Acetogenesis from pyruvate by<i>Desulfotomaculum thermobenzoicum</i>and differences in pyruvate metabolism among three sulfate-reducing bacteria in the absence of sulfate

Abstract

Desulfotomaculum thermobenzoicum TSB converted 4 mol pyruvate to 5 tool acetate in the absence of sulfate. The cells grown on pyruvate without sulfate showed both carbon monoxide dehydrogenase (CODH) and methylmalonyl-CoA: pyruvate transcarboxylase activities. However, considering the fermentation products, the acetogenesis from pyruvate might be conducted by CODH pathway rather than methylmalonyl-CoA pathway. Contrary to this finding, Desulfobulbus propionicus MUD fermented 3 mol pyruvate to 2 mol acetate and 1 tool propionate stoichiometrically via methylmalonyl-CoA pathway. Desulfovibrio vulgaris Marburg, which has neither the CODH pathway nor the methylmalonyl-CoA pathway, converted pyruvate to acetate, H 2 and CO2 as the main products. These results indicate that the fermentation pattern of pyruvate depends on the metabolic characteristics of each sulfate-reducing bacterium.