J. Dufrenne et al., CHARACTERISTICS OF BACILLUS-CEREUS RELATED TO SAFE FOOD-PRODUCTION, International journal of food microbiology, 23(1), 1994, pp. 99-109
Thirty Bacillus cereus strains, isolated from different sources, were
characterized in relation to safe food production. The minimal growth
temperatures of the strains varied from less-than-or-equal-to 5-degree
s-C to 11-degrees-C. Generation times at 7-degrees-C of strains capabl
e of growing at temperatures less-than-or-equal-to 5-degrees-C were ap
proximately 8.2 h. The D90-degrees-C-values of spores of strains with
a minimal growth temperature of 11-degrees-C determined in phosphate b
uffer at pH 7.0 ranged from 4.8 to > 200 min. Strains with the capacit
y to grow at temperatures less-than-or-equal-to 9-degrees-C, had a D90
-degrees-C value ranging from 4.6 to 14 min. Addition of either nisin
(250 mug/ml) or diacetyl (1500 mug/ml) to the heating menstruem at the
single concentrations investigated seemed not to influence the therma
l destruction of spores. Germination of spores of almost all strains o
ccurred in all three media tested (Brain Heart Infusion, rice extract
and milk) even at temperatures below the minimal growth temperature. A
ll B. cereus strains tested yielded positive results with a commercial
test kit for diarrhoeal enterotoxin. The results indicate that strain
s with the capacity to grow at temperatures less-than-or-equal-to 7-de
grees-C are not essentially different from those with minimal growth t
emperatures of > 10-degrees-C.