Deep Conversion of Carbon Monoxide to Hydrogen and Formation of Acetate by the Anaerobic ThermophileCarboxydothermus hydrogenoformans

摘要

Carboxydothermus hydrogenoformansis a thermophilic strictly anaerobic bacterium that catalyses the water gas shift reaction, the conversion of carbon monoxide with water to molecular hydrogen and carbon dioxide. The thermodynamically favorable growth temperature, compared to existing industrial catalytic processes, makes this organism an interesting alternative for production of cheap hydrogen gas suitable to fuel CO-sensitive fuel cells in a future hydrogen economy, provided sufficiently low levels of CO are reached. Here we study CO conversion and final CO levels in cultures ofC. hydrogenoformansgrown in batch cultures that were started with a 100% CO gas phase with and without removal of formed CO2. Final CO levels were 117 ppm without CO2removal and below 2 ppm with CO2removal. The Gibbs free energy change calculated with measured end concentrations and the detection of acetate suggest thatC. hydrogenoformansshifted from a hydrogenogenic to an acetogenic metabolism.