(11c) Engineering Acetogenic Clostridia for Ethanol and n-Butanol Production From CO2

Some Clostridia, including C. ljungdahlii and C. carboxidivorans, are capable of producing ethanol and butanol from CO₂ and H₂. However, the alcohol productivity, yield, and titer from these native strains are low and uneconomical for industrial applications. In contrast, several acetogenic Clostridia can convert CO₂ and H₂ to acetate with high yield, titer, and productivity comparable to those from glucose as the substrate. A high metabolic flux from CO₂ to acetyl-CoA, the immediate precursor for both acetate and ethanol, is the prerequisite for developing a highly productive ethanol and butanol producers. In this work, we engineered homoacetogens for ethanol and n-butanol production by introducing aldehyde/alcohol dehydrogenase and genes in the acetyl-CoA to butyryl-CoA pathway using modular clostridia plasmids. The fermentation kinetics of these engineered mutants and their ability to produce ethanol and butanol from CO₂ and H₂were studied and will be presented in this paper.

AIChE 2012 Annual Meeting, Pittsburgh