Medycyna Wet. 65 (1), 15-19, 2009
Berthold A., Doroszkiewicz B.
Characteristics of Bacillus cereus emetic toxin
Cereulide, an emetic toxin produced by specific Bacillus cereus strains, is neither able to degrade starch, nor can it ferment salicin, and shows weak haemolysis. It is a cyclic low-molecular (1.2 kDa) ring-shaped peptide. Cereulide is resistant to heat (121oC/90 minutes), digestive enzymes, trypsin and pepsin. Pathological symptoms evoked by cereulide are nausea and vomiting, which may occur 1 to 5 hours after the ingestion of a contaminated food product and continue for about 24 hours. Cereulide causes changes in hepatic cell mitochondria (vacuolation) that consequently lead to liver damage. The toxic dose for an adult is 400-500 µg of cereulide. Since it is a very widespread species in the environment, there is a high risk of Bacillus cereus-mediated food poisoning. The main cause of this type of food poisoning are products containing boiled or fried rice and foods rich in starch, such as pasta. Since the condition has a short duration, cases of emetic type food poisoning provoked by cereulide are frequently not even reported to the health service authorities and are therefore highly underestimated in official statistics. The presence of L-leucine, or L-valine aminoacids in a product markedly intensifies the process of the emetic toxin production by Bacillus cereus. Cereulide synthesis is also positively affected by the presence of oxygen. The optimal temperature for cereulide formation ranges from 15 to 20oC, whereas its production at 8-10oC or at a temperature exceeding 35oC is minimal.
Keywords – cereulide, emetic toxin, food products, Bacillus cereus.