Cold Temperature Growth of Clinical and Food Isolates of Bacillus cereus .

A collection of 27 Bacillus cereus food and clinical isolates were screened for the ability to grow at cold temperatures. Growth was examined using fluid or solid nutrient media or milk incubated at 10, 7, or 5°C. Fourteen isolates were capable of visible colony formation on brain heart infusion (BHI) agar by day 7 at 10°C; two isolates formed visible colonies by day 10 at 7°C on Trypticase soy agar. Nineteen of the isolates could grow in BHI at 7°C if previously adapted to 7°C over a five-week period. Both food and clinical isolates demonstrated a cold adaptation response. This should be considered when modeling B. cereus growth in foods or in assessing shelf life or safety relative to B. cereus .