title: Vitamin B12 Uptake by the Gut Commensal Bacteria Bacteroides thetaiotaomicron Limits the Production of Shiga Toxin by Enterohemorrhagic Escherichia coli.
abstract: Enterohemorrhagic Escherichia coli (EHEC) are foodborne pathogens responsible for the development of bloody diarrhea and renal failure in humans. Many environmental factors have been shown to regulate the production of Shiga toxin 2 (Stx2), the main virulence factor of EHEC. Among them, soluble factors produced by human gut microbiota and in particular, by the predominant species Bacteroides thetaiotaomicron (B. thetaiotaomicron), inhibit Stx2 gene expression. In this study, we investigated the molecular mechanisms underlying the B. thetaiotaomicron-dependent inhibition of Stx2 production by EHEC. We determined that Stx2-regulating molecules are resistant to heat treatment but do not correspond to propionate and acetate, two short-chain fatty acids produced by B. thetaiotaomicron. Moreover, screening of a B. thetaiotaomicron mutant library identified seven mutants that do not inhibit Stx2 synthesis by EHEC. One mutant has impaired production of BtuB, an outer membrane receptor for vitamin B12. Together with restoration of Stx2 level after vitamin B12 supplementation, these data highlight vitamin B12 as a molecule produced by gut microbiota that modulates production of a key virulence factor of EHEC and consequently may affect the outcome of an infection.
authors.affiliation: INRA, UR454 Microbiologie, F-63122 Saint-Genès-Champanelle, France. charlotte.cordonnier@udamail.fr.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Cordonnier
authors.affiliation: Groupe de Recherche sur les Maladies Infectieuses du Porc (GREMIP), Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Université de Montréal, Faculté de Médecine Vétérinaire, C.P. 5000, Saint-Hyacinthe, QC J2S 7C6, Canada. guillaume.le.bihan@umontreal.ca.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Le Bihan
authors.affiliation: Groupe de Recherche sur les Maladies Infectieuses du Porc (GREMIP), Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Université de Montréal, Faculté de Médecine Vétérinaire, C.P. 5000, Saint-Hyacinthe, QC J2S 7C6, Canada. jeang.emond6@gmail.com.
authors.forename: Jean-Guillaume
authors.initials: JG
authors.lastname: Emond-Rheault
authors.affiliation: INRA, UR454 Microbiologie, F-63122 Saint-Genès-Champanelle, France. annie.garrivier@clermont.inra.fr.
authors.forename: Annie
authors.initials: A
authors.lastname: Garrivier
authors.affiliation: Groupe de Recherche sur les Maladies Infectieuses du Porc (GREMIP), Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Université de Montréal, Faculté de Médecine Vétérinaire, C.P. 5000, Saint-Hyacinthe, QC J2S 7C6, Canada. josee.harel@umontreal.ca.
authors.forename: Josée
authors.initials: J
authors.lastname: Harel
authors.affiliation: INRA, UR454 Microbiologie, F-63122 Saint-Genès-Champanelle, France. gregory.jubelin@clermont.inra.fr.
authors.forename: Grégory
authors.initials: G
authors.lastname: Jubelin
mesh_terms: D001439:Bacteroides / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D054324:Enterohemorrhagic Escherichia coli / Q000378:metabolism*; D000069196:Gastrointestinal Microbiome / Q000187:drug effects / Q000502:physiology; D009154:Mutation; D022641:Shiga Toxin 2 / Q000096:biosynthesis*; D014805:Vitamin B 12 / Q000494:pharmacology*
chemical_list: D022641:Shiga Toxin 2; D014805:Vitamin B 12
keywords: Bacteroides thetaiotaomicron; Shiga toxin; enterohemorrhagic Escherichia coli; vitamin B12