Submitted to: American Society for Microbiology Meeting
Publication Type: Abstract only
Publication Acceptance Date: 6/5/2008
Publication Date: 6/5/2008
Citation: Whitehead, T.R., Adeuya, A., Price, N.P. 2008. Analyses of the bifid shunt and carbohydrate metabolism in Bifidobacterium spp. using **13C-labeled substrates and gas chromatography-mass spectrometry. American Society for Microbiology Meeting. p. Interpretive Summary:
Technical Abstract: Bifidobacteria are Gram-positive, anaerobic bacteria whose presence in the gastrointestinal tract (GIT) is widely considered as a positive influence on human health. This is especially true in the early development of the infant GIT. Analyses of the genome sequence of Bifidobacterium longum suggest these bacteria have the ability to utilize a variety of oligosaccharides, as well as simple carbohydrates, which may contribute to the successful colonization of the GIT. Bifidobacteria lack certain enzymes required for both glycolysis and gluconeogenesis. However, they utilize a unique hexose catabolic pathway termed the bifid shunt that involves a phosphoketolase pathway. Little is known regarding the distribution of carbohydrate substrates into metabolic end products in these bacterial species. Therefore, growth experiments were carried out with B. longum and B. infantis using a minimal medium and isotopically-labeled carbohydrates, primarily fructose. Results of labeling experiments confirm that the bifid shunt is the predominant pathway for carbohydrate catabolism. The distribution of **13C into carbohydrate and fatty acid end-products was determined, and chase experiments were also carried out with unlabeled carbohydrates. Results from these studies demonstrate for the first time that acetate derived from sugars via the bifid shunt is both secreted and incorporated into the Bifidobacterium de novo fatty acids. A second novel result is the confirmation that ribose is synthesized by the pentose phosphate pathway, rather than by the transaldolase/transketolase recovery pathways. These and other results are consistent with the genome data for Bifidobacterium strains and provide insight into the metabolism of these important GIT bacteria.