Novel high butanol production from lactic acid and pentose by Clostridium saccharoperbutylacetonicum(BIOCHEMICAL ENGINEERING)

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We previously reported a butanol production process with pH-stat continuous feeding of DL-lactic acid and glucose as the co-substrate (Oshiro et al., Appl. Microbiol. Biotechnol., 87, 1177-1185, 2010). To accomplish butanol production from completely inedible substrates, in this study, we investigated acetone-butanol-ethanol (ABE) fermentation of Clostridium saccharoperbutylacetonicum N1-4 with lactic acid by using pentose as the co-substrate. Examination for optimum cosubstrate indicated that arabinose was superior to glucose and xylose for ABE fermentation. Actually batch culture with lactic acid and arabinose without pH control exhibited higher butanol production (7.11 g/l) and lactic acid consumption (2.02 g) than those (6.62 g/l and 1.45 g, respectively) with glucose. Fed-batch culture without pH control increased these values to 12.08 g/l and 15.60 g/l butanol production, and to 3.83 g and 5.91 g lactic acid consumption by feeding the substrate once and twice, respectively. Finally, the result of gas chromatography-mass spectroscopy analysis using [1,2,3-^<13>C_3]-lactic acid indicated that lactic acid was converted to butanol with the efficiency of 51.9%. Thus, we established a novel high butanol production from lactic acid using arabinose as the co-substrate in simple fed-batch culture.