Figure 1. Effect of L-methionine on the frequency of persisters at different temperatures.

The 16-h cultures of the strains WE (A, B) and JW0195 (C) grown in M9 glucose medium with or without L-methionine (50 µg/ml) at 37 or 42°C were diluted to an OD₆₀₀ of 0.1 in fresh M9 glucose medium supplemented with ampicillin (A, C) or ofloxacin (B) and incubated at 37°C for 10 hours. Samples were analyzed as described in the Materials and Methods.