title: Incubation at 25 °C prevents acid crash and enhances alcohol production in Clostridium carboxidivorans P7.
abstract: 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.
authors.affiliation: LEQUIA, Institute of the Environment, University of Girona, Campus Montilivi, E-17071 Girona, Catalonia, Spain; Group of Molecular Microbial Ecology, Institute of Aquatic Ecology (IEA), University of Girona, Campus Montilivi, E-17071 Girona, Catalonia, Spain.
authors.forename: Sara
authors.initials: S
authors.lastname: Ramió-Pujol
authors.affiliation: LEQUIA, Institute of the Environment, University of Girona, Campus Montilivi, E-17071 Girona, Catalonia, Spain. Electronic address: ramon.ganigue@lequia.udg.cat.
authors.forename: Ramon
authors.initials: R
authors.lastname: Ganigué
authors.affiliation: Group of Molecular Microbial Ecology, Institute of Aquatic Ecology (IEA), University of Girona, Campus Montilivi, E-17071 Girona, Catalonia, Spain.
authors.forename: Lluís
authors.initials: L
authors.lastname: Bañeras
authors.affiliation: LEQUIA, Institute of the Environment, University of Girona, Campus Montilivi, E-17071 Girona, Catalonia, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Colprim
mesh_terms: D000085:Acetates / Q000378:metabolism; D000143:Acids / Q000378:metabolism*; D056804:Biofuels / Q000382:microbiology; D019149:Bioreactors / Q000382:microbiology; D000440:Butanols / Q000378:metabolism; D002208:Caproates / Q000378:metabolism; D002244:Carbon / Q000378:metabolism; D003013:Clostridium / Q000378:metabolism*; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation / Q000502:physiology; D000441:Hexanols / Q000378:metabolism; D013696:Temperature
chemical_list: D000085:Acetates; D000143:Acids; D056804:Biofuels; D000440:Butanols; D002208:Caproates; D000441:Hexanols; C037652:hexanoic acid; D000431:Ethanol; D002244:Carbon
keywords: Acid crash; Biofuels; Clostridium carboxidivorans; Syngas fermentation; Temperature