FIG 5.

Cells lacking SigB have decreased sensitivity to blue light. Shown is the influence of blue light (470 nm, 1.5 to 2 mW cm⁻²) on the growth of L. monocytogenes ΔsigB compared to the wild-type EGD-e on BHI agar (A) and in BHI liquid culture (B). Overnight cultures were standardized to an OD₆₀₀ of 1.0 and diluted to 10⁻⁸. Four microliters of each dilution was spotted in triplicate onto BHI agar and grown at 30°C for 24 h. (B) Final OD measurements (left) and difference in lag time (right). The number over the lag time indicates the time taken to reach 0.1. Starting cells were equalized to an OD₆₀₀ of 0.05 and diluted to 10⁻⁶. Cultures were grown in 96-well plates at 30°C for 24 h. The values represent the means of the results from three individual replicates. The error bars represent the standard deviations between samples. Student's t test was carried out to determine the statistical difference between EGD-e and ΔsigB. The asterisks in panel B indicate a P value of ≤0.05.