Study on Liquid Fermentation of Nattokinase

The effect of liquid fermentation on Nattokinase activity produced by Bacillus natto No.ZN-4 strain was studied. Results showed that the optimal culture conditions were 2 % glucose, 1 % peptone, 0.6 % Na2HPO4,0.1 % NaH2PO4,0.05 % MgSO4, 0.02 % CaCl2, pH 7.0, the inoculums size 3 % and temperature 35 ℃ . Under these conditions, the Nattokinase activities of the strain reached 1903 U/mL in shake-flask, 2210 U/mL for 50 L fermentation, and 1934 U/mL for 500L fermentation, respectively.