Stable high-titer n-butanol production from sucrose and sugarcane juice by Clostridium acetobutylicum JB200 in repeated batch fermentations Wenyan Jiang, Jingbo Zhao, Zhongqiang Wang, Shang-Tian Yang ⇑ William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 140 W. 19th Ave., Columbus, OH 43210, USA highlights  Butanol production from sugarcane juice by C. acetobutylicum JB200 was studied.  Cells were immobilized in a fibrous bed bioreactor for ABE fermentation.  ABE production reached 28 g/L, the highest ever achieved in fermentation with sucrose.  This hyper butanol-producing strain was stable for 16 consecutive repeated batches.  This process can be used to economically produce butanol in a sugarcane biorefinery. article info Article history: Received 28 February 2014 Received in revised form 13 April 2014 Accepted 15 April 2014 Available online 21 April 2014 Keywords: Acetone–butanol–ethanol fermentation Butanol Clostridium acetobutylicum Fibrous bed bioreactor Sugarcane juice abstract The production of n-butanol, a widely used industrial chemical and promising transportation fuel, from abundant, low-cost substrates, such as sugarcane juice, in acetone–butanol–ethanol (ABE) fermentation was studied with Clostridium acetobutylicum JB200, a mutant with high butanol tolerance and capable of producing high-titer (>20 g/L) n-butanol from glucose. Although JB200 is a favorable host for industrial bio-butanol production, its fermentation performance with sucrose and sugarcane juice as substrates has not been well studied. In this study, the long-term n-butanol production from sucrose by JB200 was evaluated with cells immobilized in a fibrous-bed bioreactor (FBB), showing stable performance with high titer (16–20 g/L), yield (0.21 g/g sucrose) and productivity (0.32 g/L h) for 16 consecutive batches over 800 h. Sugarcane thick juice as low-cost substrate was then tested in 3 consecutive batches, which gave similar n-butanol production, demonstrating that JB200 is a robust and promising strain for industrial ABE fermentation. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction N-Butanol is a four-carbon primary alcohol with the molecular formula C 4 H 10 O. It is widely used as an industrial solvent and intermediate in producing butyl acrylate, butyl acetate and other butyl esters. In addition, butanol has also been considered as a promising fuel substitute for gasoline, as well as a fuel additive. Compared to ethanol, butanol is less corrosive, has higher energy content, and can be better burnt in existing gasoline engines. Historically, n-butanol production via acetone–butanol–ethanol (ABE) fermentation was once the second largest industrial fermen- tation and recently has regained increasing attention (Jang et al., 2012; Zhao et al., 2013) because butanol production from biomass is more environmentally friendly and can reduce costs, especially considering the recent dramatic increase in crude oil prices (Green, 2011). However, in order to commercialize bio-butanol, bacterial strains that can use low-cost substrates in ABE fermenta- tion with high butanol titer, yield and productivity are needed (Ezeji et al., 2010; Lee et al., 2008; Zhao et al., 2013). Because butanol at concentrations above 1% (v/v) is highly toxic to cells and can cause significant growth inhibition and cell death, the final butanol titer in conventional ABE fermentation usually cannot surpass 12 g/L. Consequently, it is highly energy intensive and costly to recover butanol from the ABE fermentation broth (García et al., 2011; Xue et al., 2012). However, the separation cost for butanol recovery from ABE fermentation broth can be reduced by 50% if the final butanol titer is increased from 12 g/L to 19 g/L (Papoutsakis et al., 2005). Although extensive research has been done to improve butanol production by metabolically engineered mutants, only limited success has been achieved due to complicated and difficult to control metabolic and regulatory pathways involving acidogenesis, solventogenesis, and spore formation (Lee et al., 2008; Papoutsakis, 2008). Recently, a hyper http://dx.doi.org/10.1016/j.biortech.2014.04.047 0960-8524/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +1 614 292 6611; fax: +1 614 292 3769. E-mail address: yang.15@osu.edu (S.-T. Yang). Bioresource Technology 163 (2014) 172–179 Contents lists available at ScienceDirect Bioresource Technology journal homepage: www.elsevier.com/locate/biortech