产L-色氨酸营养缺陷型突变菌株谷氨酸棒杆菌LG-332的选育

Study on breeding of high L-Tryptophan-producing strain

以谷氨酸棒杆菌(Corynebacterium glutamicum)Tx5-32为出发菌株,对其遗传标记和产酸能力进行了验证。在此基础上,通过DES和UV多次诱变处理,筛选得到苯丙氨酸和酪氨酸营养缺陷型菌株LG-210。以双营缺LG-210为出发菌株,再经DES和UV多次诱变,有目的地筛选有利于L-色氨酸积累的结构类似物抗性突变株,通过单菌落分离、摇瓶初筛和摇瓶复筛,最后获得消除色氨酸阻遏作用并且产量进一步提高的L-色氨酸产生菌LG-332(Phe-+Tyr-+4MTr+6-FTr+4-FPr),其遗传性状稳定。在未经优化的摇瓶发酵条件下,发酵96 h,最高产酸量达7.84mg/mL,较出发菌株Tx5-32提高了64%。

Corynebacterium glutamicum Tx5-32 as a starting strain was stepwise mutated with DES and UV.One L-Tryptophan high-producing strain LG210 with genetic marker was screened through shake tube primary screening,shake flask compound screening,genetic marker test,single clone isolation and continuous passage cultivation.This strain could produce L-Tryptophan 7.84 g/L after fermentation under the fermentation condition without being optimized.Genetic characteristics of the strain LG-332 was very stable.