Abstract:Fifteen Nattokinase-producing strains separated from Japanese food-natto were investigated in this study. The strain N-15 was selected from the examined striains for its high level of nattokinase-producing activity (900 IU/mL). The fermention conditions of the strain N-15 for the nattokinase production were optimized by single factor and orthogonal tests. It was found that the optimal soybean residue content, sucrose content, incubation temperature and the original pH value were 20%, 2%, 37 ℃ and 7.0, respectively. Under the optimized fermentation conditions, Nattokinase was produced with a high activity level of 1033 IU/mL.
