FIG. 7.

Effect of heat activation at various temperatures on germination of B. subtilis (A) and B. megaterium (B) spores. Spores of B. subtilis PS533 (wild type) and B. megaterium were either not heat activated (○) or heat activated for 30 min at 60°C (•), 70°C (▵), 75°C (▴), or 80°C (□) and germinated with l-valine (B. subtilis) or for 15 min at 60°C (•), 65°C (▵), or 70°C (▴) and germinated with d-glucose (B. megaterium). Germination was followed, and the extents of germination were determined, as described in Materials and Methods. The percentages of germinated spores at the end of the various germinations were 40% (○), 50% (•), 70% (▵), 85% (▴), and 60% (□) (A) and 60% (○), 95% (•), 85% (▵), and 65% (▴) (B).