Roshini Govinden | University of KwaZulu-Natal (original) (raw)
Papers by Roshini Govinden
Journal of Food Protection, 2002
This study was undertaken to determine the effectiveness of modified atmospheres and packaging ma... more This study was undertaken to determine the effectiveness of modified atmospheres and packaging materials on the growth of Penicillium expansum and patulin production in apples. Granny Smith apples were surface sterilized with 76% ethanol and inoculated with 0.1 ml of a 1.1 × 107 spore/ml P. expansum spore suspension. The apples were packaged either in polyethylene (PE) or polypropylene (PP) and treated with three different gas combinations, viz., 58% CO2/42% N2, 48% CO2/52% N2, and 88% CO2/12% N2, and were then incubated for 14 days at 25°C. Fungal growth was monitored every 2 to 4 days by measuring radial growth from the point of inoculation. After the 14th day, apples were pulped, and patulin was extracted, purified, and quantified by high-performance liquid chromatography. PP did not inhibit fungal growth in any of the atmospheres tested, and it only inhibited patulin production in atmospheric gas and 58% CO2/42% N2. PE was very effective and inhibited fungal growth by four- or f...
Scientific Reports
Dendritic cells (DCs) are the antigen-presenting cells that initiate and direct adaptive immune r... more Dendritic cells (DCs) are the antigen-presenting cells that initiate and direct adaptive immune responses, and thus are critically important in vaccine design. Although DC-targeting vaccines have attracted attention, relevant studies on chicken are rare. A high diversity T7 phage display nanobody library was constructed for bio-panning of intact chicken bone marrow DCs to find DC-specific binding nanobodies. After three rounds of screening, 46 unique sequence phage clones were identified from 125 randomly selected phage clones. Several DC-binding phage clones were selected using the specificity assay. Phage-54, -74, -16 and -121 bound not only with chicken DCs, but also with duck and goose DCs. In vitro, confocal microscopy observation demonstrated that phage-54 and phage-74 efficiently adsorbed onto DCs within 15 min compared to T7-wt. The pull-down assay, however, did not detect any of the previously reported proteins for chicken DCs that could have interacted with the nanobodies ...
Journal of Food …, 2002
This study was undertaken to determine the effectiveness of modified atmospheres and packaging ma... more This study was undertaken to determine the effectiveness of modified atmospheres and packaging materials on the growth of Penicillium expansum and patulin production in apples. Granny Smith apples were surface sterilized with 76% ethanol and inoculated with 0.1 ml of a 1.1 x 10(7) spore/ml P. expansum spore suspension. The apples were packaged either in polyethylene (PE) or polypropylene (PP) and treated with three different gas combinations, viz., 58% CO2/42% N2, 48% CO2/52% N2, and 88% CO2/12% N2, and were then incubated for 14 days at 25 degrees C. Fungal growth was monitored every 2 to 4 days by measuring radial growth from the point of inoculation. After the 14th day, apples were pulped, and patulin was extracted, purified, and quantified by high-performance liquid chromatography. PP did not inhibit fungal growth in any of the atmospheres tested, and it only inhibited patulin production in atmospheric gas and 58% CO2/42% N2. PE was very effective and inhibited fungal growth by four- or fivefold, depending on the modified atmosphere. Patulin production in PE-packaged apples was almost completely inhibited by all three gas combinations. Gas chromatographic analysis of the PE-packaged samples before and after the incubation period showed that CO2 levels dropped and N2 levels increased for all of the atmospheres tested. Our studies showed conclusively that PE is an excellent packaging material for the storage of apples since it inhibited the growth of P. expansum, thereby allowing <3.2 microg/ml of patulin to be produced, regardless of gaseous environment.
![Research paper thumbnail of Genealogy, expression, and cellular function of transforming growth factor-[beta]](https://attachments.academia-assets.com/82178823/thumbnails/1.jpg)
](Pharmacology & therapeutics, 2003
The transforming growth factor-β (TGF-β) gene superfamily expresses a large set of structurally a... more The transforming growth factor-β (TGF-β) gene superfamily expresses a large set of structurally and functionally related polypeptides. Three TGF-β isoforms are regulated by specific genes and have been identified in mammals (TGF-β1, -β2, and -β3). All three-protein isoforms ...
AFRICAN JOURNAL OF BIOTECHNOLOGY
Eucalyptus is the predominant exotic wood species used in South African pulp and paper industry. ... more Eucalyptus is the predominant exotic wood species used in South African pulp and paper industry. Once chipped and stored in piles, the wood becomes vulnerable to microbial degradation and spontaneous combustion. The denaturing gradient gel electrophoresis (DGGE) technique was optimized for the detection of microbial diversity in the wood. Wood chips were collected and milled to different specifications. The 16S and 18S rRNA genes were amplified using 338F-GC/518R and 933F-GC/1387R for bacteria and NS26/518R-GC and EF4F/518R for fungi. Several gel gradients were examined to determine optimal separation. A comparison of DGGE profiles revealed greater diversity in the milled wood chips amplified using primer sets of 338F-GC/518R (16S) and NS26/518R-GC (18S) with gradients of 30/60% (16S) and 25/50% (18S), respectively. Once optimized, this protocol was tested against five samples to assess its applicability to wood chip samples. Profiles were generated and amplicons excised from gels, ...
Additional file 1: Figure S1. Pyrogram of commercial PHB. Figure S2. Pyrogram of commercial PHBV.... more Additional file 1: Figure S1. Pyrogram of commercial PHB. Figure S2. Pyrogram of commercial PHBV. Figure S3. Pyrogram of PHA extracted after cycle 1 of cyclic fed-batch fermentation. Figure S4. Pyrogram of PHA extracted after cycle 2 of cyclic fed-batch fermentation. Figure S5. Pyrogram of PHA extracted after cycle 3 of cyclic fed-batch fermentation. Figure S6. Pyrogram of PHA extracted after cycle 4 of cyclic fed-batch fermentation.
Lipophilic extractives naturally occurring in wood tend to coalesce during pulping to form pitch ... more Lipophilic extractives naturally occurring in wood tend to coalesce during pulping to form pitch deposits, which have particularly undesirable effects on the pulping process and quality of pulp produced. A chemical characterization of different eucalypt species [Eucalyptus nitens, E. grandis, and E. dunnii (of different site qualities)] wood and generated pulp was performed. This study aimed at determining the effects of wood storage at-20 °C (for 6 months), by examining their chemical composition and indigenous microflora. Fatty acids were the main lipophilic compounds among E. dunnii (SQ3 and SQ4) and E. grandis wood extractives. The wood of E. nitens posed the least risk for pitch deposit formation, making it the most suitable Eucalyptus species for pulping. Storage of wood chips at-20 °C had a similar effect as the traditional method of seasoning (storage of wood outdoors prior to pulping) used for the reduction of lipophilic extractives. A 25 to 44% reduction of total extractiv...
Background: South Africa, with its scientific capacity, good infrastructure and high HIV incidenc... more Background: South Africa, with its scientific capacity, good infrastructure and high HIV incidence rates, is ideally positioned to conduct large-scale HIV prevention trials. The HIV Prevention Research Unit of the South African Medical Research Council conducted four phase III and one phase IIb trials of women-initiated HIV prevention options in KwaZulu-Natal between 2003 and 2009. A total of 7046 women participated, with HIV prevalence between 25 % and 45 % and HIV incidence ranging from 4.5-9.1 % per year. Unfortunately none of the interventions tested had any impact on reducing the risk of HIV acquisition; however, extremely valuable experience was gained, lessons learned and capacity built, while the communities gained associated benefits. Experience: Our experience in conducting these trials ranged from setting up community partnerships to developing clinical research sites and dissemination of trial results. Community engagement included setting up communitybased research site...
women [1], and the number of new HIV infections in women worldwide continues to escalate. The hig... more women [1], and the number of new HIV infections in women worldwide continues to escalate. The high incidence of HIV in many African countries provides the optimum environment for research on technologies that could prevent women from becoming infected, including microbicides. In this article, we discuss the recent highly publicised closure of a trial of cellulose sulphate (CS), which we conducted. We discuss the impact of the closure on the participants, the community at the trial site and the public at large, the public health sector,
Mycotoxin contamination of feeds results in economic loss and transmission of toxins in the food ... more Mycotoxin contamination of feeds results in economic loss and transmission of toxins in the food chain. Animal feeds, the raw ingredients used in their manufacture, namely, maize, wheat, sunflower seeds, cottonseeds, bagasse, wheaten bran, gluten feed and pet foods from South Africa were surveyed for contaminating mycotoxin-producing fungi and their toxins: aflatoxins, fumonisins, zearalenone and ochratoxins. Toxins were extracted and analysed by high performance liquid chromatography and fluorometry. Twenty-one of the twenty-three samples were contaminated by Aspergillus flavus which co-occurred with A. parasiticus in two samples, A. tamarii in seven and Fusarium moniliforme in one. Rhizopus stolonifer, R. oryzae and yeast were also isolated. Aflatoxins were detected in seventeen samples, fumonisin in six and zearalenone in three. Aflatoxin levels ranged between 0.8 ± 0.2 and 156 ± 8 µg/kg (ppb), zearalenone between 100 ± 10.5 and 165 000 ± 200 µg/kg and fumonisin B1 between 15 ± 3...
Frontiers in Microbiology, 2021
Bacteriophage T7 gene 17.5 coding for the only known holin is one of the components of its lysis ... more Bacteriophage T7 gene 17.5 coding for the only known holin is one of the components of its lysis system, but the holin activity in T7 is more complex than a single gene, and evidence points to the existence of additional T7 genes with holin activity. In this study, a T7 phage with a gene 17.5 deletion (T7-△holin) was rescued and its biological characteristics and effect on cell lysis were determined. Furthermore, the genomic evolution of mutant phage T7-△holin during serial passage was assessed by whole-genome sequencing analysis. It was observed that deletion of gene 17.5 from phage T7 delays lysis time and enlarges the phage burst size; however, this biological characteristic recovered to normal lysis levels during serial passage. Scanning electron microscopy showed that the two opposite ends of E. coli BL21 cells swell post-T7-△holin infection rather than drilling holes on cell membrane when compared with T7 wild-type infection. No visible progeny phage particle accumulation was ...
Scientific Reports
Fungal endophytes have the capacity to biosynthesize secondary metabolites that are produced by t... more Fungal endophytes have the capacity to biosynthesize secondary metabolites that are produced by their host plants. In this study, a dilactone terpenoid of C16 architecture was isolated from the fungal endophytes of Kigeliaafricana, in our attempt to identify anti-Pseudomonasaeruginosa metabolites. Thirty-eight fungal isolates were cultured for biomolecule production over a period of thirty days. Extracts from three (ZF 34, ZF 52 and ZF 91) of the fungi showed good anti-P.aeruginosa activity, with ZF 52 presenting the best MIC of 19.53 µg/mL and was accordingly subjected to chromatographic separation. Based on nuclear magnetic resonance (NMR) spectroscopy, high resolution mass spectrometry and single crystal X-ray diffraction (XRD) analyses, the isolated compound was identified as a C16-terpene dilactone, with a structure consistent with that of the known diterpene, CJ-14445. The isolated dilactone showed anti-P.aeruginosa activity with MIC of 0.61 µg/mL, signifying the antibacterial...
Background: South Africa, with its scientific capacity, good infrastructure and high HIV incidenc... more Background: South Africa, with its scientific capacity, good infrastructure and high HIV incidence rates, is ideally positioned to conduct large-scale HIV prevention trials. The HIV Prevention Research Unit of the South African Medical Research Council conducted four phase III and one phase IIb trials of women-initiated HIV prevention options in KwaZulu-Natal between 2003 and 2009. A total of 7046 women participated, with HIV prevalence between 25% and 45% and HIV incidence ranging from 4.5-9.1% per year. Unfortunately none of the interventions tested had any impact on reducing the risk of HIV acquisition; however, extremely valuable experience was gained, lessons learned and capacity built, while the communities gained associated benefits. Experience: Our experience in conducting these trials ranged from setting up community partnerships to developing clinical research sites and dissemination of trial results. Community engagement included setting up communitybased research sites w...
Current Trends in Biotechnology and Pharmacy, 2017
The objective of this present study was to isolate, identify and screen for potential fungal isol... more The objective of this present study was to isolate, identify and screen for potential fungal isolates from local wood chips with respect to xylanase production. The fungal strains were isolated from degrading wood chips. All the fungal strains were screened for their ability to produce xylanase by the plate screening method using Congo red as indicator. Two isolates were further selected among them and screened for the production of the enzymes in liquid medium and identified by 18S rRNA. Phialophora alba, had the highest xylanase activity of 24.43 U/ml with temperature optima at 50°C and 90°C respectively. Enzymatic hydrolysis of pre-treated sugarcane bagasse using crude enzyme resulted in the production of 0.36 g/ml reducing sugars after 48 hours. This is the first report of a thermophilic xylanase from Phialophora alba. These results suggest that the application of this xylanase in bioethanol production may be very promising.
Journal of Wood Chemistry and Technology, 2020
The South African pulp and paper industry generates an estimated 0.5 million tons of pulp and pap... more The South African pulp and paper industry generates an estimated 0.5 million tons of pulp and paper mill sludge (PPMS) annually. As PPMS is generated, it requires safe, efficient, and economical collection and disposal. However, PPMS is typically land-filled and subsequently emits nuisance odors, methane, and leaches toxins. Thus, PPMS is an environmental hazard and a potential pollutant of air, soil, and water systems. PPMS is primarily composed of cellulose and coupled with the prospect of biorefinery practices, a value-added product such as glucose-rich hydrolyzate can be derived from this lignocellulosic waste stream. The current study applied a Box-Behnken design to establish the appropriate conditions to obtain the highest possible yield of glucose from PPMS. The PPMS contained 6.89% ash and 64.21% cellulose. De-ashing using acidic pretreatment reduced the ash content by 51%, thereby increasing the amenability of the cellulose fibers to enzymatic hydrolysis. The optimized cond...
Canadian Journal of Microbiology
In the pulp and paper industry, during the manufacturing process, the agglomeration of pitch part... more In the pulp and paper industry, during the manufacturing process, the agglomeration of pitch particles (composed of triglycerides, fatty acids, and esters) leads to the formation of black pitch deposits in the pulp and on machinery, which impacts on the process and pulp quality. Traditional methods of pitch prevention and treatment are no longer feasible due to environmental impact and cost. Consequently, there is a need for more efficient and environmentally friendly approaches. The application of lipolytic enzymes, such as lipases and esterases, could be the sustainable solution to this problem. Therefore, an understanding of their structure, mechanism, and sources are essential. In this report, we review the microbial sources for the different groups of lipolytic enzymes, the differences between lipases and esterases, and their potential applications in the pulping industry.
Bioresources and Bioprocessing
The accumulation of petrochemical plastic waste is detrimental to the environment. Polyhydroxyalk... more The accumulation of petrochemical plastic waste is detrimental to the environment. Polyhydroxyalkanoates (PHAs) are bacterial-derived polymers utilized for the production of bioplastics. PHA-plastics exhibit mechanical and thermal properties similar to conventional plastics. However, high production cost and obtaining high PHA yield and productivity impedes the widespread use of bioplastics. This study demonstrates the concept of cyclic fed-batch fermentation (CFBF) for enhanced PHA productivity by Bacillus thuringiensis using a glucose-rich hydrolyzate as the sole carbon source. The statistically optimized fermentation conditions used to obtain high cell density biomass (OD600 of 2.4175) were: 8.77 g L−1 yeast extract; 66.63% hydrolyzate (v/v); a fermentation pH of 7.18; and an incubation time of 27.22 h. The CFBF comprised three cycles of 29 h, 52 h, and 65 h, respectively. After the third cyclic event, cell biomass of 20.99 g L−1, PHA concentration of 14.28 g L−1, PHA yield of 68...
BioResources
Lipophilic extractives naturally occurring in wood tend to coalesce during pulping to form pitch ... more Lipophilic extractives naturally occurring in wood tend to coalesce during pulping to form pitch deposits, which have particularly undesirable effects on the pulping process and quality of pulp produced. A chemical characterization of different eucalypt species [Eucalyptus nitens, E. grandis, and E. dunnii (of different site qualities)] wood and generated pulp was performed. This study aimed at determining the effects of wood storage at-20 °C (for 6 months), by examining their chemical composition and indigenous microflora. Fatty acids were the main lipophilic compounds among E. dunnii (SQ3 and SQ4) and E. grandis wood extractives. The wood of E. nitens posed the least risk for pitch deposit formation, making it the most suitable Eucalyptus species for pulping. Storage of wood chips at-20 °C had a similar effect as the traditional method of seasoning (storage of wood outdoors prior to pulping) used for the reduction of lipophilic extractives. A 25 to 44% reduction of total extractives was observed in the raw material after storage. Variations in bacterial and fungal communities were observed after storage, and should be taken into consideration when conducting lab scale trials. If storage of wood chips is necessary for lab testing, it should be retained for a maximum of 3 months at-20 °C.
BioResources, Nov 3, 2017
Lipophilic extractives naturally occurring in wood tend to coalesce during pulping to form pitch ... more Lipophilic extractives naturally occurring in wood tend to coalesce during pulping to form pitch deposits, which have particularly undesirable effects on the pulping process and quality of pulp produced. A chemical characterization of different eucalypt species [Eucalyptus nitens, E. grandis, and E. dunnii (of different site qualities)] wood and generated pulp was performed. This study aimed at determining the effects of wood storage at-20 °C (for 6 months), by examining their chemical composition and indigenous microflora. Fatty acids were the main lipophilic compounds among E. dunnii (SQ3 and SQ4) and E. grandis wood extractives. The wood of E. nitens posed the least risk for pitch deposit formation, making it the most suitable Eucalyptus species for pulping. Storage of wood chips at-20 °C had a similar effect as the traditional method of seasoning (storage of wood outdoors prior to pulping) used for the reduction of lipophilic extractives. A 25 to 44% reduction of total extractives was observed in the raw material after storage. Variations in bacterial and fungal communities were observed after storage, and should be taken into consideration when conducting lab scale trials. If storage of wood chips is necessary for lab testing, it should be retained for a maximum of 3 months at-20 °C.
Journal of Environmental Management
Journal of Food Protection, 2002
This study was undertaken to determine the effectiveness of modified atmospheres and packaging ma... more This study was undertaken to determine the effectiveness of modified atmospheres and packaging materials on the growth of Penicillium expansum and patulin production in apples. Granny Smith apples were surface sterilized with 76% ethanol and inoculated with 0.1 ml of a 1.1 × 107 spore/ml P. expansum spore suspension. The apples were packaged either in polyethylene (PE) or polypropylene (PP) and treated with three different gas combinations, viz., 58% CO2/42% N2, 48% CO2/52% N2, and 88% CO2/12% N2, and were then incubated for 14 days at 25°C. Fungal growth was monitored every 2 to 4 days by measuring radial growth from the point of inoculation. After the 14th day, apples were pulped, and patulin was extracted, purified, and quantified by high-performance liquid chromatography. PP did not inhibit fungal growth in any of the atmospheres tested, and it only inhibited patulin production in atmospheric gas and 58% CO2/42% N2. PE was very effective and inhibited fungal growth by four- or f...
Scientific Reports
Dendritic cells (DCs) are the antigen-presenting cells that initiate and direct adaptive immune r... more Dendritic cells (DCs) are the antigen-presenting cells that initiate and direct adaptive immune responses, and thus are critically important in vaccine design. Although DC-targeting vaccines have attracted attention, relevant studies on chicken are rare. A high diversity T7 phage display nanobody library was constructed for bio-panning of intact chicken bone marrow DCs to find DC-specific binding nanobodies. After three rounds of screening, 46 unique sequence phage clones were identified from 125 randomly selected phage clones. Several DC-binding phage clones were selected using the specificity assay. Phage-54, -74, -16 and -121 bound not only with chicken DCs, but also with duck and goose DCs. In vitro, confocal microscopy observation demonstrated that phage-54 and phage-74 efficiently adsorbed onto DCs within 15 min compared to T7-wt. The pull-down assay, however, did not detect any of the previously reported proteins for chicken DCs that could have interacted with the nanobodies ...
Journal of Food …, 2002
This study was undertaken to determine the effectiveness of modified atmospheres and packaging ma... more This study was undertaken to determine the effectiveness of modified atmospheres and packaging materials on the growth of Penicillium expansum and patulin production in apples. Granny Smith apples were surface sterilized with 76% ethanol and inoculated with 0.1 ml of a 1.1 x 10(7) spore/ml P. expansum spore suspension. The apples were packaged either in polyethylene (PE) or polypropylene (PP) and treated with three different gas combinations, viz., 58% CO2/42% N2, 48% CO2/52% N2, and 88% CO2/12% N2, and were then incubated for 14 days at 25 degrees C. Fungal growth was monitored every 2 to 4 days by measuring radial growth from the point of inoculation. After the 14th day, apples were pulped, and patulin was extracted, purified, and quantified by high-performance liquid chromatography. PP did not inhibit fungal growth in any of the atmospheres tested, and it only inhibited patulin production in atmospheric gas and 58% CO2/42% N2. PE was very effective and inhibited fungal growth by four- or fivefold, depending on the modified atmosphere. Patulin production in PE-packaged apples was almost completely inhibited by all three gas combinations. Gas chromatographic analysis of the PE-packaged samples before and after the incubation period showed that CO2 levels dropped and N2 levels increased for all of the atmospheres tested. Our studies showed conclusively that PE is an excellent packaging material for the storage of apples since it inhibited the growth of P. expansum, thereby allowing <3.2 microg/ml of patulin to be produced, regardless of gaseous environment.
Pharmacology & therapeutics, 2003
The transforming growth factor-β (TGF-β) gene superfamily expresses a large set of structurally a... more The transforming growth factor-β (TGF-β) gene superfamily expresses a large set of structurally and functionally related polypeptides. Three TGF-β isoforms are regulated by specific genes and have been identified in mammals (TGF-β1, -β2, and -β3). All three-protein isoforms ...
AFRICAN JOURNAL OF BIOTECHNOLOGY
Eucalyptus is the predominant exotic wood species used in South African pulp and paper industry. ... more Eucalyptus is the predominant exotic wood species used in South African pulp and paper industry. Once chipped and stored in piles, the wood becomes vulnerable to microbial degradation and spontaneous combustion. The denaturing gradient gel electrophoresis (DGGE) technique was optimized for the detection of microbial diversity in the wood. Wood chips were collected and milled to different specifications. The 16S and 18S rRNA genes were amplified using 338F-GC/518R and 933F-GC/1387R for bacteria and NS26/518R-GC and EF4F/518R for fungi. Several gel gradients were examined to determine optimal separation. A comparison of DGGE profiles revealed greater diversity in the milled wood chips amplified using primer sets of 338F-GC/518R (16S) and NS26/518R-GC (18S) with gradients of 30/60% (16S) and 25/50% (18S), respectively. Once optimized, this protocol was tested against five samples to assess its applicability to wood chip samples. Profiles were generated and amplicons excised from gels, ...
Additional file 1: Figure S1. Pyrogram of commercial PHB. Figure S2. Pyrogram of commercial PHBV.... more Additional file 1: Figure S1. Pyrogram of commercial PHB. Figure S2. Pyrogram of commercial PHBV. Figure S3. Pyrogram of PHA extracted after cycle 1 of cyclic fed-batch fermentation. Figure S4. Pyrogram of PHA extracted after cycle 2 of cyclic fed-batch fermentation. Figure S5. Pyrogram of PHA extracted after cycle 3 of cyclic fed-batch fermentation. Figure S6. Pyrogram of PHA extracted after cycle 4 of cyclic fed-batch fermentation.
Lipophilic extractives naturally occurring in wood tend to coalesce during pulping to form pitch ... more Lipophilic extractives naturally occurring in wood tend to coalesce during pulping to form pitch deposits, which have particularly undesirable effects on the pulping process and quality of pulp produced. A chemical characterization of different eucalypt species [Eucalyptus nitens, E. grandis, and E. dunnii (of different site qualities)] wood and generated pulp was performed. This study aimed at determining the effects of wood storage at-20 °C (for 6 months), by examining their chemical composition and indigenous microflora. Fatty acids were the main lipophilic compounds among E. dunnii (SQ3 and SQ4) and E. grandis wood extractives. The wood of E. nitens posed the least risk for pitch deposit formation, making it the most suitable Eucalyptus species for pulping. Storage of wood chips at-20 °C had a similar effect as the traditional method of seasoning (storage of wood outdoors prior to pulping) used for the reduction of lipophilic extractives. A 25 to 44% reduction of total extractiv...
Background: South Africa, with its scientific capacity, good infrastructure and high HIV incidenc... more Background: South Africa, with its scientific capacity, good infrastructure and high HIV incidence rates, is ideally positioned to conduct large-scale HIV prevention trials. The HIV Prevention Research Unit of the South African Medical Research Council conducted four phase III and one phase IIb trials of women-initiated HIV prevention options in KwaZulu-Natal between 2003 and 2009. A total of 7046 women participated, with HIV prevalence between 25 % and 45 % and HIV incidence ranging from 4.5-9.1 % per year. Unfortunately none of the interventions tested had any impact on reducing the risk of HIV acquisition; however, extremely valuable experience was gained, lessons learned and capacity built, while the communities gained associated benefits. Experience: Our experience in conducting these trials ranged from setting up community partnerships to developing clinical research sites and dissemination of trial results. Community engagement included setting up communitybased research site...
women [1], and the number of new HIV infections in women worldwide continues to escalate. The hig... more women [1], and the number of new HIV infections in women worldwide continues to escalate. The high incidence of HIV in many African countries provides the optimum environment for research on technologies that could prevent women from becoming infected, including microbicides. In this article, we discuss the recent highly publicised closure of a trial of cellulose sulphate (CS), which we conducted. We discuss the impact of the closure on the participants, the community at the trial site and the public at large, the public health sector,
Mycotoxin contamination of feeds results in economic loss and transmission of toxins in the food ... more Mycotoxin contamination of feeds results in economic loss and transmission of toxins in the food chain. Animal feeds, the raw ingredients used in their manufacture, namely, maize, wheat, sunflower seeds, cottonseeds, bagasse, wheaten bran, gluten feed and pet foods from South Africa were surveyed for contaminating mycotoxin-producing fungi and their toxins: aflatoxins, fumonisins, zearalenone and ochratoxins. Toxins were extracted and analysed by high performance liquid chromatography and fluorometry. Twenty-one of the twenty-three samples were contaminated by Aspergillus flavus which co-occurred with A. parasiticus in two samples, A. tamarii in seven and Fusarium moniliforme in one. Rhizopus stolonifer, R. oryzae and yeast were also isolated. Aflatoxins were detected in seventeen samples, fumonisin in six and zearalenone in three. Aflatoxin levels ranged between 0.8 ± 0.2 and 156 ± 8 µg/kg (ppb), zearalenone between 100 ± 10.5 and 165 000 ± 200 µg/kg and fumonisin B1 between 15 ± 3...
Frontiers in Microbiology, 2021
Bacteriophage T7 gene 17.5 coding for the only known holin is one of the components of its lysis ... more Bacteriophage T7 gene 17.5 coding for the only known holin is one of the components of its lysis system, but the holin activity in T7 is more complex than a single gene, and evidence points to the existence of additional T7 genes with holin activity. In this study, a T7 phage with a gene 17.5 deletion (T7-△holin) was rescued and its biological characteristics and effect on cell lysis were determined. Furthermore, the genomic evolution of mutant phage T7-△holin during serial passage was assessed by whole-genome sequencing analysis. It was observed that deletion of gene 17.5 from phage T7 delays lysis time and enlarges the phage burst size; however, this biological characteristic recovered to normal lysis levels during serial passage. Scanning electron microscopy showed that the two opposite ends of E. coli BL21 cells swell post-T7-△holin infection rather than drilling holes on cell membrane when compared with T7 wild-type infection. No visible progeny phage particle accumulation was ...
Scientific Reports
Fungal endophytes have the capacity to biosynthesize secondary metabolites that are produced by t... more Fungal endophytes have the capacity to biosynthesize secondary metabolites that are produced by their host plants. In this study, a dilactone terpenoid of C16 architecture was isolated from the fungal endophytes of Kigeliaafricana, in our attempt to identify anti-Pseudomonasaeruginosa metabolites. Thirty-eight fungal isolates were cultured for biomolecule production over a period of thirty days. Extracts from three (ZF 34, ZF 52 and ZF 91) of the fungi showed good anti-P.aeruginosa activity, with ZF 52 presenting the best MIC of 19.53 µg/mL and was accordingly subjected to chromatographic separation. Based on nuclear magnetic resonance (NMR) spectroscopy, high resolution mass spectrometry and single crystal X-ray diffraction (XRD) analyses, the isolated compound was identified as a C16-terpene dilactone, with a structure consistent with that of the known diterpene, CJ-14445. The isolated dilactone showed anti-P.aeruginosa activity with MIC of 0.61 µg/mL, signifying the antibacterial...
Background: South Africa, with its scientific capacity, good infrastructure and high HIV incidenc... more Background: South Africa, with its scientific capacity, good infrastructure and high HIV incidence rates, is ideally positioned to conduct large-scale HIV prevention trials. The HIV Prevention Research Unit of the South African Medical Research Council conducted four phase III and one phase IIb trials of women-initiated HIV prevention options in KwaZulu-Natal between 2003 and 2009. A total of 7046 women participated, with HIV prevalence between 25% and 45% and HIV incidence ranging from 4.5-9.1% per year. Unfortunately none of the interventions tested had any impact on reducing the risk of HIV acquisition; however, extremely valuable experience was gained, lessons learned and capacity built, while the communities gained associated benefits. Experience: Our experience in conducting these trials ranged from setting up community partnerships to developing clinical research sites and dissemination of trial results. Community engagement included setting up communitybased research sites w...
Current Trends in Biotechnology and Pharmacy, 2017
The objective of this present study was to isolate, identify and screen for potential fungal isol... more The objective of this present study was to isolate, identify and screen for potential fungal isolates from local wood chips with respect to xylanase production. The fungal strains were isolated from degrading wood chips. All the fungal strains were screened for their ability to produce xylanase by the plate screening method using Congo red as indicator. Two isolates were further selected among them and screened for the production of the enzymes in liquid medium and identified by 18S rRNA. Phialophora alba, had the highest xylanase activity of 24.43 U/ml with temperature optima at 50°C and 90°C respectively. Enzymatic hydrolysis of pre-treated sugarcane bagasse using crude enzyme resulted in the production of 0.36 g/ml reducing sugars after 48 hours. This is the first report of a thermophilic xylanase from Phialophora alba. These results suggest that the application of this xylanase in bioethanol production may be very promising.
Journal of Wood Chemistry and Technology, 2020
The South African pulp and paper industry generates an estimated 0.5 million tons of pulp and pap... more The South African pulp and paper industry generates an estimated 0.5 million tons of pulp and paper mill sludge (PPMS) annually. As PPMS is generated, it requires safe, efficient, and economical collection and disposal. However, PPMS is typically land-filled and subsequently emits nuisance odors, methane, and leaches toxins. Thus, PPMS is an environmental hazard and a potential pollutant of air, soil, and water systems. PPMS is primarily composed of cellulose and coupled with the prospect of biorefinery practices, a value-added product such as glucose-rich hydrolyzate can be derived from this lignocellulosic waste stream. The current study applied a Box-Behnken design to establish the appropriate conditions to obtain the highest possible yield of glucose from PPMS. The PPMS contained 6.89% ash and 64.21% cellulose. De-ashing using acidic pretreatment reduced the ash content by 51%, thereby increasing the amenability of the cellulose fibers to enzymatic hydrolysis. The optimized cond...
Canadian Journal of Microbiology
In the pulp and paper industry, during the manufacturing process, the agglomeration of pitch part... more In the pulp and paper industry, during the manufacturing process, the agglomeration of pitch particles (composed of triglycerides, fatty acids, and esters) leads to the formation of black pitch deposits in the pulp and on machinery, which impacts on the process and pulp quality. Traditional methods of pitch prevention and treatment are no longer feasible due to environmental impact and cost. Consequently, there is a need for more efficient and environmentally friendly approaches. The application of lipolytic enzymes, such as lipases and esterases, could be the sustainable solution to this problem. Therefore, an understanding of their structure, mechanism, and sources are essential. In this report, we review the microbial sources for the different groups of lipolytic enzymes, the differences between lipases and esterases, and their potential applications in the pulping industry.
Bioresources and Bioprocessing
The accumulation of petrochemical plastic waste is detrimental to the environment. Polyhydroxyalk... more The accumulation of petrochemical plastic waste is detrimental to the environment. Polyhydroxyalkanoates (PHAs) are bacterial-derived polymers utilized for the production of bioplastics. PHA-plastics exhibit mechanical and thermal properties similar to conventional plastics. However, high production cost and obtaining high PHA yield and productivity impedes the widespread use of bioplastics. This study demonstrates the concept of cyclic fed-batch fermentation (CFBF) for enhanced PHA productivity by Bacillus thuringiensis using a glucose-rich hydrolyzate as the sole carbon source. The statistically optimized fermentation conditions used to obtain high cell density biomass (OD600 of 2.4175) were: 8.77 g L−1 yeast extract; 66.63% hydrolyzate (v/v); a fermentation pH of 7.18; and an incubation time of 27.22 h. The CFBF comprised three cycles of 29 h, 52 h, and 65 h, respectively. After the third cyclic event, cell biomass of 20.99 g L−1, PHA concentration of 14.28 g L−1, PHA yield of 68...
BioResources
Lipophilic extractives naturally occurring in wood tend to coalesce during pulping to form pitch ... more Lipophilic extractives naturally occurring in wood tend to coalesce during pulping to form pitch deposits, which have particularly undesirable effects on the pulping process and quality of pulp produced. A chemical characterization of different eucalypt species [Eucalyptus nitens, E. grandis, and E. dunnii (of different site qualities)] wood and generated pulp was performed. This study aimed at determining the effects of wood storage at-20 °C (for 6 months), by examining their chemical composition and indigenous microflora. Fatty acids were the main lipophilic compounds among E. dunnii (SQ3 and SQ4) and E. grandis wood extractives. The wood of E. nitens posed the least risk for pitch deposit formation, making it the most suitable Eucalyptus species for pulping. Storage of wood chips at-20 °C had a similar effect as the traditional method of seasoning (storage of wood outdoors prior to pulping) used for the reduction of lipophilic extractives. A 25 to 44% reduction of total extractives was observed in the raw material after storage. Variations in bacterial and fungal communities were observed after storage, and should be taken into consideration when conducting lab scale trials. If storage of wood chips is necessary for lab testing, it should be retained for a maximum of 3 months at-20 °C.
BioResources, Nov 3, 2017
Lipophilic extractives naturally occurring in wood tend to coalesce during pulping to form pitch ... more Lipophilic extractives naturally occurring in wood tend to coalesce during pulping to form pitch deposits, which have particularly undesirable effects on the pulping process and quality of pulp produced. A chemical characterization of different eucalypt species [Eucalyptus nitens, E. grandis, and E. dunnii (of different site qualities)] wood and generated pulp was performed. This study aimed at determining the effects of wood storage at-20 °C (for 6 months), by examining their chemical composition and indigenous microflora. Fatty acids were the main lipophilic compounds among E. dunnii (SQ3 and SQ4) and E. grandis wood extractives. The wood of E. nitens posed the least risk for pitch deposit formation, making it the most suitable Eucalyptus species for pulping. Storage of wood chips at-20 °C had a similar effect as the traditional method of seasoning (storage of wood outdoors prior to pulping) used for the reduction of lipophilic extractives. A 25 to 44% reduction of total extractives was observed in the raw material after storage. Variations in bacterial and fungal communities were observed after storage, and should be taken into consideration when conducting lab scale trials. If storage of wood chips is necessary for lab testing, it should be retained for a maximum of 3 months at-20 °C.
Journal of Environmental Management