Medium optimization by orthogonal array and response surface methodology for cholesterol oxidase production by Streptomyces lavendulae NCIM 2499

Abstract

This paper deals with the optimization of culture conditions for the production of cholesterol oxidase (COD) by Streptomyces lavendulae NCIM 2499 using the one-factor-at-a-time method, orthogonal array method and response surface methodology (RSM) approaches. The one-factor-at-a-time method was adopted to investigate the effects of medium components (i.e. carbon and nitrogen) and environmental factors (i.e. initial pH) on biomass growth and COD production. Subsequently, an L₁₂ orthogonal matrix was used to evaluate the significance of glycerol, soyabean meal, malt extract, K₂HPO₄, MgSO₄ and NaCl. The effects of media components were ranked according to their effects on the production of COD as malt extract > soyabean meal > K₂HPO₄ > NaCl > MgSO₄ > glycerol. The subsequent optimization of the four most significant factors viz. malt extract, soyabean meal, K₂HPO₄ and NaCl, was carried out by employing a central composite rotatable design (CCRD) of RSM. There was a 2.48-fold increase in productivity of COD as compared to the unoptimized media by using these statistical approaches.