FIG. 5.

sHsps are necessary for improvement of survival at 70°C. Cells of strain χ3306 (wild type) and mutants CS2458 (ΔagsA), CS2042 (ΔibpAB), and CS2565 (ΔagsA and ΔibpAB) were grown to mid-exponential growth at 30°C. The same numbers of wild-type and shsp mutant cells were mixed and then sifted at 70°C for 1 min. The numbers of viable shsp mutant cells were determined by using a drug resistance marker (Km for ΔagsA; Cm for ΔibpAB). Survival ratios were calculated as described in Materials and Methods. Each value is the average from two different experiments.