Glycosyl hydrolases from Bifidobacterium adolescentis DSM20083. An overview

It is claimed that bifidobacteria have several health-promoting effects. To increase the amount of bifidobacteria in the colon the concept of probiotics and/or prebiotics can be applied. Bifidobacterium adolescentis is one of the main species of bifidobacteria in the gastro-intestinal tract of human adults. B. adolescentis is able to degrade a wide range of oligosaccharides and a number of glycosyl hydrolases have been characterized in detail. The hydrolytic activity of the glycosyl hydrolases from B. adolescentis toward prebiotics like arabinoxylan-oligosaccharides, isomalto-oligosaccharides, arabinogalactan, and sucrose-based oligosaccharides (raffinose, stachyose, and fructo- oligosaccharides) is reviewed. Alternatively, some of these glycosyl hydrolases are able to catalyze transglycosylation, which allows them to elongate oligosaccharides and to prepare potentially prebiotic oligosaccharides. Such oligo saccharides might be used to influence the microbial composition in the more distal parts of the colon. In nature, not all enzyme-substrate encounters are transglycosylating. So, the hydrolytic activity of the enzyme makes the oligosaccharide elongation less efficient than desired. Site-directed mutagenesis was applied to improve the transglycosylation reaction of the ¿-galactosidase from B. adolescentis.