title: Genetic analysis of Salmonella enteritidis biofilm formation: critical role of cellulose.
abstract: We report here a new screening method based on the fluorescence of colonies on calcofluor agar plates to identify transposon insertion mutants of Salmonella enteritidis that are defective in biofilm development. The results not only confirmed the requirement of genes already described for the modulation of multicellular behaviour in Salmonella typhimurium and other species, but also revealed new aspects of the biofilm formation process, such as two new genetic elements, named as bcsABZC and bcsEFG operons, required for the synthesis of an exopolysaccharide, digestible with cellulase. Non-polar mutations of bcsC and bcsE genes and complementation experiments demonstrated that both operons are responsible for cellulose biosynthesis in both S. enteritidis and S. typhimurium. Using two different growth media, ATM and LB, we showed that the biofilm produced by S. enteritidis is made of different constituents, suggesting that biofilm composition and regulation depends on environmental conditions. Bacterial adherence and invasion assays of eukaryotic cells and in vivo virulence studies of cellulose-deficient mutants indicated that, at least under our experimental conditions, the production of cellulose is not involved in the virulence of S. enteritidis. However, cellulose-deficient mutants were more sensitive to chlorine treatments, suggesting that cellulose production and biofilm formation may be an important factor for the survival of S. enteritidis on surface environments.
authors.affiliation: Instituto de Agrobiotecnología y Recursos Naturales and Departamento de Producción Agraria, Universidad Pública de Navarra-Consejo Superior de Investigaciones Científicas, 31006 Pamplona, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Solano
authors.forename: Begoña
authors.initials: B
authors.lastname: García
authors.forename: Jaione
authors.initials: J
authors.lastname: Valle
authors.forename: Carmen
authors.initials: C
authors.lastname: Berasain
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Ghigo
authors.forename: Carlos
authors.initials: C
authors.lastname: Gamazo
authors.forename: Iñigo
authors.initials: I
authors.lastname: Lasa
mesh_terms: D000818:Animals; D029681:Arabidopsis Proteins; D001483:Base Sequence; D018441:Biofilms / Q000254:growth & development*; D002482:Cellulose / Q000378:metabolism*; D002645:Chickens; D002713:Chlorine / Q000494:pharmacology; D005260:Female; D005453:Fluorescence; D015964:Gene Expression Regulation, Bacterial; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009154:Mutation; D009876:Operon; D011135:Polysaccharides, Bacterial / Q000378:metabolism; D012481:Salmonella Infections, Animal / Q000382:microbiology; D012477:Salmonella enteritidis / Q000187:drug effects / Q000472:pathogenicity* / Q000502:physiology*; D014774:Virulence / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D011135:Polysaccharides, Bacterial; D002713:Chlorine; D002482:Cellulose; D005964:Glucosyltransferases; C457769:PRC1 protein, Arabidopsis; C028634:cellulose synthase (UDP-forming)