|Cote, Gregory - Greg|
Submitted to: American Society for Microbiology
Publication Type: Abstract only
Publication Acceptance Date: 6/9/2005
Publication Date: 6/9/2005
Citation: Holt, S.M., Cote, G.L. 2005. The influence of disaccharides and alternansucrase-derived oligosaccharides on a-galactosidase expression in Bifidobacterium adolescentis [abstract]. American Society for Microbiology, June 5-9, 2005, Atlanta, Georgia. Abstract K-041. Interpretive Summary:
Technical Abstract: Bifidobacteria are anaerobes that reside within the gastrointestinal tract of many animals including humans and are generally considered beneficial to their host. Bifidobacteria have the ability to metabolize certain carbohydrates and oligosaccharides considered nondigestible to the host animal. Despite their significance, very little is known about how bifidobacteria metabolize carbohydrates. Identification of enzymes associated with carbohydrate metabolism would enhance our knowledge of bifidobacterial physiology and help in the design of new prebiotic oligosaccharides. In this study, the influence of various carbohydrates on alpha-galactosidase enzyme expression in Bifidobacterium adolescentis was examined. The carbohydrates included mono, di, tri, and oligosaccharides. Oligosaccharides used in this study were prepared from the bacterial enzyme alternansucrase (ASR), sucrose, and carbohydrate acceptor molecules. The ASR-derived oligosaccharides have been shown to selectively stimulate the growth of bifidobacteria in previous work. B. adolescentis was cultivated anaerobically on each test carbohydrate for 48 h. The cells were collected, washed, lysed open using ballistic disintegration, and the cell-free extracts were assayed in triplicate for alpha-galactosidase and protein. Alpha-Galactosidase was detected on glucose cultures and was the basis for all activity comparisons. Most carbohydrates tested displayed an increase in alpha-galactosidase activity except glucitol and gentiobiose. The beta–linked carbohydrates showed the lowest activity increases and the alpha–linked showed the highest activity increases. Galactose (1.5-fold), melibiose (4.2-fold), and ASR-derived maltose-oligosaccharide (4.6-fold) displayed the highest alpha-galactosidase activities among mono, di, and oligosaccharides tested. The oligosaccharides displayed the highest activity increases among all carbohydrates tested except for melibiose-oligosaccharide. In conclusion, alpha-galactosidase in B. adolescentis appears to be induced by alpha-linked carbohydrates with the highest activities detected on ASR-derived oligosaccharides.