Degradation of glyoxylate and glycolate with ATP synthesis by a thermophilic anaerobic bacterium, Moorella sp strain HUC22-1

The thermophilic homoacetogenic bacterium Moorella sp. strain HUC22-1 ferments glyoxylate to acetate roughly according to the reaction 2 glyoxylate -> acetate + 2 CO2. A batch culture with glyoxylate and yeast extract yielded 11.7 g per mol of cells per substrate, which was much higher than that obtained with H-2 Plus CO2. Crude extracts of glyoxylate-grown cells catalyzed the ADP- and NADP-dependent condensation of glyoxylate and acetyl coenzyme A (acetyl-CoA) to pyruvate and CO2 and converted pyruvate to acetyl-CoA and CO2, which are the key reactions of the malyll-CoA pathway. ATP generation was also detected during the key enzyme reactions of this pathway. Furthermore, this bacterium consumed L-malate, an intermediate in the malyl-CoA pathway, and produced acetate. These findings suggest that Moorella sp. strain HUC22-1 can generate ATP by substrate-level phosphorylation during glyoxylate catabolism through the malyll-CoA pathway.