Statistical Optimization of the Medium for the Production of α-Amylase by the Mutant Aspergillus flavus MS-12 Using Response Surface Methodology

Abstract

The present study is concerned with the improvement of Aspergillus flavus S-12 for α-amylase production. The mutant’s ability to produce α-amylase increased 1.24 times after the treatment with Ultraviolet radiation. Also, the medium composition was optimized using response surface methodology. A fractional factorial design (2^8 − 3) was applied to elucidate the medium components that significantly affect α-amylase production. The concentration of starch, CaCl₂ and triton X-100 in the medium were significant factors. The central composite design was used to estimate the quadratic response surface from which the factor levels for maximum production of α-amylase were determined. The experimental results showed that the optimum concentration of starch, CaCl₂ and triton X-100 were 15 g/L, 0.2 g/L and 0.2% (v/v), respectively. The conventional methods for optimization used in previous studies involve varying one parameter at a time and keeping the others constant. Being single-dimensional, this laborious and time-consuming method often does not guarantee determination of optimal conditions. The method of optimization used in this study was proved to be efficient as only 20 experiments were necessary to asses the optimal conditions of enzyme production, and model adequacy was very satisfactory, as the coefficient of determination was 0.988.