Stability of spores of Bacillus cereus stored on silicagel.

Spores of four different strains of Bacillus cereus were stored on silicagel at 22 degrees C and in physiological saline solution at -20 degrees C for a period of 260 days. At different intervals the spores were tested for survival, heat sensitivity and capacity to germinate. There was no clear change in any of the parameters tested, so storage on silicagel can be a good alternative for storage as a frozen suspension. Spores stored in this way can easily be exchanged for reference material and used for microbiological challenge testing.