Use of response surface methodology for optimizing process parameters for the production of α-amylase by Aspergillus oryzae

Abstract

Optimization of three parameters (incubation temperature, initial substrate moisture and inoculum size) was attempted by using a Box–Behnken design under the response surface methodology for the optimal production of α-amylase by Aspergillus oryzae NRRL 6270 in solid-state fermentation (SSF). Spent brewing grains (SBG) was used as sole carbon source. The experimental data was fitted into a polynomial model for the yield of enzyme and an optimum level was arrived at which nutrient supplements were optimized. A Plackett–Burman design was employed to screen nineteen nutrient components for their influence on α-amylase production by the fungal culture. Three components (soybean meal, calcium chloride and magnesium sulphate) were selected based on their positive influence on enzyme formation. A Box–Behnken design was employed to optimize their composition, which showed that an incubation temperature of 30 °C, an initial moisture of 70% and an inoculum rate of 1×107 spores/g dry substrate were the best conditions to produce α-amylase with A. oryzae NRRL 6270 on SBG. Under optimized conditions of SSF, about 20% increase in enzyme yield was observed.