Behavior of Vegetative Cells and Spores of Bacillus Cereus in Two Food Systems.

The survival and growth of vegetative cells and spores of toxigenic Bacillus cereus
CFR 1534 was investigated in a dehydrated (dry mix) blend of flour (roasted
finger millet and Bengal gram) and chocolate milk. In the case of dry mix, there
was a marginal initial increase of 2 logs in 2 days of storage at 20 and 30C, respectively.
In chocolate milk, there was an increase of 1 log with certain inoculum
levels introduced and storage temperatures. The survival pattern of vegetative
cells/spores was primarily influenced by the initial numbers and, to a slight extent,
by the water activity of food matrices. Although stored samples were negative for
toxigenic trait of phosphatidylinositol phospholipase C in polymerase chain reaction,
associated lecithinase activity was detected in plate assay. Response surface
plots for vegetative cells and spores of B. cereus CFR 1534 did indicate the potential
risk associated with post-processing contamination of B. cereus.
PRACTICAL APPLICATIONS
The ability of vegetative cells and spores of a toxigenic culture of Bacillus cereus to
survive and grow in two food matrices was studied. Often, the bacterial species
tend to remain in the product and increase in their numbers in a slow paced
manner. The product with no visual changes, but harbors viable population of
toxigenic Bacillus cereus can be of serious public health concern. The understanding
of product profile would be of help in assessing the probable risk factors that
could be associated with opportunistic foodborne pathogen like B. cereus in the
food chain establishment.