Final answer:
Bacillus cereus is the species causing food poisoning from rice by producing enterotoxins when food is improperly stored at room temperature.
Step-by-step explanation:
The Bacillus species known for causing food poisoning, particularly from rice, is Bacillus cereus. This gram-positive, endospore-forming bacterium is commonly found in soil and can survive cooking processes due to its endospores. It is particularly notorious for causing illnesses when rice or other foods are left out at room temperature, allowing the bacteria to produce enterotoxins.
These toxins can either induce vomiting or diarrhea and symptoms typically appear within a few hours post-ingestion. Severe cases, while less common, can involve more grave symptoms. Unlike its relative Bacillus anthracis, which causes anthrax and requires the presence of two plasmids to be virulent, B. cereus can induce food poisoning without such specific genetic elements. On a TSA plate, B. cereus can be identified by its oval, central endospores contrasted against other species like B. subtilis.
Prevention of B. cereus food poisoning involves proper food handling, such as promptly refrigerating prepared foods and reheating them thoroughly before consumption. Notably, cooked rice should not be left at room temperature for prolonged periods to prevent the growth of B. cereus.