直接发酵法生产L-丝氨酸高产菌株的选育

为了解除高浓度L-丝氨酸对3-磷酸甘油酸脱氢酶的反馈抑制,进一步提高L-丝氨酸的产量,以一株能直接利用糖质原料发酵生产L-丝氨酸的谷氨酸棒杆菌SYPS-062-36为出发菌,经硫酸二乙酯逐级诱变处理,在D-丝氨酸抗性梯度平板上挑取正突变株,获得一株遗传性能稳定的高产菌株SYPS-062-33a-18,其可积累L-丝氨酸(11.0±0.25)g/L,较出发菌L-丝氨酸产量(6.65±0.23)g/L提高了65.4%。说明本研究不仅以D-丝氨酸作为抗性平板筛选得到高产L-丝氨酸的突变株,而且为下一步进行反向代谢工程的研究提供了良好的实验材料。

Breeding of High-Yield L-Serine Producing Strains Which Can Ferment Sugar Directly

C. glutamicum SYPS-062-36 could produce L-serine from sugar directly, in order to further improve L-serine production via removing the feedback inhibition of PGDH caused by high concentration of L-serine, a mutant strain C. glutamicum SYPS-062-33a-18 was obtained by DES treatment of C. glutamicum SYPS-062-36 for two rounds and selecting positive mutant in the plate containing D-serine. The genetic stable mutant strain could accumulate 11.0 ± 0.25 g/L of L-serine, with an increase of 65.4% compared with the parental strain. These results suggested that L-serine overproduced strain can be obtained by using random mutagenesis and directed selection with D-serine as the analog, and also provide a valuable basis for further improving L-serine production with inverse metabolic engineering.