OPTIMIZATION OF PRODUCTION PROCESS OF NEUTRAL PROTEASE FROM BACILLUS STRAINS BY MIXTURE-CULTURE FERMENTATION
To increase the fermentation titer unit of neutral protease from Bacillus strains, we studied the synergistic effect of multiple kinds of Bacillus strains for preparing neutral protease by mixture-culture fermentation, and optimized the combination manner of strains and the composition of the fermentation medium by single-factor experiments, fractional factorial design, steepest ascent design and central composite design to construct a proper mixture-culture fermentation system, which contained Bacillus strain A1, B1 and B3 at a ratio of 2 :3 : 3. The results showed that the optimum fermentation medium contained maltose 58.5 g/L,yeast extract 28.6 g/L,wheat bran 42.5 g/L, Tween80 3.0 g/L,K2HPO4 3.0 g/L,and CaCO3 3.0 g/L. Under these optimized conditions, the active unit of neutral protease produced from Bacillus strains by mixture-culture fermentation reached 6 728 U/mL, which was increased by 175.6 % in comparison to that of Bacillus strain A1.
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维普
