Bacillus cereus: Food Safety Risk and Toxin Gene qPCR Detection

1. Cellular Morphology
B. cereus appears as straight or slightly curved rods (1.0–1.2 μm × 3.0–5.0 μm), with flat ends.

It forms oval endospores located centrally or subterminally, which are highly resistant to environmental stress.

The bacterium is motile due to peritrichous flagella and lacks a capsule.

2. Colony Characteristics
On nutrient agar at 30–37°C for 24 hours, colonies are round, smooth, white, and slightly glossy, typically 5–7 mm in diameter.

On MYP agar, colonies appear pink to orange with a surrounding opaque precipitation zone due to lecithinase activity, aiding preliminary identification.

3. Growth Conditions
Optimal growth occurs at 30–37°C, with a growth range of 10–45°C.

The organism tolerates up to 7% NaCl and demonstrates strong resistance to heat, desiccation, and UV exposure.

While vegetative cells are killed at 100°C for 20 minutes, spores survive and require sterilization at 121°C (autoclaving) for complete inactivation.

Food poisoning caused by B. cereus is primarily mediated by toxin production.

1. Hemolysin BL (Hbl)
Encoded by the hblC gene, associated with diarrheal syndrome.

2. Cereulide Toxin
Encoded by the cesB gene, responsible for emetic (vomiting-type) food poisoning.

3. Enterotoxin T
Encoded by the bcET gene, contributes to gastrointestinal symptoms.

Detection of these toxin genes is critical for risk assessment and food safety monitoring.

Ensure contaminated food is heated to ≥100°C for at least 20 minutes to eliminate vegetative cells.

Avoid prolonged storage at room temperature (20–40°C), which promotes spore germination and toxin production.

Cooked food should be cooled to <4°C within 2 hours and stored under refrigeration.

Reheat food thoroughly to a core temperature ≥70°C before consumption.

Maintain strict hygiene in food processing environments, including regular equipment disinfection and proper handwashing practices.