Fermentative production of ethanol from syngas using novel moderately alkaliphilic strains of Alkalibaculum bacchi

Ethanol production from syngas using three moderately alkaliphilic strains of a novel genus and species Alkalibaculum bacchi CP11T, CP13 and CP15 was investigated in 250 ml bottle fermentations containing 100 ml of yeast extract medium at 37 °C and pH 8.0. Two commercial syngas mixtures (Syngas I: 20% CO, 15% CO2, 5% H2, 60% N2) and (Syngas II: 40% CO, 30% CO2, 30% H2) were used. Syngas I and Syngas II represent gasified biomass and coal, respectively. The maximum ethanol concentration (1.7 g l−1) and yield from CO (76%) were obtained with strain CP15 and Syngas II after 360 h. CP15 produced over twofold more ethanol with Syngas I compared to strains CP11T and CP13. In addition, CP15 produced 18% and 71% more ethanol using Syngas II compared to strains CP11T and CP13, respectively. These results show that CP15 is the most promising for ethanol production because of its higher growth and ethanol production rates and yield compared to CP11T and CP13.