Abstract:

Using the screening method based on fibrinolytic activity and nattokinase gene, a strain named MJ-1 with
nattokinase-producing capacity was obtained and identified as Bacillus subtilis by 16S rRNA gene sequence analysis. A
natto functional food was prepared by fermentation of soybean with MJ-1, and its nattokinase activity, and anticoagulant
and antioxidant activity were evaluated. Under the conditions of 60% initial moisture content and 37 ℃, the maximum
nattokinase activity of 90.18 FU/g dry weight was obtained after 20 h fermentation, which reached the activity level of
commercial natto. The strain MJ-1 could secret anticoagulant components, resulting in rich anticoagulant activity in natto
foods, and the anticoagulant activity of natto water extract at 3 mg/mL reached 91%. Moreover, fermentation with MJ-1
improved the antioxidant activity of soybean significantly.

Key words: nattokinase, Bacillus subtilis, gene-based screening method, anticoagulant activity, antioxidant activity