(626k) Ethanol Production Using “Alkalibaculum Bacchi” Strains CP11, CP13 and CP15 From Syngas

Ethanol production from syngas components CO and H₂ using “Alkalibaculum bacchi” strains CP11, CP13 and CP15 was investigated in 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.  Strains CP11, CP13 and CP15 were fed syngas every 24 h for 360 h.  Liquid samples were collected to measure pH, optical density (OD) and product concentrations.  Gas samples were collected to measure the gas composition in the head space and calculate the product yields and conversion efficiencies of syngas components to ethanol. The results showed that the three strains were able to convert CO and H₂ into ethanol and acetic acid.  Maximum ethanol concentration (1.7 g/L) and yield (61%) were obtained in fermentations with strain CP15 and Syngas II. Strain CP15 produced over twofold more ethanol in Syngas I, compared to strains CP11 and CP13. In addition, CP15 produced 18% and 71% more ethanol than strains CP11 and CP13, respectively, with Syngas II. Strain CP13 produced over two fold more acetic acid than strains CP11 and CP15 in both gas mixtures after 360 h of fermentation. These results showed the potential of the new “Alkalibaculum bacchi” strains CP11, CP13 and CP15 to produce ethanol from CO and H₂.