The rate of decline is also dependent on the intrinsic properties
of the pathogens. Vegetative B. cereus counts gradually decline with
storage time, whereas those of spores do not (probably due to the
spore’s higher resistance to stressful environments) (Andersson,
Rönner, & Granum, 1995). Among the vegetative bacteria used in
the present study, B. cereus showed the best survival rates under
different conditions. The initial population of B. cereus (3e4 log CFU/ml) inoculated into sterilized Korean turbid rice wine
declined rapidly (to 1.53e1.71 log CFU/ml) after 1 day; however,
these counts were maintained for up to 28 days. This suggests that
B. cereus formed spores during storage at both 5 C and 22 C, which
enabled the bacteria to survive. Indeed, spores were observed in
turbid rice wine inoculated with vegetative cells of B. cereus using
optical microscopy (data not shown).