title: Simultaneous production of butanol and acetoin by metabolically engineered Clostridium acetobutylicum.
abstract: Biobutanol is a potential fuel substitute and has been receiving increased attention in recent years. However, the economics of biobutanol production have been hampered by a number of bottlenecks such as high cost of raw material and low yield of solvent. Co-production of value-added products is a possible way to improve the economics of biobutanol production. Here, we present metabolic engineering strategies to substitute the major by-product acetone for a value-added product acetoin during butanol fermentation. By overexpressing the α-acetolactate decarboxylase gene alsD in Clostridium acetobutylicum B3, the acetoin yield was markedly increased while acetone formation was reduced. Subsequent disruption of adc gene effectively abolished acetone formation and further increased acetoin yield. After optimization of fermentation conditions, the alsD-overexpressing adc mutant generated butanol (13.8g/L), acetoin (4.3g/L), and ethanol (3.9g/L), but no acetone. Thus, acetone was completely substituted for acetoin, and both mass yield and product value were improved. This study provides valuable insights into the regulation of acetoin synthesis and should be highly useful for the development of acetoin-derived products like 2,3-butanediol and 2-butanol in C. acetobutylicum.
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing 211816, China.
authors.forename: Dong
authors.initials: D
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing 211816, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing 211816, China.
authors.forename: Fengying
authors.initials: F
authors.lastname: Ding
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing 211816, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Guo
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing 211816, China.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Xie
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing 211816, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhuang
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing 211816, China.
authors.forename: Haunqing
authors.initials: H
authors.lastname: Niu
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing 211816, China.
authors.forename: Xinchi
authors.initials: X
authors.lastname: Shi
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing 211816, China.
authors.forename: Chenjie
authors.initials: C
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing 211816, China. Electronic address: yinghanjie@njtech.edu.cn.
authors.forename: Hanjie
authors.initials: H
authors.lastname: Ying
mesh_terms: D000093:Acetoin / Q000378:metabolism*; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D000440:Butanols / Q000378:metabolism*; D002262:Carboxy-Lyases / Q000096:biosynthesis / Q000235:genetics; D046969:Clostridium acetobutylicum / Q000201:enzymology / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D009154:Mutation
chemical_list: D001426:Bacterial Proteins; D000440:Butanols; D000093:Acetoin; D002262:Carboxy-Lyases; C023746:acetolactate decarboxylase
keywords: Acetoin; Acetolactate decarboxylase; AlsR; Clostridium acetobutylicum; Redox balance; hydA