Fig. 2From: Tofu processing wastewater as a low-cost substrate for high activity nattokinase production using Bacillus subtilisEffects of various amino acids (a) and soy milk hydrolysate (b) on the nattokinase activity. Control: 20 g/L Tryptone as nitrogen source for blank control. *Significance code: P < 0.05; **Significance code: P < 0.01.Back to article page