title: Enhanced butanol production in a microbial electrolysis cell by Clostridium beijerinckii IB4.
abstract: Reducing power such as NADH is an essential factor for acetone/butanol/ethanol (ABE) fermentation using Clostridium spp. The objective of this study was to increase available NADH in Clostridium beijerinckii IB4 by a microbial electrolysis cell (MEC) with an electron carrier to enhance butanol production. First of all, a MEC was performed without electron carrier to study the function of cathodic potential applying. Then, various electron carriers were tested, and neutral red (NR)-amended cultures showed an increase of butanol concentration. Optimal NR concentration (0.1 mM) was used to add in a MEC. Electricity stimulated the cell growth obviously and dramatically diminished the fermentation time from 40 to 28 h. NR and electrically reduced NR improved the final butanol concentration and inhibited the acetone generation. In the MEC with NR, the butanol concentration, yield, proportion and productivity were increased by 12.2, 17.4, 7.2 and 60.3 %, respectively. To further understand the mechanisms of NR, cathodic potential applying and electrically reduced NR, NADH and NAD(+) levels, ATP levels and hydrogen production were determined. NR and electrically reduced NR also improved ATP levels and the ratio of NADH/NAD(+), whereas they decreased hydrogen production. Thus, the MEC is an efficient method for enhancing the butanol production.
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, 211816, Nanjing, People's Republic of China.
authors.forename: Ai-Yong
authors.initials: AY
authors.lastname: He
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, 211816, Nanjing, People's Republic of China.
authors.forename: Chun-Yan
authors.initials: CY
authors.lastname: Yin
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, 211816, Nanjing, People's Republic of China.
authors.forename: Hao
authors.initials: H
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, 211816, Nanjing, People's Republic of China.
authors.forename: Xiang-Ping
authors.initials: XP
authors.lastname: Kong
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, 211816, Nanjing, People's Republic of China.
authors.forename: Jia-Wei
authors.initials: JW
authors.lastname: Xue
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, 211816, Nanjing, People's Republic of China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, 211816, Nanjing, People's Republic of China. bioengine@njtech.edu.cn.
authors.forename: Min
authors.initials: M
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Puzhu South Road 30#, 211816, Nanjing, People's Republic of China. wuhao@njtech.edu.cn.
authors.forename: Hao
authors.initials: H
authors.lastname: Wu
mesh_terms: D001674:Bioelectric Energy Sources / Q000382:microbiology*; D000440:Butanols / Q000378:metabolism*; D046970:Clostridium beijerinckii / Q000378:metabolism*; D004572:Electrolysis
chemical_list: D000440:Butanols
keywords: ATP; Butanol; Clostridium; MEC; Reducing power