FIGURE 2.

Stress resistance of late-exponential phase cells of L. monocytogenes LO28 WT and acid resistant variants in BHI broth. Late-exponential phase cells were exposed to pH 2.5 for 3.5 min at 37∘C (adapted from Metselaar et al., 2013) (A), 55∘C for 6 min (B), 420 mM hydrogen peroxide for 9 min at 30∘C (C), and 20 mg/L benzalkonium chloride (BAC) for 5 min at 30∘C (D). Results are expressed as reduction in log₁₀ cfu/ml after exposure compared to log₁₀ cfu/ml at t = 0. Errors bars represent the SD and significant differences from the WT are indicated with ∗(p < 0.05).