Research Publications (Applied Sciences)
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Item Microbial production of phytases for combating environmental phosphate pollution and other diverse applications(Taylor and Fancis Online, 2016) Kumar, Ashwani; Chanderman, Ashira; Makolomakwa, Melvin; Perumal, Kugen; Singh, SurenConcerns of phosphorus pollution and its impact on environments have driven the biotechnological development of phytases. Phosphoric acid, inositol phosphate, or inositols are produced after hydrolysis of phosphate from phytate, initiated by phytase. Research over the last two decades on microbial phytases has deepened our understanding of their production, optimization, and characterization. Despite the wide availability of phytase producing microorganisms, only a few have been commercially exploited. The current high cost of phytases, inability to withstand high temperatures (>85 C), a limited pH range, and poor storage stability are a major bottleneck in the commercialization of phytases. The development of novel phytases with optimal properties for various applications is a major research challenge. In this paper, recent advances in microbial phytase production, application of tools to optimize higher enzyme production, and characterization of phytases along with potential biotechnological applications are reviewed. Additionally the development of phytase assay methods and functions of phytate and phytate degradation products are discussed.Item Purification and characterization of an Endoinulinase from Xanthomonas campestris pv. phaseoli KM 24 Mutant(University of Zagreb, 2015) Naidoo, Kameshnee; Kumar, Ajit; Sharma, Vikas; Permaul, Kugen; Singh, SurenAn extracellular endoinulinase from Xanthomonas campestris pv. phaseoli KM 24 mutant was purifi ed to homogeneity by gel fi ltration chromatography and showed a specifi c activ-ity of 119 U/mg. The optimum pH and temperature of the purifi ed enzyme were found to be 6.0 and 50 °C, respectively. The enzyme was stable up to 60 °C, retaining 60 % of residu-al activity for 30 min, but inactivated rapidly above 60 °C. The enzyme was found to be stable at pH=6–9 when it retained 100 % of its residual activity. The Lineweaver-Burk plot showed that the apparent Km and vmax values of the inulinase when using inulin as a sub-strate were 1.15 mg/mL and 0.15 μM/min, respectively, whereas the kcat value was found to be 0.145 min–1. The calculated catalytic effi ciency of the enzyme was found to be 0.126 (mg·min)/mL. The purifi ed inulinase can be used in the production of high fructose syr-ups.Item Inactivation of Listeria monocytogenes ATCC7 644 Biofilms using Sodium Dodecyl Sulphate, Levulinic Acid and Sodium Hypochlorite solution(MN Khan, 2014-06) Singh, Suren; Mnyandu, Elizabeth; Oluwatosin Ademola IjabadeniyiA study was done to assess the effectiveness of 200 ppm sodium hypochlorite (chlorine), 1% sodium dodecyl sulphate (SDS) and 0.5% levulinic acid in reducing L. monocytogenes ATCC7644 biofilms. 0.05% SDS and 0.5% levulinic acid were also used combined (mixture). After treatment with sanitizers, the biofilms were stored at 4°C for up to 72 hours and samples were tested at 0, 24, 48 and 72 hours. The contact times were varied to 1, 3, 5 minutes. Results revealed that biofilms were still viable after treatment with these sanitizers. There was no significance difference between storage times. Varying contact times from 1 to 3 minutes did not show a significance difference however there was a significance difference when the contact time was increased to 5 minutes. Non-adapted biofilms had highest log reductions compared to chlorine adapted and heat adapted biofilms. Treatment with chlorine was least effective in reducing viability of biofilms, followed by levulinic acid then a mixture of levulinic acid and SDS. SDS used alone had highest log reductions. Application of sanitizers at different contact times combined or individually may be successful in reducing biofilms in food manufacturing units. A careful selection of sanitizer for each specific pathogen may be required if sanitizers are to work effectively against biofilms.Item Biodegradation of glycerol using bacterial isolates from soil under aerobic conditions(Taylor and Francis, 2014) Raghunandan, Kerisha; Mchunu, Siphesihle; Kumar, Ashwani; Kumar, Kuttanpillai Santhosh; Govender, Algasan; Permaul, Kugen; Singh, SurenGlycerol, a non-biodegradable by-product during biodiesel production is a major concern to the emerging biodiesel industry. Many microbes in natural environments have the ability to utilize glycerol as a sole carbon and energy source. The focus of this study was to screen for microorganisms from soil, capable of glycerol utilization and its conversion to value added products such as ethanol and 1,3-propanediol (1,3-PDO). Twelve bacterial isolates were screened for glycerol utilization ability in shake flask fermentations using M9 media supplemented with analytical grade glycerol (30 g/L) at various pH values (6, 7 and 8) and temperatures (30◦C, 35◦Cand 40◦C). Among these, six bacterial isolates (SM1, SM3, SM4, SM5, SM7 and SM8) with high glycerol degradation efficiency (>80%) were selected for further analysis. Highest level of 1,3-PDO production (15 g/L) was observed with isolate SM7 at pH 7 and 30◦C, while superior ethanol production (14 g/L) was achieved by isolate SM9 at pH 8 and 35◦C, at a glycerol concentration of 30 g/L. The selected strains were further evaluated for their bioconversion efficiency at elevated glycerol concentrations (50–110 g/L). Maximum 1,3-PDO production (46 g/L and 35 g/L) was achieved at a glycerol concentration of 70 g/L by isolates SM4 and SM7 respectively, with high glycerol degradation efficiency (>90). Three isolates (SM4, SM5 and SM7) also showed greater glycerol tolerance (up to 110 g/L). The isolates SM4 and SM7 were identified as Klebsiella pneumoniae and SM5 as Enterobacter aerogenes by 16S rDNA analysis. These novel isolates with greater glycerol tolerance could be used for the biodegradation of glycerol waste generated from the biodiesel industry into value-added commercial products.Item Improvement of ethanol production from sugarcane molasses through enhanced nutrient supplementation using Saccharomyces cerevisiae(Academic Journals, 2012-03) Nofemele, Zuko; Shukla, Pratyoosh; Trussler, Arthur; Permaul, Kugen; Singh, SurenSaccharomyces cerevisiae as a yeast cream was utilized for alcoholic fermentation using sugar cane molasses. In the present study, fermentation was optimized for urea and yeast hydrolysate (YH) dosage and the combined effect was evaluated. Total sugars as inverts (TSAI) composition of molasses were -1 determined by HPLC as 39% (m/v). Urea concentrations of 4, 2 and 3 gl showed optimal ethanol -1 production at 30, 35 and 40°C respectively. A YH concentration of 0.5 gl resulted in an ethanol yield of 8.7% (m/v) with a fermentation efficiency of 85.12%. Under optimized conditions (35°C) significant improvements were noticed with ethanol yield of 7.8% (m/v) and efficiency of 76.3%.Item Xylanase superproducer : genome sequence of a compost-loving thermophilic fungus, thermomyces lanuginosus strain SSBP(American Society for Microbiology, 2013-06-20) Mchunu, Nokuthula Peace; Permaul, Kugen; Rahman, Ahmad Yamin; Saito, Jennifer A.; Singh, Suren; Alam, MaqsudulWe report here the draft genome sequence of Thermomyces lanuginosus strain SSBP, which was isolated from soil in South Africa. This fungus produces the largest amount of xylanase ever reported in the literature.