cereulide and Hemolysis

Producers of cereulide, the emetic toxin of Bacillus cereus, are known to constitute a specific subset within this species. We investigated physiological and genetic properties of 24 strains of B. cereus including two high cereulide producers (600-1,800 ng cereulide mg(-1) wet weight biomass), seven average producers (180-600 ng cereulide mg(-1) wet weight biomass), four low cereulide producers (20-160 ng cereulide mg(-1) wet weight biomass) and 11 non-producers representing isolates from food, food poisoning, human gut and environment. The 13 cereulide producers possessed 16S rRNA gene sequences identical to each other and identical to that of B. anthracis strains Ames, Sterne from GenBank and strain NC 08234-02, but showed diversity in the adk gene (two sequence types), in ribopatterns obtained with EcoRI and PvuII (three types of patterns), in tyrosin decomposition, haemolysis and lecithin hydrolysis (two phenotypes). The cereulide-producing isolates from the human gut represented two ribopatterns of which one was novel to cereulide-producing B. cereus and two phenotypes. We conclude that the cereulide-producing B. cereus are genetically and biochemically more diverse than hitherto thought.

Topics: Adenylyl Cyclases; Bacillus anthracis; Bacillus cereus; Deoxyribonuclease EcoRI; Deoxyribonucleases, Type II Site-Specific; Depsipeptides; DNA, Bacterial; DNA, Ribosomal; Environmental Microbiology; Food Microbiology; Foodborne Diseases; Gastrointestinal Tract; Genetic Variation; Hemolysis; Molecular Sequence Data; Phosphatidylcholines; Ribotyping; RNA, Ribosomal, 16S; Sequence Analysis, DNA; Sequence Homology; Tyrosine

To study the correlation between emetic toxin and HEp-2 vacuole activity produced by Bacillus cereus isolated from an outbreak of vomiting-type food poisoning, some properties and emetic activities of both purified HEp-2 factor (cereulide) and partially purified factor to rhesus monkeys were determined. The results indicate that both cereulide and partially purified factor were very stable to digestion with proteolytic enzymes, different pH, and heating. Vomiting was induced in the rhesus monkeys orally administered with both substances. From these findings, cereulide (or HEp-2 vacuole factor) is strongly suggested to be an emetic toxin itself.

Topics: Administration, Oral; Animals; Bacillus cereus; Bacterial Toxins; Capillary Permeability; Cell Line; Depsipeptides; Emetics; Enterotoxins; Hemolysis; Hot Temperature; Hydrogen-Ion Concentration; Macaca mulatta; Mice; Pepsin A; Peptides, Cyclic; Trypsin; Vacuoles