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Feb 10, 2026 - Foods
Recognizing and Accurately Assessing the Risks of Bacillus cereus in Food
What is presumptive Bacillus cereus?
The term "presumptive Bacillus cereus" describes a group of closely related Bacillus strains that can cause diseases in humans and animals. Not all representatives of this group are health-relevant—the risk largely depends on their toxin production capacity.
Typical characteristics of Bacillus cereus
- rod-shaped, gram-positive bacteria
- spore-forming with high environmental resistance
- catalase-positive, oxidase-negative
- ability to produce various toxins
- partially heat- and acid-resistant toxins
Occurrence and significance in food
Bacillus cereus and its spores naturally occur in soil, dust, water, as well as in animals and humans. The germ is particularly often detected in plant-based foods, but also in milk and dairy products.
Typical affected foods
- cooked rice and cooked pasta
- vegetables, sauces, and soups
- desserts like pudding or semolina
- spices, herbs, and dried mushrooms
- dairy products
Plant-based foods, especially starchy products, are significantly more common causes of gastrointestinal diseases than animal-based foods.
Toxin production as a central health risk
Certain strains of the presumptive Bacillus cereus group can produce various toxins that lead to foodborne illnesses. Two different clinical pictures are distinguished.
Emetic disease: Cereulide
The emetic emetic toxin Cereulide is acid- and very heat-stable. It is already formed in the food and can withstand normal heating steps. After oral intake, symptoms such as nausea and severe vomiting usually occur within 0.5 to 6 hours.
Diarrheal illness: Enterotoxins
The diarrheal enterotoxins (Hbl, Nhe, CytK) are heat-sensitive and are only formed after bacteria intake in the intestine. The incubation period is generally 8 to 16 hours, and the symptoms are mainly diarrhea.
Why microbiological examinations alone are often not enough
The Cereulide toxin is not perceptible by sensory means and remains in the food even after heating. Therefore, a product may appear microbiologically inconspicuous, although health-relevant amounts of toxin are already present.
For a sound risk assessment, it is therefore crucial to consider germ detection, genetic potential, and actual toxin production together.
Growth conditions and toxin production
Bacillus cereus prefers to multiply under favorable environmental conditions:
Optimal conditions
- Temperature: optimal 30–40 °C, cold-tolerant strains also grow at 4 °C
- pH-value: usually between 5.5 and 8.0
- Water activity: ≥ 0.92
- Oxygen: facultatively anaerobic, preferably aerobic
Toxin production is highly strain-specific and usually occurs under optimal growth conditions.
Inactivation through heating – limitations of thermal processes
Vegetative cells of Bacillus cereus are killed at a core temperature of at least 72 °C for 2 minutes. However, the spores are extremely heat-stable and survive even cooking processes.
The heat-stable Cereulide toxin is only inactivated at very high temperatures (e.g., ≥ 121 °C for extended periods)—conditions that are rarely achieved in food production practice.
Holistic analysis at the BAV Institute
For a reliable assessment of Bacillus cereus risks, the BAV Institute offers a comprehensive investigation portfolio:
Investigation possibilities
- Microbiological detection of presumptive Bacillus cereus
using ISO procedures or accredited rapid methods (result within 24 hours) - RT-PCR examinations
for the detection of toxin-producing genes - Immunological detection
of Bacillus cereus enterotoxins - Analytical detection of Cereulide toxin
using highly sensitive LC-MS/MS analytics
This combination enables a differentiated, preventive risk assessment and supports companies in minimizing recall and liability risks.
Consultation and contact
The BAV Institute ensures a fast, reliable, and technically sound processing of your samples.
We are happy to advise you individually on suitable investigation strategies.
Contact:
Dirk Lorenz
State-certified food chemist
Key Account Manager
📞 +49 (0)781 / 969 47-23
✉️ Dirk.Lorenz@bav-institut.de