Statistical optimization of conditions for protease production from Bacillus sp.

Response surface methodology was employed for the optimization of different nutritional and physical parameters for the production of protease by a soil isolated Bacillus strain in submerged fermentation. Initial screening of production parameters as carbon (glu- cose) and nitrogen source (soybean) were optimized together with four variables K 2 HPO 4 , NaCl, MgSO 4 .7H 2 O, CaCl 2. 2H 2 O and four physical parameters including agitation, inoculum size, pH and time was performed using Plackett Burman design and the variables with statistically sig- nificant effect on the protease production identified. These variables were selected for further optimization studies using central composite design in RSM. The protease activity under unop- timized conditions was 330 U/ml. Under the final optimized conditions, the predicted response for protease production was 449 U/ml, and the observed validated experimental value was 577 U/ml. The statistical optimization by response surface methodology resulted in about two fold increase in the production of the enzyme by the selected bacterial strain Acta Biol Szeged 54(2):135-141 (2010)