As stated by Dow, ‘this commodity clearance application is to support the potential shortage of s... more As stated by Dow, ‘this commodity clearance application is to support the potential shortage of soybean in South Africa and the subsequent need to import grain from exporting countries that may be commercially growing DAS-68416-4 and other genetically modified soybean (p.87)’. This is mainly to feed South Africa’s rapidly growing poultry industry. Despite a huge increase in domestically produced soybean in recent years (from 100,000ha cultivated in 1999 to 418,000ha in 2011), production costs (including feed) are squeezing the margins of many domestic producers. A recent, well publicised trade spat with Brazilian poultry producers highlights this (ACB, 2011). The underlying purpose is to open markets for a new generation of herbicide tolerant crops that have been developed in the United States in response to an epidemic of glyphosate tolerant weeds. This will be expanded upon below.
The effective and accurate assessment of the total microbial community diversity is one of the pr... more The effective and accurate assessment of the total microbial community diversity is one of the primary challenges in modem microbial ecology, especially for the detection and characterization of unculturable populations and populations with a low abundance. Accordingly, this study was undertaken to investigate the diversity of the microbial community during the biodegradation of cis- and trans-dichloroethenes in soil and wastewater enrichment cultures. Community profiling using PCR targeting the 16S rRNA gene and denaturing gradient gel electrophoresis (PCR-DGGE) revealed an alteration in the bacterial community profiles with time. Exposure to cis- and trans-dichloroethenes led to the disappearance of certain genospecies that were initially observed in the untreated samples. A cluster analysis of the bacterial DGGE community profiles at various sampling times during the degradation process indicated that the community profile became stable after day 10 of the enrichment. DNA sequenc...
Copyright: 2018, Pretoria: Human Sciences Research Council, also the Africa Institute of South Af... more Copyright: 2018, Pretoria: Human Sciences Research Council, also the Africa Institute of South Africa. Due to copyright restrictions, the attached PDF file only contains the pre-print version of the full-text item. For access to the full-text item, please consult the publisher's website.
Renewable Energy Technologies are rapidly gaining uptake in South Africa, already having more tha... more Renewable Energy Technologies are rapidly gaining uptake in South Africa, already having more than 3900 MW operational wind, solar PV, Concentrating Solar Power (CSP) and biogas capacity. CSP has the potential to become a leading Renewable Energy Technology, as it is the only one inherently equipped with the facility for large-scale thermal energy storage for increased dispatchability. There are many studies that aim to determine the potential for CSP development in certain regions or countries. South Africa has a high solar irradiation resource by global standards, but few studies have been carried out to determine the potential for CSP. One such study was conducted in 2009, prior to any CSP plants having been built in South Africa. As part of a broader study to determine the impact of CSP on South Africa’s water resources, a geospatial approach was used to optimise this potential based on technological changes and improved spatial data. A tiered approach, using a comprehensive set...
A systematic approach to evaluate Concentrating Solar Power (CSP) plant fleet deployment and sust... more A systematic approach to evaluate Concentrating Solar Power (CSP) plant fleet deployment and sustainable water resource use in arid regions is presented. An overview is given of previous work carried out. Once CSP development scenarios, suitable areas for development, and the water demand from CSP operations were evaluated, appropriate spatiotemporal CSP performance models were developed. The resulting consumptive patterns and the impact of variable resource availability on CSP plant operation are analysed. This evaluation considered the whole of South Africa, with focus on the areas identified as suitable for CSP, in order to study the impact on local water resources. It was found that the hydrological limitations imposed by variable water resources on CSP development are severe. The national annual theoretical net generation potential of wet-cooled Parabolic Trough decreased from 11,277 to 120 TWh, and that of wet-cooled Central Receiver decreased from 12,003 to 170 TWh. Dry coole...
Wiley Interdisciplinary Reviews: Energy and Environment
Copyright: 2017 Wiley. Due to copyright restrictions, the attached PDF file only contains the abs... more Copyright: 2017 Wiley. Due to copyright restrictions, the attached PDF file only contains the abstract of the full text item. For access to the full text item, please consult the publisher's website.
South Africa has experienced great uncertainty in its electricity supply sector. Many energy syst... more South Africa has experienced great uncertainty in its electricity supply sector. Many energy system modeling efforts have been undertaken. This is to determine the most appropriate energy mix and manage uncertainty. We review all available, relevant studies and summarize their results, modeling approaches, and input assumptions. From this, we try to understand their impact on CSP development in South Africa.
The Bacillus licheniformis ydaP gene encodes for a pyruvate oxidase that catalyses the oxidative ... more The Bacillus licheniformis ydaP gene encodes for a pyruvate oxidase that catalyses the oxidative decarboxylation of pyruvate to acetate and CO. The YdaP form of this enzyme was purified about 48.6-folds to homogeneity in three steps. The enzyme was recovered in a soluble form and demonstrated significant activity on pyruvate using 2, 6-dichlorophenolindophenol (DCPIP) as an artificial electron acceptor. HPLC analysis of the YdaP-enzyme catalysed conversion of pyruvate showed acetate as the sole product, confirming the putative identity of pyruvate oxidase. Analysis of the substrate specificity showed that the YdaP enzyme demonstrated preference for short chain oxo acids; however, it was activated by 1% Triton X-100. The YdaP substrate-binding pocket from the YdaP protein differed substantially from the equivalent site in all of the so far characterized pyruvate oxidases, suggesting that the B. licheniformis YdaP might accept different substrates. This could allow more accessibility ...
The effective and accurate assessment of the total microbial community diversity is one of the pr... more The effective and accurate assessment of the total microbial community diversity is one of the primary challenges in modem microbial ecology, especially for the detection and characterization of unculturable populations and populations with a low abundance. Accordingly, this study was undertaken to investigate the diversity of the microbial community during the biodegradation of cis- and trans-dichloroethenes in soil and wastewater enrichment cultures. Community profiling using PCR targeting the 16S rRNA gene and denaturing gradient gel electrophoresis (PCR-DGGE) revealed an alteration in the bacterial community profiles with time. Exposure to cis- and trans-dichloroethenes led to the disappearance of certain genospecies that were initially observed in the untreated samples. A cluster analysis of the bacterial DGGE community profiles at various sampling times during the degradation process indicated that the community profile became stable after day 10 of the enrichment. DNA sequenc...
It is now widely accepted that the application of standard microbiological methods for the recove... more It is now widely accepted that the application of standard microbiological methods for the recovery of microorganisms from the environment has had limited success in providing access to the true extent of microbial biodiversity. It follows that much of the extant microbial genetic diversity (collectively termed the metagenome) remains unexploited, an issue of considerable relevance to a wider understanding of microbial communities and of considerable importance to the biotechnology industry. The recent development of technologies designed to access this wealth of genetic information through environmental nucleic acid extraction has provided a means of avoiding the limitations of culture-dependent genetic exploitation.
As stated by Dow, ‘this commodity clearance application is to support the potential shortage of s... more As stated by Dow, ‘this commodity clearance application is to support the potential shortage of soybean in South Africa and the subsequent need to import grain from exporting countries that may be commercially growing DAS-68416-4 and other genetically modified soybean (p.87)’. This is mainly to feed South Africa’s rapidly growing poultry industry. Despite a huge increase in domestically produced soybean in recent years (from 100,000ha cultivated in 1999 to 418,000ha in 2011), production costs (including feed) are squeezing the margins of many domestic producers. A recent, well publicised trade spat with Brazilian poultry producers highlights this (ACB, 2011). The underlying purpose is to open markets for a new generation of herbicide tolerant crops that have been developed in the United States in response to an epidemic of glyphosate tolerant weeds. This will be expanded upon below.
The effective and accurate assessment of the total microbial community diversity is one of the pr... more The effective and accurate assessment of the total microbial community diversity is one of the primary challenges in modem microbial ecology, especially for the detection and characterization of unculturable populations and populations with a low abundance. Accordingly, this study was undertaken to investigate the diversity of the microbial community during the biodegradation of cis- and trans-dichloroethenes in soil and wastewater enrichment cultures. Community profiling using PCR targeting the 16S rRNA gene and denaturing gradient gel electrophoresis (PCR-DGGE) revealed an alteration in the bacterial community profiles with time. Exposure to cis- and trans-dichloroethenes led to the disappearance of certain genospecies that were initially observed in the untreated samples. A cluster analysis of the bacterial DGGE community profiles at various sampling times during the degradation process indicated that the community profile became stable after day 10 of the enrichment. DNA sequenc...
Copyright: 2018, Pretoria: Human Sciences Research Council, also the Africa Institute of South Af... more Copyright: 2018, Pretoria: Human Sciences Research Council, also the Africa Institute of South Africa. Due to copyright restrictions, the attached PDF file only contains the pre-print version of the full-text item. For access to the full-text item, please consult the publisher's website.
Renewable Energy Technologies are rapidly gaining uptake in South Africa, already having more tha... more Renewable Energy Technologies are rapidly gaining uptake in South Africa, already having more than 3900 MW operational wind, solar PV, Concentrating Solar Power (CSP) and biogas capacity. CSP has the potential to become a leading Renewable Energy Technology, as it is the only one inherently equipped with the facility for large-scale thermal energy storage for increased dispatchability. There are many studies that aim to determine the potential for CSP development in certain regions or countries. South Africa has a high solar irradiation resource by global standards, but few studies have been carried out to determine the potential for CSP. One such study was conducted in 2009, prior to any CSP plants having been built in South Africa. As part of a broader study to determine the impact of CSP on South Africa’s water resources, a geospatial approach was used to optimise this potential based on technological changes and improved spatial data. A tiered approach, using a comprehensive set...
A systematic approach to evaluate Concentrating Solar Power (CSP) plant fleet deployment and sust... more A systematic approach to evaluate Concentrating Solar Power (CSP) plant fleet deployment and sustainable water resource use in arid regions is presented. An overview is given of previous work carried out. Once CSP development scenarios, suitable areas for development, and the water demand from CSP operations were evaluated, appropriate spatiotemporal CSP performance models were developed. The resulting consumptive patterns and the impact of variable resource availability on CSP plant operation are analysed. This evaluation considered the whole of South Africa, with focus on the areas identified as suitable for CSP, in order to study the impact on local water resources. It was found that the hydrological limitations imposed by variable water resources on CSP development are severe. The national annual theoretical net generation potential of wet-cooled Parabolic Trough decreased from 11,277 to 120 TWh, and that of wet-cooled Central Receiver decreased from 12,003 to 170 TWh. Dry coole...
Wiley Interdisciplinary Reviews: Energy and Environment
Copyright: 2017 Wiley. Due to copyright restrictions, the attached PDF file only contains the abs... more Copyright: 2017 Wiley. Due to copyright restrictions, the attached PDF file only contains the abstract of the full text item. For access to the full text item, please consult the publisher's website.
South Africa has experienced great uncertainty in its electricity supply sector. Many energy syst... more South Africa has experienced great uncertainty in its electricity supply sector. Many energy system modeling efforts have been undertaken. This is to determine the most appropriate energy mix and manage uncertainty. We review all available, relevant studies and summarize their results, modeling approaches, and input assumptions. From this, we try to understand their impact on CSP development in South Africa.
The Bacillus licheniformis ydaP gene encodes for a pyruvate oxidase that catalyses the oxidative ... more The Bacillus licheniformis ydaP gene encodes for a pyruvate oxidase that catalyses the oxidative decarboxylation of pyruvate to acetate and CO. The YdaP form of this enzyme was purified about 48.6-folds to homogeneity in three steps. The enzyme was recovered in a soluble form and demonstrated significant activity on pyruvate using 2, 6-dichlorophenolindophenol (DCPIP) as an artificial electron acceptor. HPLC analysis of the YdaP-enzyme catalysed conversion of pyruvate showed acetate as the sole product, confirming the putative identity of pyruvate oxidase. Analysis of the substrate specificity showed that the YdaP enzyme demonstrated preference for short chain oxo acids; however, it was activated by 1% Triton X-100. The YdaP substrate-binding pocket from the YdaP protein differed substantially from the equivalent site in all of the so far characterized pyruvate oxidases, suggesting that the B. licheniformis YdaP might accept different substrates. This could allow more accessibility ...
The effective and accurate assessment of the total microbial community diversity is one of the pr... more The effective and accurate assessment of the total microbial community diversity is one of the primary challenges in modem microbial ecology, especially for the detection and characterization of unculturable populations and populations with a low abundance. Accordingly, this study was undertaken to investigate the diversity of the microbial community during the biodegradation of cis- and trans-dichloroethenes in soil and wastewater enrichment cultures. Community profiling using PCR targeting the 16S rRNA gene and denaturing gradient gel electrophoresis (PCR-DGGE) revealed an alteration in the bacterial community profiles with time. Exposure to cis- and trans-dichloroethenes led to the disappearance of certain genospecies that were initially observed in the untreated samples. A cluster analysis of the bacterial DGGE community profiles at various sampling times during the degradation process indicated that the community profile became stable after day 10 of the enrichment. DNA sequenc...
It is now widely accepted that the application of standard microbiological methods for the recove... more It is now widely accepted that the application of standard microbiological methods for the recovery of microorganisms from the environment has had limited success in providing access to the true extent of microbial biodiversity. It follows that much of the extant microbial genetic diversity (collectively termed the metagenome) remains unexploited, an issue of considerable relevance to a wider understanding of microbial communities and of considerable importance to the biotechnology industry. The recent development of technologies designed to access this wealth of genetic information through environmental nucleic acid extraction has provided a means of avoiding the limitations of culture-dependent genetic exploitation.
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Papers by William H L Stafford