title: Enterohaemorrhagic Escherichia coli gains a competitive advantage by using ethanolamine as a nitrogen source in the bovine intestinal content.
abstract: The bovine gastrointestinal tract is the main reservoir for enterohaemorrhagic Escherichia coli (EHEC) responsible for food-borne infections. Characterization of nutrients that promote the carriage of these pathogens by the ruminant would help to develop ecological strategies to reduce their survival in the bovine gastrointestinal tract. In this study, we show for the first time that free ethanolamine (EA) constitutes a nitrogen source for the O157:H7 EHEC strain EDL933 in the bovine intestinal content because of induction of the eut (ethanolamine utilization) gene cluster. In contrast, the eut gene cluster is absent in the genome of most species constituting the mammalian gut microbiota. Furthermore, the eutB gene (encoding a subunit of the enzyme that catalyses the release of ammonia from EA) is poorly expressed in non-pathogenic E. coli. Accordingly, EA is consumed by EHEC but is poorly metabolized by endogenous microbiota of the bovine small intestine, including commensal E. coli. Interestingly, the capacity to utilize EA as a nitrogen source confers a growth advantage to E. coli O157:H7 when the bacteria enter the stationary growth phase. These data demonstrate that EHEC strains take advantage of a nitrogen source that is not consumed by the resident microbiota, and suggest that EA represents an ecological niche favouring EHEC persistence in the bovine intestine.
authors.affiliation: Institut National de la Recherche Agronomique, Unité de Microbiologie UR 454, Centre de Recherche de Clermont-Ferrand/Theix, 63122 Saint-Genès-Champanelle, France. yolande.bertin@clermont.inra.fr
authors.forename: Yolande
authors.initials: Y
authors.lastname: Bertin
authors.forename: J P
authors.initials: JP
authors.lastname: Girardeau
authors.forename: F
authors.initials: F
authors.lastname: Chaucheyras-Durand
authors.forename: Bernard
authors.initials: B
authors.lastname: Lyan
authors.forename: Estelle
authors.initials: E
authors.lastname: Pujos-Guillot
authors.forename: Josée
authors.initials: J
authors.lastname: Harel
authors.forename: Christine
authors.initials: C
authors.lastname: Martin
mesh_terms: D000818:Animals; D002417:Cattle / Q000382:microbiology*; D002418:Cattle Diseases / Q000382:microbiology; D003470:Culture Media; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary; D019453:Escherichia coli O157 / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics; D019856:Ethanolamine / Q000378:metabolism*; D005766:Gastrointestinal Contents / Q000737:chemistry* / Q000382:microbiology; D041981:Gastrointestinal Tract / Q000382:microbiology; D015964:Gene Expression Regulation, Bacterial; D008297:Male; D005810:Multigene Family; D009584:Nitrogen / Q000378:metabolism; D009876:Operon; D012329:RNA, Bacterial / Q000235:genetics
chemical_list: D003470:Culture Media; D029968:Escherichia coli Proteins; D012329:RNA, Bacterial; D019856:Ethanolamine; D009584:Nitrogen