Glucose and Pyruvate Metabolism of Spirochaeta litoralis , an Anaerobic Marine Spirochete

Abstract

The pathways of glucose and pyruvate metabolism in Spirochaeta litoralis , a free-living, strictly anaerobic marine spirochete, were studied. Addition of 0.2 to 0.4 M NaCl (final concentration) to suspending buffers prevented cell lysis and was necessary for gas evolution from various substrates by cell suspensions. The organism fermented glucose mainly to ethanol, acetate, CO 2 , and H 2 . Determination of radioactivity in products formed from 14 C-labeled glucose and assays of enzymatic activities in cell extracts indicated that S. litoralis catabolized glucose via the Embden-Meyerhof pathway. A clostridial-type clastic reaction was utilized by the spirochete to degrade pyruvate to acetyl-coenzyme A, CO 2 , and H 2 . Formation of acetate from acetyl-coenzyme A was catalyzed by phosphotransacetylase and acetate kinase. Nicotinamide adenine dinucleotide-dependent acetaldehyde and alcohol dehydrogenases converted acetyl-coenzyme A to ethanol. A reversible hydrogenase activity was detected in cell extracts. S. litoralis cell extracts contained a rubredoxin similar in spectral properties to other bacterial rubredoxins.