大肠杆菌工程菌ptsG基因敲除及其缺陷株混合糖同型乙醇发酵

Knockout of the ptsG gene in engineered Escherichia coli for homoethanol fermentation from sugar mixture

摘要:

为实现可同时利用木糖和葡萄糖进行生产发酵，以产乙醇的大肠杆菌工程菌SZ470为出发菌株 (?pflB，?frdABCD，?ackA，?ldhA)，采用同源重组技术，敲除葡萄糖转运基因ptsG，以构建不受葡萄糖抑制效应影响的菌株SZ470P。SZ470P在5％混合糖 (2.5％木糖和2.5％葡萄糖) 培养基中能同时利用葡萄糖和木糖进行发酵，葡萄糖消耗量是13 g/L，为对照菌株SZ470的一半；木糖消耗量是20 g/L，是SZ470的3.8倍；乙醇的最高产量为15.01 g/L，转化率为89.13％，比SZ470提高了14.32％。结果表明，工程菌SZ470P可同时利用葡萄糖和木糖发酵生产高产量的乙醇

Abstract:

To realize the simultaneous fermentation of xylose and glucose, ptsG (one of the glucose-PTS genes) was deleted from the engineered ethanologenic Escherichia coli SZ470 (?pflB, ?frdABCD, ?ackA, ?ldhA), resulting in loss of glucose effect in the mutant SZ470P (?ptsG). When tested in 5% mixture of glucose (2.5%) and xylose (2.5%), SZ470P simultaneously used glucose (13 g/L) and xylose (20 g/L) whereas the parent strain SZ470 sequentially used glucose (25?g/L) then xylose (5 g/L). Upon completion of the fermentation, both strains achieved similar product yield of 89%. SZ470P produced 15.01 g/L of ethanol, which was 14.32% higher than that produced by SZ470 (12.86 g/L). Deleting ptsG gene enabled the mutant strain SZ470P to simultaneously use both glucose and xylose and achieve better ethanol production