Origins of Fermentation Products Formed during Growth of Bacteroides ruminicola on Glucose

Abstract

B. ruminicola grown on complex medium with glucose as C source gave acetate, CO2, formate and succinate as main fermentation products. No evidence was found for significant glucose catabolism by pathways other than the Embden-Meyerhof sequence. [U-14C]glucose fermentation gave products whose specific radioactivities were much lower than expected. There appear to be 2 main causes: a rapid exchange occurred between metabolic intermediates and CO2, probably due to reversibility of the pathway between phosphoenolpyruvate and fumarate; non-glucose precursors, mainly peptides and acetate, added to the medium as growth factors, also gave rise to the above end-products. The distortions that such reactions introduce into measurements of ATP molar growth yields based on product analyses and measurements of C flux, based on radioactivity recovered in products, are discussed.