Butanol fermentation by Clostridium acetobutylicum immobilized in a fibrous bed bioreactor

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Wei-Lun Chang, vaylen@gmail.com and Shang-Tian Yang, yangst@chbmeng.ohio-state.edu. Department of Chemical and Biomolecular Engineering, The Ohio State University, 140 West 19th Ave., Columbus, OH 43210
The acetone-butanol-ethanol (ABE) fermentation by Clostridium acetobutylicum was one of the oldest and largest biotechnological processes. Butanol is an important industrial solvent and potentially a better fuel source than ethanol. Because of the high toxicity of butanol, its microbiological productivity via fermentation is limited to less than 20 g/L. In this work, C. acetobutylicum cells are immobilized in a fibrous bed bioreactor (FBB) to adapt cells to tolerate higher butanol concentrations. The FBB is an effective reactor device that can not only maintain high cell densities but also help cell to be more tolerant to solvent toxicity, thus yield higher product concentration. Several process parameters, including concentrations of glucose and butyric acid were found to affect butanol production. Butanol yield increased by 50% to 100% when butyric acid was used as a cosubstrate with glucose. The metabolic engineering of the bacterium to enhance the butanol production will also be discussed.