利用30L自控发酵罐研究了大肠杆菌TRJTH0709产L-色氨酸的发酵工艺。考察了初始葡萄糖浓度和发酵过程中葡萄糖维持浓度对菌体比生长速率、质粒稳定性、乙酸含量、菌体生物量及L-色氨酸产量的影响。最终确定:初始葡萄糖浓度为20g/L,葡萄糖维持浓度采用葡萄糖限制流加培养方式。根据溶氧响应信号的特征反馈控制葡萄糖的流加速率,可将菌体比生长速率控制在较低水平,有效地减少了发酵过程中乙酸的产生及提高了质粒稳定性,实现了重组大肠杆菌的高密度培养,菌体生物量和L-色氨酸分别为50.21g/L和33.50g/L。

The fermentation of L-tryptophan by Escherichia coli TRJTH0709 in 30 L bioreactor was investigated. The effects of initial glucose concentration and glucose concentration in fermentation process on specific growth rate,plasmid stability,concentration of acetic acid,biomass and yield of L-tryptophan were studied. The optimal concentration of initial glucose was 20g/L. The concentration of glucose in process of L-tryptophan fermentation was controlled by glucose-limited fed-batch mode. According to the dissolved oxygen response signal,using feedback control,the feed rate in fermentation process was effectively manipulated and the specific growth rate was controlled at low level. The accumulation of acetic acid was reduced effectively and the plasmid stability was improved obviously. Biomass of 50.21 g/L dry cell weight could be obtained and the yield of L-tryptophan was 33.50 g/L. The high cell density cultivation was achieved eventually by using the strategy of feedback control of dissolved oxygen.