Optimization of α-amylase production by Bacillus sp. using response surface methodology

The combined effects of macronutrients of media on α-amylase production by Bacillus sp. were studied using response surface methodology. A 22 full-factorial central composite design was chosen to explain four medium constituents, viz. starch, glycerol, yeast extract (YE) and peptone, and to analysis of the results. This procedure limited the number of actual experiments performed while allowing for possible interactions between four components. The P-value of the coefficient for quadratic effect of glycerin concentration was <0.0001, suggesting that this was the principal experimental variable having the greatest effect on the production of α-amylase. It was found that YE had no effect on α-amylase production. The optimal combinations of media constituents for maximum α-amylase production were determined as 17.58 g/l starch, 12.37% (v/v) glycerin, 8.77 g/l peptone and 0.00 g/l YE.