Faculty of Health Sciences
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Item Directed evolution: tailoring biocatalysts for industrial applications(Taylor and Francis Online, 2012-09-18) Kumar, Ashwani; Singh, SurenCurrent challenges and promises of white biotechnology encourage protein engineers to use a directed evolution approach to generate novel and useful biocatalysts for various sets of applications. Different methods of enzyme engineering have been used in the past in an attempt to produce enzymes with improved functions and properties. Recent advancement in the field of random mutagenesis, screening, selection and computational design increased the versatility and the rapid development of enzymes under strong selection pressure with directed evolution experiments. Techniques of directed evolution improve enzymes fitness without understanding them in great detail and clearly demonstrate its future role in adapting enzymes for use in industry. Despite significant advances to date regarding biocatalyst improvement, there still remains a need to improve mutagenesis strategies and development of easy screening and selection tools without significant human intervention. This review covers fundamental and major development of directed evolution techniques, and highlights the advances in mutagenesis, screening and selection methods with examples of enzymes developed by using these approaches. Several commonly used methods for creating molecular diversity with their advantages and disadvantages including some recently used strategies are also discussed.Item Carbon utilization profile of a thermophilic fungus, Thermomyces lanuginosus using phenotypic microarray(Scientific Research Publishing, 2013-09) Mchunu, Nokuthula Peace; Permaul, Kugen; Alam, Maqsudul; Singh, SurenThe thermophilic filamentous fungus, Thermomyces lanuginosus produces the largest amount of xylanase reported. In addition to this, it expresses large amount of other enzymes that have been used indus- trially or have academic interest. Thus, this fungus has a potential to be applied for biomass conversion to produce biofuel or other applications. In this study, the Biolog system was used to characterize the utilisa- tion and growth of T. lanuginosus on 95 carbon sources. The carbohydrates based compounds, both single sugars and oligosaccharide, showed the best utilisation profile, with the pentose sugar xylose in- ducing the highest growth, followed by trehelose, raf- finose, D-mannose turanose fructose and glucose. Among oligosaccharides, sucrose had the highest my- celium formation followed by stachyose, maltose, maltotriose, glycogen and dextrin. Interestingly the fungus also grew well on cellobiose suggesting that this fungus can produce cellulose hydrolysing pro- teins. D-alanine was the best amino acid to promote fungal growth while the effect of other amino acids tested was similar to the control. These results dem- onstrate the ability of this fungus to grow relatively well on most plant based compounds thus making this fungus a possible candidate for plant biomass conver- sion which can be applied to a number of biotechno- logical applications including biofuel production.