STUDY ON THE CONDITIONS OF PRODUCTING NATTOKINASE BY BACILLUS NATTO STRAIN B-12 AND THE ENZYME PROPERTY OF NATTOKINASE

The conditions of producing nattokinase by Bacillus natto strain B-12 and the partial enzyme properties of nattokinase were researched,and the effects of carbon source,nitrogen source,fermentation time,fermentation temperature and original media pH on production of nattokinase were investigated in this paper.Based on optimized conditions for fermentation,the yield of nattokinase by Bacillus natto strain B-12 was 903 IU Urokinase/mL. Nattokinase was stable, and the residual activity was about 80 % at 50 ℃ for 100 min. It was also stable in pH6.0-9.0,and the residual activity was about 80 %. Fe3+ and Al3+ could obviously inhibit enzyme activity,and Zn2+ could faintly activate the activity.