title: The role of periplasmic antioxidant enzymes (superoxide dismutase and thiol peroxidase) of the Shiga toxin-producing Escherichia coli O157:H7 in the formation of biofilms.
abstract: This study examined the role of the periplasmic oxidative defense proteins, copper, zinc superoxide dismutase (SodC), and thiol peroxidase (Tpx), from the Shiga toxin-producing Escherichia coli O157:H7 (STEC) in the formation of biofilms. Proteomic analyses have shown significantly higher expression levels of both periplasmic antioxidant systems (SodC and Tpx) in STEC cells grown under biofilm conditions than under planktonic conditions. An analysis of their growth phase-dependent gene expression indicated that a high level of the sodC expression occurred during the stationary phase and that the expression of the tpx gene was strongly induced only during the exponential growth phase. Exogenous hydrogen peroxide reduced the aerobic growth of the STEC sodC and tpx mutants by more than that of their parental strain. The two mutants also displayed significant reductions in their attachment to both biotic (HT-29 epithelial cell) and abiotic surfaces (polystyrene and polyvinyl chloride microplates) during static aerobic growth. However, the growth rates of both wild-type and mutants were similar under aerobic growth conditions. The formation of an STEC biofilm was only observed with the wild-type STEC cells in glass capillary tubes under continuous flow-culture conditions compared with the STEC sodC and tpx mutants. To the best of our knowledge, this is the first mutational study to show the contribution of sodC and tpx gene products to the formation of an E. coli O157:H7 biofilm. These results also suggest that these biofilms are physiologically heterogeneous and that oxidative stress defenses in both the exponential and stationary growth stages play important roles in the formation of STEC biofilms.
authors.affiliation: Division of Food Science, Korea University, Seoul, South Korea.
authors.forename: Young Hoon
authors.initials: YH
authors.lastname: Kim
authors.forename: Yunho
authors.initials: Y
authors.lastname: Lee
authors.forename: Saehun
authors.initials: S
authors.lastname: Kim
authors.forename: Jinki
authors.initials: J
authors.lastname: Yeom
authors.forename: Sujin
authors.initials: S
authors.lastname: Yeom
authors.forename: Beom
authors.initials: B
authors.lastname: Seok Kim
authors.forename: Sangnam
authors.initials: S
authors.lastname: Oh
authors.forename: Sungsu
authors.initials: S
authors.lastname: Park
authors.forename: Che Ok
authors.initials: CO
authors.lastname: Jeon
authors.forename: Woojun
authors.initials: W
authors.lastname: Park
mesh_terms: D000332:Aerobiosis; D018441:Biofilms / Q000254:growth & development*; D019453:Escherichia coli O157 / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development; D029968:Escherichia coli Proteins / Q000235:genetics / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D019073:HT29 Cells; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D018384:Oxidative Stress / Q000502:physiology; D033903:Periplasmic Proteins / Q000235:genetics / Q000502:physiology*; D010544:Peroxidases / Q000235:genetics / Q000502:physiology*; D040901:Proteomics; D022621:Shiga Toxin / Q000096:biosynthesis; D013482:Superoxide Dismutase / Q000235:genetics / Q000502:physiology*
chemical_list: D029968:Escherichia coli Proteins; D033903:Periplasmic Proteins; D022621:Shiga Toxin; D006861:Hydrogen Peroxide; D010544:Peroxidases; C097049:Tpx protein, E coli; D013482:Superoxide Dismutase