title: The rebalanced pathway significantly enhances acetoin production by disruption of acetoin reductase gene and moderate-expression of a new water-forming NADH oxidase in Bacillus subtilis.
abstract: Bacillus subtilis produces acetoin as a major extracellular product. However, the by-products of 2,3-butanediol, lactic acid and ethanol were accompanied in the NADH-dependent pathways. In this work, metabolic engineering strategies were proposed to redistribute the carbon flux to acetoin by manipulation the NADH levels. We first knocked out the acetoin reductase gene bdhA to block the main flux from acetoin to 2,3-butanediol. Then, among four putative candidates, we successfully screened an active water-forming NADH oxidase, YODC. Moderate-expression of YODC in the bdhA disrupted B. subtilis weakened the NADH-linked pathways to by-product pools of acetoin. Through these strategies, acetoin production was improved to 56.7g/l with an increase of 35.3%, while the production of 2,3-butanediol, lactic acid and ethanol were decreased by 92.3%, 70.1% and 75.0%, respectively, simultaneously the fermentation duration was decreased 1.7-fold. Acetoin productivity by B. subtilis was improved to 0.639g/(lh).
authors: The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, PR China.
authors: Xian
authors: X
authors: Zhang
authors: The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, PR China.
authors: Rongzhen
authors: R
authors: Zhang
authors: The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, PR China.
authors: Teng
authors: T
authors: Bao
authors: The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, PR China. Electronic address: raozhm@jiangnan.edu.cn.
authors: Zhiming
authors: Z
authors: Rao
authors: The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, PR China.
authors: Taowei
authors: T
authors: Yang
authors: The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, PR China.
authors: Meijuan
authors: M
authors: Xu
authors: School of Medicine and Pharmaceuticals, Jiangnan University, Wuxi, Jiangsu 214122, PR China.
authors: Zhenghong
authors: Z
authors: Xu
authors: The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, PR China.
authors: Huazhong
authors: H
authors: Li
authors: Department of Chemical Engineering, Ohio State University, 140 West 19th Avenue, Columbus, OH 43210, USA.
authors: Shangtian
authors: S
authors: Yang
mesh_terms: D000093:Acetoin / Q000378:metabolism*; D000429:Alcohol Oxidoreductases / Q000235:genetics*; D001412:Bacillus subtilis / Q000201:enzymology / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics*; D009097:Multienzyme Complexes / Q000096:biosynthesis / Q000235:genetics; D009243:NAD / Q000235:genetics / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000096:biosynthesis / Q000235:genetics; D014867:Water / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D009097:Multienzyme Complexes; D014867:Water; D009243:NAD; D000093:Acetoin; D000429:Alcohol Oxidoreductases; C019801:butanediol dehydrogenase; C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases
keywords: Acetoin pathway; Acetoin reductase/2,3-butanediol dehydrogenase; Bacillus subtilis; Gene disruption; NADH oxidase