Gao Songsong, Guo Wenyi, Shi Litao, Yu Yue, Zhang Cuikun, Yang Hongjiang
Key Laboratory of Industrial Microbiology, Ministry of Education, Tianjin Key Laboratory of Industrial Microbiology, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, China.
J Ind Microbiol Biotechnol. 2014 Aug;41(8):1267-74. doi: 10.1007/s10295-014-1464-x. Epub 2014 May 31.
The 2,3-butanediol (2,3-BD) dehydrogenase gene budC of Serratia marcescens G12 was disrupted to construct the acetoin (AC) producing strain G12M. In shake-flask cultures, AC production was enhanced by increased concentrations of glucose or sodium acetate in G12M. In fed-batch fermentation, G12M produced 47.5 g/L AC along with 9.8 g/L 2,3-BD. The expression of the key enzymes for AC synthesis was further investigated. Alpha-acetolactate synthase gene budB decreased its expression significantly in G12M compared with G12. This probably explained the moderate AC production in G12M cultures. Additionally, overexpression of budB gene and α-acetolactate decarboxylase gene budA was conducted in G12M and no significant increase of AC was observed. The results suggested that intracellular AC accumulation might inhibit the expression of budB and budA gene and induce budC gene expression in G12M. Our analyses offered the bases for further genetic manipulations in improving AC production in microbial fermentations.
破坏了粘质沙雷氏菌G12的2,3-丁二醇（2,3-BD）脱氢酶基因budC，构建了产乙偶姻（AC）的菌株G12M。在摇瓶培养中，G12M中葡萄糖或醋酸钠浓度的增加提高了AC产量。在分批补料发酵中，G12M产生了47.5 g/L的AC以及9.8 g/L的2,3-BD。进一步研究了AC合成关键酶的表达。与G12相比，α-乙酰乳酸合酶基因budB在G12M中的表达显著降低。这可能解释了G12M培养物中AC产量适中的原因。此外，在G12M中过表达budB基因和α-乙酰乳酸脱羧酶基因budA，未观察到AC有显著增加。结果表明，细胞内AC的积累可能抑制G12M中budB和budA基因的表达，并诱导budC基因表达。我们的分析为进一步通过基因操作提高微生物发酵中AC产量提供了依据。
