Fig 4.

RelE-mediated appearance of persisters at high cell densities. Exponentially growing IKA121/pCA24N-relB was inoculated at an initial concentration of 10⁴ (open symbols) or 10⁷ (closed symbols) cells/ml and cultured in the absence (A) and presence (B) of 1% rhamnose in M9 medium containing 0.2% Casamino Acids and 25 μg/ml chloramphenicol to maintain plasmid. After 3 h of incubation, either ampicillin (squares), ofloxacin (diamonds), or kanamycin (circles) was added, and the culture was incubated for another 3 h and 6 h. The CFU were determined using LB agar containing 100 μM IPTG. The data represent the average results from triplicate experiments, and the error bars indicate the standard deviations. (C) Percentage of surviving cells after exposure to antibiotics for 6 h. The data points represent the average results from triplicate experiments, and the error bars indicate the standard deviations. Amp, ampicillin; Ofl, ofloxacin; Km, kanamycin.