Monday, November 9, 2009
P16

Membrane-assisted extractive butanol fermentation using 1-dodecanol as extractant employing by Clostridium saccharoperbutylacetonicum N1-4

Shigemitsu Tanaka1, Genta Kobayashi1, Toru Ikegami2, Hideyuki Negishi2, and Keiji Sakaki2. (1) Department of Applied Biochemistry and Food Science, Saga University, 1, Honjo-cho, Saga, 840-8502, Japan, (2) Research Institute for Innovations in Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), AIST Central 5-2, 1-1-1 Higashi, Tsukuba, Ibaraki, Japan

In butanol fermentation, product inhibition is one of the inherent problems. Extractive fermentation is a logical approach toward alleviating this problem. 1-dodecanol is a high potential extractant because of high partition coefficient of 1-butanol. For equivalent amount of 1.0 wt% of 1-butanol in water under the fermentation condition, it showed a partition coefficient of equilibrium stages corresponding to approximately 1.5-fold of it of butanol to oleyl alcohol generally used. However, 1-dodecanol has heavy toxicity to the fermentative organism, and the growth was barely observed in the conventional extractive fermentation. Then in this study, the membrane-assisted extractive butanol fermentation with 1-dodecanol was investigated and compared with the conventional fermentation. All fermentation was carried out at an initial glucose concentration of 90 g/L. The membrane used in this experiment was a polytetrafluoroethylene (PTFE) membrane. Without butanol extraction, butanol production ceased at the butanol concentration of 1.5 wt% in the broth and the glucose consumption was 56.8 g/L due to the product inhibition. Applying 1-dodecanol as the extractant across a PTFE membrane, the butanol concentration in the broth could be maintained at less than 1.1 wt% and the glucose consumption was increased to approximately 75.5 g/L at the butanol concentration of 1.9 wt% in the broth. These results indicated that PTFE membrane-assisted extractive butanol fermentation released the inhibition of 1-dodecanol to the butanol fermentation and would enable to provide the efficient butanol fermentation. This research was supported by a research grant for New Energy and Industrial Technology Development Organization (NEDO).

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