PROPIONATE METABOLISM IN ANAEROBIC-BACTERIA - DETERMINATION OF CARBOXYLATION REACTIONS WITH C-13-NMR SPECTROSCOPY

The role of carboxylation reactions in propionate metabolism was studied with in vivo high-resolution NMR in two syntrophic propionate oxidizing cocultures and compared with anaerobic propionate forming bacteria with well-established biochemical properties. The inclusion of [C-13]propionate and (H13CO3-)-H-13 gave insight into the process of randomization at the level of propionate in relation to the type of the (de)carboxylating enzyme involved. Propionibacterium but not Veillonella and Desulfobulbus showed a propionate randomization in the absence of substrate. These differences are explained by the type of carboxylation mechanism and the energy state of the cells. Both syntrophic cocultures tested degrade propionate via the succinate pathway involving a transcarboxylase.