聚唾液酸高产菌株的高通量诱变选育及发酵工艺优化

High-throughput screen and fermentation optiminzation of polysialic acid-producing strains

从自然水体中筛选得到1株产聚唾液酸的微生物菌株SA-1,经Biolog生化和分子生物学分析,鉴定其为大肠杆菌。以大肠杆菌SA-1为出发菌株,通过常压室温等离子体(ARTP)诱变育种,借助酸碱透明圈和高通量自动挑选仪筛选获得高产聚唾液酸的突变菌株SA-18。摇瓶发酵结果显示,大肠杆菌突变株SA-18的聚唾液酸产量可达0.95 g/L,是出发菌株产量(0.20 g/L)的4.75倍;进一步,通过调控优化K_(2)HPO_(4)浓度实现了突变大肠杆菌SA-18的高密度发酵:当K_(2)HPO_(4)质量浓度为5.0 g/L时,在10 L发酵罐中,36 h时聚唾液酸产量达到12.20 g/L,继续补料发酵,至60 h时,聚唾液酸产量最高可达16.10 g/L。

A polysialic acid-producing microbial strain SA-1 was screened from natural waters and identified as Escherichia coli by Biolog biochemical and molecular biology analysis.Taking.coli SA-1 as the starting strain,atmospheric and room temperature plasma(ARTP) plasma mutagenesis was used to screen the mutant strain SA-18 with high production of polysialic acid by means of acid-base transparent circle and high-throughput automatic selection instrument.The results of shake flask fermentation showed that the polysialic acid production of E.coli mutant SA-18 could reach 0.95 g/L,which was 4.75 times that of the original strain(0.20 g/L).Further,improvement was achieved by adjusting and optimizing the K_(2)HPO_(4) concentration.High-density fermentation of SA-18 was done with K_(2)HPO_(4) 5.0 g/L in a 10-L fermentor to reach,a polysialic acid concentration of 12.20 g/L at 36 h.In a fed-batch fermentation of 60 h,The maximum polysialic acid concentration reached 16.10 g/L.