FIG. 1.

Intracellular DnaK concentration (A) and surviving-cell counts (B) of E. coli ATCC 25922 cells exposed to heat treatment of various intensities (F₇₀¹⁰). The concentrations per cell were calculated with the number of cells present before the treatment. (A) Horizontal line indicates the DnaK level found in cells during exponential growth (OD₆₀₀ = 0.5) at 37°C (38,500 molecules/cell). (B) Horizontal line indicates the cell count detection limit. The experiment was repeated three times. Bars represent the mean plus or minus standard deviation. For a specific process lethality value, results with a similar lowercase letter are not significantly different. Capital letters are used for a specific temperature, i.e., AB for 50°C and XYZ for 55°C. Results below the detection level are indicated by an asterisk.