TABLE 1.

Characteristics of strains used

Strainσs productionaH2O2 resistance (%)bGrowth on propionatecspvRAB-lacZ expressiond
Salmonella serotype Typhi controls
    5959+100742 ± 122
    5959K (ΔrpoS::kan)0e+9 ± 2
Salmonella serotype Typhi blood isolates
    Ty01, Ty10, Ty13, Ty14, Ty15, Ty16, Ty17, Ty18, Ty20, Ty21, Ty22, Ty24, Ty25, Ty27, Ty29, Ty32, Ty35, Ty36, Ty37, Ty38, Ty40, Ty41, Ty42, Ty43, Ty44, Ty45+100f473 ± 95
    Ty020+8 ± 3
    Ty03+0+11 ± 4
    Ty04+881 ± 12
    Ty06+0+ND
    Ty080+7 ± 2
    Ty090+ND
    Ty110+7 ± 1
    Ty12+7620 ± 6
    Ty23+0.001+159 ± 52
    Ty260+5 ± 1
    Ty28+0+21 ± 2
    Ty300+9 ± 2
    Ty310+ND
    Ty330+ND
    Ty39Truncated0+8 ± 2
Salmonella serotype Typhimurium controls
    SL1344+100ND
    SL1344K (ΔrpoS::kan)0+ND
Salmonella serotype Typhimurium blood     isolates
    H1, H2, H4, H5, H6, H7, H8, H9, H10, H11, H15, H16, H17, H18, H19, H20, H21, H22, H23, H25, H28, H30, H31, H32, H33, H34, H35, H36, H37, H38, H39, H40, H41, H42+100gND
    H3+0.0003ND
    H12+0.007ND
    H24+0.0004ND
    H26+0.001ND
Salmonella serotype Typhimurium fecal isolates
    C1, C2, C3, C4, C5, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, C20, C21, C22, C23, C24, C25, C26, C27, C28, C30, C31, C32, C33, C34, C35, C36, C37, C38, C39+100hND
    C6+0.0003ND
  • a σs production was examined by analyzing total proteins by Western blotting with an anti-σs polyclonal rabbit serum.

  • b Level of survival after 60 min of exposure to 15 mM H2O2 compared to the survival at time zero. The data are from one representative experiment.

  • c An overnight LB culture was diluted 106-fold in 5 ml of minimal medium containing 0.2% propionate and incubated on a shaker at 37°C. Growth was recorded after 3 days for Salmonella serotype Typhimurium and after 5 days for Salmonella serotype Typhi. Strains were able to grow in minimal medium containing glucose. Similar results were obtained in two independent experiments.

  • d Strains containing the spvRAB-lacZ fusion on pSTF4 were grown overnight in LB and assayed for β-galactosidase activity. The results are expressed in Miller units (27). The values are means ± standard deviations from three independent experiments. ND, not determined.

  • e No CFU were detectable when 109 bacteria were exposed to 15 mM H2O2 for 60 min.

  • f Determined for only Ty10.

  • g Determined for only H1.

  • h Determined for only C1.