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Ethanol production from H2 and CO2 by a newly isolated thermophilic bacterium, Moorella sp. HUC22-1

Sakai, S., Nakashimada, Y., Yoshimoto, H., Watanabe, S., Okada, H., Nishio, N.
Biotechnology letters 2004 v.26 no.20 pp. 1607-1612
thermophilic bacteria, ethanol production, hydrogen, carbon dioxide, batch fermentation
The thermophilic bacterium, Moorella sp. HUC22-1, newly isolated from a mud sample, produced ethanol from H2 and CO2 during growth at 55 degrees C. In batch cultures in serum bottles, 1.5 mM ethanol was produced from 270 mM H2 and 130 mM CO2 after 156 h, whereas less than 1 mM ethanol was produced from 23 mM fructose after 33 h. Alcohol dehydrogenase and acetaldehyde dehydrogenase activities were higher in cells grown with H2 and CO2 than those grown with fructose. The NADH/NAD(+) and NADPH/NADP(+) ratios in cells grown with H2 and CO2 were also higher than those in cells grown with fructose. When the culture pH was controlled at 5 with H2 and CO2 in a fermenter, ethanol production was 3.7-fold higher than that in a pH-uncontrolled culture after 220 h.