Optimization of culture medium and fermentation conditions for neutral protease produced by Bacillus coagulans Liu-g

In order to improve the activity of neutral protease produced by Bacillus coagulans Liu-g1,single factor test and orthogonal test on Bacillus coagulans Liu-g1 protease activity were carried out. The results showed that the optimal culture medium formula was 1% of soybean powder,4% of corn starch and 0.6% of calcium carbonate.The results also indicated that the best initial p H was 7.5,fermentation volume of 30 m L /250 m L,incubation temperature at 45 ℃,fermentation time for 72 h. The protease activity reached 243.874 U / m L in such conditions,5.8 times the amount of initial conditions.