Preparation of Alkaline Protease by Fermentation of Bacillus subtilis

Medium compositions and fermentation conditions for producing alkaline protease through the fermentation of Bacillus subtilis were optimized by orthogonal design based on single factor experiments. Results indicated that optimal medium compositions were 2% yeast powder, 1.0% sugar, 0.5% Tween 80, and 0.02% MgSO4. The optimal fermentation condition was 4% inoculation amount in 25 ml of medium filled in 150 ml Erlenmeyer flasks at the initial pH 9 for 36 h of fermentation. The activity of alkaline protease obtained at this optimal fermentation condition was 1670 U/ml.