代谢工程改造大肠杆菌提高乙醇酸产率

Improving glycolic acid yield by metabolic engineering in Escherichia coli

摘要:

乙醇酸 (Glycolate) 是一种在工业上有多种用途的重要化合物。本研究首先在大肠杆菌MG1655(DE3)中敲除了ldhA (乳酸脱氢酶)，获得菌株Mgly1，作为出发菌株。然后通过调节乙醇酸合成途径的关键酶——异柠檬酸裂解酶 (aceA)、乙醛酸还原酶 (ycdW)、异柠檬酸脱氢酶激酶/磷酸化酶 (aceK) 的表达水平，得到乙醇酸产率为0.24 g/g葡萄糖 (占理论产率的28.2%)。过量表达柠檬酸合成酶 (gltA)，乙醇酸产率提高到0.326 g/g葡萄糖 (占理论产率的38.3%)。然后在Mgly1中敲除了glcB和aceB (苹果酸合成酶)，减少了乙醇酸合成的前体乙醛酸的消耗。最终获得的工程菌株Mgly335乙醇酸产率达到0.522 g/g葡萄糖 (占理论产率的61.4%)。

Abstract:

Glycolic acid is an important industrial compound. To improve glycolic acid yield, we knocked out ldhA (lactate dehydrogenase) in Escherichia coli MG1655 (DE3) to get the strain Mgly1. Then, we regulated expression levels of isocitrate lyase (aceA), glyoxylic acid reductase (ycdW) and isocitrate dehydrogenase kinase/phosphorylase (aceK) that are key enzymes of glycolate synthesis pathway. The yield of glycolic acid increased to 0.326 g/g glucose (38.3% of the theoretical yield) by overexpressing citrate synthase (gltA). Then we knocked out glcB and aceB (malate synthase) in Mgly1. The engineering strain Mgly335 was obtained and the yield of glycolic acid reached 0.522 g/g glucose (61.4% of the theoretical yield).