Fig 1. RyhB is involved in gentamicin resistance during iron starvation.

A to D: strains were grown in LB (left panels) or in LB with DIP (250 μM) (right panels) for 3 h with or without the following antibiotics A: ampicillin (5 μg/mL); B: norfloxacin (25 ng / mL); C: tetracycline (5 μg/mL) and D: gentamicin (5 μg/mL). Colony forming units were counted to determine the number of surviving bacteria. Points were normalized relatively to t0 and plotted as log₁₀ of surviving bacteria. The absolute c.f.u. at time-point zero was ≈ 5.10⁷ c.f.u. / mL for each sample. Error bars represent the standard deviations of three independent experiments. Statistical analyses were performed with Student’s T-test: *p < 0.05; **p < 0.01; ***p < 0.001. E: WT (squares) and ryhB mutant (circles) strains were grown in LB (regular lines) or LB depleted for iron (dashed lines) with (red curves) or without (black curves) gentamicin. The number of c.f.u. was determined at different times. Error bars represent the standard deviations of three independent experiments. Statistical analyses were performed with Student’s T—test: *p < 0,05; N.S.: Not significant.