Expression and characterization of monofunctional alcohol dehydrogenase enzymes in .

is a thermophilic anaerobic bacterium that could be used for cellulosic biofuel production due to its strong native ability to consume cellulose, however its ethanol production ability needs to be improved to enable commercial application. In our previous strain engineering work, we observed a spontaneous mutation in the native gene that reduced ethanol production. Here we attempted to complement this mutation by heterologous expression of 18 different alcohol dehydrogenase ( genes. We were able to express all of them successfully in . Surprisingly, however, none of them increased ethanol production, and several actually it. Our findings contribute to understanding the correlation between ethanol production and Adh enzyme cofactor preferences. The identification of a set of genes that can be successfully expressed in this organism provides a foundation for future investigations into how the properties of Adh enzymes affect ethanol production.