Optimization of culture conditions by response surface methodology for production of extracellular esterase from Serratia sp. EST-4

Objective: The aim of present study was to determine the effect of interaction among different production variables on esterase production from Serratia sp. EST-4. Method: The optimum and combined effect of independent parameters were determined using Plackett-Burman and Central Composite Design (CCD) (Design Expert 11). Results: The effect of six parameters-cotton seed oil, peptone and maltose concentrations, pH, temperature and inoculum volume for production of esterase was determined by Plackett-Burman design. Four factors i.e. inoculum size, pH, peptone concentration and cotton seed oil concentration had significant effect on yield of esterase as suggested by the Pareto chart. Under optimized conditions, (inoculum size (1.0%, v/v), pH (8.0), peptone concentration (1.5%, w/v) and cotton seed oil concentration (4.0%, v/v)), the maximum esterase production was 9.77 U/ml. Analysis of variance (ANOVA) of the Central Composite Design (CCD)-based experiment exhibited the model F-value of 44.24 and P-value of <0.0001 which implies that model was significant and adequate to represent the system. Conclusion: Inoculum size 1.0%, v/v, pH 8.0, concentration of peptone 1.5%, w/v and concentration of cotton seed oil 4.0%, v/v had positive effect on esterase production and provided 1.52-fold increase in esterase production than that obtained by optimizing one factor at one time.