(635f) Improved Production of Biofuel Precursors From CO2 Fermentation Via Growth and Physiology Optimization of Moorella Thermoacetica

Approximately half of the glucose feedstock used during the biofuel (e.g. ethanol) fermentation process is lost as CO2. This is the result of carbon oxidation that is necessary to generate the reducing equivalents required to lower the oxygen content of an initial glucose molecule (C6H12O6) to that of the more reduced products (e.g. ethanol). It has been suggested that if the emitted CO2 could be captured using hydrogen from a non-fossil fuel source, the amount of land required to produce a given amount of biofuel would be reduced by two thirds. While thermochemical processes were contemplated in the above CO2 fixation concept, biological methods are just as applicable. Furthermore, the latter will have a higher overall yield as they operate closer to equilibrium and are consequently more efficient.

A group of anaerobic bacteria known as acetogens, have the ability to grow on CO₂ and H₂ and produce various chemical (e.g. acetate) and biofuels (e.g. ethanol). However, a major challenge facing this process is the poor solubility of gaseous substrates and consequently the low productivity of the process. In this presentation we describe the growth and physiology optimization of an improved strain of a thermophilic acetogen, Moorella thermoacetica, and the design and operation of a high pressure bioreactor to increase the productivity of H₂/CO₂ conversion to acetate. The produced acetate could be then used as a precursor by oleaginous microorganisms for producing biodiesel. The results on effects of various components of the medium and bioreactor operating conditions on growth, productivity and adaptation of M. thermoacetica to convert H₂/CO₂ to acetate will be presented.