Figure 3

SigB is involved in HQNO-mediated emergence of SCVs and biofilm production. (A) Pictures show SCV colonies grown on agar containing a selective concentration of gentamicin following or not an overnight exposure to 10 μg/ml of HQNO for strains Newbould and NewbouldΔsigB. (B) Relative number of SCV CFUs recovered after 18 h of growth for strains Newbould and NewbouldΔsigB in the presence (black bars) or not (open bars) of 10 μg HQNO/ml. Results are normalized to unexposed Newbould (dotted line). Data are presented as means with standard deviations from at least three independent experiments. Significant differences between unexposed and HQNO-exposed conditions (*, P < 0.05), and between strains in the same experimental condition (Δ, P < 0.05) were revealed by a one-way ANOVA with tuckey's post test. (C) Growth curves of Newbould (□) and NewbouldΔsigB (●) exposed (dotted lines) or not (solid lines) to 10 μg/ml of HQNO. (D) Relative biofilm formation as a function of the concentration of HQNO for strains Newbould (open bars) and NewbouldΔsigB (grey bars). Results are normalized to the unexposed condition for each strain (dotted line). Data are presented as means with standard deviations from two independent experiments. Significant differences between Newbould and NewbouldΔsigB for each concentration of HQNO are shown (*, P < 0.05; **, P < 0.01; two-way ANOVA with bonferroni's post test).