Assessing the potential role of microorganisms in the production of seedlings for the restoration of Albany Thicket
- Authors: Mpama, Nelisa
- Date: 2017
- Subjects: Vesicular-arbuscular mycorrhizas , Rhizobacteria , Restoration ecology South Africa Albany , Microorganisms
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/64555 , vital:28558
- Description: The role of microorganisms in restoration of the Albany Thicket has not been well documented, although the benefits to plants of these various interactions has been well documented. Microorganisms are chief ecological engineers and assist in resolving environmental problems and act to restore degraded ecosystem function by forming mutual relationships with the roots of the plants. The aim of this study was to assess the potential of microorganisms for the improved biomass production of selected woody and succulent seedlings used in mesic thicket restoration. Three tree species were selected for propagation in this study namely; Mystroxylon aethiopicum Scutia myrtina and Aloe ferox. Soil samples were collected from a degraded and intact thicket site from Bathurst, South Africa. Soils were evaluated for number of arbuscular mycorrhizal (AM) spores, mycorrhizal infectivity potential and nutrient availability both before and after seedling propagation. Pasteurized soil from the degraded site was used in a pot trial. Ten replicates seedling for plant species were planted and subjected to four treatments which included inoculation with AM fungi and the rhizobacterium, Enterobacter sp., alone and in combination; the fourth treatment was an un-inouclated control. Plant growth parameters were recorded at regular intervals where appropriate and seedlings were harvested after 24 weeks for biomass measurements and AM colonisation assessments. Although generally low (< 1 spore per gram) the density of AM fungal spores was significantly higher in soils from the intact site when compared with soils from the degraded site. The mycorrhizal potential of the soils was however not significantly different. Mystroxylon aethiopicum seedling shoot height, canopy diameter and shoot biomass showed a significant increase when inoculated with AM fungi while S. myrtina seedlings showed increased shoot height when inoculated with both AM fungi and Enterobacter sp. Aloe ferox seedlings did not respond to microbial inoculation. The concentration of soil P and Na increased in treatments with Enterobacter sp. alone and in combination with AM fungi. Mystroxylon aethiopicum and S. myrtina seedlings showed a dependency on microbial inoculants indicating the importance of inoculation in the nursery before planting out into the field. Overall AM fungal inoculants applied to seedlings can be used to compensate for nutrient deficiency in soils. Although the Enterobacter isolate used was known to have various plant growth promoting capabilities. It is recommended that other rhizobacterial isolates be investigated. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2017
- Full Text:
- Authors: Mpama, Nelisa
- Date: 2017
- Subjects: Vesicular-arbuscular mycorrhizas , Rhizobacteria , Restoration ecology South Africa Albany , Microorganisms
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/64555 , vital:28558
- Description: The role of microorganisms in restoration of the Albany Thicket has not been well documented, although the benefits to plants of these various interactions has been well documented. Microorganisms are chief ecological engineers and assist in resolving environmental problems and act to restore degraded ecosystem function by forming mutual relationships with the roots of the plants. The aim of this study was to assess the potential of microorganisms for the improved biomass production of selected woody and succulent seedlings used in mesic thicket restoration. Three tree species were selected for propagation in this study namely; Mystroxylon aethiopicum Scutia myrtina and Aloe ferox. Soil samples were collected from a degraded and intact thicket site from Bathurst, South Africa. Soils were evaluated for number of arbuscular mycorrhizal (AM) spores, mycorrhizal infectivity potential and nutrient availability both before and after seedling propagation. Pasteurized soil from the degraded site was used in a pot trial. Ten replicates seedling for plant species were planted and subjected to four treatments which included inoculation with AM fungi and the rhizobacterium, Enterobacter sp., alone and in combination; the fourth treatment was an un-inouclated control. Plant growth parameters were recorded at regular intervals where appropriate and seedlings were harvested after 24 weeks for biomass measurements and AM colonisation assessments. Although generally low (< 1 spore per gram) the density of AM fungal spores was significantly higher in soils from the intact site when compared with soils from the degraded site. The mycorrhizal potential of the soils was however not significantly different. Mystroxylon aethiopicum seedling shoot height, canopy diameter and shoot biomass showed a significant increase when inoculated with AM fungi while S. myrtina seedlings showed increased shoot height when inoculated with both AM fungi and Enterobacter sp. Aloe ferox seedlings did not respond to microbial inoculation. The concentration of soil P and Na increased in treatments with Enterobacter sp. alone and in combination with AM fungi. Mystroxylon aethiopicum and S. myrtina seedlings showed a dependency on microbial inoculants indicating the importance of inoculation in the nursery before planting out into the field. Overall AM fungal inoculants applied to seedlings can be used to compensate for nutrient deficiency in soils. Although the Enterobacter isolate used was known to have various plant growth promoting capabilities. It is recommended that other rhizobacterial isolates be investigated. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2017
- Full Text:
Synthesis, characterisation and evaluation of benzoxaborole-based hybrids as antiplasmodial agents
- Authors: Gumbo, Maureen
- Date: 2017
- Subjects: Malaria Chemotherapy , Antimalarials , Boron compounds , Drug resistance , Plasmodium falciparum , Drug development
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/59193 , vital:27456
- Description: Malaria is a mosquito-borne disease, which continues to pose a threat to the entire humanity. About 40% of the world population is estimated to be at risk of infections by malaria. Despite efforts undertaken by scientific community, government entities and international organizations, malaria is still rampant. The major problem is drug resistance, where the Plasmodium spp have over the past decades developed drug resistance against available drugs. In order to counter this problem, novel antimalarial drugs that are efficacious and with novel mode of action are of great necessity. Benzoxaborole derivatives have been shown to exhibit promising antimalarial activity against Plasmodium falciparum strains. Previous studies reported on the compounds such as 6-(2- (alkoxycarbonyl)pyrazinyl-5-oxy)-1,3-dihydro-1-hydroxy-2,1-benzoxaboroles, which showed good antimalarial activity against both W7 and 3D7 strains without significant toxicity. On the other hand, chloroquine (CQ) and cinnamic acids have a wide variety of biological activity including antimalarial activity. Herein, a hybridisation strategy was employed to synthesise new CQ-benzoxaborole and cinnamoyl-benzoxaborole hybrids. CQ-Benzoxaborole 2.12a-c and cinnamoylbenzoxaborole 2.11a-g hydrid molecules were synthesised in low to good yields. Their structural identities were confirmed using conventional spectroscopic techniques (1H and 13C NMR, and mass spectrometry). CQ-benzoxaborole compounds, however, showed instability, and only 2.12b was used for in vitro biological assay and showed activity comparable to CQ. Furthermore, in vitro biological assay revealed that compounds 2.11a-g poorly inhibited the growth of P. falciparum parasites. Interestingly, these compounds, however, exhibited satisfactory activity against Trypanosoma brucei with IC50 = 0.052 μM for compound 2.11g. The cell cytotoxicity assay of all final compounds confirmed that all CQ-benzoxaborole 2.12b and cinnamoyl-benzoxaborole 2.11a-g hybrids were non-toxic against HeLa cell lines. However, efforts to further expand the structure-activity relationship (SAR) of CQbenzoxaborole by increasing the length of the linker with one extra carbon (Scheme 2.10) were not possible as an important precursor 6-formylbenzoxaborole 2.29 could not be synthesized in sufficient yields. , Thesis (MSc) -- Faculty of Faculty of Science, Chemistry, 2017
- Full Text:
- Authors: Gumbo, Maureen
- Date: 2017
- Subjects: Malaria Chemotherapy , Antimalarials , Boron compounds , Drug resistance , Plasmodium falciparum , Drug development
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/59193 , vital:27456
- Description: Malaria is a mosquito-borne disease, which continues to pose a threat to the entire humanity. About 40% of the world population is estimated to be at risk of infections by malaria. Despite efforts undertaken by scientific community, government entities and international organizations, malaria is still rampant. The major problem is drug resistance, where the Plasmodium spp have over the past decades developed drug resistance against available drugs. In order to counter this problem, novel antimalarial drugs that are efficacious and with novel mode of action are of great necessity. Benzoxaborole derivatives have been shown to exhibit promising antimalarial activity against Plasmodium falciparum strains. Previous studies reported on the compounds such as 6-(2- (alkoxycarbonyl)pyrazinyl-5-oxy)-1,3-dihydro-1-hydroxy-2,1-benzoxaboroles, which showed good antimalarial activity against both W7 and 3D7 strains without significant toxicity. On the other hand, chloroquine (CQ) and cinnamic acids have a wide variety of biological activity including antimalarial activity. Herein, a hybridisation strategy was employed to synthesise new CQ-benzoxaborole and cinnamoyl-benzoxaborole hybrids. CQ-Benzoxaborole 2.12a-c and cinnamoylbenzoxaborole 2.11a-g hydrid molecules were synthesised in low to good yields. Their structural identities were confirmed using conventional spectroscopic techniques (1H and 13C NMR, and mass spectrometry). CQ-benzoxaborole compounds, however, showed instability, and only 2.12b was used for in vitro biological assay and showed activity comparable to CQ. Furthermore, in vitro biological assay revealed that compounds 2.11a-g poorly inhibited the growth of P. falciparum parasites. Interestingly, these compounds, however, exhibited satisfactory activity against Trypanosoma brucei with IC50 = 0.052 μM for compound 2.11g. The cell cytotoxicity assay of all final compounds confirmed that all CQ-benzoxaborole 2.12b and cinnamoyl-benzoxaborole 2.11a-g hybrids were non-toxic against HeLa cell lines. However, efforts to further expand the structure-activity relationship (SAR) of CQbenzoxaborole by increasing the length of the linker with one extra carbon (Scheme 2.10) were not possible as an important precursor 6-formylbenzoxaborole 2.29 could not be synthesized in sufficient yields. , Thesis (MSc) -- Faculty of Faculty of Science, Chemistry, 2017
- Full Text:
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