The rqlI mutant experiences increased genotoxic stress, especially under low oxygen conditions.

(A-D) WT F11 or F11ΔrqlI were grown 24 h aerobically, microaerobically, or anaerobically, at which point bacteria were spread on a slide and imaged. (A) Representative images. (B-D) Histograms show the distribution of bacterial cell lengths after growth at varying oxygen levels. (E) WT F11 and F11ΔrqlI strains carrying either the PsulA-GFP reporter plasmid (pJLJ3) or an empty vector control (pJLJ1) were grown aerobically ± mitomycin C, microaerobically, or anaerobically, as indicated. Fluorescence measurements were normalized to culture densities. Bars indicate mean values ± SEM from three or more independent experiments performed in triplicate. *, P ≤ 0.05; **, P ≤ 0.01; ***, P ≤ 0.001; as determined by Student’s t test.