Open AccessMetabolism of a plant derived galactose‐containing polysaccharide by Bifidobacterium breve UCC2003
Author(s) -
O'Connell Motherway Mary,
Fitzgerald Gerald F.,
van Sinderen Douwe
Publication year - 2011
Publication title -
microbial biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.287
H-Index - 74
ISSN - 1751-7915
DOI - 10.1111/j.1751-7915.2010.00218.x
Subject(s) - bifidobacterium breve , biochemistry , galactose , operon , gene , chemistry , biology , gene cluster , bifidobacterium , lactobacillus , escherichia coli , fermentation
Summary In this study, we describe the functional characterization of the Bifidobacterium breve UCC2003 gal locus, which is dedicated to the utilization of galactan, a plant‐derived polysaccharide. Using a combination of molecular approaches we conclude that the gal A gene of B. breve UCC2003 encodes a β‐1,4‐endogalactanase producing galacto‐oligosaccharides, which are specifically internalized by an ABC transport system, encoded by gal BCDE, and which are then hydrolysed to galactose moieties by a dedicated intracellular β‐galactosidase, specified by gal G. The generated galactose molecules are presumed to be fed into the fructose‐6‐phosphate phosphoketolase pathway via the Leloir pathway, thereby allowing B. breve UCC2003 to use galactan as its sole carbon and energy source. In addition to these findings we demonstrate that GalR is a LacI‐type DNA‐binding protein, which not only appears to control transcription of the gal CDEGR operon, but also that of the gal A gene.