Degradation of Glyoxylate and Glycolate with ATP Synthesis by a Thermophilic Anaerobic Bacterium, Moorella sp. Strain HUC22-1

Abstract

ABSTRACT The thermophilic homoacetogenic bacterium Moorella sp. strain HUC22-1 ferments glyoxylate to acetate roughly according to the reaction 2 glyoxylate → acetate + 2 CO 2 . 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 CO 2 . Crude extracts of glyoxylate-grown cells catalyzed the ADP- and NADP-dependent condensation of glyoxylate and acetyl coenzyme A (acetyl-CoA) to pyruvate and CO 2 and converted pyruvate to acetyl-CoA and CO 2 , which are the key reactions of the malyl-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 malyl-CoA pathway.