Optimization of fermentation process for Bacillus subtilis WB800N/pHT43-npr-PrsA recombinant strain with protease activity
The experiment aimed to optimize the fermentation protease activity of the engineered Bacillus subtilis strain WB800N/pHT43-npr-PrsA,providing technical support for domestic feed protease enterprises.The fermentation process was monitored for glucose content and specific consumption rate to determine the dynamic impact of carbon and nitrogen sources on the glucose consumption of this strain.The components of the fermentation medium were optimized through single-factor and response surface experiments.The results showed that optimizing the fermentation medium with the OD600nm value of the cell body from 0 to 10 hours as a parameter can promote cell growth and achieve a higher cell quantity.After 10 hours,supplementing with 5 g/L yeast extract and 70 g/L peptone could extend the stationary phase to achieve the maximum specific enzyme activity.The optimized fermentation medium conditions were:60 g/L yeast extract,30 g/L peptone,10 g/L racemic glucose,and 3 g/L MgSO4.At 8 h of fermentation,adding 0.5‰ IPTG and 2‰ protease inhibitor,the final fermentation protease activity reached 1 156 U/mL.The study indicates that delayed stable period can increase the peptone content in the medium,which is beneficial for improving the specific glucose consumption rate of the cells.Peptone promotes the adaptation of the cells to the surrounding environment.Maintaining a low glucose concentration during the fermentation process can effectively avoid the formation of acetic acid,promote cell growth,and enhance enzyme production efficiency,keeping the cell consumption of the substrate at its most vigorous state.
proteaseengineering strainsenzyme activityfermentation process
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