Transcriptional and functional characterization of genetic elements involved in galacto-oligosaccharide utilization by Bifidobacterium breve UCC2003

Microb Biotechnol. 2013 Jan;6(1):67-79. doi: 10.1111/1751-7915.12011. Epub 2012 Dec 2.


Several prebiotics, such as inulin, fructo-oligosaccharides and galacto-oligosaccharides, are widely used commercially in foods and there is convincing evidence, in particular for galacto-oligosaccharides, that prebiotics can modulate the microbiota and promote bifidobacterial growth in the intestinal tract of infants and adults. In this study we describe the identification and functional characterization of the genetic loci responsible for the transport and metabolism of purified galacto-oligosaccharides (PGOS) by Bifidobacterium breve UCC2003. We further demonstrate that an extracellular endogalactanase specified by several B. breve strains, including B. breve UCC2003, is essential for partial degradation of PGOS components with a high degree of polymerization. These partially hydrolysed PGOS components are presumed to be transported into the bifidobacterial cell via various ABC transport systems and sugar permeases where they are further degraded to galactose and glucose monomers that feed into the bifid shunt. This work significantly advances our molecular understanding of bifidobacterial PGOS metabolism and its associated genetic machinery to utilize this prebiotic.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP-Binding Cassette Transporters / genetics
  • ATP-Binding Cassette Transporters / metabolism*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Bifidobacterium / classification
  • Bifidobacterium / enzymology
  • Bifidobacterium / genetics*
  • Bifidobacterium / metabolism*
  • Galactose / metabolism*
  • Humans
  • Infant, Newborn
  • Membrane Transport Proteins / genetics
  • Membrane Transport Proteins / metabolism*
  • Oligosaccharides / metabolism*
  • Prebiotics
  • Transcriptome*
  • beta-Galactosidase / genetics
  • beta-Galactosidase / metabolism*


  • ATP-Binding Cassette Transporters
  • Bacterial Proteins
  • Membrane Transport Proteins
  • Oligosaccharides
  • Prebiotics
  • beta-Galactosidase
  • Galactose