Optimization of bacillus natto liquid fermentation for low purine and high enzyme activity

The bacteria growth curve was drew by detecting OD660 nm. The optimal growth time was defined as12 h after researching. The fermentation factors were optimized by single factor and orthogonal experiment. The final optimization fermentation factors were as follows (g/L) :full peas powder 20, lactose 20, yeast extract 10, KH2PO40.1, K2HPO4·3H2O 0.1, MgSO4·7H2O 0.5, NaCl 10, CaCl20.3. And the initial fermentation pH was 7.0, inoculum was 2%, liquid volume was 30mL/50 mL, shaking speed was 100r/min, fermentation temperature was37℃ and fermentation time was 36 h. Through the verification experiments, results indicated that enzyme activity increased from 1005.77IU/mL to 2835.50IU/mL while purine content decreased from 65.56mg/L to 29.36mg/L.