Optimization of medium composition for thermostable protease production by <i>Bacillus</i> sp. HS08 with a statistical method

Abstract

Optimization of the fermentation medium for maximization of thermostable neutral protease production by Bacillus sp. HS08 was carried out. After screening various elements, carbon and nitrogen sources, response surface methodology (RSM) was applied to optimize the medium constituents. A 24 fullfactorial central composite design (CCD) was chosen to explain the combined effects of the four medium constituents; corn starch, soybean meal, glucose and yeast extract. The optimized values obtained by the statistical analysis showed that corn starch at 19.8 g/l, soybean meal at 9.7 g/l, glucose at 3.6 g/l and yeast extract at 3.9 g/l gived maximum protease activity of 6804 U/ml.