DUGi

Incubation at 25°C prevents acid crash and enhances alcohol production in Clostridium carboxidivorans P7

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Incubation of carboxydotrophs at 37. °C provides optimal conditions for their growth. However, a fast accumulation of organic acids, specifically acetate, during the exponential growth phase may result in low alcohol production and substrate consumption due to a phenomenon known as "acid crash". The present work investigates growth and productivity of Clostridium carboxidivorans P7 at two incubation temperatures. At 37. °C the culture was not able to override the "acid crash", resulting in low ethanol titers (1.56. mM). On the other hand, lower metabolic rates at 25. °C enhanced ethanol and butanol production (32.1 and 14.5. mM, respectively). Moreover, at low temperatures, hexanol and caproic acid were also produced at significant concentrations, 8.21 and 9.02. mM respectively, among the highest values reported for P7. Our results demonstrate that production of biofuels with longer carbon chains molecules may be enhanced incubating syngas-fermenting acetogenic bacteria at sub-optimal temperatures

The authors would like to thank the Generalitat de Catalunya (2013 FI-DGR) and Spanish Ministry (CTQ2014-53718-R and CTM2013-43454-R) for their financial support in this study. LEQUIA and IEA are recognized as consolidated research groups by the Generalitat de Catalunya (2014-SGR-1168 and 2014-SGR-2016). R.G. gratefully acknowledges support from Beatriu de Pinos fellowship (BP-2011-B) and FP7 Marie Curie Career Integration Grants (PCIG13-GA-2013-618593)

Elsevier