Microbe-based Fusion Technology Research Center, Jeonbuk Branch Institute, Korea Research Institute of Bioscience and Biotechnology, Jeongeup, Jeonbuk, South Korea.
Appl Biochem Biotechnol. 2012 Jan;166(1):127-37. doi: 10.1007/s12010-011-9409-6. Epub 2011 Nov 10.
In the present work, mutant strains of Klebsiella pneumoniae with deletions of the als gene encoding acetolactate synthase involved in synthesis of 2,3-butanediol, the ldhA gene encoding lactate dehydrogenase required for lactate synthesis, or both genes, were prepared. Production of 1,3-propanediol (1,3-PD) from glycerol was enhanced in the ldhA mutant strain (ΔldhA), but lower in Δals or Δals ΔldhA mutant strains compared to the parent strain, concomitant with a reduction in the glycerol consumption rate, indicating that deletion of ldhA alone was useful to improve 1,3-PD production. Fed-batch fermentation analysis revealed that, in the ΔldhA mutant strain, 1,3-PD production was higher at low pH than at neutral pH; the reverse was true for the parent strain. Further optimization of culture conditions, by variation of aeration and glycerol feed rates, dramatically improved the production of 1,3-PD by the mutant strain. The maximum level attained was 102.7 g l(-1) of 1,3-PD from glycerol.
在本工作中，制备了缺失编码参与 2,3-丁二醇合成的乙酰乳酸合酶（als 基因）、或缺失编码乳酸合成所需的乳酸脱氢酶（ldhA 基因）、或同时缺失这两个基因的肺炎克雷伯氏菌突变株。与亲本株相比，ldhA 突变株（ΔldhA）中甘油到 1,3-丙二醇（1,3-PD）的生产得到增强，但在Δals 或 ΔalsΔldhA 突变株中则降低，甘油消耗速率也降低，表明单独缺失 ldhA 有利于提高 1,3-PD 的生产。分批补料发酵分析表明，在ΔldhA 突变株中，1,3-PD 的生产在低 pH 值时高于中性 pH 值；而在亲本株中则相反。通过改变通气和甘油进料速率对培养条件进行进一步优化，显著提高了突变株的 1,3-PD 生产。突变株从甘油中获得的 1,3-PD 的最高水平达到 102.7 g/L。
