Wei Xiao-Xing, Zheng Wei-Tao, Hou Xue, Liang Jian, Li Zheng-Jun
Department of Basic Medicine, Medical College of Qinghai University, Xining 810016, China.
Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.
Biomed Res Int. 2015;2015:789315. doi: 10.1155/2015/789315. Epub 2015 Apr 7.
The alcohol dehydrogenase promoter PadhE and mixed acid fermentation pathway deficient mutants of Escherichia coli were employed to produce poly(3-hydroxybutyrate) (P3HB) under microaerobic condition. The E. coli mutant with ackA-pta, poxB, ldhA, and adhE deletions accumulated 0.67 g/L P3HB, up to 78.84% of cell dry weight in tube cultivation. The deletion of pyruvate formate-lyase gene pflB drastically decreased P3HB production and P3HB content to 0.09 g/L and 24.44%, respectively. Overexpressing pflB via the plasmid in its knocked out mutant restored cell growth and P3HB accumulation, indicating the importance of the pyruvate formate-lyase in microaerobic carbon metabolism. The engineered E. coli BWapld (pWYC09) produced 5.00 g/L P3HB from 16.50 g/L glucose in 24 h batch fermentation, and P3HB production yield from glucose was 0.30 g/g, which reached up to 63% of maximal theoretical yield.
利用乙醇脱氢酶启动子PadhE和大肠杆菌混合酸发酵途径缺陷型突变体在微需氧条件下生产聚（3-羟基丁酸酯）（P3HB）。缺失ackA-pta、poxB、ldhA和adhE的大肠杆菌突变体在试管培养中积累了0.67 g/L的P3HB，占细胞干重的78.84%。丙酮酸甲酸裂解酶基因pflB的缺失使P3HB产量和P3HB含量分别大幅降至0.09 g/L和24.44%。通过质粒在其敲除突变体中过表达pflB可恢复细胞生长和P3HB积累，表明丙酮酸甲酸裂解酶在微需氧碳代谢中的重要性。工程化的大肠杆菌BWapld（pWYC09）在24小时分批发酵中从16.50 g/L葡萄糖生产了5.00 g/L的P3HB，葡萄糖的P3HB产率为0.30 g/g，达到最大理论产率的63%。
