Fig 1.

Comparative analysis of the oxidative stress resistances of wild-type (WT) strain 168 and its isogenic sigB mutant strain ML6. The upper graphs indicate the growth curves, and the lower graphs indicate the survival rates. Both strains were cultivated in synthetic medium, and growth was monitored by measuring the OD₅₀₀. At an OD₅₀₀ of 0.4 (t of −20 min), the cells were treated with 2% ethanol (EtOH) (as indicated), followed by a preadaptation period of 20 min. After preadaptation (t₀), the cells were stressed with 100 mM paraquat (A) or 5 mM H₂O₂ (B) (as indicated). Survival rates were determined by plating appropriate dilutions of control samples taken before oxidative stress treatment at t₀ and after 60, 120, 180, and 240 min for the paraquat-stressed cells and after 30, 60, and 90 min for the H₂O₂-stressed cells. The values are arithmetic means and standard errors of the means.