41 results on '"Roshini Govinden"'
Search Results
2. Screening for cellulases and preliminary optimisation of glucose tolerant β-glucosidase production and characterisation
- Author
-
Nivisti Singh, Bruce Sithole, and Roshini Govinden
- Subjects
Endoglucanases ,exoglucanases ,β- glucosidases ,glucose tolerant ,cellulases ,Biology (General) ,QH301-705.5 ,Microbiology ,QR1-502 - Abstract
ABSTRACTThe search for a novel microbial producer of cellulases including a glucose tolerant β-glucosidase is a challenge as most are inhibited by their product glucose. This study aims to screen for cellulolytic fungi using qualitative and quantitative screening methods. Primary screening revealed 34 of 46 fungal isolates with β-glucosidase activity. Eleven and 13 of these also displayed endoglucanase and exoglucanase activities, respectively. During secondary screening, this number was reduced to 26 β-glucosidase producers with 13 also having endoglucanase and exoglucanase activities. Isolate C1 displayed enhanced production of β-glucosidases in the presence of 0.05 M glucose (69% higher activity). Optimisation of growth conditions for β-glucosidase production by one variable at a time experiments improved production for (isolates) PS1 (64%), MB5 (84%), and C2 (69%). Isolate PS1 identified as Chaetomella sp. BBA70074 displayed the highest tolerance to glucose, retaining 10% of β-glucosidase activity in the presence of 0.8 M glucose. Tolerance to glucose increased to 14% when produced under optimal conditions. β-Glucosidase had a molecular weight of 170 kDa with a pH and temperature optima of 6 and 70 °C, respectively. Future studies will include optimisation of the production of the glucose tolerant enzyme by Chaetomella sp. BBA70074.
- Published
- 2023
- Full Text
- View/download PDF
3. A glucose tolerant β-glucosidase from a newly isolated Neofusicoccum parvum strain F7: production, purification, and characterization
- Author
-
Nivisti Singh, Bruce Sithole, Ajit Kumar, and Roshini Govinden
- Subjects
Medicine ,Science - Abstract
Abstract Cellulase-producing microorganisms produce low titres of β-glucosidases with low tolerance to glucose. This study aimed to improve production, purify, and characterize a β-glucosidase from a newly isolated Neofusicoccum parvum strain F7. β-Glucosidase production was significantly enhanced by a sequential statistical modelling approach from 1.5-fold in Plackett–Burman design to 2.5 U/ml in the Box–Behnken design compared to the preliminary one variable at a time experiments (1.6 U/ml). The optimal conditions for enzyme production by BBD were 12 days of fermentation at 20 °C, 175 rpm, 0.5% glycerol and 1.5% casein in pH 6.0 buffer. Three β-glucosidase isoforms referred to as Bgl1, Bgl2, Bgl3 were purified and characterized from the optimized crude extract displaying IC50 values of 2.6, 22.6 and 319.5 mM for glucose, respectively. Bgl3 with a molecular mass of approximately 65 kDa demonstrated the highest tolerance to glucose among the isoforms. The optimum activity and stability for Bgl3 was observed at pH 4.0 in 50 mM sodium acetate buffer with 80% β-glucosidase residual activity retained for three hours. This isoform also retained 60% residual activity at 65 °C for one hour which was then reduced to 40% which remained stable for another 90 min. The β-glucosidase activity of Bgl3 was not enhanced after the addition of metal ions in assay buffers. The K m and v max for 4-nitrophenyl-β-d-glucopyranoside were 1.18 mM and 28.08 µmol/min, respectively indicating high affinity for the substrate. The ability to withstand the presence of glucose in conjunction with its thermophilic nature indicates promise for this enzyme in industrial application.
- Published
- 2023
- Full Text
- View/download PDF
4. Optimization, purification, and characterization of xylanase production by a newly isolated Trichoderma harzianum strain by a two-step statistical experimental design strategy
- Author
-
Priyashini Dhaver, Brett Pletschke, Bruce Sithole, and Roshini Govinden
- Subjects
Medicine ,Science - Abstract
Abstract Xylanases are hydrolytic enzymes with a wide range of applications in several industries such as biofuels, paper and pulp, food, and feed. The objective of this study was to optimize the culture conditions and medium components for maximal xylanase production from a newly isolated Trichoderma harzianum strain using the Plackett–Burman Design (PBD) and Box Behnken Design (BBD) experimental strategies. Xylanase production was enhanced 4.16-fold to 153.80 U/ml by BBD compared to a preliminary one-factor-at-a-time (OFAT) activity of 37.01 U/ml and 2.24-fold compared to the PBD (68.70 U/ml). The optimal conditions for xylanase production were: 6 days of fermentation, incubation temperature of 70 °C, pH 5.0, agitation of 160 rpm, and 1.2% wheat bran and ammonium sulphate. The experimental design effectively provided conditions for the production of an acidic-thermostable enzyme with exciting potential for application in animal feed improvement. The acidic-thermostable xylanase was purified from the submerged culture and SDS-PAGE analysis revealed a molecular weight of 72 kDa. This protein had maximum xylanolytic activity at pH 6.0 and 65 °C and was stable for 4 h retaining > 70% activity and exhibited substrate specificity for beechwood xylan with a K m of 5.56 mg/ml and V max of 1052.63 µmol/min/mg. Enzyme activity was enhanced by Fe2+, Mg2+, and Zn2+. There was an absence of strong inhibitors of xylanase activity. Overall, these characteristics indicate the potential for at least two industrial applications.
- Published
- 2022
- Full Text
- View/download PDF
5. Construction of a T7 phage display nanobody library for bio-panning and identification of chicken dendritic cell-specific binding nanobodies
- Author
-
Hai Xu, Ling Li, Bihua Deng, Weiming Hong, Ruiting Li, Zijie Guo, Jibo Hou, Roshini Govinden, and Hafizah Y. Chenia
- Subjects
Medicine ,Science - Abstract
Abstract 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 displayed on phage-54 and phage-74. Nonetheless, Specified pathogen-free chickens immunized with phage-54 and phage-74 displayed higher levels of anti-p10 antibody than the T7-wt, indicating enhanced antibody production by nanobody mediated-DC targeting. Therefore, this study identified two avian (chicken, duck and goose) DC-specific binding nanobodies, which may be used for the development of DC-targeting vaccines.
- Published
- 2022
- Full Text
- View/download PDF
6. Optimization of Xylooligosaccharides Production by Native and Recombinant Xylanase Hydrolysis of Chicken Feed Substrates
- Author
-
Priyashini Dhaver, Brett Pletschke, Bruce Sithole, and Roshini Govinden
- Subjects
xylooligosaccharides ,chicken feed ,lignocellulosic biomass ,response surface methodology ,xylanase ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Poultry production faces several challenges, with feed efficiency being the main factor that can be influenced through the use of different nutritional strategies. Xylooligosaccharides (XOS) are functional feed additives that are attracting growing commercial interest due to their excellent ability to modulate the composition of the gut microbiota. The aim of the study was to apply crude and purified fungal xylanases, from Trichoderma harzianum, as well as a recombinant glycoside hydrolase family 10 xylanase, derived from Geobacillus stearothermophilus T6, as additives to locally produced chicken feeds. A Box–Behnken Design (BBD) was used to optimize the reducing sugar yield. Response surface methodology (RSM) revealed that reducing sugars were higher (8.05 mg/mL, 2.81 mg/mL and 2.98 mg/mL) for the starter feed treated with each of the three enzymes compared to the treatment with grower feed (3.11 mg/mL, 2.41 mg/mL and 2.62 mg/mL). The hydrolysis products were analysed by thin-layer chromatography (TLC), and high-performance liquid chromatography (HPLC) analysis and showed that the enzymes hydrolysed the chicken feeds, producing a range of monosaccharides (arabinose, mannose, glucose, and galactose) and XOS, with xylobiose being the predominant XOS. These results show promising data for future applications as additives to poultry feeds.
- Published
- 2023
- Full Text
- View/download PDF
7. Isolation, screening, preliminary optimisation and characterisation of thermostable xylanase production under submerged fermentation by fungi in Durban, South Africa
- Author
-
Priyashini Dhaver, Brett Pletschke, Bruce Sithole, and Roshini Govinden
- Subjects
Fungi ,xylanase ,screening ,isolation ,xylan plate assay ,Biology (General) ,QH301-705.5 ,Microbiology ,QR1-502 - Abstract
Fungi are renowned for their ability to produce extracellular enzymes into their surrounding environment. Xylanases are hydrolytic enzymes capable of xylan degradation. The objectives of this study were to isolate, screen for potential xylanolytic fungi from soil and tree bark samples from three locations in South Africa and to determine their growth conditions for maximum xylanase production. Forty-six isolates were obtained based on clearing zone formation on xylan-enriched agar plates using Congo red indicator. Xylanase activity was quantified during submerged fermentation. Isolate MS5, identified as Trichoderma harzianum with the highest enzyme activity (38.17 U/ml) was selected for further studies based on thermophilic properties (70°C) and pH (5.0). The culture conditions; incubation period (5 days), agitation speed (160 rpm) wheat bran (1%) and ammonium sulphate (1.2%) were optimised further. Biochemical characterisation of the crude enzyme revealed two pH and temperature optima (pH 6.0 at 60°C and 70°C, pH 8.0 at 55°C and 75°C). The enzyme retained >70% activity after 4 h at pH 6.0 at 70°C. SDS-PAGE revealed multiple protein bands with a prominent band at 70 kDa. Substrate Native PAGE revealed multiple isoforms between 55 and 130 kDa. This enzyme will be beneficial for applications in the animal feed and biofuels industries.
- Published
- 2022
- Full Text
- View/download PDF
8. Anti-Pseudomonas aeruginosa activity of a C16-terpene dilactone isolated from the endophytic fungus Neofusicoccum luteum of Kigelia africana (Lam.)
- Author
-
Olusola Bodede, Mamokoena Kuali, Gerhard Prinsloo, Roshila Moodley, and Roshini Govinden
- Subjects
Medicine ,Science - Abstract
Abstract 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 Kigelia africana, in our attempt to identify anti-Pseudomonas aeruginosa 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 potential of the biomolecule. The bioactive fungal isolate (ZF 52) was identified as Neofusicoccum luteum based on genomic DNA sequencing. This is the first report of the endophyte N. luteum from K. africana and the first reported occurrence of CJ-14445 in the fungus.
- Published
- 2022
- Full Text
- View/download PDF
9. Multiple Vaccines and Strategies for Pandemic Preparedness of Avian Influenza Virus
- Author
-
Hai Xu, Shanyuan Zhu, Roshini Govinden, and Hafizah Y. Chenia
- Subjects
avian influenza virus ,prevention ,vaccine ,delivery system ,immune response ,Microbiology ,QR1-502 - Abstract
Avian influenza viruses (AIV) are a continuous cause of concern due to their pandemic potential and devasting effects on poultry, birds, and human health. The low pathogenic avian influenza virus has the potential to evolve into a highly pathogenic avian influenza virus, resulting in its rapid spread and significant outbreaks in poultry. Over the years, a wide array of traditional and novel strategies has been implemented to prevent the transmission of AIV in poultry. Mass vaccination is still an economical and effective approach to establish immune protection against clinical virus infection. At present, some AIV vaccines have been licensed for large-scale production and use in the poultry industry; however, other new types of AIV vaccines are currently under research and development. In this review, we assess the recent progress surrounding the various types of AIV vaccines, which are based on the classical and next-generation platforms. Additionally, the delivery systems for nucleic acid vaccines are discussed, since these vaccines have attracted significant attention following their significant role in the fight against COVID-19. We also provide a general introduction to the dendritic targeting strategy, which can be used to enhance the immune efficiency of AIV vaccines. This review may be beneficial for the avian influenza research community, providing ideas for the design and development of new AIV vaccines.
- Published
- 2023
- Full Text
- View/download PDF
10. Evaluation of dendritic cell-targeting T7 phages as a vehicle to deliver avian influenza virus H5 DNA vaccine in SPF chickens
- Author
-
Hai Xu, Ling Li, Ruiting Li, Zijie Guo, Mengzhou Lin, Yu Lu, Jibo Hou, Roshini Govinden, Bihua Deng, and Hafizah Y. Chenia
- Subjects
avian influenza ,DNA vaccine ,dendritic cell-targeting ,T7 phage ,SPF chicken ,Immunologic diseases. Allergy ,RC581-607 - Abstract
IntroductionThere is a growing demand for effective technologies for the delivery of antigen to antigen-presenting cells (APCs) and their immune-activation for the success of DNA vaccines. Therefore, dendritic cell (DC)-targeting T7 phages were used as a vehicle to deliver DNA vaccine.MethodsIn this study, a eukaryotic expression plasmid pEGFP-C1-HA2-AS containing the HA2 gene derived from the avian H5N1 virus and an anchor sequence (AS) gene required for the T7 phage packaging process was developed. To verify the feasibility of phage delivery, the plasmid encapsulated in DC-targeting phage capsid through the recognition of AS was evaluated both in vitro and in vivo. The pEGFP-C1-HA2-AS plasmid could evade digestion by DNase I by becoming encapsulated into the phage particles and efficiently expressed the HA2 antigen in DCs with the benefit of DC-targeting phages.ResultsFor chickens immunized with the DC-targeting phage 74 delivered DNA vaccine, the levels of IgY and IgA antibodies, the concentration of IFN-γ and IL-12 cytokines in serum, the proliferation of lymphocytes, and the percentage of CD4+/CD8+ T lymphocytes isolated from peripheral blood were significantly higher than chickens which were immunized with DNA vaccine that was delivered by non-DC-targeting phage or placebo (p
- Published
- 2022
- Full Text
- View/download PDF
11. Optimisation of β-Glucosidase Production in a Crude Aspergillus japonicus VIT-SB1 Cellulase Cocktail Using One Variable at a Time and Statistical Methods and its Application in Cellulose Hydrolysis
- Author
-
Nivisti Singh, Bishop Bruce Sithole, and Roshini Govinden
- Subjects
cellulases ,β-glucosidase ,endoglucanase ,exoglucanase ,Plackett Burman design ,Box Behnken design ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Pulp and paper mill sludge (PPMS) is currently disposed of into landfills which are reaching their maximum capacity. Valorisation of PPMS by enzymatic hydrolysis using cellulases is an alternative strategy. Existing commercial cellulases are expensive and contain low titres of β-glucosidases. In this study, β-glucosidase production was optimised by Aspergillus japonicus VIT-SB1 to obtain higher β-glucosidase titres using the One Variable at a Time (OVAT), Plackett Burman (PBD), and Box Behnken design (BBD)of experiments and the efficiency of the optimised cellulase cocktail to hydrolyse cellulose was tested. β-Glucosidase production was enhanced from 0.4 to 10.13 U/mL, representing a 25.3-fold increase in production levels after optimisation. The optimal BBD production conditions were 6 days of fermentation at 20 °C, 125 rpm, 1.75% soy peptone, and 1.25% wheat bran in (pH 6.0) buffer. The optimal pH for β-glucosidase activity in the crude cellulase cocktail was (pH 5.0) at 50 °C. Optimal cellulose hydrolysis using the crude cellulase cocktail occurred at longer incubation times, and higher substrate loads and enzyme doses. Cellulose hydrolysis with the A. japonicus VIT-SB1 cellulase cocktail and commercial cellulase cocktails resulted in glucose yields of 15.12 and 12.33 µmol/mL glucose, respectively. Supplementation of the commercial cellulase cocktail with 0.25 U/mg of β-glucosidase resulted in a 19.8% increase in glucose yield.
- Published
- 2023
- Full Text
- View/download PDF
12. Optimization of cultivation medium and cyclic fed-batch fermentation strategy for enhanced polyhydroxyalkanoate production by Bacillus thuringiensis using a glucose-rich hydrolyzate
- Author
-
Sarisha Singh, Bruce Sithole, Prabashni Lekha, Kugenthiren Permaul, and Roshini Govinden
- Subjects
Polyhydroxyalkanoate ,Glucose-rich hydrolyzate ,Response surface methodology ,Cyclic fed-batch fermentation ,PHA productivity ,Pulp and paper mill sludge ,Technology ,Chemical technology ,TP1-1185 ,Biotechnology ,TP248.13-248.65 - Abstract
Abstract 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 68.03%, and PHA productivity of 0.219 g L−1 h−1 was achieved. This cyclic strategy yielded an almost threefold increase in biomass concentration and a fourfold increase in PHA concentration compared with batch fermentation. FTIR spectra of the extracted PHAs display prominent peaks at the wavelengths unique to PHAs. A copolymer was elucidated after the first cyclic event, whereas, after cycles CFBF 2–4, a terpolymer was noted. The PHAs obtained after CFBF cycle 3 have a slightly higher thermal stability compared with commercial PHB. The cyclic events decreased the melting temperature and degree of crystallinity of the PHAs. The approach used in this study demonstrates the possibility of coupling fermentation strategies with hydrolyzate derived from lignocellulosic waste as an alternative feedstock to obtain high cell density biomass and enhanced PHA productivity.
- Published
- 2021
- Full Text
- View/download PDF
13. Biological Characterization and Evolution of Bacteriophage T7-△holin During the Serial Passage Process
- Author
-
Hai Xu, Xi Bao, Weiming Hong, Anping Wang, Kaimin Wang, Hongyan Dong, Jibo Hou, Roshini Govinden, Bihua Deng, and Hafizah Y. Chenia
- Subjects
T7 phage ,holin ,lysis ,compensatory host ,evolution ,Microbiology ,QR1-502 - Abstract
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 observed inside the E. coli BL21 cells by transmission electron microscopy. Following serial passage of T7-△holin from the 1st to 20th generations, the mRNA levels of gene 3.5 and gene 19.5 were upregulated and several mutation sites were discovered, especially two missense mutations in gene 19.5, which indicate a potential contribution to the evolution of the T7-△holin. Although the burst size of T7-△holin increased, high titer cultivation of T7-△holin was not achieved by optimizing the culture process. Accordingly, these results suggest that gene 19.5 is a potential lysis-related component that needs to be studied further and that the T7-△holin strain with its gene 17.5 deletion is not adequate to establish the high-titer phage cultivation process.
- Published
- 2021
- Full Text
- View/download PDF
14. Biochar-Mediated Control of Phytophthora Blight of Pepper Is Closely Related to the Improvement of the Rhizosphere Fungal Community
- Author
-
Guangfei Wang, Yan Ma, Hafizah Yousuf Chenia, Roshini Govinden, Jia Luo, and Gaidi Ren
- Subjects
biochar ,application time ,Phytophthora blight of pepper ,soil chemical properties ,fungal community ,biocontrol fungi ,Microbiology ,QR1-502 - Abstract
Biochar is a new eco-material with the potential to control soilborne diseases. This study explored the relationship between the rhizosphere fungal community and the suppression of Phytophthora blight of pepper in the context of time after biochar application. A pot experiment was conducted and rhizosphere soils were sampled to determine the biochar-induced soil chemical properties, fungal community composition, and abundance of biocontrol fungi. The biochar-enriched fungal strains were screened by the selective isolation method, and their control effects against Phytophthora blight of pepper were determined using a pot experiment. Biochar treatments effectively inhibited pathogen growth and controlled the disease, with biochar applied immediately before planting (BC0) having greater effects than that applied 20 days before planting (BC20). Compared to the control, biochar-amended rhizosphere soils had a higher pH, available nutrient content, and fungal richness and diversity. Moreover, biochar treatments significantly increased the abundance of potential biocontrol fungi. The proliferation in BC0 was stronger as compared to that in BC20. Several strains belonging to Aspergillus, Chaetomium, and Trichoderma, which were enriched by biochar amendment, demonstrated effective control of Phytophthora blight of pepper. Canonical correspondence and Pearson’s correlation analysis showed that a high content of soil-available nutrients in biochar treatments was favorable to the proliferation of beneficial fungi, which was negatively correlated with both the abundance of Phytophthora capsici and disease severity. In conclusion, biochar-mediated improvement in the fungal community suppressed the Phytophthora blight of pepper. The biochar application time had a great impact on the control effect, possibly due to the short-term proliferative effect of the biochar on biocontrol fungi.
- Published
- 2020
- Full Text
- View/download PDF
15. South Africa's experience of the closure of the cellulose sulphate microbicide trial.
- Author
-
Gita Ramjee, Roshini Govinden, Neetha S Morar, and Anthony Mbewu
- Subjects
Medicine - Published
- 2007
- Full Text
- View/download PDF
16. Unveiling the draft genome sequence of diesel-degrading Paenibacillus sp. strain d9, a surfactant producer isolated from diesel-contaminated soil
- Author
-
Vikas, Sharma, primary, Roshini, Govinden, additional, and Johnson, Lin, additional
- Published
- 2023
- Full Text
- View/download PDF
17. Purification and Characterization of a Glucose tolerant β-Glucosidase from a Newly Isolated Neofusicoccum Parvum strain F7: Production Optimization using Plackett Burman and Box Behnken
- Author
-
Nivisti Singh, Bruce Sithole, Ajit Kumar, and Roshini Govinden
- Abstract
Endoglucanases, exoglucanases and β-glucosidases act synergistically to hydrolyse cellulose into glucose monomers. Thus, this study aimed to improve production of a β-glucosidase from a newly isolated Neofusicoccum parvum strain F7 by optimizing the culture conditions and medium components using Plackett-Burman Design (PBD) and Box Behnken Design (BBD). β-Glucosidase production was significantly enhanced (p-value≤0.05) by 1.5-fold to 2.5 U/ml by BBD as compared to the preliminary one variable at a time (OVAT) experiments of (1.6 U/ml). The optimal conditions for enzyme production by BBD were 12 days of fermentation at 20°C, 175 rpm, 0.5% glycerol and 1.5% casein in 50 mM sodium phosphate (pH 6.0) buffer. Three β-glucosidase isoforms referred to as Bgl1, Bgl2, Bgl3 were purified and characterized from the optimized crude extract displaying IC50 values of 2.6, 22.6 and 319.5 mM for glucose, respectively. Bgl3 with a molecular weight of approximately 65 kDa displayed the highest tolerance to glucose among the isoforms. The optimum activity and stability for Bgl3 was observed at pH 4.0 in 50 mM sodium acetate buffer with 80% β-glucosidase residual activity retained for three hours. This isoform also retained 60% residual activity at 65°C for one hour which was then reduced to 40 % which remained stable for another 90 minutes. The β-Glucosidase activity of Bgl3 was not enhanced after the addition of metal ions in assay buffers. The Km and vmax for 4-nitrophenyl-β-D-glucopyranoside were found to be 1.18 mM and 28.08 µmol/min, respectively indicating high affinity to the substrate. The ability to withstand the presence of glucose in conjunction with its thermophilic nature indicates promise for the enzyme in industrial application.
- Published
- 2023
18. Pretreatment and enzymatic saccharification of sludge from a prehydrolysis kraft and kraft pulping mill
- Author
-
Bruce Sithole, Prabashni Lekha, Roshini Govinden, Sarisha Singh, and Kugenthiren Permaul
- Subjects
0106 biological sciences ,Chemistry ,business.industry ,General Chemical Engineering ,Pulp (paper) ,Paper mill ,02 engineering and technology ,General Chemistry ,engineering.material ,021001 nanoscience & nanotechnology ,Pulp and paper industry ,01 natural sciences ,Hydrolysis ,Kraft process ,010608 biotechnology ,Enzymatic hydrolysis ,engineering ,Mill ,General Materials Science ,0210 nano-technology ,business ,Kraft paper - Abstract
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 co...
- Published
- 2021
19. Screening for cellulases and preliminary optimisation of glucose tolerant β-glucosidase production and characterisation
- Author
-
Nivisti Singh, Bruce Sithole, and Roshini Govinden
- Subjects
Infectious Diseases ,Microbiology - Abstract
The search for a novel microbial producer of cellulases including a glucose tolerant β-glucosidase is a challenge as most are inhibited by their product glucose. This study aims to screen for cellulolytic fungi using qualitative and quantitative screening methods. Primary screening revealed 34 of 46 fungal isolates with β-glucosidase activity. Eleven and 13 of these also displayed endoglucanase and exoglucanase activities, respectively. During secondary screening, this number was reduced to 26 β-glucosidase producers with 13 also having endoglucanase and exoglucanase activities. Isolate C1 displayed enhanced production of β-glucosidases in the presence of 0.05 M glucose (69% higher activity). Optimisation of growth conditions for β-glucosidase production by one variable at a time experiments improved production for (isolates) PS1 (64%), MB5 (84%), and C2 (69%). Isolate PS1 identified as Chaetomella sp. BBA70074 displayed the highest tolerance to glucose, retaining 10% of β-glucosidase activity in the presence of 0.8 M glucose. Tolerance to glucose increased to 14% when produced under optimal conditions. β-Glucosidase had a molecular weight of 170 kDa with a pH and temperature optima of 6 and 70°C, respectively. Future studies will include optimisation of the production of the glucose tolerant enzyme by Chaetomella sp. BBA70074.
- Published
- 2022
- Full Text
- View/download PDF
20. Suppression of Phytophthora blight of pepper by biochar amendment is associated with improved soil bacterial properties
- Author
-
Hafizah Y. Chenia, Roshini Govinden, Yan Ma, Dejie Guo, Gaidi Ren, and Guangfei Wang
- Subjects
0303 health sciences ,biology ,fungi ,Pseudomonas ,Amendment ,food and beverages ,Soil Science ,04 agricultural and veterinary sciences ,biology.organism_classification ,Microbiology ,03 medical and health sciences ,Horticulture ,Pepper ,Biochar ,040103 agronomy & agriculture ,0401 agriculture, forestry, and fisheries ,Blight ,Transplanting ,Phytophthora ,Agronomy and Crop Science ,Bacteria ,030304 developmental biology - Abstract
Biochar amendment effectively controlled the Phytophthora blight of pepper and suppressed the pathogen abundance, with biochar applied just before transplanting (BC0) producing greater effects than that applied 20 days before transplanting (BC20). Biochar treatments stimulated the proliferation of total bacteria, Bacillus spp., Pseudomonas spp. , Streptomyces spp., and Sphingomonas spp. The proliferative effect of BC20 treatment gradually weakened compared to that of BC0 treatment with extended planting time. Moreover, biochar amendment strongly promoted the antagonist percentage and antagonistic ability of total bacteria, Bacillus spp., and Pseudomonas spp. and the promoting effect of BC0 treatment was stronger than that of BC20 treatment. Biochar-enriched Bacillus and Streptomyces strains, followed by Pseudomonas strains, were the best in terms of reducing the abundance of P. capsici and controlling Phytophthora blight of pepper. In addition, MiSeq sequencing data indicated that biochar treatments altered the soil bacterial community and enriched some beneficial bacteria, with BC0 treatment producing greater effects than BC20 treatment. Overall, the biochar-induced improvement of soil properties (particularly the abundance of biocontrol bacteria such as Bacillus spp., Pseudomonas spp. and Streptomyces spp. and bacterial antagonisms against P. capsici) may constitute one of the important mechansims of biochar-mediated control of Phytophora blight of pepper.
- Published
- 2019
21. Anti-Pseudomonas aeruginosa activity of a C
- Author
-
Olusola, Bodede, Mamokoena, Kuali, Gerhard, Prinsloo, Roshila, Moodley, and Roshini, Govinden
- Subjects
Chemistry ,Ascomycota ,Terpenes ,Antimicrobials ,Bignoniaceae ,Drug Resistance, Bacterial ,Pseudomonas aeruginosa ,Endophytes ,Fungi ,Organic chemistry ,Medicinal chemistry ,Microbiology ,Article - Abstract
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 Kigelia africana, in our attempt to identify anti-Pseudomonas aeruginosa 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 potential of the biomolecule. The bioactive fungal isolate (ZF 52) was identified as Neofusicoccum luteum based on genomic DNA sequencing. This is the first report of the endophyte N. luteum from K. africana and the first reported occurrence of CJ-14445 in the fungus.
- Published
- 2021
22. Additional file 1 of Optimization of cultivation medium and cyclic fed-batch fermentation strategy for enhanced polyhydroxyalkanoate production by Bacillus thuringiensis using a glucose-rich hydrolyzate
- Author
-
Sarisha Singh, Sithole, Bruce, Prabashni Lekha, Kugenthiren Permaul, and Roshini Govinden
- Abstract
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.
- Published
- 2021
- Full Text
- View/download PDF
23. Optimisation of protocol for effective detachment and selective recovery of the representative bacteria for extraction of metagenomic DNA from Eucalyptus spp. woodchips
- Author
-
Chika F. Nnadozie, Johnson Lin, and Roshini Govinden
- Subjects
DNA, Bacterial ,0301 basic medicine ,Microbiology (medical) ,Sonication ,030106 microbiology ,Microbiology ,law.invention ,Matrix (chemical analysis) ,03 medical and health sciences ,chemistry.chemical_compound ,law ,Molecular Biology ,Filtration ,Eucalyptus ,Chromatography ,Bacteria ,biology ,Chemistry ,Extraction (chemistry) ,biology.organism_classification ,Wood ,DNA extraction ,Woodchips ,Metagenomics ,Stress, Mechanical ,DNA - Abstract
For some environments such as planktonic/aqueous environments, the separation of bacteria cells from eukaryotic cells prior to DNA extraction using filtration is relatively straightforward. However, for woodchips, the bacteria are attached/embedded within the wood matrix, which prevents easy removal of bacterial cells. In this study, a method for the selective extraction of DNA from bacteria inhabiting Eucalyptus spp. woodchips has been developed. The objective was to compare milled and unmilled woodchips processed via three detachment methods, viz., sonication, vortexing and shaking followed by filtration using Teflon filters according to three relevant criteria: DNA yield, DNA purity and quality of DNA. Highest DNA yield was obtained by milling and vortexing for 10 min (77.50 ± 5.17 ng/μl), followed by milling and vortexing for 2 min (61.00 ± 6.56 ng/μl), unmilled and vortexing for 10 min (38.67 ± 5.17 ng/μl) and milled and shaking for 2 h (31.62 ± 5.17 ng/μl). The lowest DNA yield was obtained by using unmilled woodchips and 5 min of sonication treatment (7.00 ± 1.22 ng/μl). There was no significant difference in DNA purity for milled or unmilled woodchips processed via the three detachment methods. Duration of cell detachment treatment did not significantly influence DNA yield and purity. Following optimisation experiments, it was possible to extract bacterial DNA using milled woodchips and 10 minute vortexing devoid of DNA from the host background and other associated eukaryotes and of sufficient quality and quantity for metagenomic analysis.
- Published
- 2018
24. Identification of lipolytic enzymes isolated from bacteria indigenous to Eucalyptus wood species for application in the pulping industry
- Author
-
Lucretia Ramnath, Bishop B Sithole, and Roshini Govinden
- Subjects
0106 biological sciences ,0301 basic medicine ,Paper ,Tributyrin ,lcsh:Biotechnology ,Substrate specificity ,Cellulase ,Pulp ,engineering.material ,Valerate ,Esterase ,01 natural sciences ,Applied Microbiology and Biotechnology ,03 medical and health sciences ,chemistry.chemical_compound ,010608 biotechnology ,lcsh:TP248.13-248.65 ,Full Length Article ,Lipase ,chemistry.chemical_classification ,Phenol red ,Chromatography ,biology ,Pulp (paper) ,Pitch ,030104 developmental biology ,Enzyme ,chemistry ,biology.protein ,engineering ,Biotechnology - Abstract
Highlights • Phenol red screening plates is the best method for detecting lipolytic activity. • Substrate specificity is affected by temperature and pH. • Essential to test substrates at various pH and temperature to determine optima. • Lipolytic enzymes indigenous to Eucalyptus sp. can assist in pitch control., This study highlights the importance of determining substrate specificity at variable experimental conditions. Lipases and esterases were isolated from microorganisms cultivated from Eucalyptus wood species and then concentrated (cellulases removed) and characterized. Phenol red agar plates supplemented with 1% olive oil or tributyrin was ascertained to be the most favourable method of screening for lipolytic activity. Lipolytic activity of the various enzymes were highest at 45–61 U/ml at the optimum temperature and pH of between at 30–35 °C and pH 4–5, respectively. Change in pH influenced the substrate specificity of the enzymes tested. The majority of enzymes tested displayed a propensity for longer aliphatic acyl chains such as dodecanoate (C12), myristate (C14), palmitate (C16) and stearate (C18) indicating that they could be characterised as potential lipases. Prospective esterases were also detected with specificity towards acetate (C2), butyrate (C4) and valerate (C5). Enzymes maintained up to 95% activity at the optimal pH and temperature for 2–3 h. It is essential to test substrates at various pH and temperature when determining optimum activity of lipolytic enzymes, a method rarely employed. The stability of the enzymes at acidic pH and moderate temperatures makes them excellent candidates for application in the treatment of pitch during acid bi-sulphite pulping, which would greatly benefit the pulp and paper industry.
- Published
- 2017
25. Selective Isolation of a Eucalyptus spp. Woodchip Bacterial Community and Its Taxonomic and Metabolic Profiling
- Author
-
Johnson Lin, Chika F. Nnadozie, and Roshini Govinden
- Subjects
0301 basic medicine ,biology ,Renewable Energy, Sustainability and the Environment ,food and beverages ,Bacteroidetes ,Chryseobacterium ,biology.organism_classification ,Microbiology ,Actinobacteria ,03 medical and health sciences ,030104 developmental biology ,Burkholderia ,Metagenomics ,Botany ,Proteobacteria ,Bacterial phyla ,Agronomy and Crop Science ,Energy (miscellaneous) ,Acidobacteria - Abstract
Taxonomic and metabolic profiles of bacterial inhabitants of Eucalyptus spp. woodchips from storage piles were analysed using whole genome shotgun metagenomics sequencing. The majority of the bacterial species present in the metagenome from the Eucalyptus spp. woodchips are found within four bacterial phyla: Proteobacteria (77%), Bacteroidetes (15%), Acidobacteria (3%) and Actinobacteria (2%). The most abundant species in the metagenome were Burkholderia spp. (25%; Proteobacteria) and Chryseobacterium spp. (37%; Bacteroidetes). Other species prevalent in this bacterial metagenome are Rhodanobacter spp. (7%), Klebsiella spp. (6%) and Pseudomonas spp. (5%). Both PhyloSift and Metagenome Rapid Annotation Subsystem Technology tools to estimate taxonomic diversity showed that the phylum Proteobacteria was the predominant group among the bacteria in the bacterial metagenome from the Eucalyptus spp. woodchips, followed by Bacteroidetes, Acidobacteria and Actinobacteria. Functional analysis revealed that clustering-based subsystem and carbohydrate metabolism which are key to degradation of the lignocellulose were the most abundant SEED subsystems representing 14% and 11% of the bacterial metagenome, respectively. Approximately 8% of the sequences were grouped under “miscellaneous functions” and 3% under metabolism of aromatic compounds. One thousand two hundred forty-seven potential contigs encoding biomass-degrading enzymes including glycoside hydrolases (GH, 525 contigs), glycosyl transferases (GT, 452 contigs) carbohydrate binding modules (CBM, 149 contigs), carbohydrate esterases (CE, 70 contigs), polysaccharide lyases (PL, 16 contigs) and auxiliary activity (AA, 35 contigs) were identified. Both taxonomic and functional classifications suggest that the bacterial inhabitants of the Eucalyptus spp. woodchips present a broader metabolic potential than the degradation of plant biomass.
- Published
- 2017
26. Transformation of pulp and paper mill sludge (PPMS) into a glucose-rich hydrolysate using green chemistry: Assessing pretreatment methods for enhanced hydrolysis
- Author
-
Prabashni Lekha, Bruce Sithole, Justin Emmanuel Naicker, and Roshini Govinden
- Subjects
Paper ,Environmental Engineering ,0208 environmental biotechnology ,02 engineering and technology ,010501 environmental sciences ,Management, Monitoring, Policy and Law ,engineering.material ,Raw material ,complex mixtures ,01 natural sciences ,South Africa ,chemistry.chemical_compound ,Enzymatic hydrolysis ,Hemicellulose ,Cellulose ,Waste Management and Disposal ,0105 earth and related environmental sciences ,Sewage ,Chemistry ,business.industry ,Hydrolysis ,Pulp (paper) ,food and beverages ,Paper mill ,General Medicine ,Pulp and paper industry ,020801 environmental engineering ,Glucose ,Cellulosic ethanol ,Fermentation ,engineering ,Valorisation ,business - Abstract
Pulp and paper mill sludge is a waste stream derived from the pulp and paper making industry, comprised of organic and inorganic material in the form of cellulose, hemicellulose, lignin and ash. In South Africa, approximately fivefour hundred thousand wet tonnes are produced per annum and is currently disposed via landfilling or incineration. However, these disposal methods raise environmental and financial concerns. This waste stream is an attractive feedstock for fermentable sugars, mainly glucose, recovery and can be redirected for valorisation as a feedstock for microbial fermentation to produce value-added products. Sugar recovery by enzymatic hydrolysis, as opposed to acidic hydrolysis, is a promising approach but is hampered by the lignin and inorganic material found in pulp and paper mill sludge. Several treatment steps to reduce or remove these components prior to enzymatic hydrolysis are assessed in this review. Pretreatment improves hydrolysis of cellulosic fibres and ensures a substantial yield of sugars.
- Published
- 2020
27. The Effects of Wood Storage on the Chemical Composition and Indigenous Microflora of Eucalyptus species Used in the Pulping Industry
- Author
-
Roshini Govinden, Bruce Sithole, and Lucretia Ramnath
- Subjects
Environmental Engineering ,Materials science ,Seasoning ,biology ,020209 energy ,Pulp (paper) ,Lab scale ,Bioengineering ,02 engineering and technology ,engineering.material ,Raw material ,Pulp and paper industry ,biology.organism_classification ,Eucalyptus ,stomatognathic system ,0202 electrical engineering, electronic engineering, information engineering ,engineering ,Eucalyptus nitens ,Waste Management and Disposal ,Chemical composition - Abstract
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.
- Published
- 2017
28. Classification of lipolytic enzymes and their biotechnological applications in the pulping industry
- Author
-
Bruce Sithole, Lucretia Ramnath, and Roshini Govinden
- Subjects
0301 basic medicine ,Paper ,Lipolysis ,030106 microbiology ,Immunology ,engineering.material ,Applied Microbiology and Biotechnology ,Microbiology ,Mini review ,03 medical and health sciences ,stomatognathic system ,Genetics ,Industry ,Lipase ,Molecular Biology ,Triglycerides ,chemistry.chemical_classification ,biology ,Manufacturing process ,business.industry ,Pulp (paper) ,Esterases ,General Medicine ,Pulp and paper industry ,Environmentally friendly ,Biotechnology ,030104 developmental biology ,Enzyme ,chemistry ,biology.protein ,engineering ,business - Abstract
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.
- Published
- 2017
29. Method optimization for denaturing gradient gel electrophoresis (DGGE) analysis of microflora from Eucalyptus sp. wood chips intended for pulping
- Author
-
Tamara Bush, Roshini Govinden, and Lucretia Ramnath
- Subjects
Chromatography ,biology ,Chemistry ,Microbial diversity ,Ribosomal RNA ,biology.organism_classification ,complex mixtures ,Applied Microbiology and Biotechnology ,Eucalyptus ,18S ribosomal RNA ,Microbial population biology ,Genetics ,Food science ,Microbial biodegradation ,Agronomy and Crop Science ,Molecular Biology ,Temperature gradient gel electrophoresis ,Bacteria ,Biotechnology - Abstract
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, re-amplified and sequenced to determine origin of DNA. Using this technique, 18 bacterial and 12 fungal species were identified, compared to ten bacterial and nine fungal isolates which were identified using the culturing technique and standard rRNA gene sequence analysis. The optimised DGGE is an appropriate tool for microbial community studies of Eucalyptus wood chips. Key words: Wood chips, Eucalyptus, community analysis using denaturing gradient gel electrophoresis (DGGE), microfloral variations.
- Published
- 2014
30. Lack of Effectiveness of Cellulose Sulfate Gel for the Prevention of Vaginal HIV Transmission
- Author
-
Lut, Van Damme, Roshini, Govinden, Florence M, Mirembe, Fernand, Guédou, Suniti, Solomon, Marissa L, Becker, B S, Pradeep, A K, Krishnan, Michel, Alary, Bina, Pande, Gita, Ramjee, Jennifer, Deese, Tania, Crucitti, Doug, Taylor, and C, Saunders
- Subjects
Adult ,medicine.medical_specialty ,Anti-HIV Agents ,Sexual Behavior ,HIV Infections ,Effectiveness ,Kaplan-Meier Estimate ,Viral diseases ,Placebo ,law.invention ,Placebos ,Gonorrhea ,Double-Blind Method ,Randomized controlled trial ,Acquired immunodeficiency syndrome (AIDS) ,law ,Internal medicine ,Disease Transmission, Infectious ,Humans ,Medicine ,Treatment Failure ,Cellulose ,Evaluation ,Sida ,Cellulose sulfate ,biology ,business.industry ,Vaginal microbicide ,Hazard ratio ,Transmission prevention ,HIV ,General Medicine ,Chlamydia Infections ,biology.organism_classification ,medicine.disease ,Microbicides ,AIDS ,Microbicides for sexually transmitted diseases ,Administration, Intravaginal ,Lentivirus ,Immunology ,Randomized controlled trials ,Female ,business ,Gels - Abstract
Background Women make up more than 50% of adults living with human immunodeficiency virus (HIV) infection or the acquired immunodeficiency syndrome (AIDS) in sub-Saharan Africa. Thus, female-initiated HIV prevention methods are urgently needed. Methods We performed a randomized, double-blind, placebo-controlled trial of cellulose sulfate, an HIV-entry inhibitor formulated as a vaginal gel, involving women at high risk for HIV infection at three African and two Indian sites. The primary end point was newly acquired infection with HIV type 1 or 2. The secondary end point was newly acquired gonococcal or chlamydial infection. The primary analysis was based on a log-rank test of no difference in the distribution of time to HIV infection, stratified according to site. Results A total of 1398 women were enrolled and randomly assigned to receive cellulose sulfate gel (706 participants) or placebo (692 participants) and had follow-up HIV test data. There were 41 newly acquired HIV infections, 25 in the cellulose sulfate group and 16 in the placebo group, with an estimated hazard ratio of infection for the cellulose sulfate group of 1.61 (P=0.13). This result, which is not significant, is in contrast to the interim finding that led to the trial being stopped prematurely (hazard ratio, 2.23; P=0.02) and the suggestive result of a preplanned secondary (adherence-based) analysis (hazard ratio, 2.02; P=0.05). No significant effect of cellulose sulfate as compared with placebo was found on the risk of gonorrheal infection (hazard ratio, 1.10; 95% confidence interval [CI], 0.74 to 1.62) or chlamydial infection (hazard ratio, 0.71; 95% CI, 0.47 to 1.08). Conclusions Cellulose sulfate did not prevent HIV infection and may have increased the risk of HIV acquisition. (ClinicalTrials.gov number, NCT00153777 ; and Current Controlled Trials number, ISRCTN95638385.)
- Published
- 2008
31. Selective isolation of bacteria for metagenomic analysis: Impact of membrane characteristics on bacterial filterability
- Author
-
Chika F. Nnadozie, Johnson Lin, and Roshini Govinden
- Subjects
education.field_of_study ,Lysis ,Chromatography ,biology ,Bacteria ,Population ,Size-exclusion chromatography ,Membranes, Artificial ,biology.organism_classification ,law.invention ,Suspension (chemistry) ,Filter (aquarium) ,Membrane ,law ,Metagenomics ,education ,Hydrophobic and Hydrophilic Interactions ,Porosity ,Filtration ,Biotechnology - Abstract
For indirect DNA extraction for metagenomics studies, bacterial cells can be effectively separated from sample debris by using a simple size exclusion technique, such as filtration, and thereafter lysed. The requirement for the optimal recovery of cells in filtrates is critical to achieve sufficient DNA yield and a representative population. Particles smaller than the filter pore size are expected to be found in the filtrate, whereas particles larger than the filter pore sizes are excluded. However, this is not always the case. It is established that the membrane pore size influences filtration efficiency to some degree. In addition the physicochemical characteristics of the filter suspension and characteristics of the microbial cells being filtered influence the exclusion property of a membrane. This review provides an overview of membrane filtration techniques and the factors that affect filterability of bacteria cells through a filter membrane.
- Published
- 2015
32. Evaluating the bioreducing potential of the leaves, knobs and roots ofZanthoxylum capense(small knobwood) for the synthesis of silver nanoparticles, applicable toin vitrofungal contamination control
- Author
-
Roshini Govinden, Olusola Bodede, Shakira Shaik, and Roshila Moodley
- Subjects
biology ,010405 organic chemistry ,Stereochemistry ,02 engineering and technology ,Zanthoxylum capense ,021001 nanoscience & nanotechnology ,biology.organism_classification ,01 natural sciences ,Industrial and Manufacturing Engineering ,Silver nanoparticle ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Transmission electron microscopy ,Sodium hypochlorite ,Shoot ,General Materials Science ,Kinetin ,Electrical and Electronic Engineering ,0210 nano-technology ,Nuclear chemistry ,Explant culture ,Aminopurine - Abstract
In this study we report on the green synthesis of silver nanoparticles using extracts from selected morphological parts of Zanthoxylum capense. UV–vis spectra of the biosynthesised silver nanoparticles (AgNPs) revealed absorption peaks at around 450 nm, indicative of the nanoparticles' surface plasmon resonance, whilst infrared vibrational frequencies indicated the presence of flavonoids, alkaloids, and free and bonded sugars which could be responsible for the reduction and stabilisation of the AgNPs. 1H-NMR fingerprinting of the aqueous knob extract confirmed the active bio-reducing phytochemical of the knobs to be 6-O-p-coumaroyl-β-D-glucopyranoside. The nature, shape and morphology of the biosynthesised AgNPs were examined using transmission electron microscopy (TEM), selected area electron diffraction (SAED), scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) analysis. Z. capense AgNPs were mostly spherical in shape with particle sizes in the range of 4–28 nm, 7–20 nm and 4–32 nm for leaves, knobs and roots, respectively. Leaf extracts were the most efficient in the synthesis of AgNPs with an average yield of 0.027 g AgNPs per g of plant (dry mass). The AgNPs were more effective than sodium hypochlorite (NaOCl) and sodium dichloroisocyanurate (NaDCC) in the control of in vitro fungal contamination in nodal explants of Z. capense up to two weeks. Shoots induced from the surface sterilised explants were further used for shoot multiplication on benzyl aminopurine (BAP) and kinetin (KIN). BAP at 0.5 mg l−1 gave the highest percentage (88.6%) of explants bearing shoots with an average of 4.78 shoots per explant. A total of 15 fungal endophyte strains associated with Z. capense were identified using molecular methods.
- Published
- 2017
33. Experiences in conducting multiple community-based HIV prevention trials among women in KwaZulu-Natal, South Africa
- Author
-
Shay Ganesh, Nicola Coumi, Gita Ramjee, Rashika Maharaj, Neetha S. Morar, Nozizwe Dladla-Qwabe, Jothi Moodley, Sarita Naidoo, Vijayanand Guddera, Thesla Palanee, Roshini Govinden, and Sharika Gappoo
- Subjects
Gerontology ,lcsh:Immunologic diseases. Allergy ,medicine.medical_specialty ,Referral ,media_common.quotation_subject ,Psychological intervention ,030204 cardiovascular system & hematology ,03 medical and health sciences ,0302 clinical medicine ,Denial ,5. Gender equality ,Virology ,Health care ,medicine ,Infection control ,Pharmacology (medical) ,030212 general & internal medicine ,10. No inequality ,media_common ,Community engagement ,business.industry ,Public health ,Research ,3. Good health ,Health promotion ,Family medicine ,Molecular Medicine ,business ,lcsh:RC581-607 - Abstract
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 community-based research sites with approval from both political and traditional leaders, and developing community advisory groups to assist with the research process. Community-wide education on HIV/sexually transmitted infection prevention, treatment and care was provided to over 90 000 individuals. Myths and misconceptions were addressed through methods such as anonymous suggestion boxes in clinic waiting areas and intensive education and counselling. Attempts were made to involve male partners to foster support and facilitate recruitment of women. Peer educator programmes were initiated to provide ongoing education and also to facilitate recruitment of women to the trials. Recruitment strategies such as door-to-door recruitment and community group meetings were initiated. Over 90% of women enrolled were retained. Community benefits from the trial included education on HIV prevention, treatment and care and provision of ancillary care (such as Pap smears, reproductive health care and referral for chronic illnesses). Social benefits included training of home-based caregivers and sustainable ongoing HIV prevention education through peer educator programmes. Challenges Several challenges were encountered, including manipulation by participants of their eligibility criteria in order to enroll in the trial. Women attempted to co-enroll in multiple trials to benefit from financial reimbursements and individualised care. The trials became ethically challenging when participants refused to take up referrals for care due to stigma, denial of their HIV status and inadequate health infrastructure. Lack of disclosure of HIV status to partners and family members was particularly challenging. Some of the ethical dilemmas put to the test our responsibility as researchers and our obligation to provide health care to research participants. Conclusion Conducting these five trials in a period of six years provided us with invaluable insights into trial implementation, community participation, recruitment and retention, provision of care and dissemination of trial results. The critical mass of scientists trained as clinical trialists will continue to address the relentless HIV epidemic in our setting and ensure our commitment to finding a biomedical HIV prevention option for women in the future.
- Published
- 2010
34. Method optimization for denaturing gradient gel electrophoresis (DGGE) analysis of microflora from Eucalyptus sp. wood chips intended for pulping
- Author
-
Lucretia, Ramnath, primary, Tamara, Bush, additional, and Roshini, Govinden, additional
- Published
- 2014
- Full Text
- View/download PDF
35. Naturally occurring phenols: a detoxification strategy for fumonisin B1
- Author
-
Roshini Govinden, S. Beekrum, Bharti Odhav, and T Padayachee
- Subjects
Fusarium ,Health, Toxicology and Mutagenesis ,Food Contamination ,Microbial Sensitivity Tests ,Biology ,Toxicology ,Fumonisins ,Ferulic acid ,chemistry.chemical_compound ,Phenols ,Fumonisin ,Vanillic acid ,Caffeic acid ,Humans ,Mycotoxin ,Fumonisin B1 ,Plant Extracts ,Public Health, Environmental and Occupational Health ,food and beverages ,General Chemistry ,biology.organism_classification ,chemistry ,Biochemistry ,Chemistry (miscellaneous) ,Food Science - Abstract
Phenolic compounds from plants offer a means for both the prevention and detoxification of mycotoxins that affect human health. This research investigates the control of fungal growth and toxin production by Fusarium verticillioides with plant phenolic compounds, namely chlorophorin, iroko and maakianin, benzoic acid, caffeic acid, ferulic acid, and vanillic acid. Inhibition by these compounds of fungal growth was determined by the agar overlay method and their effect on fumonisin B(1) (FB(1)) production was determined by high-performance liquid chromatography. Chlorophorin was the most effective compound in inhibiting fungal growth, followed by iroko, maakianin, vanillic acid and caffeic acid. Chlorophorin also was the most effective compound in reducing toxin production (94% reduction), followed by caffeic acid, ferulic acid, vanillic acid and iroko, which reduced FB(1) levels by 90-91%. The widespread occurrence of fumonisins world-wide and the lack of adequate prevention of fumonisins require 'biologically safe' alternatives to prevent the transfer of fungi and their health hazardous toxins into our daily foods and environment.
- Published
- 2003
36. The effect of modified atmospheres and packaging on patulin production in apples
- Author
-
R. S. Moodley, Roshini Govinden, and Bharti Odhav
- Subjects
Fungal growth ,Chromatography, Gas ,Time Factors ,Food Handling ,Nitrogen ,Microbiology ,Patulin ,chemistry.chemical_compound ,Botany ,Food science ,Ethanol ,biology ,Inoculation ,fungi ,Food Packaging ,Penicillium ,Polyethylene ,Carbon Dioxide ,biology.organism_classification ,Spore ,Oxygen ,Radial growth ,chemistry ,Malus ,Penicillium expansum ,Food Science ,Mutagens - Abstract
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 allowing3.2 microg/ml of patulin to be produced, regardless of gaseous environment.
- Published
- 2002
37. Spice oils for the control of co-occurring mycotoxin-producing fungi
- Author
-
S. Juglal, Bharti Odhav, and Roshini Govinden
- Subjects
Fusarium ,Aflatoxin ,Food Handling ,Microbiology ,law.invention ,chemistry.chemical_compound ,law ,Botany ,Eugenol ,Plant Oils ,Food science ,Spices ,Mycotoxin ,Thymol ,Essential oil ,biology ,food and beverages ,Mycotoxins ,biology.organism_classification ,Aspergillus parasiticus ,Aspergillus ,chemistry ,Eucalyptus oil ,Food Microbiology ,Food Science - Abstract
The effect of nine different oils was evaluated on the growth of Aspergillus parasiticus and Fusarium moniliforme. The experimental design to examine the inhibition of mycotoxins involved the incorporation of each of seven oils into broth and patty cultures. The fungal mycotoxin was identified by high-pressure liquid chromatography. Clove oil (eugenol) was the most inhibitory to the growth of A. parasiticus and F. moniliforme, followed by cinnamon (cinnamic aldehyde), oregano (thymol and carvacol) and mace oils (myristin). Neem and eucalyptus oil (cineole) did not affect fungal growth. The feasibility of implementing the results of this study to control mycotoxin toxicity was examined by costoring whole and ground cloves with mycotoxin-infected grain. Addition of both whole and ground cloves markedly reduced the aflatoxin contamination of the grain. These results clearly suggest that commonly occurring mycotoxigenic fungi can be controlled with clove oil (eugenol), thus spice oil successfully inhibited the growth of A. parasiticus and F. moniliforme, regulated the production of fumonisins, and prevented the formation of aflatoxins. The social implication of this finding is that rural communities can prevent the formation of fungal toxins in contaminated grain by simple measures. Dans cette etude, l'effet de 9 huiles d'epices sur la multiplication de moisissures produisant de l'aflatoxine et de la fumonisine (Aspergillus parasiticus et Fusarium monoliforme) est evalue par la methode de recouvrement en gelose. L'huile de clou de girofle (eugenol) est la plus efficace pour l'inhibition de A. parasiticus et F. monoliforme, suivie de la cannelle (aldehyde cinnamique), l'origan (thymol et carcvacrol) et muscade (myristine).
- Published
- 2002
38. Xylitol production by recombinant Saccharomyces cerevisiae expressing the Pichia stipitis and Candida shehatae XYL1 genes
- Author
-
W.H. van Zyl, Balakrishna Pillay, Dorsamy Pillay, and Roshini Govinden
- Subjects
Saccharomyces cerevisiae ,Biology ,Xylose ,Xylitol ,Applied Microbiology and Biotechnology ,Pichia ,Microbiology ,law.invention ,chemistry.chemical_compound ,law ,Aldehyde Reductase ,Pichia stipitis ,Candida ,food and beverages ,General Medicine ,Maltose ,biology.organism_classification ,Yeast ,Culture Media ,carbohydrates (lipids) ,Electroporation ,chemistry ,Biochemistry ,Galactose ,Recombinant DNA ,Genetic Engineering ,Biotechnology - Abstract
The xylose reductase gene (XYL1) was isolated from Pichia stipitis and Candida shehatae, cloned into YEp-based vectors under the control of ADH2 and PGK1 promoter/terminator cassettes and introduced into Saccharomyces cerevisiae Y294 by electroporation. Shake-flask fermentations were carried out with 5% xylose and 1% galactose, glucose or maltose as co-substrates. Xylose uptake was similar in both the recombinant strains when different co-substrates were used and slowed once the co-substrate was depleted. The recombinant strains converted xylose to xylitol with yields approaching the theoretical maxima. Xylitol production was most rapid when the co-substrate was still present. Approximately 50% of the xylose was not metabolized due to the depletion of the co-substrate.
- Published
- 2001
39. Genomic comparisons among parental and fusant strains of Candida shehatae and Pichia stipitis
- Author
-
Abindra S. Gupthar, Roshini Govinden, Balakrishna Pillay, Dorsamy Pillay, and Ephraim T. Selebano
- Subjects
Biology ,Genome ,Pichia ,law.invention ,Karyogamy ,Meiosis ,law ,Sequence Homology, Nucleic Acid ,Genetics ,Cloning, Molecular ,Pichia stipitis ,DNA, Fungal ,Gene ,Candida ,Electrophoresis, Agar Gel ,Recombination, Genetic ,Base Composition ,fungi ,Nucleic Acid Hybridization ,Karyotype ,General Medicine ,biology.organism_classification ,Phenotype ,Karyotyping ,Recombinant DNA ,Chromosomes, Fungal ,Genome, Fungal - Abstract
DNA-DNA binding experiments on selected fusants of Candida shehatae and Pichia stipitis showed that the nucleus of these strains was composed predominantly of Pichia DNA. Electrophoretic karyotyping revealed that the fusants contained four chromosomes, similar to those found in the Pichia parental strain. In addition, the fusants showed only marginal increases in cell DNA content when compared with the parents. Karyogamy was confirmed, however, by the isolation of recombinant phenotypic segregants, induced by meiotic and mitotic segregation. The results suggest that the fusion led to integration of Candida genes, rather than whole chromosomes, with the entire genome of P. stipitis.
- Published
- 1993
40. South Africa's Experience of the Closure of the Cellulose Sulphate Microbicide Trial
- Author
-
Neetha S. Morar, Roshini Govinden, Gita Ramjee, and Anthony Mbewu
- Subjects
Male ,medicine.medical_specialty ,Economic growth ,Guiding Principles ,Science Policy ,education ,Public Health and Epidemiology ,Alternative medicine ,Human immunodeficiency virus (HIV) ,lcsh:Medicine ,HIV Infections ,medicine.disease_cause ,Microbiology ,South Africa ,Anti-Infective Agents ,Microbicide ,HIV Infection/AIDS ,Humans ,Medicine ,Closure (psychology) ,Cellulose ,Randomized Controlled Trials as Topic ,Policy Forum ,Geography ,business.industry ,Public health ,lcsh:R ,General Medicine ,Clinical trial ,Microbicides for sexually transmitted diseases ,Treatment Outcome ,Infectious Diseases ,Practice Guidelines as Topic ,Health education (including prevention and promotion) ,Immunology ,Patient Compliance ,Women's Health ,Female ,Public Health ,business ,Gels - Abstract
In sub-Saharan Africa, almost 60% of HIV infections are among 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, national regulatory bodies, the media, and on other ongoing microbicide trials. The local lessons that we learnt from the closure may provide guiding principles for researchers and advocates in the HIV prevention field as a whole, who may face similar situations in the future.
- Published
- 2007
41. Evaluating the bioreducing potential of the leaves, knobs and roots of Zanthoxylum capense (small knobwood) for the synthesis of silver nanoparticles, applicable to in vitro fungal contamination control.
- Author
-
Olusola Bodede, Shakira Shaik, Roshini Govinden, and Roshila Moodley
- Published
- 2017
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.