2,3-丁二醇代谢途径关键酶基因敲除对克雷伯氏菌发酵产1,3-丙二醇的影响

2,3-丁二醇是克雷伯氏菌发酵产1,3-丙二醇的主要副产物,为减少2,3-丁二醇的产生,利用Red重组技术对克雷伯氏菌2,3-丁二醇合成途径关键酶基因budC和budA进行了敲除。突变株发酵性能实验结果表明,所获得的两株突变株生长性能受到不同程度的影响;budC基因的缺失使菌株1,3-丙二醇产量提高了10%,2,3-丁二醇降低为原来的70%,而budA基因缺失则使菌株无2,3-丁二醇和1,3-丙二醇的产生,但乳酸、琥珀酸、乙醇和乙酸的产量较出发菌株都有明显增长。通过进一步对budC基因缺失菌株主要产物分析,推测在该菌中存在2,3-丁二醇回补途径,这一结果为低副产物克雷伯氏菌的改造提供了新依据。

Effects of knockout of 2,3-butanediol synthesis key enzyme genes on 1,3-propandediol production in Klebsiella pneumoniae

2,3-butanediol (2,3-BD) is a major byproduct of 1,3-propandediol (1,3-PDO) fermentation by Klebsiella pneumoniae. To decrease the formation of 2,3-BD, the budC and budA gene, coding two key enzymes of 2,3-BD synthetic pathway in K. pneumoniae, were knocked out using Red recombination technology. The growth of the two mutants were suppressed in different level. The budC deficient strain fermentation results showed that 1,3-PDO concentration increased to 110% and 2,3-butanediol concentration dropped to 70% of the parent strain. However, the budA deficient strain did not produce 1,3-PDO and 2,3-BD, and the final titer of lactic acid, succinic acid, ethanol and acetic acid increased remarkably compared with the parent strain. Further analysis of budC deficient strain fermentation inferred that K. pneumoniae possessed the 2,3-BD cycle as a replenishment pathway. The consequence provided a new evidence for reforming low-byproduct K. pneumoniae.