Metabolism of host-derived carbohydrates by Bifidobacterium breve UCC2003

dc.check.reasonThis thesis is due for publication or the author is actively seeking to publish this materialen
dc.contributor.advisorvan Sinderen, Douween
dc.contributor.authorEgan, Muireann
dc.contributor.funderScience Foundation Irelanden
dc.description.abstractBifidobacteria are Gram positive, anaerobic, typically Y-shaped bacteria which are naturally found in the digestive tract of certain mammals, birds and insects. Bifidobacterium breve strains are numerically prevalent among the gut microbiota of many healthy breast-fed infants. The prototypical B. breve strain UCC2003 has previously been shown to utilise numerous carbohydrates of plant origin. Various aspects of host-derived carbohydrate metabolism occurring in this bacterium will be described in this thesis. Chapter II describes B. breve UCC2003 utilisation of sialic acid, a nine-carbon monosaccharide, which is found in human milk oligosaccharides (HMOs) and the mucin glycoprotein. B. breve UCC2003 was also shown to cross-feed on sialic acid released from 3’ sialyllactose, a prominent HMO, by the extracellular sialidase activity of Bifidobacterium bifidum PRL2010. Chapter III reports on the transcriptional regulation of sialic acid metabolism in B. breve UCC2003 by a transcriptional repressor encoded by the nanR gene. NanR belongs to the GntR-family of transcriptional regulators and represents the first bifidobacterial member of this family to be characterised. Chapter IV investigates B. breve UCC2003 utilisation of mucin. B. breve UCC2003 was shown to be incapable of degrading mucin; however when grown in co-culture with B. bifidum PRL2010 it exhibits enhanced growth and survival properties. A number of methods were used to investigate and identify the mucin components supporting this enhanced growth/viability phenotype. Chapter V describes the characterisation of two sulfatase-encoding gene clusters from B. breve UCC2003. The transcriptional regulation of both sulfatase-encoding gene clusters was also investigated. The work presented in this thesis represents new information on the metabolism of host-derived carbohydrates in bifidobacteria, thus increasing our understanding of how these gut commensals are able to colonise and persist in the gastrointestinal tract.en
dc.description.sponsorshipScience Foundation Ireland (SFI Grant Nos. 07/CE/B1368 and 12/RC/2273)en
dc.description.statusNot peer revieweden
dc.description.versionAccepted Version
dc.identifier.citationEgan, M. 2015. Metabolism of host-derived carbohydrates by Bifidobacterium breve UCC2003. PhD Thesis, University College Cork.en
dc.publisherUniversity College Corken
dc.rights© 2015, Muireann Egan.en
dc.subjectHuman milk oligosaccharidesen
dc.subjectSialic aciden
dc.subjectHost-derived carbohydratesen
dc.titleMetabolism of host-derived carbohydrates by Bifidobacterium breve UCC2003en
dc.typeDoctoral thesisen
dc.type.qualificationnamePhD (Science)en
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