TABLE 2.

Contributions of σB to survival under acid and oxidative stress conditions for all four L. monocytogenes lineages

LineageDeath rate (log CFU/h) at pH 2.5Death (log CFU) with 13 mM CHP
Wild typeaΔsigB strainbP valuecWild typedΔsigB straineP valuef
I3.95 ± 0.936.62 ± 0.660.00041.27 ± 0.042.10 ± 0.230.0225
II1.75 ± 0.496.76 ± 0.79<0.00011.10 ± 0.082.57 ± 0.12<0.0001
IIIA4.02 ± 2.235.74 ± 1.890.29201.14 ± 0.221.74 ± 0.400.0827
IIIB3.65 ± 0.776.37 ± 0.730.00471.38 ± 0.302.09 ± 0.220.0291
  • a Average death rate (± standard deviation) for wild-type parent strain exposed to pH 2.5 for 1 h.

  • b Average death rate (± standard deviation) (log CFU/h) for isogenic ΔsigB strain exposed to pH 2.5 for 1 h.

  • c P value for the time-strain interaction. A P value of <0.05 indicates there that was a significant difference in the average death rate between the wild-type and isogenic ΔsigB strains.

  • d Average death value (± standard deviation) (log CFU) for wild-type parent strain after 15 min of exposure to 13 mM CHP.

  • e Average death value (± standard deviation) (log CFU) for isogenic ΔsigB strain after 15 min of exposure to 13 mM CHP.

  • f P value for one-sided t test. A P value of <0.05 indicates that there was a significant difference in the average death value between the wild-type and isogenic ΔsigB strains.