pH值对大肠杆菌发酵异亮氨酸的影响

Effect of pH on the Process of Escherichia coli L-isoleucine Fermentation

以L-异亮氨酸生产菌E.coli TRFP为出发菌株,考察不同pH值对发酵过程中重组酶酶活、菌体生物量、L-异亮氨酸产量和葡萄糖消耗速率以及副产物积累等方面的影响。研究表明:与恒定pH 7.2控制策略相比,采用分段控制pH值的工艺可使最大生物量和异亮氨酸产量分别提高了6.1%和9.2%,乙酸及NH4+浓度分别减少7.8%和11.6%;同时,采用NaOH和氨水混合碱调节pH值能够有效降低NH4+对菌体的抑制作用,减缓菌体衰退。

The effects of pH on the fermentation of L-isoleucine were studied with L-isoleucine producing strain E.coli TRFC.The effects of pH in fermentation process on enzyme activity,biomass,yield of L-isoleucine,glucose consumption rate and accumulation of byproduct were studied by carrying out fed-batch fermentation.Results showed that the yield of biomass and L-isoleucine by three stage pH control strategy was increased by 6.1% and 9.2% compared to that from the condition of constant pH 7.2.Besides,the concentration of acetate and ammonium was decreased by 7.8% and 11.6%.The combined neutralizing agents,NaOH and ammonia,which were used to maintain pH level could effectively reduce the inhibitory effects of ammonium and delay cell aging.