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

Abstract Ethanol production from syngas using three moderately alkaliphilic strains of a novel genus and species Alkalibaculum bacchi CP11 T , 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% CO 2 , 5% H 2 , 60% N 2 ) and (Syngas II: 40% CO, 30% CO 2 , 30% H 2 ) 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 CP11 T and CP13. In addition, CP15 produced 18% and 71% more ethanol using Syngas II compared to strains CP11 T 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 CP11 T and CP13.