L-色氨酸混菌发酵工艺

Mixed bacteria fermentation process of L-tryptophan production

为解决L-色氨酸发酵过程中乙酸、乳酸等抑制性副产物积累对对菌体活力和色氨酸积累造成抑制的问题,利用2株色氨酸生产菌,即大肠杆菌TRTH和谷氨酸棒杆菌TQ2223进行混合发酵,利用谷氨酸棒杆菌代谢大肠杆菌产生的乙酸、乳酸等副产物,降低乙酸等副产物对大肠杆菌发酵的负面影响。通过单因素试验确定了混菌发酵的最佳接种间隔时间为14h,谷氨酸棒杆菌TQ2223接种量为7.5%,培养温度为36℃,pH7.0。在最佳工艺条件下进行了30L发酵罐小试验证,结果显示,与普通发酵工艺相比,混菌发酵工艺的乙酸积累量减少84.8%,乳酸积累量减少82.9%,L-色氨酸产量提高13.6%,糖酸转化率提高19.1%。为发酵法高效生产L-色氨酸提供了新方案,为混菌发酵在氨基酸发酵中的应用提供了理论依据。

In this study,Escherichia coli TRTH and Corynebacterium glutamicum TQ2223 were used for mixed fermentation in order to solve the problem related to the fermentation by-products(acetic acid and lactic acid)formation during L-tryptophan fermentation.During fermentation,acetic acid and lactic acid produced by E.coli were metabolized by C.glutamicum to reduce their negative effects on E.coli fermentation.The optimum condition for mixed fermentation was to inoculate 7.5%C.glutamicum TQ2223 after a 14 h interval,followed by incubating at 36℃and pH 7.0.By using a 30 L fermenter,it was found that compared with conventional fermentation,mixed fermentation under the optimum condition decreased accumulated acetic acid and lactic acid by 84.8%and 82.9%,respectively.Moreover,the yield of L-tryptophan increased by 13.6%,and the conversion rate of sugar to acid increased by 19.1%.Overall,this study provides a new strategy for efficient L-tryptophan fermentation and builds a theoretical basis for applying mixed bacterial fermentation in amino acid fermentation.