Figure 3

ΔVNG0258H is impaired for growth and survival upon exposure to hydrogen peroxide (H ₂ O ₂ ). (A) Comparison of ΔVNG0258H and Δura3 parent growth rates under standard conditions across all experiments (n = 63, see also Additional file 3: Table S1). (B) Mean growth rates for 4 biological replicate cultures treated with H₂O₂ in lag phase. Blue bars represent Δura3 cultures; red bars represent ΔVNG0258H cultures. Concentration of H₂O₂ added is indicated on the x-axis. (C) Representative growth curves (1 of 4 biological replicates) for cultures treated with H₂O₂ at beginning of growth (OD600 ≈ 0.05). Line colors are as in (B). Thin, medium, and thick lines indicate H₂O₂ added to a final concentration of 0, 5, or 6 mM, respectively (see legend; 7 mM curves omitted for clarity). Downward arrow indicates time of H₂O₂ addition. Bracket indicates period for which mean growth rates were calculated. (D) Mean growth rates for 7 biological replicate cultures treated with H₂O₂ in mid-logarithmic growth phase. (E) Representative growth curves for cultures treated with H₂O₂ in mid-logarithmic phase (OD600 ≈ 0.3). Thin, medium, and thick lines indicate H₂O₂ added to a final concentration of 0, 18.75, or 25 mM, respectively (curves for 6.25 and 12.5 mM conditions are omitted for clarity). Downward arrow indicates time of treatment. Bracket indicates period for which mean growth rates were calculated. In all bar graphs, error bars represent standard deviation. Asterisks represent statistically significant differences between ΔVNG0258H and parent strain Δura3 under the same growth conditions, where single asterisk indicates a p-value < 0.01, double asterisk indicates p < 0.001, and triple asterisk indicates p < 0.0001. All raw data are given in Additional file 3: Table S1.