Study on the liquid fermentation of Selem’Nattokinase

This study realized the biological transformation form inorganic selenium into organic selenium by liquid fermentation of the Bacillus natto, and obtained Selem’Nattokinase. Optimal fermentation conditions were 2.5% soy peptone, 2% glucose, 10-6 mol/L Na2SeO3, 0.05% MgSO4, 0.02% CaCl2, 0.2% /0.1% K2 HPO4/KH2PO4, pH7.0, fermentation temperature 37℃ , inoculum size 2% , fermentation time 60h. Under these conditions, the activity of the Selem’Nattokinase reached 196.81U/mL (Folin-phenol method) , and the selenium content of its SDS-PAGE protein band was 0.060μg/g.