Study on the optimization of nattokinase liquid fermentation by Bacillus natto

The optimization of Nattokinase liquid fermentation by Bacillus natto was investigated in this paper. The results indicated that when the fermentation medium was prepared with soya peptone 3%, glucose 2%, Na2HPO4 0.6%, NaH2PO4 0.1%, CaCl2 0.02% and MgSO4 0.05%, pH 7.0-7.2, and inoculums 2%, the yield of Nattokinase reached 736 IU Urokinase/ml after fermentation for 60 h at 37℃ under 200 r/min condition.