title: Bile-inducible efflux transporter from Bifidobacterium longum NCC2705, conferring bile resistance.
abstract: Bifidobacteria are normal inhabitants of the human gut. Some strains of this genus are considered health promoting or probiotic, being included in numerous food products. In order to exert their health benefits, these bacteria must overcome biological barriers, including bile salts, to colonize and survive in specific parts of the intestinal tract. The role of multidrug resistance (MDR) transporters in bile resistance of probiotic bacteria and the effect of bile on probiotic gene expression are not fully understood. In the present study, the effect of subinhibitory concentrations of bile on the expression levels of predicted MDR genes from three different bifidobacterial strains, belonging to Bifidobacterium longum subsp. longum, Bifidobacterium breve, and Bifidobacterium animalis subsp. lactis, was tested. In this way, two putative MDR genes whose expression was induced by bile, BL0920 from B. longum and its homolog, Bbr0838, from B. breve, were identified. The expression of the BL0920 gene in Escherichia coli was shown to confer resistance to bile, likely to be mediated by active efflux from the cells. To the best of our knowledge, this represents the first identified bifidobacterial bile efflux pump whose expression is induced by bile.
authors.affiliation: Department of Microbiology and Biochemistry of Dairy Products, Instituto de Productos Lácteos de Asturias (IPLA), Consejo Superior de Investigaciones Científicas (CSIC), Villaviciosa, Asturias, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Gueimonde
authors.forename: Christel
authors.initials: C
authors.lastname: Garrigues
authors.forename: Douwe
authors.initials: D
authors.lastname: van Sinderen
authors.forename: Clara G
authors.initials: CG
authors.lastname: de los Reyes-Gavilán
authors.forename: Abelardo
authors.initials: A
authors.lastname: Margolles
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000378:metabolism*; D001644:Bifidobacterium / Q000187:drug effects* / Q000378:metabolism*; D001646:Bile / Q000378:metabolism*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics; D020869:Gene Expression Profiling; D026901:Membrane Transport Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D017385:Sequence Homology
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D026901:Membrane Transport Proteins