Zhou Jidong, Wang Dexin, Wang Chenghong, Gu Jinjie, Kim Chul Ho, Shi Jiping, Jiang Biao, Wang Min, Hao Jian
Key Laboratory of Industrial Fermentation Microbiology (Tianjin University of Science and Technology), Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China.
Lab of Biorefinery, Shanghai Advanced Research Institute, Chinese Academy of Sciences, No. 99 Haike Road, Pudong, Shanghai, 201210, People's Republic of China.
Appl Biochem Biotechnol. 2017 Mar;181(3):1199-1210. doi: 10.1007/s12010-016-2278-2. Epub 2016 Oct 12.
Pyruvate dehydrogenase-complex (AcoABCD) and pyruvate formate-lyase (PFL) are two pathways responsible for synthesis of acetyl-CoA from pyruvate (pyruvate acetyl-CoA switch). The two pathways were individually deleted in Klebsiella pneumoniae, and the role of the pyruvate acetyl-CoA switch in 1,3-propanediol production was investigated. Fermentation results showed that the two pathways were both active in the wild-type strain. Acetyl-CoA formation between the two pathways was equal in the wild-type strain. The pflB mutant produced high level of lactic acid, and deletion of ldhA eliminated lactic acid synthesis. The conversion ratio of glycerol to 1,3-propanediol in the pflB-ldhA mutant reached 0.541 g/g, which was 9.4 % higher than that of the wild-type strain. However, the productivity of 1,3-propanediol was decreased in the pflB-ldhA mutant. In contrast, the productivity of 1,3-propanediol was increased by 19 % in the acoABCD mutant, with the disadvantage of lower substrate conversion ratio. Regulating the pyruvate acetyl-CoA switch presents a novel way to improve the conversion ratio or productivity of 1,3-propanediol produced by K. pneumoniae.
丙酮酸脱氢酶复合体（AcoABCD）和丙酮酸甲酸裂解酶（PFL）是负责从丙酮酸合成乙酰辅酶A的两条途径（丙酮酸-乙酰辅酶A转换）。在肺炎克雷伯菌中分别删除了这两条途径，并研究了丙酮酸-乙酰辅酶A转换在1,3-丙二醇生产中的作用。发酵结果表明，这两条途径在野生型菌株中均有活性。在野生型菌株中，两条途径之间的乙酰辅酶A形成量相等。pflB突变体产生高水平的乳酸，而删除ldhA消除了乳酸合成。pflB-ldhA突变体中甘油到1,3-丙二醇的转化率达到0.541 g/g，比野生型菌株高9.4%。然而，pflB-ldhA突变体中1,3-丙二醇的生产率降低。相反，acoABCD突变体中1,3-丙二醇的生产率提高了19%，缺点是底物转化率较低。调节丙酮酸-乙酰辅酶A转换为提高肺炎克雷伯菌生产1,3-丙二醇的转化率或生产率提供了一种新方法。
