Pathway of propionate degradation inDesulfobulbus propionicus

The degradation of [1-14C]- and [2-14C] propionate to acetate and bicarbonate by the sulfate-reducing bacterium Desulfobulbus propionicus was studied. When [1-14C]propionate was used, more than 95% of the label was recovered in the HCO3− fraction. [2-14C]Propionate was quantitatively converted into labeled acetate of which the methyl and carboxyl group were equally labeled. These results are in accordance with a randomizing route such as the methylmalonyl-CoA pathway for propionate degradation and support earlier evidence for the functioning of this pathway on the basis of enzyme assays.