Behavior of Vegetative Cells and Spores of Bacillus cereus in Two Food Systems

Abstract

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.

Safety aspects of stingless bee pot-pollen from the Philippines

“…Though some of the identified Bacillus spp. were reported to be human pathogens (Ehling-Schulz et al, 2019;Celandroni et al, 2016;Desai and Varadaraj, 2013), their counts were low and can therefore be considered to be at a safe level. Bacteria of the B. pumilus clade were not identified up to the species level using the MALDI-TOF MS analysis and partial 16S rDNA sequencing.…”

Survival of a native toxigenic isolate of Listeria monocytogenes CFR 1302 during storage of milk-based foods can be a potential cause of health risk

“…Considering the public health significance of foodborne pathogenic bacterial species and the hazards that could be associated with their survival during storage of food products, in an earlier study by the authors (Desai and Varadaraj, 2013), it was reported that survival pattern of vegetative cells/spores of Bacillus cereus in two selected food products was primarily influenced by initial number of contamination and to a certain extent by the water activity of food matrices. In the present study, the focus was on a more serious pathogen, L. monocytogenes in milk-based foods, wherein the study included two very popular and more commonly consumed products, namely (i) ice cream and (ii) mango pulp-based lactic fermented milk.…”