjects: Soil erosion , River sediments
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22677 , vital:52642
- Description: This study evaluated soil inherent properties for the development of gullies and their erodibility potential using the holistic field and laboratory sample investigation approach. The potential of negative impact of sedimentation on dam and water infrastructure performance has raised the need to evaluate the factors promoting soil erosion leading to land degradation. The study aimed to assess the relationship among the selected properties of soil and variability among various soil groups. A case study design approach was adopted at the T35D and T35E areas of Tsitsa hydrologic Basin, Eastern Cape, South Africa. The task was accomplished through detailed random soil sampling in the field, soil chemical analysis and comparative analysis of soil variables. Based on the scope of the study soil laboratory analysis included the following: particle size distribution, soil textural analysis, physicochemical parameters analysis, macro-and-micronutrient analysis, and micro-porosity analysis. Further spatial and scenario analysis of soil erodibility was done using selected erodibility indices such as Sodium Adsorption Ratio (SAR), Exchangeable Sodium Percentage (ESP), Dispersivity Ratio (DR), Clay Dispersion Ratio (CDR), Clay Flocculation Index (CFI), Water-Stable Aggregate analysis (WSA), and Soil Erodibility factor analysis (KEF). The findings of the study showed that the catchment hosts sixteen distinct soil forms categorized into seven unique soil groups. The results further indicated that the Katspruit soil form of the gleyic soil group has the highest clay-size particles and a considerably high clay dispersion attribute among others soil forms. It was further deduced that gleyic soil type exhibited the highest soil pH (6.36), a considerably low Ca:Mg ratio (1.43), a substantially high sodium ion (0.50 mg/kg), the highest SAR (0.5), lowest WSA (0.018percent) and a substantially high KEF (0.018ab). Similarly, saprolite soils exhibited the nature of the lixisol with a virtually equal amount of clay (43.63percent) and fine sands (41.68percent), the lowest amount of Ca:Mg ratio (1.35), the highest acid saturation (50.59), the highest ESP (8.39), and a considerably high WSA (38.75). Other remarkable problematic soils identified in the study include the lithic soil and the duplex soil. For instance, the Lithic soil is characterized by the highest fine sand-size texture (61.38percent), considerably low organic carbon (2.63percent), low cation exchange capacity (3.55 cmol(+)/kg), much high DR (0.75), very low WSA (0.027percent), and the highest KEF (0.027a). Whereas, the duplex soil is characterized by the highest DR (0.81), critically high CDR (38.19percent), very low WSA (0.019percent), and a considerably high KEF (0.019a). The relatively stable soils within the catchment are the oxidic, and melanic, where the WSA is highest in oxidic (38.19percent) and relatively high for melanic (36.6percent), CFI is highest in melanic (85.02percent), and oxidic (74.32percent), and KEF is relatively low (0.016b) for both. Correlation of the selected soil erodibility indices shows that CFI shares a perfect inverse relationship with CDR while maintaining a strong significant relationship with DR (R = -0.504). Findings also show that the SAR expectedly produced a robust significant relationship with ESP (R = 0.644), while KEF exhibited a solid inverse relationship with WSA (R = 0.913). The correlation across the physical and chemical properties suggests that DR and CDR can be firmly and positively influenced by dispersive clay. At the same time, the two factors maintain a significantly negative relationship with dispersive sand. Also, clay-sized particles depicted a significant relationship with WSA. Physicochemical and chemical parameters influence only the ESP and SAR. A remarkable finding is the influence of iron and its presence on SAR. On the other hand, ESP was distinguished from SAR due to the inverse influence of potassium. The lithic soils identify as members of the collapsible soil of South Africa, while the gleyic soils identify with duplex and saprolite soils in the class of dispersive soils. The vertic soils characterize as expansive soil, while the Duplex soil also exhibits a soft soil attribute. In general, the study suggests that T35D and T35E areas of Tsitsa catchment vary spatially in soil erodibility potential. T35D area is characterized by dominant oxidic soil cover of relatively stable aggregate whose iron oxide enrichment could be attributed to inculcation of dolerite debris. Overall, the soil erodibility indices showed that the development of gully erosion in Tsitsa catchment is driven by high clay dispersivity ratio of the soil (mean = 0.70; 24percent CV), and poor soil structure relative to the low WSA range (18.1 – 34.0). Erodibility due to high sodicity are associated with saprolite (ESP = 8.02) and gleyic soils (ESP = 7.43) while the high soil dispersion was due to the vertic (46percent), duplex (38percent), cumulic (30percent), and lithic (27percent) soil components. The poor soil aggregates (WSA) were mainly controlled by the lithic (10percent), vertic (27percent), duplex (28percent), cumulic (31percent), and gleyic (34percent) soil components. Meanwhile, the T35E area is dominated by the dispersive and collapsible soils dominated by saprolites and lithic soils. Therefore, the environmental stakeholders are advised to adopt the best management practices within the dam area considering the vulnerability of the catchment to the development of gullies and the potential impact of sedimentation on the adequate performance of Tsitsa dam and its water infrastructures. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-01
The use of earth observation multi-sensor systems to monitor and model Pastures: a case of Savannah Grasslands in Hluvukani Village, Bushbuckridge Local Municipality, Mpumalanga Province, South Africa
- Nduku, Lwandile https://orcid.org/0000-0001-9168-4548
- Authors: Nduku, Lwandile https://orcid.org/0000-0001-9168-4548
- Date: 2022-01
- Subjects: Climatic changes , Grassland conservation
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22578 , vital:52470
- Description: Grassland degradation associated with climate change and inappropriate grassland management has been characterized as a global environmental concern driving decreased grassland ecosystem's ecological functioning. More than 60% of South African grassland is degraded or permanently transformed to other land uses and nearly 2% properly conserved. Yet, grasslands are a major source of food for livestock grazing and provide material and non-material benefits to many livelihoods. Therefore, grassland above-ground biomass (AGB) estimation is crucial in planning and managing pastoral agriculture and the benefits derived from it. However, current grassland monitoring techniques used in rural smallholder livestock farms rely on conventional methods, which are destructive, labour-intensive, costly, and restricted to small areas. This study investigated the monitoring and modelling of protected grasslands biomass using current Earth observation systems (EOS), an approach, which is non-destructive, cost-effective, cover larger areas and is a time-saving alternative to conventional methods. Hence, the research objectives were: (i) to map the trends and advances in data and models used in the monitoring of grassland (pastures) with Earth observation systems, and (ii) to assess above-ground biomass estimation in semi-arid savannah grassland integrating Sentinel-1 and Sentinel-2 data with Machine-Learning. This goal was to assess if this approach could provide the requisite information, which could contribute to the long-term goal of developing a semi-automated system for data processing, and mapping grassland biomass to benefit local communities. For this investigation, it was crucial to understanding what research had achieved so far in this area of pasture management. An assessment of the Scopus database showed the recent developments in European Union (EU) programs and Sentinel missions, including statistical models and machine learning for monitoring grassland changes at multiple scales. However, Sentinel-1 and Sentinel-2 data, machine learning models, and variable importance techniques were applied for grassland AGB estimation. These techniques have been used in similar studies to determine optimum machine learning models, influential variables, and the capability of integrated Sentinel datasets for mapping grassland AGB, spatial distribution, and abundance. Results showed improved performance with the Random forest regression (RFR) model (R² of 34.7%, RMSE of 9.47 Mg and MAE of 7.68 Mg ). The study also observed optimum sensitivity of Difference Vegetation Index (DVI) and Enhanced Vegetation Index (EVI) in all three machine learning models for modelling grassland AGB estimation in the study area. A further, statistical comparison of all three machine learning models showed an insignificant difference in the predictive capacity for AGB in the study area with Gradient Boosting regression (GBR) model (R² of 27.7, RMSE of 9.97 Mg and MAE of 8.03 Mg ) and Extreme Gradient Boost Regression (XGBR) model (R² of 17.3%, RMSE of 10.66 Mg and MAE of 8.83 Mg ). The study revealed that an integration of Sentinel-1 and Sentinel-2 has improved capabilities for monitoring grassland AGB estimation. This research sheds light on the timely and cost-effective techniques for grassland management strategies to enhance or restore the ecological functioning of grassland ecosystems and promote community sustainability. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-01
- Authors: Nduku, Lwandile https://orcid.org/0000-0001-9168-4548
- Date: 2022-01
- Subjects: Climatic changes , Grassland conservation
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22578 , vital:52470
- Description: Grassland degradation associated with climate change and inappropriate grassland management has been characterized as a global environmental concern driving decreased grassland ecosystem's ecological functioning. More than 60% of South African grassland is degraded or permanently transformed to other land uses and nearly 2% properly conserved. Yet, grasslands are a major source of food for livestock grazing and provide material and non-material benefits to many livelihoods. Therefore, grassland above-ground biomass (AGB) estimation is crucial in planning and managing pastoral agriculture and the benefits derived from it. However, current grassland monitoring techniques used in rural smallholder livestock farms rely on conventional methods, which are destructive, labour-intensive, costly, and restricted to small areas. This study investigated the monitoring and modelling of protected grasslands biomass using current Earth observation systems (EOS), an approach, which is non-destructive, cost-effective, cover larger areas and is a time-saving alternative to conventional methods. Hence, the research objectives were: (i) to map the trends and advances in data and models used in the monitoring of grassland (pastures) with Earth observation systems, and (ii) to assess above-ground biomass estimation in semi-arid savannah grassland integrating Sentinel-1 and Sentinel-2 data with Machine-Learning. This goal was to assess if this approach could provide the requisite information, which could contribute to the long-term goal of developing a semi-automated system for data processing, and mapping grassland biomass to benefit local communities. For this investigation, it was crucial to understanding what research had achieved so far in this area of pasture management. An assessment of the Scopus database showed the recent developments in European Union (EU) programs and Sentinel missions, including statistical models and machine learning for monitoring grassland changes at multiple scales. However, Sentinel-1 and Sentinel-2 data, machine learning models, and variable importance techniques were applied for grassland AGB estimation. These techniques have been used in similar studies to determine optimum machine learning models, influential variables, and the capability of integrated Sentinel datasets for mapping grassland AGB, spatial distribution, and abundance. Results showed improved performance with the Random forest regression (RFR) model (R² of 34.7%, RMSE of 9.47 Mg and MAE of 7.68 Mg ). The study also observed optimum sensitivity of Difference Vegetation Index (DVI) and Enhanced Vegetation Index (EVI) in all three machine learning models for modelling grassland AGB estimation in the study area. A further, statistical comparison of all three machine learning models showed an insignificant difference in the predictive capacity for AGB in the study area with Gradient Boosting regression (GBR) model (R² of 27.7, RMSE of 9.97 Mg and MAE of 8.03 Mg ) and Extreme Gradient Boost Regression (XGBR) model (R² of 17.3%, RMSE of 10.66 Mg and MAE of 8.83 Mg ). The study revealed that an integration of Sentinel-1 and Sentinel-2 has improved capabilities for monitoring grassland AGB estimation. This research sheds light on the timely and cost-effective techniques for grassland management strategies to enhance or restore the ecological functioning of grassland ecosystems and promote community sustainability. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-01
Bayesian spatio-temporal zero-inflated mixed models for overdispersion on chronic disease mapping
- Osuji, Georgeleen O https://orcid.org/0000-0002-8408-3928
- Authors: Osuji, Georgeleen O https://orcid.org/0000-0002-8408-3928
- Date: 2021-12
- Subjects: Medical mapping , Bayesian statistical decision theory
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/23644 , vital:58230
- Description: Background: Life expectancy in most developing countries has remarkably increased and decreased in mortality, but under 5 years old mortality has increased due to HIV and Tuberculosis incidence. Many factors have been established to influence the mortality rate among HIV patients and understanding the factors contribution to the risk of under 5-year-old mortality is important for designing appropriate health interventions. Excess zeros usually occur in such HIV mortality count data. Mixed models consisting of count part and zero part are often used to describe the observed excess zero in the data. Poisson models are popular modeling inference, but Negative-Binomial models are more flexible in analyzing count data and dealing with overdispersion. Method: This research proposed to develop two-part hurdle models in analyzing areal zero count data. A spatial Bayesian lognormal-logit hurdle model (BLLHM) with random effects characterizes and cross-spatial dependencies were introduced. The parameter inferences and predictions were evaluated using the Markov Chain Monte Carlo algorithm. The model proposed was applied to HIV-positive under 5-year-old mortality collected from the Eastern Cape Department of Health. Results: Bayesian lognormal-logit hurdle model is selected as the best model fit. It is observed that the total number of HIV patients not on ART-HIVnotTB (0.000612, p <0.000) was positively and statistically significantly associated with the HIV-positive mortality of under 5 years patients. Both CD4 counts were done on newly diagnosed HIV rate (CD4count) and HIV-positive new patients screened for TB rate (HIVTBrate) were negatively and statistically significantly associated with the HIV-positive mortality of under 5 years patients (-0.6294, p = 0.000 and -0.00056, p = 0.0052). However, the covariate HIV positive Tuberculosis Preventive therapy (TPT) uptake rate (HIVandTB) was not statistically significantly associated with the HIV-positive mortality of under 5 years patients (-0.00155, p = 0.5392). Conclusion: The model is flexible to deal with zero-inflated and over-dispersed count data. There is a need to consider the risk of cause-specific under-5-year-old mortality in terms of spatial effects. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Osuji, Georgeleen O https://orcid.org/0000-0002-8408-3928
- Date: 2021-12
- Subjects: Medical mapping , Bayesian statistical decision theory
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/23644 , vital:58230
- Description: Background: Life expectancy in most developing countries has remarkably increased and decreased in mortality, but under 5 years old mortality has increased due to HIV and Tuberculosis incidence. Many factors have been established to influence the mortality rate among HIV patients and understanding the factors contribution to the risk of under 5-year-old mortality is important for designing appropriate health interventions. Excess zeros usually occur in such HIV mortality count data. Mixed models consisting of count part and zero part are often used to describe the observed excess zero in the data. Poisson models are popular modeling inference, but Negative-Binomial models are more flexible in analyzing count data and dealing with overdispersion. Method: This research proposed to develop two-part hurdle models in analyzing areal zero count data. A spatial Bayesian lognormal-logit hurdle model (BLLHM) with random effects characterizes and cross-spatial dependencies were introduced. The parameter inferences and predictions were evaluated using the Markov Chain Monte Carlo algorithm. The model proposed was applied to HIV-positive under 5-year-old mortality collected from the Eastern Cape Department of Health. Results: Bayesian lognormal-logit hurdle model is selected as the best model fit. It is observed that the total number of HIV patients not on ART-HIVnotTB (0.000612, p <0.000) was positively and statistically significantly associated with the HIV-positive mortality of under 5 years patients. Both CD4 counts were done on newly diagnosed HIV rate (CD4count) and HIV-positive new patients screened for TB rate (HIVTBrate) were negatively and statistically significantly associated with the HIV-positive mortality of under 5 years patients (-0.6294, p = 0.000 and -0.00056, p = 0.0052). However, the covariate HIV positive Tuberculosis Preventive therapy (TPT) uptake rate (HIVandTB) was not statistically significantly associated with the HIV-positive mortality of under 5 years patients (-0.00155, p = 0.5392). Conclusion: The model is flexible to deal with zero-inflated and over-dispersed count data. There is a need to consider the risk of cause-specific under-5-year-old mortality in terms of spatial effects. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-12
Sediment characteristics and hydrodynamic conditions of the Swartkops estuary, Eastern Cape Province of South Africa
- Best, Lutho https://orcid.org/0000-0001-6400-9061
- Authors: Best, Lutho https://orcid.org/0000-0001-6400-9061
- Date: 2021-11
- Subjects: Geology, Stratigraphic , Estuarine oceanography , Swartkops River Estuary (South Africa)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22611 , vital:52596
- Description: This study is a part of an environmental research project aimed at providing assessment information to the grain-size distribution, mineral compositions, sedimentary structures and coastal erosion and rehabilitation methods along the Swartkops estuary, a recent developing industry area of South Africa. The methodologies used in this study comprise desk study of literature, field geological investigation and sampling, and laboratory analyses including grainsize analysis, thin section microscope study, XRD mineral composition study and SEM-EDX grain surface texture and composition analyses.The basement and surrounding areas of the Swartkops estuary consist of three formations: the Enon Formation of mainly conglomerate, the Kirkwood Formation of sandstone and mudstone, and the Sundays River Formation of dominantly mudstone with sandstone, which integrated as Uitenhage Group of Cretaceous sequence with modern estuarine sand and alluvial sediments filled in the entire basin. Grain size analysis is a useful tool to assess hydrodynamic environments. The grain size parameters showed that most of the Swartkops estuary sediments are moderately sorted with very few well and poorly sorted, coarse to fine skewed in grain size distribution.Whereas the Bluewater Bay beach sediments are mostly fine grained, well sorted, fine to coarse skewed in grain size distribution. The bivariate scatter plots are an indication of shallow marine environment by beach and coastal processes with the influence of water flow and wind influence during transportation and deposition processes. Mineralogy studies revealed that the Swartkops estuary sediments are dominantly composed of minerals such as: quartz, calcite, feldspar (orthoclase and plagioclase), aragonite, clay minerals (smectite and illite), and salts such as NaCl and MgCl2. Skeletal carbonate minerals (shell fragments) are more than chemical precipitated carbonate minerals. Quartz is the most abundant detrital mineral observed in all the sediments and it comes from inland and transported into the estuary and the beach by fluvial streams, whereas skeletal calcite/aragonite is the most abundant biogenic carbonate derived from sea side and transported by marine currents. The study shows that grain surface textures reveal the existence of several features that reflect the depositional environments. Observed grain surface textures by microscope and SEM include V-shape pits, upturned pits caused by mechanical crashing and corrosion during transportation; crystalline precipitation of calcite, quartz, salt and clay by chemical precipitation and crystallization; dissolution pits and pores formed by dissolution, and burrow and boring by biogenetic activities. The grain surface morphologies are closely linked to different formation mechanisms and depositional environments. Well-developed sedimentary structures have been found in the beach and estuary, including sand dune, sand ridge, straight and sinuous ripple, ripple marks, aeolian nail marks, high angle tabular cross bedding, antidune, rill mark, rhomboid mark, swash line, mud crack, gravel pavement, interfering ripples, flat topped ripple mark, linguiod mark, asymmetric sinuous ripples, dendritic pattern on sandy beach, boring and bioturbation, burrows desiccation cracks and water escape hole. Different sedimentary structures are reflective of different hydrodynamic conditions and depositional environments. Coastal erosion is a major problem for damage of road, bridge and properties in the industrial areas in Swartkops, which is also a task for this study. The author had suggested some practical mitigation-methods to local government, such as groins, revetments, shoreline hardening, planting of vegetation, and vertical walls, bulkheads, sills, which could be useful for the protection of coastal erosion. , Thesis (MSc) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-11
- Authors: Best, Lutho https://orcid.org/0000-0001-6400-9061
- Date: 2021-11
- Subjects: Geology, Stratigraphic , Estuarine oceanography , Swartkops River Estuary (South Africa)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22611 , vital:52596
- Description: This study is a part of an environmental research project aimed at providing assessment information to the grain-size distribution, mineral compositions, sedimentary structures and coastal erosion and rehabilitation methods along the Swartkops estuary, a recent developing industry area of South Africa. The methodologies used in this study comprise desk study of literature, field geological investigation and sampling, and laboratory analyses including grainsize analysis, thin section microscope study, XRD mineral composition study and SEM-EDX grain surface texture and composition analyses.The basement and surrounding areas of the Swartkops estuary consist of three formations: the Enon Formation of mainly conglomerate, the Kirkwood Formation of sandstone and mudstone, and the Sundays River Formation of dominantly mudstone with sandstone, which integrated as Uitenhage Group of Cretaceous sequence with modern estuarine sand and alluvial sediments filled in the entire basin. Grain size analysis is a useful tool to assess hydrodynamic environments. The grain size parameters showed that most of the Swartkops estuary sediments are moderately sorted with very few well and poorly sorted, coarse to fine skewed in grain size distribution.Whereas the Bluewater Bay beach sediments are mostly fine grained, well sorted, fine to coarse skewed in grain size distribution. The bivariate scatter plots are an indication of shallow marine environment by beach and coastal processes with the influence of water flow and wind influence during transportation and deposition processes. Mineralogy studies revealed that the Swartkops estuary sediments are dominantly composed of minerals such as: quartz, calcite, feldspar (orthoclase and plagioclase), aragonite, clay minerals (smectite and illite), and salts such as NaCl and MgCl2. Skeletal carbonate minerals (shell fragments) are more than chemical precipitated carbonate minerals. Quartz is the most abundant detrital mineral observed in all the sediments and it comes from inland and transported into the estuary and the beach by fluvial streams, whereas skeletal calcite/aragonite is the most abundant biogenic carbonate derived from sea side and transported by marine currents. The study shows that grain surface textures reveal the existence of several features that reflect the depositional environments. Observed grain surface textures by microscope and SEM include V-shape pits, upturned pits caused by mechanical crashing and corrosion during transportation; crystalline precipitation of calcite, quartz, salt and clay by chemical precipitation and crystallization; dissolution pits and pores formed by dissolution, and burrow and boring by biogenetic activities. The grain surface morphologies are closely linked to different formation mechanisms and depositional environments. Well-developed sedimentary structures have been found in the beach and estuary, including sand dune, sand ridge, straight and sinuous ripple, ripple marks, aeolian nail marks, high angle tabular cross bedding, antidune, rill mark, rhomboid mark, swash line, mud crack, gravel pavement, interfering ripples, flat topped ripple mark, linguiod mark, asymmetric sinuous ripples, dendritic pattern on sandy beach, boring and bioturbation, burrows desiccation cracks and water escape hole. Different sedimentary structures are reflective of different hydrodynamic conditions and depositional environments. Coastal erosion is a major problem for damage of road, bridge and properties in the industrial areas in Swartkops, which is also a task for this study. The author had suggested some practical mitigation-methods to local government, such as groins, revetments, shoreline hardening, planting of vegetation, and vertical walls, bulkheads, sills, which could be useful for the protection of coastal erosion. , Thesis (MSc) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-11
Study on the effect of shade net on internal and external quality parameters and chilling injury of fruits of citrus species in the Eastern Cape Province of South Africa
- Moabelo, Phillipine https://orcid.org/0000-0001-9040-1390
- Authors: Moabelo, Phillipine https://orcid.org/0000-0001-9040-1390
- Date: 2021-11
- Subjects: Fruit-culture , Horticulture , Citrus fruits
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22622 , vital:52600
- Description: Pre-harvest technology of shade net is environmental friendly and was found previously to improve fruit growth and yield. In addition, it reduces wind blemishes and sunburn, and effectively act as a buffer against climate fluctuations, such as excessive light, wind and hail damages. However, commercial shade nets are capital intensive; therefore, it is important for farmers to understand its impact on fruit quality that is desired for export market and assess whether the investment is profitable to the industry or not. It was brought to attention that several citrus cultivars grown in Addo, Eastern Cape under 20percent commercial shade net shows sensitivity to chilling injury (CI); however. no information is yet documented about the impact of this technology on fruit quality. To determine the efficacy of 20percent-shade net technology in relation to the control (no shade net), the present study was designed with the objective to compare internal and external quality parameters of ‘Washington and Cambria’ navels, ‘Valley Gold’ mandarin, and ‘Eureka’ lemon fruit grown in shade netted orchards and stored at low temperatures (4 and -0.6°C) for 30 days in Addo area, Eastern Cape. Internal quality attributes assessed includes juice content, °Brixpercent, titratable acid (TA), °Brix:acid ratio and average number of seeds. External quality data assessed include rind colour, and fruit size, firmness/texture and fresh weight loss. For chilling injury, fruits were evaluated by examining the degree of rind pitting and assigning levels of severity namely 0, 1, 2 or 3 where 0 = no pitting detected, 1 = 1 pit, 2 = 2 or more pitting detected and 3 = severe pitting detected. The post-harvest experiments were done on fruits harvested from commercial citrus orchards in Sundays River Valley, between Kirkwood and Addo (33° 34' 0" South, 25° 41' 0" East), in the Eastern Cape Province of South Africa, over two harvesting seasons (2018 and 2019). The ‘Eureka’ lemon and ‘Washington navel’ fruit were collected from Allendale farm; the ‘Cambria’ navel fruits from the Nuwelande and Olifantsbos farms; and the ‘Valley Gold’ mandarin fruits from the Dunbrody/Unifruitti farm. The quality attributes were recorded in the Laboratory of the Citrus Research International (CRI), Port Elizabeth, Eastern Cape, South Africa during Season 1, and in the Horticulture lab of the University of Fort Hare (UFH), Alice, Eastern Cape, South, Africa during Season 2. The experimental layout was a typical pseudo randomised completely block design (RCBD) (not truly randomised) whereby treatments tested were subjected over time (pre-test, post-test). The two treatments i.e. shade vs. control (no shade net) could not be randomly allocated to orchards due to the practical issue of working on a commercial farm, . The sub-factor consisted of three postharvest treatments: Ambiemt temperature (at 0 days storage), 4°C and -0.6°C storages for 30 days. Secondly, an experiment to evaluate the impact of petroleum-based wax mixed with 2-(4-thiazolyl) benzimidazole [thiabendazole (TBZ)] (TBZ: 500 mg.L-1) on shade net vs control fruits was conducted. The fruits were stored at 4°C and - 0.6°C (coated) for 30 days and were evaluated after 7 days storage at room temperature. Shade net did not significantly affect the internal quality attributes of citrus fruits. The 20percent- shade net promoted size of ‘Washington’, ‘Cambria’ navels and ‘Valley Gold’ mandarin, whilst rind colour was not affect. Firmness loss was higher on ‘Eureka’ lemon and ‘Washington’ navel, regardless of the growing conditions and cold storage duration. Rind firmness of ‘Cambria’ navel and ‘Valley Gold’ mandarin were not significantly affected by shade net and storage duration. ‘Eureka’ lemon was found to be more sensitive to CI. However, the application of wax+ TBZ eliminated CI on all 4-cultivars. Therefore, it is recommended to apply wax+ TBZ in packline to eliminate CI and fungal development. , Thesis (MSc) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-11
- Authors: Moabelo, Phillipine https://orcid.org/0000-0001-9040-1390
- Date: 2021-11
- Subjects: Fruit-culture , Horticulture , Citrus fruits
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22622 , vital:52600
- Description: Pre-harvest technology of shade net is environmental friendly and was found previously to improve fruit growth and yield. In addition, it reduces wind blemishes and sunburn, and effectively act as a buffer against climate fluctuations, such as excessive light, wind and hail damages. However, commercial shade nets are capital intensive; therefore, it is important for farmers to understand its impact on fruit quality that is desired for export market and assess whether the investment is profitable to the industry or not. It was brought to attention that several citrus cultivars grown in Addo, Eastern Cape under 20percent commercial shade net shows sensitivity to chilling injury (CI); however. no information is yet documented about the impact of this technology on fruit quality. To determine the efficacy of 20percent-shade net technology in relation to the control (no shade net), the present study was designed with the objective to compare internal and external quality parameters of ‘Washington and Cambria’ navels, ‘Valley Gold’ mandarin, and ‘Eureka’ lemon fruit grown in shade netted orchards and stored at low temperatures (4 and -0.6°C) for 30 days in Addo area, Eastern Cape. Internal quality attributes assessed includes juice content, °Brixpercent, titratable acid (TA), °Brix:acid ratio and average number of seeds. External quality data assessed include rind colour, and fruit size, firmness/texture and fresh weight loss. For chilling injury, fruits were evaluated by examining the degree of rind pitting and assigning levels of severity namely 0, 1, 2 or 3 where 0 = no pitting detected, 1 = 1 pit, 2 = 2 or more pitting detected and 3 = severe pitting detected. The post-harvest experiments were done on fruits harvested from commercial citrus orchards in Sundays River Valley, between Kirkwood and Addo (33° 34' 0" South, 25° 41' 0" East), in the Eastern Cape Province of South Africa, over two harvesting seasons (2018 and 2019). The ‘Eureka’ lemon and ‘Washington navel’ fruit were collected from Allendale farm; the ‘Cambria’ navel fruits from the Nuwelande and Olifantsbos farms; and the ‘Valley Gold’ mandarin fruits from the Dunbrody/Unifruitti farm. The quality attributes were recorded in the Laboratory of the Citrus Research International (CRI), Port Elizabeth, Eastern Cape, South Africa during Season 1, and in the Horticulture lab of the University of Fort Hare (UFH), Alice, Eastern Cape, South, Africa during Season 2. The experimental layout was a typical pseudo randomised completely block design (RCBD) (not truly randomised) whereby treatments tested were subjected over time (pre-test, post-test). The two treatments i.e. shade vs. control (no shade net) could not be randomly allocated to orchards due to the practical issue of working on a commercial farm, . The sub-factor consisted of three postharvest treatments: Ambiemt temperature (at 0 days storage), 4°C and -0.6°C storages for 30 days. Secondly, an experiment to evaluate the impact of petroleum-based wax mixed with 2-(4-thiazolyl) benzimidazole [thiabendazole (TBZ)] (TBZ: 500 mg.L-1) on shade net vs control fruits was conducted. The fruits were stored at 4°C and - 0.6°C (coated) for 30 days and were evaluated after 7 days storage at room temperature. Shade net did not significantly affect the internal quality attributes of citrus fruits. The 20percent- shade net promoted size of ‘Washington’, ‘Cambria’ navels and ‘Valley Gold’ mandarin, whilst rind colour was not affect. Firmness loss was higher on ‘Eureka’ lemon and ‘Washington’ navel, regardless of the growing conditions and cold storage duration. Rind firmness of ‘Cambria’ navel and ‘Valley Gold’ mandarin were not significantly affected by shade net and storage duration. ‘Eureka’ lemon was found to be more sensitive to CI. However, the application of wax+ TBZ eliminated CI on all 4-cultivars. Therefore, it is recommended to apply wax+ TBZ in packline to eliminate CI and fungal development. , Thesis (MSc) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-11
Assessing the local awareness and perception of invasive alien plants: A case study of Port St Johns Local Municipality, Eastern Cape Province, South Africa
- Authors: Somkala, Avela Abongile
- Date: 2021-10
- Subjects: Alien plants , Invasive plants
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22600 , vital:52595
- Description: Invasive alien plants (IAPs) are introduced species that constitute a self-sustaining population, consistently producing offspring in large numbers and at considerable distances from the parent plants with the potential to spread over a large area. Species invasions are one of the main conservation threats today and have caused modification of ecosystems, particularly in coastal areas. Therefore, Port St Johns Local Municipality (PSJ LM) was an appropriate study site to evaluate the local awareness and perceptions of IAPs. The study investigated the local community’s perceptions of invasive alien plants' uses and ecological impacts. Information about the local awareness and perceptions of invasive alien plant species in PSJ LM was gathered through semi-structured interviews, observation and guided field walks with 120 participants between February and April 2021. The participants included 30 people working on the alien plant eradication project in PSJ LM (Wards 1, 2 and 3) and 90 randomly selected community members. The data collected were entered in Microsoft Excel 2016 programme and analyzed for descriptive statistical patterns using Statistical Package for Social Studies (SPSS) version 22.0. Biological invasion by IAPs was ubiquitously perceived, with participants working on invasive alien plant eradication project in the area exhibiting more scientifically based knowledge on IAPs than ordinary community members. Invasive alien plants in the area appear to have adverse environmental and socio-economic impacts, as the participants are not benefiting from these plant species. Similarly, costs of eradicating these species were also acknowledged. The ability of local community members to identify IAPs is vital in effective management of the spread of these species. A total of seven invasive IAPs were recorded. Evaluating the perceptions of local people towards IAPs provides valuable insights for development planning and future management programmes focusing on biological invasions. The study will provide a basis for an enabling policy and institutional environment that provides a coherent framework for the sustainable management of IAPs in the Eastern Cape Province. , Thesis (MPhil) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Somkala, Avela Abongile
- Date: 2021-10
- Subjects: Alien plants , Invasive plants
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22600 , vital:52595
- Description: Invasive alien plants (IAPs) are introduced species that constitute a self-sustaining population, consistently producing offspring in large numbers and at considerable distances from the parent plants with the potential to spread over a large area. Species invasions are one of the main conservation threats today and have caused modification of ecosystems, particularly in coastal areas. Therefore, Port St Johns Local Municipality (PSJ LM) was an appropriate study site to evaluate the local awareness and perceptions of IAPs. The study investigated the local community’s perceptions of invasive alien plants' uses and ecological impacts. Information about the local awareness and perceptions of invasive alien plant species in PSJ LM was gathered through semi-structured interviews, observation and guided field walks with 120 participants between February and April 2021. The participants included 30 people working on the alien plant eradication project in PSJ LM (Wards 1, 2 and 3) and 90 randomly selected community members. The data collected were entered in Microsoft Excel 2016 programme and analyzed for descriptive statistical patterns using Statistical Package for Social Studies (SPSS) version 22.0. Biological invasion by IAPs was ubiquitously perceived, with participants working on invasive alien plant eradication project in the area exhibiting more scientifically based knowledge on IAPs than ordinary community members. Invasive alien plants in the area appear to have adverse environmental and socio-economic impacts, as the participants are not benefiting from these plant species. Similarly, costs of eradicating these species were also acknowledged. The ability of local community members to identify IAPs is vital in effective management of the spread of these species. A total of seven invasive IAPs were recorded. Evaluating the perceptions of local people towards IAPs provides valuable insights for development planning and future management programmes focusing on biological invasions. The study will provide a basis for an enabling policy and institutional environment that provides a coherent framework for the sustainable management of IAPs in the Eastern Cape Province. , Thesis (MPhil) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-10
Investigating the feasibility of using remote sensing in index-based crop insurance for South Africa’s smallholder farming systems
- Masiza, Wonga https://orcid.org/0000-0002-6224-3812
- Authors: Masiza, Wonga https://orcid.org/0000-0002-6224-3812
- Date: 2021-10
- Subjects: Precision farming , Agricultural engineering , Climatic changes
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/23000 , vital:54890
- Description: Crop farming in Sub-Saharan Africa (SSA) is largely practiced by resource-poor farmers under rain-fed and unpredictable weather conditions. Since agriculture is the mainstay of SSA’s economy, the lack of improved and adapted agricultural technologies in this region sets back economic development and the fight against poverty. Overcoming this constraint and achieving the sustainable development goal to end poverty, requires innovative tools that can be used for weather risk management. One tool that has been gaining momentum recently is index-based crop insurance (IBCI). Since the launch of the first IBCI program in Africa around 2005, the number of IBCI programs has increased. Unfortunately, these programs are constrained by poor product design, basis risk, and low uptake of contracts. When these issues were first pointed-out in the earliest IBCI programs, many reports suggested satellite remote sensing (RS) as a viable solution. Hence, the first objective of this study was to assess how RS has been used in IBCI, the challenges RS faces, and potential contributions of RS that have not yet been meaningfully exploited. The literature shows that IBCI programs are increasingly adopting RS. RS has improved demarcation of unit areas of insurance and enabled IBCI to reach inaccessible areas that do not have sufficient meteorological infrastructure. However, the literature also shows that IBCI is still tainted by basis risk, which emanates from poor contract designs, the influence of non-weather factors on crop yields, imperfect correlations between satellite-based indices and crop yields, and the lack of historical data for calibration. Although IBCI reports cover vegetation and crop health monitoring, few to none cover crop type and crop area mapping. Furthermore, areas including high-resolution mapping, data fusion, microwave RS, machine learning, and computer vision have not been sufficiently tested in IBCI. The second objective of this study was to assess how RS and machine learning techniques can be used to enhance the mapping of smallholder crop farming landscapes. The findings show that machine learning ensembles and the combination of optical and microwave data can map a smallholder farming landscape with a maximum accuracy of 97.71 percent. The third objective was to identify factors that influence crop yields and crop losses in order to improve IBCI design. Results demonstrated that the pervasive notion that low yields in smallholder farms are related to rainfall is an oversimplification. Factors including fertilizer use, seed variety, soil properties, soil moisture, growing degree-days, management, and socioeconomic conditions are some of the most important factors influencing crop yields and crop losses in smallholder farming systems. This shows why IBCI needs to be part of a comprehensive risk management system that understands and approaches smallholder crop farming as complex by linking insurance with advisories and input supplies. Improved inputs and good farming practices could reduce the influence of non-weather factors on crop losses, and thereby reduce basis risk in weather-based index insurance (WII) contracts. The fourth objective of this study was to assess how well the combination of synthetic aperture radar (SAR) and optical indices estimate soil moisture. As stated earlier, soil moisture was found to be one of the most important factors affecting crop yields. Although this method better estimated soil moisture over the first half of the growing season, estimation accuracies were comparable to those found in studies that had used similar datasets (RMSE = 0.043 m3 m-3, MAE = 0.034 m3 m- 3). Further interrogation of interaction effects between the variables used in this study and consideration of other factors that affect SAR backscatter could improve the method. More importantly, incorporating high-resolution satellite-based monitoring of soil moisture into IBCI could potentially reduce basis risk. The fifth objective of this study was to develop an IBCI for smallholder crop farming systems. The proposed IBCI scheme covers maize and derives index thresholds from crop water requirements and satellite-based rainfall estimates. It covers rainfall deficits over the vegetative, mid-season, and late-season stages of maize growth. The key contribution of this system is the derivation of index thresholds from CWR and site-specific rainfall conditions. The widely used approach, which calibrates IBCI by correlating yields and rainfall, exposes contracts to basis risk because, by simply correlating yield and rainfall data, it overlooks the influence of non-weather factors on crop yields and losses. The proposed system must be linked or bundled with non-weather variables that affect crop yields. Effectively, this means that the insurance must be linked or bundled with advisories and input supplies to address the influence of non-weather factors on crop losses. This system also incorporates a crop area-mapping component, which was found to be lacking in many IBCI systems. In conclusion, an IBCI that is based on crop water requirements, which incorporates crop area mapping and links insurance with non-weather crop yield-determining factors, is potentially capable of improving crop insurance for smallholder farming systems. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Masiza, Wonga https://orcid.org/0000-0002-6224-3812
- Date: 2021-10
- Subjects: Precision farming , Agricultural engineering , Climatic changes
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/23000 , vital:54890
- Description: Crop farming in Sub-Saharan Africa (SSA) is largely practiced by resource-poor farmers under rain-fed and unpredictable weather conditions. Since agriculture is the mainstay of SSA’s economy, the lack of improved and adapted agricultural technologies in this region sets back economic development and the fight against poverty. Overcoming this constraint and achieving the sustainable development goal to end poverty, requires innovative tools that can be used for weather risk management. One tool that has been gaining momentum recently is index-based crop insurance (IBCI). Since the launch of the first IBCI program in Africa around 2005, the number of IBCI programs has increased. Unfortunately, these programs are constrained by poor product design, basis risk, and low uptake of contracts. When these issues were first pointed-out in the earliest IBCI programs, many reports suggested satellite remote sensing (RS) as a viable solution. Hence, the first objective of this study was to assess how RS has been used in IBCI, the challenges RS faces, and potential contributions of RS that have not yet been meaningfully exploited. The literature shows that IBCI programs are increasingly adopting RS. RS has improved demarcation of unit areas of insurance and enabled IBCI to reach inaccessible areas that do not have sufficient meteorological infrastructure. However, the literature also shows that IBCI is still tainted by basis risk, which emanates from poor contract designs, the influence of non-weather factors on crop yields, imperfect correlations between satellite-based indices and crop yields, and the lack of historical data for calibration. Although IBCI reports cover vegetation and crop health monitoring, few to none cover crop type and crop area mapping. Furthermore, areas including high-resolution mapping, data fusion, microwave RS, machine learning, and computer vision have not been sufficiently tested in IBCI. The second objective of this study was to assess how RS and machine learning techniques can be used to enhance the mapping of smallholder crop farming landscapes. The findings show that machine learning ensembles and the combination of optical and microwave data can map a smallholder farming landscape with a maximum accuracy of 97.71 percent. The third objective was to identify factors that influence crop yields and crop losses in order to improve IBCI design. Results demonstrated that the pervasive notion that low yields in smallholder farms are related to rainfall is an oversimplification. Factors including fertilizer use, seed variety, soil properties, soil moisture, growing degree-days, management, and socioeconomic conditions are some of the most important factors influencing crop yields and crop losses in smallholder farming systems. This shows why IBCI needs to be part of a comprehensive risk management system that understands and approaches smallholder crop farming as complex by linking insurance with advisories and input supplies. Improved inputs and good farming practices could reduce the influence of non-weather factors on crop losses, and thereby reduce basis risk in weather-based index insurance (WII) contracts. The fourth objective of this study was to assess how well the combination of synthetic aperture radar (SAR) and optical indices estimate soil moisture. As stated earlier, soil moisture was found to be one of the most important factors affecting crop yields. Although this method better estimated soil moisture over the first half of the growing season, estimation accuracies were comparable to those found in studies that had used similar datasets (RMSE = 0.043 m3 m-3, MAE = 0.034 m3 m- 3). Further interrogation of interaction effects between the variables used in this study and consideration of other factors that affect SAR backscatter could improve the method. More importantly, incorporating high-resolution satellite-based monitoring of soil moisture into IBCI could potentially reduce basis risk. The fifth objective of this study was to develop an IBCI for smallholder crop farming systems. The proposed IBCI scheme covers maize and derives index thresholds from crop water requirements and satellite-based rainfall estimates. It covers rainfall deficits over the vegetative, mid-season, and late-season stages of maize growth. The key contribution of this system is the derivation of index thresholds from CWR and site-specific rainfall conditions. The widely used approach, which calibrates IBCI by correlating yields and rainfall, exposes contracts to basis risk because, by simply correlating yield and rainfall data, it overlooks the influence of non-weather factors on crop yields and losses. The proposed system must be linked or bundled with non-weather variables that affect crop yields. Effectively, this means that the insurance must be linked or bundled with advisories and input supplies to address the influence of non-weather factors on crop losses. This system also incorporates a crop area-mapping component, which was found to be lacking in many IBCI systems. In conclusion, an IBCI that is based on crop water requirements, which incorporates crop area mapping and links insurance with non-weather crop yield-determining factors, is potentially capable of improving crop insurance for smallholder farming systems. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-10
Molecular characterization and antimicrobial resistance profiling of Salmonella species isolated from final effluent discharged from the Fort Hare Dairy Farm in Raymond Mhlaba Local Municipality
- Thinyane, Pindile https://orcid.org/0000-0001-8236-9407
- Authors: Thinyane, Pindile https://orcid.org/0000-0001-8236-9407
- Date: 2021-10
- Subjects: Salmonella typhimurium , Anti-infective agents , Multidrug resistance
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22666 , vital:52618
- Description: The exposure of livestock to antimicrobials for treatment, prophylaxis, or development advancement can select for antimicrobial resistant organisms that can be transmitted to humans. Salmonella as a significant zoonotic microorganism can go about as a likely supply of antimicrobial resistant determinants. Salmonella is a zoonotic pathogen that causes food and waterborne infections. It affects wild and domestic animals, and humans, by causing a number of infections including Salmonellosis. Salmonella species infect humans through the consumption of contaminated meat, like beef, chicken, pork etc. This study aimed to determine the molecular characterization and antimicrobial resistance profile of Salmonella species isolated from effluent discharged from the Fort Hare Dairy Farm in Raymond Mhlaba Local Municipality. Polymerase chain reaction (PCR) was used for the molecular confirmation of the presumptive Salmonella isolates targeting both ompC gene and typh gene. Standard disc diffusion method was used for the antimicrobial susceptibility testing (AST) as recommended by the Clinical and Laboratory Standards Institute. The confirmed Salmonella isolates were tested against 12 test antimicrobial agents and were screened for antimicrobial resistance genes (ARGs) including blaTEM and amp for beta-lactams, and tetC for tetracycline. The research showed that the effluent discharge from this farm is contaminated with Salmonella. Presumptive Salmonella densities were ranging between 1,7 ×102 to 6,1×102 CFU/100ml, out of 83 presumptive isolates recovered, 61 were molecularly confirmed Salmonella typhimurium. The most prevalent Salmonella species found in this study was Salmonella typhimurium, which was more abundant in the final effluent discharges than in the water samples. This may be due to the contamination from farm animal faeces. The susceptibility against 12 different antibiotics by the recovered Salmonella typhimurium were examined, and Salmonella typhimurium isolates was notably resistant to azithromycin, ampicillin, amoxiclav, but less resistance were seen on doripenem , meropenem and ciprofloxacin but none of the isolates were resistant to norfloxacin. Antibiotic results obtained from this research suggest that Quinolones (Norfloxicin, Ciprofloxacin and Nalidixic acid), and Carbapenems (Meropenem and Doripenem.) were the most effective antibiotics against Salmonella. Forty-eight percent of isolates were found to be resistant to more than 3 antibiotics from different families thus considering them to be multidrug resistant. Resistant determinants ampC, blaTEM and tetC were detected on resistant isolates. Misuse and overuse of antibiotics on animal producing farms put human lives at risk as it promotes the emergency of multidrug resistant bacteria. Findings of this study revealed that animal producing farm pose a threat to the community as they harbour and promote the emergence of multidrug resistant Salmonella typhimurium. , Thesis (MSc) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Thinyane, Pindile https://orcid.org/0000-0001-8236-9407
- Date: 2021-10
- Subjects: Salmonella typhimurium , Anti-infective agents , Multidrug resistance
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22666 , vital:52618
- Description: The exposure of livestock to antimicrobials for treatment, prophylaxis, or development advancement can select for antimicrobial resistant organisms that can be transmitted to humans. Salmonella as a significant zoonotic microorganism can go about as a likely supply of antimicrobial resistant determinants. Salmonella is a zoonotic pathogen that causes food and waterborne infections. It affects wild and domestic animals, and humans, by causing a number of infections including Salmonellosis. Salmonella species infect humans through the consumption of contaminated meat, like beef, chicken, pork etc. This study aimed to determine the molecular characterization and antimicrobial resistance profile of Salmonella species isolated from effluent discharged from the Fort Hare Dairy Farm in Raymond Mhlaba Local Municipality. Polymerase chain reaction (PCR) was used for the molecular confirmation of the presumptive Salmonella isolates targeting both ompC gene and typh gene. Standard disc diffusion method was used for the antimicrobial susceptibility testing (AST) as recommended by the Clinical and Laboratory Standards Institute. The confirmed Salmonella isolates were tested against 12 test antimicrobial agents and were screened for antimicrobial resistance genes (ARGs) including blaTEM and amp for beta-lactams, and tetC for tetracycline. The research showed that the effluent discharge from this farm is contaminated with Salmonella. Presumptive Salmonella densities were ranging between 1,7 ×102 to 6,1×102 CFU/100ml, out of 83 presumptive isolates recovered, 61 were molecularly confirmed Salmonella typhimurium. The most prevalent Salmonella species found in this study was Salmonella typhimurium, which was more abundant in the final effluent discharges than in the water samples. This may be due to the contamination from farm animal faeces. The susceptibility against 12 different antibiotics by the recovered Salmonella typhimurium were examined, and Salmonella typhimurium isolates was notably resistant to azithromycin, ampicillin, amoxiclav, but less resistance were seen on doripenem , meropenem and ciprofloxacin but none of the isolates were resistant to norfloxacin. Antibiotic results obtained from this research suggest that Quinolones (Norfloxicin, Ciprofloxacin and Nalidixic acid), and Carbapenems (Meropenem and Doripenem.) were the most effective antibiotics against Salmonella. Forty-eight percent of isolates were found to be resistant to more than 3 antibiotics from different families thus considering them to be multidrug resistant. Resistant determinants ampC, blaTEM and tetC were detected on resistant isolates. Misuse and overuse of antibiotics on animal producing farms put human lives at risk as it promotes the emergency of multidrug resistant bacteria. Findings of this study revealed that animal producing farm pose a threat to the community as they harbour and promote the emergence of multidrug resistant Salmonella typhimurium. , Thesis (MSc) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-10
Analysis of factors affecting technical efficiency of a1 smallholder maize farmers under command agriculture scheme in Zimbabwe: the case of Chegutu and Zvimba districts.
- Authors: Muzeza, Norman Tatenda
- Date: 2021-09
- Subjects: Food security , Farms, Small , Agricultural extension work
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/20826 , vital:46607
- Description: Maize is the most essential cereal crop grown in Zimbabwe. This crop is produced across the country under different conditions and environments. The study focused on analyzing technical efficiency of A1 smallholder maize farmers in Chegutu and Zvimba districts under the Command Agriculture Scheme. Understanding technical efficiency is essential under developing agriculture, especially where resources are limited, and high population growth is quite common. In such a setting, increased output depends on efficiency improvements. The specific objectives of the study focused on estimating the level of technical efficiency, determinants of technical efficiency and the level of productivity among a randomly selected sample of 240 A1 smallholder maize farmers under the Command Agriculture Scheme. Purposive, cluster and random sampling techniques were used to collect primary data from the selected sample. The study applied the single-stage modelling stochastic frontier approach to assess technical efficiency of A1 smallholder maize farmers. The stochastic frontier results revealed that A1 smallholder farmers in Chegutu and Zvimba districts are technically efficient at 85 percent and 94 percent, respectively. The major determinants of technical efficiency varied across each district. In Chegutu district, major determinants of technical efficiency were basal fertilizer, labour and area of land cultivated for maize production, and all indicated a positive relationship with level of significance less than 10 percent and 1 percent (0.012, 0.000 and 0.000) respectively. In Zvimba district, major determinants of technical efficiency were basal fertilizer, topdressing and area of land cultivated for maize production, and all indicated a positive relationship with level of significance less than 5 percent, 10 percent and 1 percent (0.002, 0.021, 0.000) respectively. The study further estimated determinants of technical inefficiency. Main determinants of technical inefficiency in Chegutu district were age, maize farming experience and level of education. In Zvimba district, main determinants were maize farming experience, level of education, marital status, occupation status and other sources of income. The return to scale that measures the productivity level of farmers varied among the two districts in which farmers from Chegutu district had increasing returns to scale (1.43), whilst famers from Zvimba district had decreasing returns to scale (0.54). The study, therefore, argues that despite observed high technical efficiencies, Chegutu farmers could bridge their 15 percent gap between their observed output and the frontier output by focusing more on input usage with increasing returns to scale (1.43 percent). On the other hand, Zvimba farmers could bridge their 6 percent gap between their observed output and frontier output by focusing more on socio-economic drivers of technical inefficiency, given the decreasing returns to scale of their inputs (0.54 percent). , Thesis (MSc) (Agricultural Economics) -- University of Fort Hare, 2021
- Full Text:
- Date Issued: 2021-09
- Authors: Muzeza, Norman Tatenda
- Date: 2021-09
- Subjects: Food security , Farms, Small , Agricultural extension work
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/20826 , vital:46607
- Description: Maize is the most essential cereal crop grown in Zimbabwe. This crop is produced across the country under different conditions and environments. The study focused on analyzing technical efficiency of A1 smallholder maize farmers in Chegutu and Zvimba districts under the Command Agriculture Scheme. Understanding technical efficiency is essential under developing agriculture, especially where resources are limited, and high population growth is quite common. In such a setting, increased output depends on efficiency improvements. The specific objectives of the study focused on estimating the level of technical efficiency, determinants of technical efficiency and the level of productivity among a randomly selected sample of 240 A1 smallholder maize farmers under the Command Agriculture Scheme. Purposive, cluster and random sampling techniques were used to collect primary data from the selected sample. The study applied the single-stage modelling stochastic frontier approach to assess technical efficiency of A1 smallholder maize farmers. The stochastic frontier results revealed that A1 smallholder farmers in Chegutu and Zvimba districts are technically efficient at 85 percent and 94 percent, respectively. The major determinants of technical efficiency varied across each district. In Chegutu district, major determinants of technical efficiency were basal fertilizer, labour and area of land cultivated for maize production, and all indicated a positive relationship with level of significance less than 10 percent and 1 percent (0.012, 0.000 and 0.000) respectively. In Zvimba district, major determinants of technical efficiency were basal fertilizer, topdressing and area of land cultivated for maize production, and all indicated a positive relationship with level of significance less than 5 percent, 10 percent and 1 percent (0.002, 0.021, 0.000) respectively. The study further estimated determinants of technical inefficiency. Main determinants of technical inefficiency in Chegutu district were age, maize farming experience and level of education. In Zvimba district, main determinants were maize farming experience, level of education, marital status, occupation status and other sources of income. The return to scale that measures the productivity level of farmers varied among the two districts in which farmers from Chegutu district had increasing returns to scale (1.43), whilst famers from Zvimba district had decreasing returns to scale (0.54). The study, therefore, argues that despite observed high technical efficiencies, Chegutu farmers could bridge their 15 percent gap between their observed output and the frontier output by focusing more on input usage with increasing returns to scale (1.43 percent). On the other hand, Zvimba farmers could bridge their 6 percent gap between their observed output and frontier output by focusing more on socio-economic drivers of technical inefficiency, given the decreasing returns to scale of their inputs (0.54 percent). , Thesis (MSc) (Agricultural Economics) -- University of Fort Hare, 2021
- Full Text:
- Date Issued: 2021-09
Chemical composition and in vitro ruminal degradation of diets containing Vachellia karro leaf meal and their effect on physiological responses of indigenous Xhosa lop-eared goats
- Authors: Mfisi, Khanyisa
- Date: 2021-09
- Subjects: Ruminants--Feeding and feeds , Animal nutrition
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/20719 , vital:46460
- Description: The objective of this study was to determine the chemical composition and in vitro ruminal dry matter degradation (DMD) of Vachellia karro leaf meal-containing diets and their effect on feed intake and physiological responses of indigenous Xhosa lop-eared goats. Experimental diets containing 0 percent (Treatment 1), 15 percent (Treatment 2) and 30 percent (Treatment 3) Vachellia karroo leaf meal were mixed with grass hay and crushed maize. Samples of each diet were analysed for chemical composition and in vitro ruminal DM degradability. A total of 18 eight-month-old indigenous Xhosa lop-eared goats, initially weighing 20.81 ± 1.83 kg were randomly assigned to each diet in a Completely Randomized Design. The goats were confined in individual well-ventilated roofed pens and each dietary treatment had a total of 6 goats. The feed was offered at a rate of 3 percent of live weight twice a day, at 08:00 in the morning and at 16:00 in the afternoon. The experimental feeding trial lasted for 80 days, where 10 days was allowed for adaptation. Goat live weight, Average daily feed intake (ADFI), and Body condition scores (BCS) were recorded weekly FAMACHA scores and fecal eggs counts were also determined weekly. Blood samples were collected via vein puncture on the last day of the feeding trial for determination of glucose, total cholesterol, albumin and blood urea. Significantly higher (P < 0.05) crude protein (CP) and condensed tannins (CT) levels were observed in Vachellia karroo containing diets., while acid detergent fibre (ADF) and neutral detergent fibre (NDF) were significantly higher (P < 0.05) in the control diet. During early hours of incubation, DMD was similar (P > 0.05) across all dietary treatments. At 12 to 72 hours, the DMD was significantly higher (P < 0.05) in Vachellia karroo containing diets except at 48 hours. Correlation between DMD and NDF, ADF and fat was only visible at 24 hours. Fibre (ADF and NDF) were negatively related to DMD, while fat was positively related. A positive correlation was observed between DMD and DM, CP and ADFI. The body weight and BCS of goats was similar (P > 0.05) in all dietary treatments (P > 0.05). The ADFI was significantly higher (P < 0.05) in Vachellia karroo supplemented goats. Faecal egg count and FAMACHA scores were significantly higher (P< 0.05) in the control group compared to the Vachellia karroo supplemented treatments; while glucose levels were significantly higher in goats supplemented with Vachellia karroo compared to non-supplemented goats. Cholesterol levels were similar (P > 0.05) across all experimental groups. Goats consuming 30 percent of Vachellia karroo leaf meal had higher (P < 0.05) creatinine levels than the non-supplemented treatment. Urea levels were significantly higher (P < 0.05) in goats fed 30 percent of Vachellia karroo leaf meal than other treatments. It was concluded that the inclusion of Vachellia karroo leaves improves diet quality, diet degradability, average daily feed intake and physiological responses. , Thesis (MSc) (Animal Science) -- University of Fort Hare, 2021
- Full Text:
- Date Issued: 2021-09
- Authors: Mfisi, Khanyisa
- Date: 2021-09
- Subjects: Ruminants--Feeding and feeds , Animal nutrition
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/20719 , vital:46460
- Description: The objective of this study was to determine the chemical composition and in vitro ruminal dry matter degradation (DMD) of Vachellia karro leaf meal-containing diets and their effect on feed intake and physiological responses of indigenous Xhosa lop-eared goats. Experimental diets containing 0 percent (Treatment 1), 15 percent (Treatment 2) and 30 percent (Treatment 3) Vachellia karroo leaf meal were mixed with grass hay and crushed maize. Samples of each diet were analysed for chemical composition and in vitro ruminal DM degradability. A total of 18 eight-month-old indigenous Xhosa lop-eared goats, initially weighing 20.81 ± 1.83 kg were randomly assigned to each diet in a Completely Randomized Design. The goats were confined in individual well-ventilated roofed pens and each dietary treatment had a total of 6 goats. The feed was offered at a rate of 3 percent of live weight twice a day, at 08:00 in the morning and at 16:00 in the afternoon. The experimental feeding trial lasted for 80 days, where 10 days was allowed for adaptation. Goat live weight, Average daily feed intake (ADFI), and Body condition scores (BCS) were recorded weekly FAMACHA scores and fecal eggs counts were also determined weekly. Blood samples were collected via vein puncture on the last day of the feeding trial for determination of glucose, total cholesterol, albumin and blood urea. Significantly higher (P < 0.05) crude protein (CP) and condensed tannins (CT) levels were observed in Vachellia karroo containing diets., while acid detergent fibre (ADF) and neutral detergent fibre (NDF) were significantly higher (P < 0.05) in the control diet. During early hours of incubation, DMD was similar (P > 0.05) across all dietary treatments. At 12 to 72 hours, the DMD was significantly higher (P < 0.05) in Vachellia karroo containing diets except at 48 hours. Correlation between DMD and NDF, ADF and fat was only visible at 24 hours. Fibre (ADF and NDF) were negatively related to DMD, while fat was positively related. A positive correlation was observed between DMD and DM, CP and ADFI. The body weight and BCS of goats was similar (P > 0.05) in all dietary treatments (P > 0.05). The ADFI was significantly higher (P < 0.05) in Vachellia karroo supplemented goats. Faecal egg count and FAMACHA scores were significantly higher (P< 0.05) in the control group compared to the Vachellia karroo supplemented treatments; while glucose levels were significantly higher in goats supplemented with Vachellia karroo compared to non-supplemented goats. Cholesterol levels were similar (P > 0.05) across all experimental groups. Goats consuming 30 percent of Vachellia karroo leaf meal had higher (P < 0.05) creatinine levels than the non-supplemented treatment. Urea levels were significantly higher (P < 0.05) in goats fed 30 percent of Vachellia karroo leaf meal than other treatments. It was concluded that the inclusion of Vachellia karroo leaves improves diet quality, diet degradability, average daily feed intake and physiological responses. , Thesis (MSc) (Animal Science) -- University of Fort Hare, 2021
- Full Text:
- Date Issued: 2021-09
Compartmentalization of mineral elements, nutritional factors, biological potentials and phytochemical profiles in the fruits of Musa sinensis L.(Banana) and Musa paradisiaca L.(Plantain): A comparison among soft flesh, peel and boiled peel extract
- Oyeyinka, Barnabas Oluwatomide https://orcid.org/0000-0003-1191-9365
- Authors: Oyeyinka, Barnabas Oluwatomide https://orcid.org/0000-0003-1191-9365
- Date: 2021-09
- Subjects: Bananas , Plantain banana
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/23655 , vital:58274
- Description: Fruits are key contributors to human nutrition and health. However, banana and plantain are typical examples of fruits that have nutritionally under-utilized peel by-products. This study was thus carried out to investigate the compartmental distribution (soft flesh, peel, and boiled peel extract) of mineral elements, nutritional factors, biological potentials, and phytochemical profiles in M. sinensis and M. paradisiaca fruits (ripening stage 4-5), with focus on the peels. Proximal and and antinutritive analyses were done with standard methods of the Association of Official Analytical Chemists (AOAC), while mineral element composition in the fruit components was analyzed with the inductively coupled plasma optical emission spectroscopy (ICP-OES). The pharmacological potential of M. sinensis and M. paradisiaca fruit components was investigated spectrophotometrically by evaluating the polyphenolic constituents (total phenol, proanthocyanidin, flavonoid) and in vitro radical scavenging activities of the aqueous, acetone and ethanol extracts, using DPPH, ABTS, and FRAP assay models. The correlational evaluation of the polyphenolics and antioxidant activity in the components of both fruits using Pearson’s correlational coefficient (r). The proximal assays revealed that moisture content, fiber content, and carbohydratecontent were substantially present in the flesh and peel of M. sinensis and M. paradisiaca, while lipid content was low. The antinutritive results revealed safe levels of alkaloid, oxalate, phytate, and saponin factors in the flesh and peel by-products. Mineral analysis results indicated substantial levels of the macroelements K, Mg, Ca, and P in the peels. Other results revealed that acetone extracts had the highest phenolic, proanthocyanidin and flavonoid constituents respectively, across the soft flesh components ofM. sinensis (119.05 ± 5.80 mgGAE/g; 337.48 ± 13.16 mgCE/g; 602.64 ± 3.65 mgQE/g), M. paradisiaca (114.80 ± 1.49 mgGAE/g; 436.09 ± 36.44 mgCE/g; 777.35 ± 150.95mgQE/g) and the peel component of M. paradisiaca (136.87 ± 5.69 mgGAE/g; 530.06 ± 53.51 mgCE/g; 750.87 ± 55.61 mgQE/g), with an exception of the phenolic content of M. sinensis peel, where it was highest in the ethanol extract (157.19 ± 4.76 mgGAE/g). The ABTS (0.03 mg/mL) and DPPH (0.03 mg/mL) activities were at their highest in the boiled peel extracts of M. sinensis and M. paradisiaca, while ferric reducing power was highest in ethanol extracts across M. sinensis soft flesh, peel, and M. paradisiaca flesh. Acetone extract of M. paradisiaca peel had the highest ferric reducing capacity at peak concentration (0.1 mg/mL). Correlational analysis revealed a negative correlation between respective phenolic, proanthocyanidin, and flavonoid content and the IC50DPPH antioxidant capacity in M. sinensis flesh, M. sinensis peel and M. paradisiaca flesh. Conversely, there was positive correlation between IC50 DPPH with proanthocyanidin and flavonoid in M. paradisiaca peel. Negative correlation was detected between the phenolic, proanthocyanidin and flavonoid contents and IC50ABTS in M. sinensis flesh. Positive correlation was observed between respective phenolic, proanthocyanidin and flavonoid contentwith IC50 ABTS in M. sinensis peel, M. paradisiaca flesh and M. paradisiaca peel. There was negative correlation between the respective phenolic, proanthocyanidin and flavonoid contents and IC50 FRAP in the flesh of M. sinensis, while positive correlation was observed in M. sinensis peel. M. paradisiaca flesh on the other hand, showed positive correlation between the IC50 FRAP and the respective phytochemical contents. However, the peel, there was negative correlation. The correlational evaluation in this study revealed general positive and negative correlational patterns, which implies that no polyphenolic constituent contributed exclusively to antioxidant activity, but rather in combination. Ultrastructure and elemental spectra of M. sinensis and M. paradisiaca exocarps were analysed with electron microscopy (SEM)and energy dispersive x-ray (EDX). Microstructures such as interlocked, polyhedral epidermal cells, ellipsoid-shaped stomata, guard cells, intercellular space, anticlinal-patterned walls, and subsidiary cells were observed. The elemental spectra revealed the presence of elements such as potassium, iron, carbon, oxygen, silicon, and gold, with consistently high to relatively high carbon and oxygen peaks in M. sinensis and M. paradisiaca exocarps. The relative similarity observed in the constituents of a number of the elemental spectra in M. sinensis and M. paradisiaca peels, reflects some degree of relatedness. These outcomes indicate that banana and plantain peel and boiled peel extracts are nutritive, medicinal and potential nutraceuticals, with food preservative, shelf-life and quality enhancement potentials. The instrumentation in this study also have potential relevance in industrial food product analysis. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-09
- Authors: Oyeyinka, Barnabas Oluwatomide https://orcid.org/0000-0003-1191-9365
- Date: 2021-09
- Subjects: Bananas , Plantain banana
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/23655 , vital:58274
- Description: Fruits are key contributors to human nutrition and health. However, banana and plantain are typical examples of fruits that have nutritionally under-utilized peel by-products. This study was thus carried out to investigate the compartmental distribution (soft flesh, peel, and boiled peel extract) of mineral elements, nutritional factors, biological potentials, and phytochemical profiles in M. sinensis and M. paradisiaca fruits (ripening stage 4-5), with focus on the peels. Proximal and and antinutritive analyses were done with standard methods of the Association of Official Analytical Chemists (AOAC), while mineral element composition in the fruit components was analyzed with the inductively coupled plasma optical emission spectroscopy (ICP-OES). The pharmacological potential of M. sinensis and M. paradisiaca fruit components was investigated spectrophotometrically by evaluating the polyphenolic constituents (total phenol, proanthocyanidin, flavonoid) and in vitro radical scavenging activities of the aqueous, acetone and ethanol extracts, using DPPH, ABTS, and FRAP assay models. The correlational evaluation of the polyphenolics and antioxidant activity in the components of both fruits using Pearson’s correlational coefficient (r). The proximal assays revealed that moisture content, fiber content, and carbohydratecontent were substantially present in the flesh and peel of M. sinensis and M. paradisiaca, while lipid content was low. The antinutritive results revealed safe levels of alkaloid, oxalate, phytate, and saponin factors in the flesh and peel by-products. Mineral analysis results indicated substantial levels of the macroelements K, Mg, Ca, and P in the peels. Other results revealed that acetone extracts had the highest phenolic, proanthocyanidin and flavonoid constituents respectively, across the soft flesh components ofM. sinensis (119.05 ± 5.80 mgGAE/g; 337.48 ± 13.16 mgCE/g; 602.64 ± 3.65 mgQE/g), M. paradisiaca (114.80 ± 1.49 mgGAE/g; 436.09 ± 36.44 mgCE/g; 777.35 ± 150.95mgQE/g) and the peel component of M. paradisiaca (136.87 ± 5.69 mgGAE/g; 530.06 ± 53.51 mgCE/g; 750.87 ± 55.61 mgQE/g), with an exception of the phenolic content of M. sinensis peel, where it was highest in the ethanol extract (157.19 ± 4.76 mgGAE/g). The ABTS (0.03 mg/mL) and DPPH (0.03 mg/mL) activities were at their highest in the boiled peel extracts of M. sinensis and M. paradisiaca, while ferric reducing power was highest in ethanol extracts across M. sinensis soft flesh, peel, and M. paradisiaca flesh. Acetone extract of M. paradisiaca peel had the highest ferric reducing capacity at peak concentration (0.1 mg/mL). Correlational analysis revealed a negative correlation between respective phenolic, proanthocyanidin, and flavonoid content and the IC50DPPH antioxidant capacity in M. sinensis flesh, M. sinensis peel and M. paradisiaca flesh. Conversely, there was positive correlation between IC50 DPPH with proanthocyanidin and flavonoid in M. paradisiaca peel. Negative correlation was detected between the phenolic, proanthocyanidin and flavonoid contents and IC50ABTS in M. sinensis flesh. Positive correlation was observed between respective phenolic, proanthocyanidin and flavonoid contentwith IC50 ABTS in M. sinensis peel, M. paradisiaca flesh and M. paradisiaca peel. There was negative correlation between the respective phenolic, proanthocyanidin and flavonoid contents and IC50 FRAP in the flesh of M. sinensis, while positive correlation was observed in M. sinensis peel. M. paradisiaca flesh on the other hand, showed positive correlation between the IC50 FRAP and the respective phytochemical contents. However, the peel, there was negative correlation. The correlational evaluation in this study revealed general positive and negative correlational patterns, which implies that no polyphenolic constituent contributed exclusively to antioxidant activity, but rather in combination. Ultrastructure and elemental spectra of M. sinensis and M. paradisiaca exocarps were analysed with electron microscopy (SEM)and energy dispersive x-ray (EDX). Microstructures such as interlocked, polyhedral epidermal cells, ellipsoid-shaped stomata, guard cells, intercellular space, anticlinal-patterned walls, and subsidiary cells were observed. The elemental spectra revealed the presence of elements such as potassium, iron, carbon, oxygen, silicon, and gold, with consistently high to relatively high carbon and oxygen peaks in M. sinensis and M. paradisiaca exocarps. The relative similarity observed in the constituents of a number of the elemental spectra in M. sinensis and M. paradisiaca peels, reflects some degree of relatedness. These outcomes indicate that banana and plantain peel and boiled peel extracts are nutritive, medicinal and potential nutraceuticals, with food preservative, shelf-life and quality enhancement potentials. The instrumentation in this study also have potential relevance in industrial food product analysis. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-09
Determination of acaricide resistance profiles, and geographic range of boophilid Rhipicephalus tick spp. (Acari: Ixodidae), and sero-status of tick-borne pathogens on communal cattle in the north-eastern regions of the Eastern Cape Province, South Africa
- Yawa, Mandla https://orcid.org/0000-0002-2402-298X
- Authors: Yawa, Mandla https://orcid.org/0000-0002-2402-298X
- Date: 2021-09
- Subjects: Cattle -- Diseases , Ticks as carriers of disease , Ticks
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/21590 , vital:49356
- Description: Cattle industry improves livelihoods for many developing farmers in South Africa, however, ticks and tick-borne diseases (TBDs) pose a detriment impact on cattle success; this is due to their resistance to acaricide application. Thus, this study was conducted to determine the extent of acaricide resistance, serostatus of tick-borne pathogens, and geographic range of boophilid ticks in communal grazing cattle in the north-eastern regions of the Eastern Cape Province (ECP), South Africa. A total of 160 structured questionnaires were prepared and randomly administered to cattle farmers to investigate their knowledge, attitudes, and practice on ticks and TBDs affecting cattle, tick control methods used, and their knowledge of acaricide resistance. Engorged visible cattle ticks were collected seasonally from 10 randomly selected cattle from the community cattle herds during dipping days between October 2018 and September 2019, and stored into the labelled test tubes containing 70 percent ethanol. For TBDs determination, a total of 240 cattle from Elundini and Senqu Municipalities were seasonally used to investigate the prevalence of ticks and TBDs, packed cell volume (PCV), and body condition scores (BCS). Shaw Larval Immersion Test (SLIT) method was used to determine the resistance of Rhipicephalus decoloratus larvae to various acaricides such as amidines, organophosphate, and synthetic pyrethroids. This study indicates that approximately 59 percent of the interviewed cattle farmers had no knowledge of the effect of TBDs affecting cattle production, and 78 percent of respondents considered ticks are the major challenge to the success of their cattle farming. Pour-on (61 percent) was the most commonly used acaricidal treatment system with fortnightly (40 percent and 31percent) treatment frequencies during the summer and winter seasons respectively. Synthetic pyrethroids (73 percent) were the most used acaricide compounds to control ticks. Moreover, approximately 85 percent of respondents perceived that they do not practice acaricide rotation, and 88 percent of the respondents had no knowledge of acaricide resistance. Interestingly, the current study record Rhipicephalus microplus for the first time at Elundini, Senqu, and Walter Sisulu. Based on the morphological traits, a total of 6176 ticks belonging to two boophilid tick species of Rhipicephalus were identified: R. decoloratus (98 percent) and R. microplus (2 percent). Rhipicephalus decoloratus was significantly higher (P<0.05) in Elundini during the hot-dry (3.37±0.121) and hot-wet (3.35±0.121) seasons compared to other localit ies. In Senqu, R. microplus had high counts (P<0.05) during the post-rainy season (1.06±0.027) compared to other localities. From this present study, it was observed that Ehrlichia ruminantium was the most prevalent at Elundini (16 percent) and (14 percent) during post-rainy and hot-dry seasons respectively and 15 percent at Senqu during the post-rainy season. Babesia bigemina was more frequent at Elundini (18 percent) and Senqu (16 percent) during the post-rainy season and hot-wet season, respectively. Cattle BCS were significantly negatively correlated with E. ruminantium (P<0.01; r = -0.203), B. bovis (P<0.01; r = -0.125), and A. marginale (P < 0.01; r = -0.122). On the other hand, PCV was significantly negatively correlated with B. bigemina (P<0.01; r =-0.138). E. ruminantium was strongly positively correlated with Amblyomma hebraeum (P<0.05; r = 0.112), while B. bovis (P<0.05; r = 0.134) and B. bigemina (P<0.05; r = 0.188) were strong positively correlated with Rhipicephalus microplus infestation and B. bigemina (P<0.05; r = 0.077) with Rhipicephalus decoloratus. During acaricide resistance testing, Shaw Larvae Immersion Testing (SLIT) was only performed on R. decoloratus larvae as engorged R. microplus ticks could not meet the required sample size for resistance testing. The current study found that the majority of the tick were susceptible at exposure to differe nt acaricide field concentrations of amidines (49 percent at 250ppm), organophosphates (33 percent and 47 percent at 300ppm and 500ppm, respectively), and synthetic pyrethroids (44 percent and 23 percent at 150ppm and 300ppm, respectively). In conclusion, less knowledge of cattle farmers on the threat pose by ticks on their cattle production results in the spatio-temporal spread of boophilid tick from region to region and from season to season thus increases incidence and risk for tick resistance. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-09
- Authors: Yawa, Mandla https://orcid.org/0000-0002-2402-298X
- Date: 2021-09
- Subjects: Cattle -- Diseases , Ticks as carriers of disease , Ticks
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/21590 , vital:49356
- Description: Cattle industry improves livelihoods for many developing farmers in South Africa, however, ticks and tick-borne diseases (TBDs) pose a detriment impact on cattle success; this is due to their resistance to acaricide application. Thus, this study was conducted to determine the extent of acaricide resistance, serostatus of tick-borne pathogens, and geographic range of boophilid ticks in communal grazing cattle in the north-eastern regions of the Eastern Cape Province (ECP), South Africa. A total of 160 structured questionnaires were prepared and randomly administered to cattle farmers to investigate their knowledge, attitudes, and practice on ticks and TBDs affecting cattle, tick control methods used, and their knowledge of acaricide resistance. Engorged visible cattle ticks were collected seasonally from 10 randomly selected cattle from the community cattle herds during dipping days between October 2018 and September 2019, and stored into the labelled test tubes containing 70 percent ethanol. For TBDs determination, a total of 240 cattle from Elundini and Senqu Municipalities were seasonally used to investigate the prevalence of ticks and TBDs, packed cell volume (PCV), and body condition scores (BCS). Shaw Larval Immersion Test (SLIT) method was used to determine the resistance of Rhipicephalus decoloratus larvae to various acaricides such as amidines, organophosphate, and synthetic pyrethroids. This study indicates that approximately 59 percent of the interviewed cattle farmers had no knowledge of the effect of TBDs affecting cattle production, and 78 percent of respondents considered ticks are the major challenge to the success of their cattle farming. Pour-on (61 percent) was the most commonly used acaricidal treatment system with fortnightly (40 percent and 31percent) treatment frequencies during the summer and winter seasons respectively. Synthetic pyrethroids (73 percent) were the most used acaricide compounds to control ticks. Moreover, approximately 85 percent of respondents perceived that they do not practice acaricide rotation, and 88 percent of the respondents had no knowledge of acaricide resistance. Interestingly, the current study record Rhipicephalus microplus for the first time at Elundini, Senqu, and Walter Sisulu. Based on the morphological traits, a total of 6176 ticks belonging to two boophilid tick species of Rhipicephalus were identified: R. decoloratus (98 percent) and R. microplus (2 percent). Rhipicephalus decoloratus was significantly higher (P<0.05) in Elundini during the hot-dry (3.37±0.121) and hot-wet (3.35±0.121) seasons compared to other localit ies. In Senqu, R. microplus had high counts (P<0.05) during the post-rainy season (1.06±0.027) compared to other localities. From this present study, it was observed that Ehrlichia ruminantium was the most prevalent at Elundini (16 percent) and (14 percent) during post-rainy and hot-dry seasons respectively and 15 percent at Senqu during the post-rainy season. Babesia bigemina was more frequent at Elundini (18 percent) and Senqu (16 percent) during the post-rainy season and hot-wet season, respectively. Cattle BCS were significantly negatively correlated with E. ruminantium (P<0.01; r = -0.203), B. bovis (P<0.01; r = -0.125), and A. marginale (P < 0.01; r = -0.122). On the other hand, PCV was significantly negatively correlated with B. bigemina (P<0.01; r =-0.138). E. ruminantium was strongly positively correlated with Amblyomma hebraeum (P<0.05; r = 0.112), while B. bovis (P<0.05; r = 0.134) and B. bigemina (P<0.05; r = 0.188) were strong positively correlated with Rhipicephalus microplus infestation and B. bigemina (P<0.05; r = 0.077) with Rhipicephalus decoloratus. During acaricide resistance testing, Shaw Larvae Immersion Testing (SLIT) was only performed on R. decoloratus larvae as engorged R. microplus ticks could not meet the required sample size for resistance testing. The current study found that the majority of the tick were susceptible at exposure to differe nt acaricide field concentrations of amidines (49 percent at 250ppm), organophosphates (33 percent and 47 percent at 300ppm and 500ppm, respectively), and synthetic pyrethroids (44 percent and 23 percent at 150ppm and 300ppm, respectively). In conclusion, less knowledge of cattle farmers on the threat pose by ticks on their cattle production results in the spatio-temporal spread of boophilid tick from region to region and from season to season thus increases incidence and risk for tick resistance. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-09
Effect of grazing systems and age on enteric methane production and performance plus grazing system effect on ruminal fermentation parameters of Nguni and Bonsmara beef cows
- Authors: Kayima, Denis
- Date: 2021-09
- Subjects: Grazing , Pastures--Management , Ruminants--Feeding and feeds
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/20583 , vital:46153
- Description: Beef breeds of cattle are predominantly raised through extensive grazing and produce the highest levels of enteric methane (CH4) through ruminal fermentation. The objective of this study was to evaluate the effect of breed, grazing, and age on enteric methane production and performance of beef cows as well as effect of breed and grazing system on ruminal fermentation parameters. Two separate studies were conducted; the first study evaluated the effect of grazing system, breed, and age on ruminal enteric methane production and performance of selected beef breeds. The second study evaluated the effect of the grazing system and breed on ruminal fermentation. In the first study, two breeds (Nguni and Bonsmara) raised under two grazing systems (communal and commercial) in a random complete block design were grouped into 3 age categories. Eighty-four cows aged between 24-120 months were randomly selected and grouped by age: group A (young adult cow, n = 7, 24-48 months old), group B (adult, n = 7, 60-80 months old), and group C (old adult, n = 7, 90-120 months) in either grazing system. Data were collected on methane production per day, body condition, and weight used to estimate dry matter intake (DMI), methane per DMI, and methane per body weight. In the second study, 40 cows of the same age group, parity, and physiological status were used. Ten cows per breed (Bonsmara and Nguni) in either grazing system (communal and commercial) were used in a random complete block design. Rumen fluid collection was done by the stomach tube method. Data were collected on ruminal ammonia-nitrogen (NH3-N), pH, Temperature, volatile fatty acids (VFAs). Older animals produced higher methane per head in the order of C > B > A; (P<0.0001). Performance parameters like Body condition score (BCS), body weight (BW), dry matter intake (DMI), and daily methane were higher (P<0.05) in Bonsmara. However, Methane per BW was higher in Nguni (P<0.05), and methane per DMI did not differ among breeds (P>0.05). Body condition, BW, and DMI were higher (P<0.05) in commercial grazing system. Contrary, daily methane production, methane production per DMI, and methane produced per BW were higher in communal grazing. In the second study, Ruminal NH3-N concentration ranged between 69.05 - 96.78 mg/L and was higher (P<0.05) in Nguni. It was also higher (P<0.05) in the commercial grazing system. Ruminal pH, temperature, total VFAs, and certain individual VFAs (iso-butyrate, valeric and iso-valeric) did not differ (P>0.05) among breeds and grazing systems. However, total VFAs were slightly lower in communal grazing (78.87 mmol/L) than commercial grazing (89.80 mmol/L). Acetate, propionate, butyrate proportions, and acetate to propionate ratio did not differ (P>0.05) among breeds but differed (P<0.05) between grazing systems. Acetate (P<0.05) and acetate to propionate ratio (P<0.05) were higher in the communal grazing system, while the reverse was true for propionate (P<0.05) and butyrate (P<0.05). Bonsmara produced more methane than Nguni under similar conditions, with Nguni uniquely producing more methane per BW, indicating host genetics influence. Communal animals and older animals produced more CH4 than commercial and younger cows regardless of the breed, indicating ruminal inefficiencies in very old cows. These results emphasize the idea that host genetics or breed, grazing system, and age influence methane output and performance. Hence, breeding strategies for hard-to-measure traits like methane production need to put all these factors into consideration. , Thesis (MSc) (Animal Science) -- University of Fort Hare, 2021
- Full Text:
- Date Issued: 2021-09
- Authors: Kayima, Denis
- Date: 2021-09
- Subjects: Grazing , Pastures--Management , Ruminants--Feeding and feeds
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/20583 , vital:46153
- Description: Beef breeds of cattle are predominantly raised through extensive grazing and produce the highest levels of enteric methane (CH4) through ruminal fermentation. The objective of this study was to evaluate the effect of breed, grazing, and age on enteric methane production and performance of beef cows as well as effect of breed and grazing system on ruminal fermentation parameters. Two separate studies were conducted; the first study evaluated the effect of grazing system, breed, and age on ruminal enteric methane production and performance of selected beef breeds. The second study evaluated the effect of the grazing system and breed on ruminal fermentation. In the first study, two breeds (Nguni and Bonsmara) raised under two grazing systems (communal and commercial) in a random complete block design were grouped into 3 age categories. Eighty-four cows aged between 24-120 months were randomly selected and grouped by age: group A (young adult cow, n = 7, 24-48 months old), group B (adult, n = 7, 60-80 months old), and group C (old adult, n = 7, 90-120 months) in either grazing system. Data were collected on methane production per day, body condition, and weight used to estimate dry matter intake (DMI), methane per DMI, and methane per body weight. In the second study, 40 cows of the same age group, parity, and physiological status were used. Ten cows per breed (Bonsmara and Nguni) in either grazing system (communal and commercial) were used in a random complete block design. Rumen fluid collection was done by the stomach tube method. Data were collected on ruminal ammonia-nitrogen (NH3-N), pH, Temperature, volatile fatty acids (VFAs). Older animals produced higher methane per head in the order of C > B > A; (P<0.0001). Performance parameters like Body condition score (BCS), body weight (BW), dry matter intake (DMI), and daily methane were higher (P<0.05) in Bonsmara. However, Methane per BW was higher in Nguni (P<0.05), and methane per DMI did not differ among breeds (P>0.05). Body condition, BW, and DMI were higher (P<0.05) in commercial grazing system. Contrary, daily methane production, methane production per DMI, and methane produced per BW were higher in communal grazing. In the second study, Ruminal NH3-N concentration ranged between 69.05 - 96.78 mg/L and was higher (P<0.05) in Nguni. It was also higher (P<0.05) in the commercial grazing system. Ruminal pH, temperature, total VFAs, and certain individual VFAs (iso-butyrate, valeric and iso-valeric) did not differ (P>0.05) among breeds and grazing systems. However, total VFAs were slightly lower in communal grazing (78.87 mmol/L) than commercial grazing (89.80 mmol/L). Acetate, propionate, butyrate proportions, and acetate to propionate ratio did not differ (P>0.05) among breeds but differed (P<0.05) between grazing systems. Acetate (P<0.05) and acetate to propionate ratio (P<0.05) were higher in the communal grazing system, while the reverse was true for propionate (P<0.05) and butyrate (P<0.05). Bonsmara produced more methane than Nguni under similar conditions, with Nguni uniquely producing more methane per BW, indicating host genetics influence. Communal animals and older animals produced more CH4 than commercial and younger cows regardless of the breed, indicating ruminal inefficiencies in very old cows. These results emphasize the idea that host genetics or breed, grazing system, and age influence methane output and performance. Hence, breeding strategies for hard-to-measure traits like methane production need to put all these factors into consideration. , Thesis (MSc) (Animal Science) -- University of Fort Hare, 2021
- Full Text:
- Date Issued: 2021-09
Evaluation of bacteria laccase hybrid biosensor and application in the detection of phenolic contaminants in water
- Edoamodu, Chiedu Epiphany https://orcid.org/0000-0002-9254-3955
- Authors: Edoamodu, Chiedu Epiphany https://orcid.org/0000-0002-9254-3955
- Date: 2021-09
- Subjects: Laccase , Water -- Purification
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/22820 , vital:52802
- Description: The continuous outpour of aromatic pollutants in diverse groups, emanating from the industrial and domestic system due to population density, industrialisation and technological advancement is alarming. The increasing strength in wastewater discharge constitutes the main cause of the natural water pollution load, causing scarcity of potable water for consumption with an increasing health challenge. The physiochemical treatment approach has faced a series of limitations with little or no success. Hindrance to wastewater management can cause a point source contamination problem that might increase treatment cost and release a broad range of chemical contaminants in the environment. Hence, green, eco-friendly and cost-effective tools are imperative. The application of laccase has received much attention in bioremediation and bioprocessing matters owing to the oxidising capacity of a wide range of substrates. The process requires available molecular oxygen for its activation, releasing water as a by-product thus, establishing this research. This study was devised to examine the bioprocessing potentials of hybrid and amalgamated laccases extracted from the diverse environmental milieu of the Eastern Cape Province, South Africa. Bacteria producing laccase were isolated from marine sediment, cow dung, and wastewater samples via selective enrichment with some aromatic compounds. The axenic cultures were screened for laccase activity on various phenolic and non-phenolic substrates. The isolates were identified via molecular techniques and they belonged to the gammaproteobacteria and Bacilli classes under the following genera, Enterobacter and Bacillus. They were deposited in the NCBI database as Enterobacter asburiae ES1, Enterobacter sp. Kamsi, Enterobacter sp. AI1, and Bacillus sp. NU2 with the assigned accession number MN686602, MN686603, MN686605, MN686607, respectively. Optimisation of the laccase production via one factor at a time technique (OFAT) from the four bacteria species showed more enzyme yield in all lignocellulosic agro-waste media. However, wheat bran and mandarin peel maximally enhanced laccase production. In addition, xylose, galactose, fructose, and sorbitol were the best carbon sources utilised while (NH₄)₂SO8, KNO3 and NaNO3 were noted as the best nitrogen sources employed. Laccase yields were increased at pH 4 and 5, at temperatures 45 and 55 o C, and at 50 and 100 rpm, and precisely, at day eight of the incubation period. Further purification of the crude laccase yielded a purification fold of 4.18, 4.39, 2.78, 8.11, and the SDS-PAGE analysis showed a molecular size of 90, 55, 75 and 50 kDa for ES1, Kamsi, AI1, and NU2 laccases, respectively. The characterised purified laccase demonstrated polyextremotolerant potentials. The laccases were active through a wide temperature regime (30-90 o C) with maximum activity at 50 o C (ES1/AI1 and Kamsi/NU2) 60 o C (AI1), 70 o C (ES1, Kamsi, NU2); and were stable at 60 o C (ES1, AI1, NU2), 70 o C (ES1/AI1), 80 o C (Kamsi and Kamsi/NU2). Also, the laccases remained active through pH 3 - 8 and optimal at pH 4 (AI1, NU2), pH 5 (Kamsi, ES1/AI1), pH 7 (ES1), pH 8 (Kamsi/NU2), and the individual stability was measured at pH 4 (Kamsi, NU2), pH 5 (AI1), pH 6 (ES1), pH 7 (Kamsi/NU2), pH 10 (ES1/AI1). The purified laccases were either enhanced or left unchanged by a variable concentration of metallic salts, inhibitors, chelating agents and organic solvents. Clearly, the activities of the laccase were enhanced when pre-incubated with 1, 3, and 6 mm of CuCl2, FeCl3, MgCl2, ZnCl2 and AgCl, and 1, 2, 3 mm of Triton x-100, PMSF, EDTA, Tween 20, and NaCl. Additionally, 20, 30, and 10 percent v/v of acetone and DMSO were prominent organic solvents that also stimulated both the hybrid and amalgamated laccase activity. The gene of the purified laccases targeted showed a clear band size of 690 bp for the Enterobacter species laccases and 775 bp for the laccase from Bacillus sp. The protein sequence was deposited in NCBI database with the assigned accession numbers, MW251989, MW25990, MW251992, and MW251994 for ES1, Kamsi, AI1, and NU2 laccases, respectively. The optimised pH and temperature parameter examined on the decolourising potential of the bacteria laccases showed an effective dye removal on the five synthetic dyes (Congo Red (CR), Methyl Orange (MO), Malachite Green (MG), Reactive Blue 4 (RB4), Ramazol Brilliant Blue R (RBBR)) applied. The purified laccases were successfully immobilised in Na-alginate with cca. 88.49, 70.91, 76.04, 76.13, 90.07, and 91.99 laccase yield for the hybrid (ES1, ES1, Kamsi, AI1, NU2) and amalgamated (ES1/AI1 and Kamsi/NU2) laccases. The immobilised laccases were able to retain an average activity of 32 – 52 percent after eight dye decolourising cycles, exhibiting strong catalytic activity than the free laccases. Nonetheless, no significant difference was examined between the hybrid and amalgamated laccase activity. Also, the immobilised laccases were shown to be more efficient in biotechnological application than the free laccases. The result suggests that immobilising an enzyme in a carrier matrix served effectively as the remediation approach than the hybrid and the amalgamation of the free enzymes. Also, the application of lignocellulosic waste served as a cheaper substrate for commercial production of laccase and could help s in promoting es the biotechnology application and the bioeconomy. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-09
- Authors: Edoamodu, Chiedu Epiphany https://orcid.org/0000-0002-9254-3955
- Date: 2021-09
- Subjects: Laccase , Water -- Purification
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/22820 , vital:52802
- Description: The continuous outpour of aromatic pollutants in diverse groups, emanating from the industrial and domestic system due to population density, industrialisation and technological advancement is alarming. The increasing strength in wastewater discharge constitutes the main cause of the natural water pollution load, causing scarcity of potable water for consumption with an increasing health challenge. The physiochemical treatment approach has faced a series of limitations with little or no success. Hindrance to wastewater management can cause a point source contamination problem that might increase treatment cost and release a broad range of chemical contaminants in the environment. Hence, green, eco-friendly and cost-effective tools are imperative. The application of laccase has received much attention in bioremediation and bioprocessing matters owing to the oxidising capacity of a wide range of substrates. The process requires available molecular oxygen for its activation, releasing water as a by-product thus, establishing this research. This study was devised to examine the bioprocessing potentials of hybrid and amalgamated laccases extracted from the diverse environmental milieu of the Eastern Cape Province, South Africa. Bacteria producing laccase were isolated from marine sediment, cow dung, and wastewater samples via selective enrichment with some aromatic compounds. The axenic cultures were screened for laccase activity on various phenolic and non-phenolic substrates. The isolates were identified via molecular techniques and they belonged to the gammaproteobacteria and Bacilli classes under the following genera, Enterobacter and Bacillus. They were deposited in the NCBI database as Enterobacter asburiae ES1, Enterobacter sp. Kamsi, Enterobacter sp. AI1, and Bacillus sp. NU2 with the assigned accession number MN686602, MN686603, MN686605, MN686607, respectively. Optimisation of the laccase production via one factor at a time technique (OFAT) from the four bacteria species showed more enzyme yield in all lignocellulosic agro-waste media. However, wheat bran and mandarin peel maximally enhanced laccase production. In addition, xylose, galactose, fructose, and sorbitol were the best carbon sources utilised while (NH₄)₂SO8, KNO3 and NaNO3 were noted as the best nitrogen sources employed. Laccase yields were increased at pH 4 and 5, at temperatures 45 and 55 o C, and at 50 and 100 rpm, and precisely, at day eight of the incubation period. Further purification of the crude laccase yielded a purification fold of 4.18, 4.39, 2.78, 8.11, and the SDS-PAGE analysis showed a molecular size of 90, 55, 75 and 50 kDa for ES1, Kamsi, AI1, and NU2 laccases, respectively. The characterised purified laccase demonstrated polyextremotolerant potentials. The laccases were active through a wide temperature regime (30-90 o C) with maximum activity at 50 o C (ES1/AI1 and Kamsi/NU2) 60 o C (AI1), 70 o C (ES1, Kamsi, NU2); and were stable at 60 o C (ES1, AI1, NU2), 70 o C (ES1/AI1), 80 o C (Kamsi and Kamsi/NU2). Also, the laccases remained active through pH 3 - 8 and optimal at pH 4 (AI1, NU2), pH 5 (Kamsi, ES1/AI1), pH 7 (ES1), pH 8 (Kamsi/NU2), and the individual stability was measured at pH 4 (Kamsi, NU2), pH 5 (AI1), pH 6 (ES1), pH 7 (Kamsi/NU2), pH 10 (ES1/AI1). The purified laccases were either enhanced or left unchanged by a variable concentration of metallic salts, inhibitors, chelating agents and organic solvents. Clearly, the activities of the laccase were enhanced when pre-incubated with 1, 3, and 6 mm of CuCl2, FeCl3, MgCl2, ZnCl2 and AgCl, and 1, 2, 3 mm of Triton x-100, PMSF, EDTA, Tween 20, and NaCl. Additionally, 20, 30, and 10 percent v/v of acetone and DMSO were prominent organic solvents that also stimulated both the hybrid and amalgamated laccase activity. The gene of the purified laccases targeted showed a clear band size of 690 bp for the Enterobacter species laccases and 775 bp for the laccase from Bacillus sp. The protein sequence was deposited in NCBI database with the assigned accession numbers, MW251989, MW25990, MW251992, and MW251994 for ES1, Kamsi, AI1, and NU2 laccases, respectively. The optimised pH and temperature parameter examined on the decolourising potential of the bacteria laccases showed an effective dye removal on the five synthetic dyes (Congo Red (CR), Methyl Orange (MO), Malachite Green (MG), Reactive Blue 4 (RB4), Ramazol Brilliant Blue R (RBBR)) applied. The purified laccases were successfully immobilised in Na-alginate with cca. 88.49, 70.91, 76.04, 76.13, 90.07, and 91.99 laccase yield for the hybrid (ES1, ES1, Kamsi, AI1, NU2) and amalgamated (ES1/AI1 and Kamsi/NU2) laccases. The immobilised laccases were able to retain an average activity of 32 – 52 percent after eight dye decolourising cycles, exhibiting strong catalytic activity than the free laccases. Nonetheless, no significant difference was examined between the hybrid and amalgamated laccase activity. Also, the immobilised laccases were shown to be more efficient in biotechnological application than the free laccases. The result suggests that immobilising an enzyme in a carrier matrix served effectively as the remediation approach than the hybrid and the amalgamation of the free enzymes. Also, the application of lignocellulosic waste served as a cheaper substrate for commercial production of laccase and could help s in promoting es the biotechnology application and the bioeconomy. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-09
Evaluation of medicinal potential of Boophone disticha (L.f.) Herb. used by the indigenous people in the Raymond Mhlaba Municipality Eastern Cape
- Authors: Gwayi, Yamkela
- Date: 2021-09
- Subjects: Bulbs (Plants) , Bulbs (Plant anatomy)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/20612 , vital:46375
- Description: Boophone disticha (L.f.) Herb. is a bulbous plant native to southern African areas of the continent and spreads to tropical Africa. The plant has been noted in literature for its high toxicity and has a long lineage of its use in traditional medicine for the treatment of various diseases. Due to high demand in the conventional trade market, the plant's conservation status has been shown to be declining. The plant has been reported to cause human poisoning, which can lead to death, but the plant is still administered by an indigenous community to treat various diseases. This study investigated the therapeutic potential of B. disticha used by the people of Raymond Mhlaba municipality to show and verify its use in traditional medicine and how it can be used as a possible drug ingredient. This study was also set out to investigate the anti-mycobacterial activity of the plant for the first time for the B. disticha growing in the Eastern Cape region of South Africa. The phytochemical analysis of B. disticha was carried out on four different plant parts (i.e., roots, leaves, bulb inner and outer scales) and the plant was extracted using methanol and distilled water. The qualitative phytochemical analysis displayed the presence of tannins, flavonoids, phenols and alkaloids in all plant parts for both extraction solvents. Anthraquinones were absent in all the plant extracts. The detected phytochemicals (tannins, flavonoids, phenols and alkaloids) were quantified. The roots had the highest phytochemical content for methanol extract for each phytochemical tested [439.67±1.53 mg/g (QE) flavonoids, 2414.67±1.53 mg/g (GAE) phenols and 527.33±2.08 mg/g (GAE) alkaloids] compared to all the plant parts. Methanol extracts from B. disticha revealed highest phenolic contents (2414.67±1.53 mg/g GAE) for the roots, 1395.33±2.52 mg/g (GAE) for the bulb inner scales, 1560±1 mg/g (GAE) for the leaves and 1550.7±18.9 mg/g (GAE) for the bulb outer scales). The total flavonoid content of the bulb outer scales aqueous extract was not detected. The presence of significant amounts of phytochemical compounds indicates that B. disticha has a higher medicinal value and can be extensively investigated to extract bioactive ingredients that are useful to the society, and that could be sold for higher production than using synthetic drugs with side effects. The antimicrobial activity of B. disticha extracts (methanol and distilled water) was evaluated using micro-dilution bioassay in 96-well micro-plates against nine disease-causing bacterial strains (5 Gram-negative and 4 Gram-positive) and three fungal isolates. The results revealed that methanol and aqueous extract of B. disticha demonstrated very good activity, with Gram-positive strains being more sensitive than Gram-negative ones. Boophone disticha aqueous extracts displayed the best activity against Staphylococcus aureus with MIC and MBC values ranging from 0.39 to 0.78 mg/ml. The methanolic extract of B. disticha leaves and outer scales of bulb displayed good activity against Klebsiella pneumoniae at MIC 0.78 mg/ml. The methanolic extract of B. disticha bulb outer scales also displayed good inhibition against Proteus vulgaris at MIC 0.78 mg/ml, with the root extract exhibiting activity against Shigella flexineri (MIC value of 0.078 mg/ml). Concerning antifungal activity, B. disticha extracts showed very poor inhibition properties against the fungal isolates. Anti-mycobacterium potential of B. disticha extracts (methanol and distilled water) was evaluated using micro-dilution bioassay in 96-well microtiter plates. The plant parts tested were the roots, bulb inner scales, leaves and the bulb outer scales. The highest activity against Mycobacterium tuberculosis was observed with the root methanol extract at MIC 0.78 mg/ml. The anti-inflammatory properties of B. disticha were investigated using the 5-lypoxygenase (5- LOX) assay. The overall anti-inflammatory activity results for the B. disticha extracts were poor; at low concentrations, the plant displayed negative results. The leaves methanol extracts did show little activity at 0.4 mg/ml. , Thesis (MSc) (Botany) -- University of Fort Hare, 2021
- Full Text:
- Date Issued: 2021-09
- Authors: Gwayi, Yamkela
- Date: 2021-09
- Subjects: Bulbs (Plants) , Bulbs (Plant anatomy)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/20612 , vital:46375
- Description: Boophone disticha (L.f.) Herb. is a bulbous plant native to southern African areas of the continent and spreads to tropical Africa. The plant has been noted in literature for its high toxicity and has a long lineage of its use in traditional medicine for the treatment of various diseases. Due to high demand in the conventional trade market, the plant's conservation status has been shown to be declining. The plant has been reported to cause human poisoning, which can lead to death, but the plant is still administered by an indigenous community to treat various diseases. This study investigated the therapeutic potential of B. disticha used by the people of Raymond Mhlaba municipality to show and verify its use in traditional medicine and how it can be used as a possible drug ingredient. This study was also set out to investigate the anti-mycobacterial activity of the plant for the first time for the B. disticha growing in the Eastern Cape region of South Africa. The phytochemical analysis of B. disticha was carried out on four different plant parts (i.e., roots, leaves, bulb inner and outer scales) and the plant was extracted using methanol and distilled water. The qualitative phytochemical analysis displayed the presence of tannins, flavonoids, phenols and alkaloids in all plant parts for both extraction solvents. Anthraquinones were absent in all the plant extracts. The detected phytochemicals (tannins, flavonoids, phenols and alkaloids) were quantified. The roots had the highest phytochemical content for methanol extract for each phytochemical tested [439.67±1.53 mg/g (QE) flavonoids, 2414.67±1.53 mg/g (GAE) phenols and 527.33±2.08 mg/g (GAE) alkaloids] compared to all the plant parts. Methanol extracts from B. disticha revealed highest phenolic contents (2414.67±1.53 mg/g GAE) for the roots, 1395.33±2.52 mg/g (GAE) for the bulb inner scales, 1560±1 mg/g (GAE) for the leaves and 1550.7±18.9 mg/g (GAE) for the bulb outer scales). The total flavonoid content of the bulb outer scales aqueous extract was not detected. The presence of significant amounts of phytochemical compounds indicates that B. disticha has a higher medicinal value and can be extensively investigated to extract bioactive ingredients that are useful to the society, and that could be sold for higher production than using synthetic drugs with side effects. The antimicrobial activity of B. disticha extracts (methanol and distilled water) was evaluated using micro-dilution bioassay in 96-well micro-plates against nine disease-causing bacterial strains (5 Gram-negative and 4 Gram-positive) and three fungal isolates. The results revealed that methanol and aqueous extract of B. disticha demonstrated very good activity, with Gram-positive strains being more sensitive than Gram-negative ones. Boophone disticha aqueous extracts displayed the best activity against Staphylococcus aureus with MIC and MBC values ranging from 0.39 to 0.78 mg/ml. The methanolic extract of B. disticha leaves and outer scales of bulb displayed good activity against Klebsiella pneumoniae at MIC 0.78 mg/ml. The methanolic extract of B. disticha bulb outer scales also displayed good inhibition against Proteus vulgaris at MIC 0.78 mg/ml, with the root extract exhibiting activity against Shigella flexineri (MIC value of 0.078 mg/ml). Concerning antifungal activity, B. disticha extracts showed very poor inhibition properties against the fungal isolates. Anti-mycobacterium potential of B. disticha extracts (methanol and distilled water) was evaluated using micro-dilution bioassay in 96-well microtiter plates. The plant parts tested were the roots, bulb inner scales, leaves and the bulb outer scales. The highest activity against Mycobacterium tuberculosis was observed with the root methanol extract at MIC 0.78 mg/ml. The anti-inflammatory properties of B. disticha were investigated using the 5-lypoxygenase (5- LOX) assay. The overall anti-inflammatory activity results for the B. disticha extracts were poor; at low concentrations, the plant displayed negative results. The leaves methanol extracts did show little activity at 0.4 mg/ml. , Thesis (MSc) (Botany) -- University of Fort Hare, 2021
- Full Text:
- Date Issued: 2021-09
In vitro investigation of the anti-hyperglycemic and chemical composition of Heteromorpha arborescens (Spreng.) Cham leaf extracts used in the management of diabetes mellitus
- Abifarin, Taiwo Oluwafunmilola https://orcid.org/00000003-4994-4638
- Authors: Abifarin, Taiwo Oluwafunmilola https://orcid.org/00000003-4994-4638
- Date: 2021-09
- Subjects: Diabetes
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/22798 , vital:52760
- Description: Diabetes mellitus is currently a major threat all over the world. It is a chronic disorder characterized by elevated blood glucose levels and disturbance in carbohydrate, fat and protein metabolism which often times leads to several complications such as, atherosclerosis, diabetic nephropathy, retinopathy and neuropathy. Due to the side effects associated with synthetic oral hypoglycemic drugs, herbal remedies have become the alternative in the management of diabetes mellitus. Heteromorpha arborescens is one of the many plants used as herbal remedies for the management of diabetes mellitus in South Africa. In addition, the roots, barks and leaves are used in other parts of Southern Africa for the treatment of mental problems, asthma, cough, dysentery and tuberculosis. The roots are fed to malnourished children in Botswana and Swaziland. However, despite the high medicinal importance, there is little or no scientificinformation to prove this claim. Therefore, the basis of this study is to determine the chemical composition as well as perform and invitro investigation of the antihyperglycemic potential of H. arborescens leaf extracts to provide information that could validate the ethno-medicinal claims for the use of this plant in the management of diabetes mellitus. Phytochemical contents and antioxidant activity of the leaf extracts were determined. Phytochemical analysis of the acetone, ethanol, aqueous and blanched extracts of H. arborescens leaves indicated that the total phenol content of the extracts ranged between 15.10 mg GAE/g- 42.50 mg QAE/g, proanthocyanidin, 459-8402.1 mg QE/g and the flavonoid content, 109.24- 235.79 mg QE/g. In addition, alkaloids (7.65percent) and saponin (25.33percent) were present in significantamounts. Based on the IC50 values, the ethanol extract exhibited the highest total antioxidant activity (0.0125 mg/mL) with highest inhibition against DPPH and ABTS radicals (0.06 and 0.049 mg/mL respectively). Relatively high antioxidant activity may be attributed to the polyphenolic contents which possess hypoglycemic potentials. Minimum Inhibitory Concentrations (MIC) of H. arborescens leaf extracts against Bacillus pumilus, Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli and Klebselia pneumoniae was also determined and results indicated considerable antibacterial activity in the acetone, ethanol and blanched extracts with MIC values ranging from 1.563-12.5 mg/mL; however, the aqueous extract was inactive against all the bacteria strains. The antibacterial activity of the leaf extracts could be advantageous against diabetic related infections. The cytotoxicity, anti-obesity and antidiabetic potentials of blanched, aqueous and ethanol extracts of Heteromorpha arborescens (Spreng.) Cham leaves were also investigated. The results revealed that both ethanol and aqueous extracts indicated considerable inhibition against α-glucosidase (IC50 of 627.29 ± 4.33 μg/mL and 576.46 ± 3.21 μg/mL respectively) while the blanched extract showed weak α- glucosidase inhibition (IC50; 855.38 ± 4.29 μg/mL). The aqueous extract showed the best α- amylase inhibition (IC50; 583.74 ± 5.87 μg/mL) among the assessed extracts. However, weak α- amylase inhibition was observed in the ethanol (IC50; 724.60 ± 4.33 μg/mL) and blanched extracts (IC50; 791.63 ± 3.76 μg/mL) of H. arborescens leaves. Some level of glucose utilization in both C3A and L6 cells was also observed for the aqueous and ethanol extracts which may be attributed to the relatively lower toxicity levels present in them, however, glucose utilization was very weak for the blanched extract, which may be due to higher level of cytotoxicity it possessed. Relatively weak lipase inhibition was observed for the ethanol (IC50; 699.3 ± 1.33 μg/mL), aqueous (IC50; 811.52 ± 3.52 μg/mL) and blanched extract (IC50; 1152.7 ± 4.61 μg/mL) as compared to orlistat (IC50; 56.88 ± 0.11 μg/mL). However, there was no reasonable reduction in lipid accumulation observed in all the extract treated cells. The results obtained suggest that H.arborescens leaf extracts can serve as a potential tool for the development of new strategies for the treatment of diabetes and obesity. However, further analysis is required to ascertain its anti- obesity potential. Also, caution should be taken in the use of the plant at high concentrations in order to ensure safety and efficacy. Analyses were also carried out to determine the nutritional and antinutritional constituents of the plant for possible inclusion in the diet of diabetic patients. Proximate analysis revealed the presence of 8.5 percent total ash, 4.92 percent crude fat, 8.41 percent moisture, 15.74 percent crude protein, 21.48 percent crude fiber, 40.95 percent carbohydrates and 271.04 kcal/100g energy value. Mineral analysis showed that H. arborescens leaves are very rich in K, Ca, and Fe. Considerable amounts of Mg, Mn, Na, P, Cu and Zn were also present. Vitamin analysis showed that the plant has a high content of vitamins A, C and E. The anti-nutrients evaluated were phytate, oxalate, saponin, and alkaloids, all of which were below toxic levels except for saponin which was observed in moderately high level. This study revealed that H. arborescens leaves are a good source of nutrients and mineral elements, (with low anti-nutrient content) that are highly beneficial to human health especially in diabetic individuals, therefore, encouraging its possible inclusion as a vegetable. Essential oil composition of fresh Heteromorphaarborescens leaves were also determined by Solvent-Free-Microwave-Extraction (SFME) and Hydrodistillation (HD) methods and the compositions of both mehods were compared in terms of their chemical compositions, yield, CO2 emission and energy consumption. Solvent Free Microwave extraction method indicated higher oil yield of 0.7 mL/200 g (0.35 percent) as compared to 0.59 mL/200 g (0.295 percent), lower energy consumption and CO2 emission as compared to the hydrodistillation method. In conclusion, H. arborescens leaves indicated considerable potential efficacy in the management for diabetes mellitus and may require further structural elucidation and characterization in order to identify the bioactive constituents. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-09
- Authors: Abifarin, Taiwo Oluwafunmilola https://orcid.org/00000003-4994-4638
- Date: 2021-09
- Subjects: Diabetes
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/22798 , vital:52760
- Description: Diabetes mellitus is currently a major threat all over the world. It is a chronic disorder characterized by elevated blood glucose levels and disturbance in carbohydrate, fat and protein metabolism which often times leads to several complications such as, atherosclerosis, diabetic nephropathy, retinopathy and neuropathy. Due to the side effects associated with synthetic oral hypoglycemic drugs, herbal remedies have become the alternative in the management of diabetes mellitus. Heteromorpha arborescens is one of the many plants used as herbal remedies for the management of diabetes mellitus in South Africa. In addition, the roots, barks and leaves are used in other parts of Southern Africa for the treatment of mental problems, asthma, cough, dysentery and tuberculosis. The roots are fed to malnourished children in Botswana and Swaziland. However, despite the high medicinal importance, there is little or no scientificinformation to prove this claim. Therefore, the basis of this study is to determine the chemical composition as well as perform and invitro investigation of the antihyperglycemic potential of H. arborescens leaf extracts to provide information that could validate the ethno-medicinal claims for the use of this plant in the management of diabetes mellitus. Phytochemical contents and antioxidant activity of the leaf extracts were determined. Phytochemical analysis of the acetone, ethanol, aqueous and blanched extracts of H. arborescens leaves indicated that the total phenol content of the extracts ranged between 15.10 mg GAE/g- 42.50 mg QAE/g, proanthocyanidin, 459-8402.1 mg QE/g and the flavonoid content, 109.24- 235.79 mg QE/g. In addition, alkaloids (7.65percent) and saponin (25.33percent) were present in significantamounts. Based on the IC50 values, the ethanol extract exhibited the highest total antioxidant activity (0.0125 mg/mL) with highest inhibition against DPPH and ABTS radicals (0.06 and 0.049 mg/mL respectively). Relatively high antioxidant activity may be attributed to the polyphenolic contents which possess hypoglycemic potentials. Minimum Inhibitory Concentrations (MIC) of H. arborescens leaf extracts against Bacillus pumilus, Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli and Klebselia pneumoniae was also determined and results indicated considerable antibacterial activity in the acetone, ethanol and blanched extracts with MIC values ranging from 1.563-12.5 mg/mL; however, the aqueous extract was inactive against all the bacteria strains. The antibacterial activity of the leaf extracts could be advantageous against diabetic related infections. The cytotoxicity, anti-obesity and antidiabetic potentials of blanched, aqueous and ethanol extracts of Heteromorpha arborescens (Spreng.) Cham leaves were also investigated. The results revealed that both ethanol and aqueous extracts indicated considerable inhibition against α-glucosidase (IC50 of 627.29 ± 4.33 μg/mL and 576.46 ± 3.21 μg/mL respectively) while the blanched extract showed weak α- glucosidase inhibition (IC50; 855.38 ± 4.29 μg/mL). The aqueous extract showed the best α- amylase inhibition (IC50; 583.74 ± 5.87 μg/mL) among the assessed extracts. However, weak α- amylase inhibition was observed in the ethanol (IC50; 724.60 ± 4.33 μg/mL) and blanched extracts (IC50; 791.63 ± 3.76 μg/mL) of H. arborescens leaves. Some level of glucose utilization in both C3A and L6 cells was also observed for the aqueous and ethanol extracts which may be attributed to the relatively lower toxicity levels present in them, however, glucose utilization was very weak for the blanched extract, which may be due to higher level of cytotoxicity it possessed. Relatively weak lipase inhibition was observed for the ethanol (IC50; 699.3 ± 1.33 μg/mL), aqueous (IC50; 811.52 ± 3.52 μg/mL) and blanched extract (IC50; 1152.7 ± 4.61 μg/mL) as compared to orlistat (IC50; 56.88 ± 0.11 μg/mL). However, there was no reasonable reduction in lipid accumulation observed in all the extract treated cells. The results obtained suggest that H.arborescens leaf extracts can serve as a potential tool for the development of new strategies for the treatment of diabetes and obesity. However, further analysis is required to ascertain its anti- obesity potential. Also, caution should be taken in the use of the plant at high concentrations in order to ensure safety and efficacy. Analyses were also carried out to determine the nutritional and antinutritional constituents of the plant for possible inclusion in the diet of diabetic patients. Proximate analysis revealed the presence of 8.5 percent total ash, 4.92 percent crude fat, 8.41 percent moisture, 15.74 percent crude protein, 21.48 percent crude fiber, 40.95 percent carbohydrates and 271.04 kcal/100g energy value. Mineral analysis showed that H. arborescens leaves are very rich in K, Ca, and Fe. Considerable amounts of Mg, Mn, Na, P, Cu and Zn were also present. Vitamin analysis showed that the plant has a high content of vitamins A, C and E. The anti-nutrients evaluated were phytate, oxalate, saponin, and alkaloids, all of which were below toxic levels except for saponin which was observed in moderately high level. This study revealed that H. arborescens leaves are a good source of nutrients and mineral elements, (with low anti-nutrient content) that are highly beneficial to human health especially in diabetic individuals, therefore, encouraging its possible inclusion as a vegetable. Essential oil composition of fresh Heteromorphaarborescens leaves were also determined by Solvent-Free-Microwave-Extraction (SFME) and Hydrodistillation (HD) methods and the compositions of both mehods were compared in terms of their chemical compositions, yield, CO2 emission and energy consumption. Solvent Free Microwave extraction method indicated higher oil yield of 0.7 mL/200 g (0.35 percent) as compared to 0.59 mL/200 g (0.295 percent), lower energy consumption and CO2 emission as compared to the hydrodistillation method. In conclusion, H. arborescens leaves indicated considerable potential efficacy in the management for diabetes mellitus and may require further structural elucidation and characterization in order to identify the bioactive constituents. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-09