| In order to improve the production of α-amylase by fed-batch culture of Aspergillus oryzae, the response surface methodology was applied to optimize the fermentation medium. Firstly, Plackett-Burman design was undertaken to evaluate the effects of seven factors. With statistic regression analysis, the significant factors affecting α-amylase production were determined as follows: soybean power, pH and FeSO4.7H2O. Box-Behnken design was used to optimize the three critical internal factors mentioned above, and the optimum levels and the relationships among these factors was found out. By quadratic regression model equation with Design Expert statistic methods, the regression model was obtained as: 18.51 g/L soybean power, 0.0092 g/L FeSO4.7H2O, pH 6.39 and 60 g/L corn flour,2.5 g/L K2HPO4.3H2O, 4.5 g/L NaNO3, 0.8 g/L MgSO4.7H2O. Under such conditions, the predicted α-amylase production was attained 839.5 U/mL, which was in excellent agreement with the experimental result 843 U/mL (with only +0.4% differences), about 20% higher than the production under the initial conditions. |
