Institute of Chemical Engineering, Bulgarian Academy of Sciences, 103, Acad. G. Bonchev str., 1113, Sofia, Bulgaria.
Appl Microbiol Biotechnol. 2014 Mar;98(6):2441-51. doi: 10.1007/s00253-013-5418-4. Epub 2013 Dec 10.
2,3-Butanediol (2,3-BD) is an organic compound, which is widely used as a fuel and fuel additive and applied in chemical, food, and pharmaceutical industries. Contemporary strategies for its economic synthesis include the development of microbial technologies that use starch as cheap and renewable feedstock. The present work encompasses the metabolic engineering of the excellent 2,3-BD producer Klebsiella pneumoniae G31. In order to perform direct starch conversion into 2,3-BD, the amyL gene encoding quite active, liquefying α-amylase in Bacillus licheniformis was cloned under lac promoter control in the recombinant K. pneumoniae G31-A. The enhanced extracellular over-expression of amyL led to the highest extracellular amylase activity (68 U/ml) ever detected in Klebsiella. The recombinant strain was capable of simultaneous saccharification and fermentation (SSF) of potato starch to 2,3-BD. In SSF batch process by the use of 200 g/l starch, the amount of total diols produced was 60.9 g/l (53.8 g/l 2,3-BD and 7.1 g/l acetoin), corresponding to 0.31 g/g conversion rate. The presented results are the first to show successful starch conversion to 2,3-BD by K. pneumoniae in a one-step process.
2,3-丁二醇（2,3-BD）是一种有机化合物，广泛用作燃料和燃料添加剂，并应用于化学、食品和制药行业。其经济合成的当代策略包括开发利用淀粉作为廉价可再生原料的微生物技术。本工作涵盖了优秀的 2,3-BD 生产菌克雷伯氏肺炎菌 G31 的代谢工程。为了将淀粉直接转化为 2,3-BD，在重组克雷伯氏肺炎菌 G31-A 中，在乳糖启动子控制下克隆编码来自地衣芽孢杆菌的相当活跃的液化α-淀粉酶的 amyL 基因。amyL 的增强型细胞外过表达导致在克雷伯氏菌中检测到的最高细胞外淀粉酶活性（68 U/ml）。重组菌株能够同时糖化和发酵（SSF）马铃薯淀粉生产 2,3-BD。在使用 200 g/l 淀粉的 SSF 分批过程中，总二醇的产量为 60.9 g/l（53.8 g/l 2,3-BD 和 7.1 g/l 乙酰基），转化率为 0.31 g/g。所呈现的结果首次表明，克雷伯氏肺炎菌能够在一步法中将淀粉成功转化为 2,3-BD。
