The Key Laboratory of Industrial Biotechnology, Ministry of Education and the Research Centre of Industrial Microbiology, Jiangnan University, Wuxi, People's Republic of China.
Biotechnol Appl Biochem. 2013 Nov-Dec;60(6):557-63. doi: 10.1002/bab.1114.
2,3-Butanediol (2,3-BD) is a major by-product of 1,3-propanediol (1,3-PDO) fermentation by Klebsiella pneumoniae ZG25. It not only consumes large amounts of its carbon source and nicotinamide adenine dinucleotide to diminish synthesis of 1,3-PDO, but also serves as an obstacle to high-purity 1,3-PDO in downstream processes. To decrease the formation of 2,3-BD and make an intrinsic improvement in 1,3-PDO production, the budC gene in K. pneumoniae, coding 2,3-BD dehydrogenase, which is a key gene of the 2,3-BD pathway, was successfully knocked out using the Red recombination system described in this paper. The results of the mutant fed-batch fermentation showed that the 1,3-PDO concentration, productivity per cell dry weight, and conversion rate increased to 880 mmol L(-1) , 22.0 mmol L(-1) h(-1) , and 0.700 mol mol(-1) , respectively, increasing by 10%, 15%, and 11% compared with the parent strain. Meanwhile, 2,3-BD was still found in fermentation broth with the 2,3-BD metabolic pathway blocked, which implies that K. pneumoniae possesses a pathway of the 2,3-BD cycle as a replenishment pathway.
2,3-丁二醇（2,3-BD）是肺炎克雷伯氏菌（Klebsiella pneumoniae）ZG25 发酵 1,3-丙二醇（1,3-PDO）的主要副产物。它不仅消耗大量的碳源和烟酰胺腺嘌呤二核苷酸来减少 1,3-PDO 的合成，而且还阻碍下游工艺中高纯度 1,3-PDO 的生产。为了减少 2,3-BD 的形成并从根本上提高 1,3-PDO 的产量，本文利用 Red 重组系统成功敲除了肺炎克雷伯氏菌中的 budC 基因，该基因编码 2,3-BD 脱氢酶，是 2,3-BD 途径的关键基因。突变株分批发酵的结果表明，1,3-PDO 浓度、细胞干重比生产率和转化率分别提高到 880mmol/L、22.0mmol/L/h 和 0.700mol/mol，与出发菌株相比分别提高了 10%、15%和 11%。同时，在阻断 2,3-BD 代谢途径的发酵液中仍发现有 2,3-BD，这表明肺炎克雷伯氏菌具有 2,3-BD 循环途径作为补充途径。
