Bijesh Kavuthodi and Denoj Sebastian*
Department of Life Sciences, University of Calicut, Kerala – 673635, India.
This study has been undertaken for the media optimization of pectinase producing strain, Bacillus subtilis BKDS1 isolated from dump yards of vegetable wastes. The ideal concentration of the substrate pectin was optimized by One–factor-at-a-time (OFAT) optimization method and found to be 0.25%. Optimization of the rest of fermentation variables (yeast extract, CaCl2, NaCl, (NH4)2SO4, KH2PO4, K2HPO4, MgSO4, NaNO3, inoculum volume and pH) was carried out by Plackett-Burman design (PBD) followed by response surface methodology (RSM). Among the ten fermentation variables, three variables (yeast extract, CaCl2 and inoculum size) were selected to significantly affect pectinase production by PBD. The optimum levels of these variables were further determined using response surface methodology (RSM) based on central composite design (CCD). The optimal medium compositions were determined as follows (g/L): yeast extract 7.6g, CaCl2 0.81g, inoculum size of 1.5% and pectin 2.5g. The pectinase activity reached the maximum value of 1065.95U/mL in the optimized medium and it showed many fold increase in enzyme production compared to other pectinase production media tested in shake flask experiments.
Keywords: Bacillus subtilis BKDS1, CCD PBD, pectinase, RSM.