Statistical optimization of α-amylase production by Escherichia coliusing extruded bean as nitrogen and carbon source

Response surface methodology based on mixture design was employed for statistical optimization of medium components for the growth and production of α-amylase by Escherichia coli pAC92. The combined effects of media constituents (peptone, yeast extract and extruded beans) were analyzed using a cubic model, which was developed by3-factor simplex lattice mixture design in predicting the optimum yield of growth and α-amylase activity. Results evidenced that extruded common bean was more effective as a nutrient source for E.colipAC92 growth. On the other hand, the completely substituted medium with extruded common bean resulted in 68% of increase in the growth of Escherichia coli pAC92. In addition, the culture medium containing 0.5% of extruded bean and 0.5% of peptone reached a α-amylase activity of 44.59 U. The optimal medium composition was determined by a numerical method based on desirability function, by which the optimal composition for maximum optical density and enzyme activity was found using 0.5% peptone and 0.5% extruded common bean as media constituents. Therefore, these results evidenced that extruded common bean can be successfully used as substitute of peptone and yeast extract in culture media for production of α-amylase byE.colipAC92.