FIG. 3.

Effects of exoA and nfo mutations on the dry-heat resistance of (A) wild-type and (B) α⁻β⁻ spores. Spores of wild-type and α⁻β⁻ strains were lyophilized, the dry spores were heated for various times at (A) 120°C or (B) 90°C, and their viability was determined as described in Materials and Methods. ▪, PS832 (wild type); ▴, PERM452 (exoA); •, PERM453 (nfo); ⧫, PERM454 (exoA nfo); □, PS356 (α⁻β⁻); ▵, PERM448 (α⁻β⁻ exoA); ○, PERM449 (α⁻β⁻ nfo); ⋄, PERM450 (α⁻β⁻ exoA nfo). The error bars are the standard deviations as described in Materials and Methods.