摘要
以前期构建的D-乳酸大肠杆菌(Escherichia coli)工程菌LHY02为出发菌株,通过在乳酸盐中对菌株进行驯化的方式来解除乳酸根对菌体的抑制作用;采用葡萄糖分批补加方式缓解高含量葡萄糖的阻遏效应,拟进一步提高大肠杆菌发酵产D-乳酸的产量、生产强度和糖酸转化率。结果表明,驯化后的菌株LHY201在16%的葡萄糖发酵中D-乳酸产量比驯化前提高了36.7%。LHY201结合葡萄糖进行补料发酵(补料方式为8%+8%+4%),乳酸产量、发酵时间、糖酸转化率以及生产强度分别为185.7 g/L、48 h、93.8%、3.87 g/L/h,D-乳酸光学纯度达到99.6%,相比一次性添加20%葡萄糖的分批发酵,乳酸产量和糖酸转化率分别提高了21.1%和21.2%,发酵周期缩短了一半。
A previously engineered D-lactic acid producing E.coli strain,LHY02,was adaptively evolved in the presence of sodium lactate to improve tolerance of product inhibition. Moreover,feed methodology was adopted to minimize osmotic pressure. The purpose of study was to further improve D-lactic acid production,productivity and conversion rate of Escherichia coli. The results showed that the evolved strain,LHY201,produced 36.7% more D-lactic acid compared to that of the parent strain LHY02 in batch fermentation using a 16% initial glucose. In addition,in the fed-batch fermentation using an 8%＋8%＋4% glucose feeding pattern,LHY201 produced 185.7 g / L of D-lactic acid in 48 h,with a conversion rate of 93.8%,a productivity of 3.87 g / L / h,and an optical puring of 99.6%. Compared to that of batch fermentation using an initial 20% glucose,fed-batch fermentation achieved an increase of 21.1% and 21.2%,respectively,for product titer and conversion rate,and a50% decreased fermentation time.
出处
《湖北农业科学》
2016年第18期4771-4775,共5页
Hubei Agricultural Sciences
基金
湖北省自然科学基金项目(2011CDB076)
湖北省教育厅项目(B20121402)
国家级本科教学质量与教学改革工程项目(201210500032)
关键词
大肠杆菌工程菌
D-乳酸
驯化
补料发酵
engineered Escherichia coli
D-lactic acid
adaptive evolution
fed fermentation
