Figure 1.

Sensitivity of L. monocytogenes to visible light is affected by growth phase and temperature. Cultures were grown to the desired growth phase in BHI broth at the appropriate temperature. Cells were centrifuged, washed once in PBS and resuspended in PBS to OD₆₀₀ 1, and then exposed to 35 mW cm⁻² 470 nm light for 8 h. Samples were taken at 0 h and at either 2 h intervals (A) or 6 h (B,C) and cfu/ml were calculated. Error bars represent SD from three technical replicates, plated in triplicate, of two independent replicates. Statistical significance was determined using either two-way ANOVA with Dunnett’s multiple comparisons test (A) or one-way ANOVA with Sidak’s multiple comparisons test (B,C). (^*p ≤ 0.05; ^**p ≤ 0.01; ^***p ≤ 0.001; ^****p ≤ 0.0001).