Fig. 2.

Heat shock-induced ClpL increases penicillin resistance. Pneumococci were cultured in THY broth at 30°C until the OD₅₅₀ was 0.2 and then heat shocked at 42°C for 30 min. After heat shock, penicillin (Pen) was added to the culture at a final concentration of 0.2 μg/ml, followed by viable cell counting. The figure shows the standard deviation from five independent experiments. Statistical differences were analyzed by Student's t test. In some cases, standard deviations are smaller than the symbol.