Energy Conservation in the Acetogenic Bacterium .

In times of global warming caused by the extensive use of fossil fuels, the need to capture gaseous carbon compounds is growing bigger. Several groups of microorganisms can fix the greenhouse gas CO. Out of these, acetogenic bacteria are role models in their ability to reduce CO with hydrogen to acetate, which makes acetogens prime candidates for genetic modification towards biotechnological production of value-added compounds from CO, such as biofuels. However, growth of acetogens on gaseous substrates is strongly energy-limited, and successful metabolic engineering requires a detailed knowledge of the bioenergetics. In 1939, was the first acetogen to be described. A recent genomic study revealed that this organism contains cytochromes and therefore may use a proton gradient in its respiratory chain. We have followed up these studies and will present data that does not use a H but a Na gradient for ATP synthesis, established by a Na-Rnf. Experimental data and in silico analyses enabled us to propose the biochemistry and bioenergetics of acetogenesis from H + CO in .