Title: Isotopomer-Flux Analysis of Bifidobacterium ssp. Carbohydrate Metabolism Authors
|Sela, David - UNIV OF CA, DAVIS|
|Mills, David - UNIV OC CA, DAVIS|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: November 9, 2007
Publication Date: November 9, 2007
Citation: Price, N.P., Adeuya, A., Whitehead, T.R., Sela, D.A., Mills, D.A. 2007. Isotopomer-Flux analysis of Bifidobacterium ssp. carbohydrate metabolism [abstract]. 4th International Symposium: Milk Genomics & Human Health. Available: http://lactoknow.ucdavis.edu/symposiums. p. 19. Technical Abstract: Bifidobacteria are gram-positive microorganisms widely applied in fermented dairy products due to their health-promoting effects. Bifidobacterium ssp. may also represent up to 91% of microbial gut population in the infant colon, but considerably less in adults. Fructose-6 phosphate phosphoketolase (F6PPK) is a key enzyme of the so-called "bifid shunt," a unique Bifidobacterium ssp. metabolic pathway involved in direct cleavage of fructose-6-phosphate to erythrose-4-phosphate and acetyl phosphate. Furthermore, bifidobacteria lack genes for glycolysis and gluconeogenesis pathways. Results of isotopic labeling experiments with **13C-fructose confirm that the bifid shunt is the predominant pathway for the degradation of carbohydrates by Bifidobacterium ssp., by-passing glycolysis. The fractional distribution of **13C into carbohydrate and fatty acid metabolites was analyzed by GC-EI-MS. The acetate derived from sugars via the bifid shunt is both secreted and incorporated into the Bifidobacterium de novo fatty acids. Moreover, several metabolic "chase" experiments have been undertaken using probiotic oligosaccharides, and human milk oligosaccharides, and differential pathways are reported for B. longum and B. infantis strains. These finding are consistent with the genome data for these strains, and suggest ways by which B. infantis has adapted to the environment of the infant human gut.