title: Enhanced 2,3-butanediol production from biodiesel-derived glycerol by engineering of cofactor regeneration and manipulating carbon flux in Bacillus amyloliquefaciens.
abstract: BACKGROUND
  Bacillus amyloliquefaciens B10-127 exhibited an excellent ability for industrial-scale microbial fermentation of 2,3-butanediol (2,3-BD) from biodiesel-derived glycerol. However, the accumulation of by-products (acetoin, acetoin, lactate and succinate) and the 2,3-BD yield remains prohibitively low for commercial production.
  
  
  RESULTS
  Several strategies were developed to manipulate the carbon flux to 2,3-BD branch in a designed B. amyloliquefaciens. Firstly, extra copies of NADH/NAD(+) regeneration system were introduced into B. amyloliquefaciens by co-overproduction of glycerol dehydrogenase and acetoin reductase, which resulting in improvement of 2,3-BD production and suppression of by-products accumulation. Subsequently, the transcriptional regulator ALsR under the control of a moderate promoter PbdhA was introduced into B. amyloliquefaciens, which increased carbon flux to 2,3-BD branch. Finally, a three-stage dissolved oxygen control strategy were proposed based on analysis of the characteristic of 2,3-BD fermentation, and a two-stage pH control strategy were proposed based on different pH preferences of ACR for reduction and oxidation. Following these strategies, a high titer (102.3 g/L), yield (0.44 g/g), and productivity (1.16 g/L/h) of 2,3-BD were achieved.
  
  
  CONCLUSIONS
  To our knowledge, this is the highest reported 2,3-BD production using biodiesel-derived glycerol as substrate, and this designed B. amyloliquefaciens should be an excellent candidate for producing 2,3-BD on an industrial scale.
authors: The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu Province, 214122, China. ytw1228@163.com.
authors: Taowei
authors: T
authors: Yang
authors: The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu Province, 214122, China. raozhm@jiangnan.edu.cn.|School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi, Jiangsu, 214122, People's Republic of China. raozhm@jiangnan.edu.cn.
authors: Zhiming
authors: Z
authors: Rao
authors: The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu Province, 214122, China. zxshengwu@126.com.
authors: Xian
authors: X
authors: Zhang
authors: The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu Province, 214122, China. xumeijuan@jiangnan.edu.cn.
authors: Meijuan
authors: M
authors: Xu
authors: Laboratory of Pharmaceutical Engineering, School of Pharmaceutical Science, Jiangnan University, Wuxi, Jiangsu Province, 214122, China. zhenghxu@163.com.
authors: Zhenghong
authors: Z
authors: Xu
authors: Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, OH, 43210, USA. yang.15@osu.edu.
authors: Shang-Tian
authors: ST
authors: Yang
mesh_terms: D001407:Bacillus / Q000235:genetics / Q000378:metabolism*; D056804:Biofuels; D019149:Bioreactors; D002072:Butylene Glycols / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism*; D005285:Fermentation; D015964:Gene Expression Regulation, Bacterial; D005818:Genetic Engineering; D005990:Glycerol / Q000378:metabolism*
chemical_list: D056804:Biofuels; D002072:Butylene Glycols; C026978:2,3-butylene glycol; D002244:Carbon; D005990:Glycerol