Engineering Klebsiella oxytoca for efficient 2, 3-butanediol production through insertional inactivation of acetaldehyde dehydrogenase gene

Ethanol was a major byproduct of 2,3-butanediol (2,3-BD) fermentation by Klebsiella oxytoca ME-UD-3. In order to achieve a high efficiency of 2,3-BD production, K. oxytoca mutants deficient in ethanol formation were successfully constructed by replace the aldA gene coding for aldehyde dehydrogenase with a tetracycline resistance cassette. The results suggested that inactivation of aldA led to a significantly improved 2,3-BD production. The carbon flux to 2,3-BD was enhanced by eliminating the byproducing ethanol and at the same time reducing the accumulation of another byproduct acetoin. At last, by fed-batch culturing of the mutant, the final 2,3-BD titer up to 130 g/l with the productivity of 1.63 g/l.h and the 2,3-BD yield relative to glucose of 0.48 g/g was obtained.

乙醇是产酸克雷伯氏菌ME - UD - 3发酵2,3 - 丁二醇（2,3 - BD）的主要副产物。为了实现2,3 - BD的高效生产，通过用四环素抗性盒替换编码醛脱氢酶的aldA基因，成功构建了乙醇形成缺陷的产酸克雷伯氏菌突变体。结果表明，aldA的失活显著提高了2,3 - BD的产量。通过消除副产物乙醇并同时减少另一种副产物乙偶姻的积累，流向2,3 - BD的碳通量得到了增强。最后，通过对突变体进行补料分批培养，最终获得的2,3 - BD滴度高达130 g/L，生产率为1.63 g/L·h，相对于葡萄糖的2,3 - BD产率为0.48 g/g。