Sunday, May 4, 2008
4-08

Stable butanol production by immobilized Clostridium acetobutylicum 824 with polyethylene glycol gel carrier in a membrane-extractive fermentor

Sun-Mi Lee1, Min-Ok Cho1, Youngsoon Um1, Yun-chul Chung1, Ji Hyeon Kim2, and Byoung In Sang1. (1) Hazardous substance research center, Korea Institute of Science and Technology, 131, Cheongryang, Seoul, South Korea, (2) Chemical & Biochemical Engineering, Dongguk University, South Korea

Biobutanol, one of the promising biofuels for future, has the potential to meet the needs of sustainable and green energy systems. However, biobutanol production has limitations such as low productivity, toxicity of butanol to solvent-producing bacteria, or degeneration during continuous fermentation. In this study, we examined the effect of membrane-extraction on the in situ removal of butanol from continuous reactor fermentation broth using immobilized Clostridium acetobutylicum ATCC 824 with polyethylene glycol gel carrier. The solvent-producing strain, Clostridium acetobutylicum ATCC 824, was not affected adversely by membrane extraction. A considerable improvement in the productivity and yield was recorded in this work in comparison with the non-integrated process. In an integrated process of butanol fermentation-extraction using Clostridium acetobutylicum ATCC 824, ABE productivities and yield were improved as compared to control fermentation data. Butanol productivity and yield were also enhanced by the immobilization of cells in the gel carrier compared to those with suspended cells. Moreover, the production of butanol was maintained stably with high concentration during long-term operation. The image of the confocal laser scanning microscopy of the gel carriers showed that the cells were successfully immobilized in those carriers. During these studies we were able to maintain the butanol concentration in the fermentation broth below solvent toxic levels.
Keyword : butanol production, clostridium acetobutylicum ATCC 824, immobilization, polyethylene glycol gel carrier, membrane extraction

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