Faculty Publications
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Item Screening and optimisation of bioconversion parameters for the reduction of 3-[5-[(4-flurophenyl)-1,5, di-oxopentol]-yl] -4-(S) phenyl oxazolidin-2-one(2009) Brahmani Priyadarshini, S.R.; Mugeraya, G.; Sandhyavali, M.S.The reduction of ketones is one of the most important and practical reaction for producing non racemic alcohols, which are needed to synthesize industrially important chemicals such as pharmaceuticals, agrochemicals and natural products. Biocatalysis has turned out to be a highly competitive technology for asymmetric ketone reduction. In the present work, an attempt was made to identify a potential microorganism for the reduction of 3-[5-[(4-flurophenyl)-1,5, di-oxopentol]-yl] -4-(S) phenyl oxazolidin-2-one. Some of the fungi screened were Saccharomyces cerevisiae, Aspergillus niger(2 strains), Pichia farinosa, Candida vishwanathii, Rhizopus stolonifer and Penicillin species. The experimental results showed that S. cerevisiae, Aspergillus niger and C. viswanathii strains were able to bring about the conversion of selected ketone to alcohol. As Saccharomyces cerevisiae was found to be more effective in bringing about reduction, it was selected for further experiment. In order to improve the yield certain bioconversion parameters like pH of reaction medium, time of incubation, incubation temperature and biomass to substrate ratio were studied. The results showed that the bioreduction of the above mentioned substrate was maximum in pH 7.6 at 30°C when incubated for 48 h. The conversion increased with increase in biomass, however it reached saturation at the ratio of 300:1.Item Bioreduction of a drug intermediate in presence of hexane and surfactants(Chemical Publishing Co., 2011) Priyadarshini, S.R.B.; Mugeraya, G.; Sandhyavali, M.S.Enhancing the dispersion and dissolution of substrate particles in substrate/water suspension is a feasible way to improve enzyme substrate contact. The aim of the present study is to investigate the effects of organic solvents like hexane and surfactants like sodium lauryl sulphate (SLS) and cetyltrimethyl ammonium bromide (CTAB) on bioreduction of 3-[5-[(4-flurophenyl)- 1,5, di-oxopentol]-yl]-4-(s)- phenyloxazolidin-2-one using Sacchromyces cerevisiae as biocatalyst. Effect of variations in the ratio of hexane to water and the concentration of an anionic and cationic surfactants, were studied to see their effect on the bioreduction of the above mentioned ketone. As the substrate is hydrophobic, the bioreduction was tried in a biphasic system using solvent like hexane. The overall yield of the alcohol decreased significantly when the reaction was carried out in presence of hexane as compared to aqueous medium. The yield of alcohol increased when the ratio of hexane to water was 2:1, but decreased significantly with further increase in hexane concentration. The use of surfactants has been reported extensively in microbial biotransformation reactions. Hence the effect of both anionic (sodium lauryl sulphate) and cationic (cetyltrimethyl ammonium bromide) surfactants on the above said bioreduction was considered for the study. The results showed that cetyltrimethyl ammonium bromide has insignificant effect in bringing about ketone reduction while sodium lauryl sulphate exhibited three fold increase in the yield.