FIG 3.

Heat tolerance of persister cells was a great deal higher than that of intact cells. (A) Scheme illustrating the setup for persister isolation and heat tolerance assay. (B) Isolated persister cells and normal (untreated) cells of WT and the ΔyafQ, ΔdinJ, and ΔtnaA mutants were adjusted to be approximately 10⁵ CFU/ml in fresh TSB and subjected to heat tolerance assay with the thermal cycler method (57°C for 5 min). The viable counts of normal cells after heat treatments were below the detection limit (10² CFU/ml); therefore, their viable counts after heat treatments were considered as 10² CFU/ml for the calculation of the cell survival rates here. Data points represent means of results from at least three independent experiments, and error bars indicate standard deviations. Significant differences between the data for normal and persister cells were analyzed by t test (*, P < 0.05).