9/21/2016 Plasmid-mediated toxins Bacillus cereus B.cereus has 3 toxins Most strains are unable to grow below B.anthracis has 1 toxin 10C B.thuringiensis has 1 insecticide Some are motile by peritrichous Plasmid-mediated toxin production flagella creates an unstable classification Plasmid may be lost or mobilized to another species con时ugation: 心p →安 one Environmental Source Environmental Source ·Widespread in nature Easily spread from environment to foods Associated with decaying matter Problematic in dairy products Isolated from soil and plants spores present in the soil 105/g spread to the cow udder then to the raw milk In soil spores are hydrophobic and spores germinate upon attach to pipelines and solid favorable conditions surfaces in the dairy converge to filamentous spores survive pasteurization multicellular forms that swarm psychrotrophic strains can grow at in a coordinated direction refrigeration 9/21/2016 3 • Plasmid-mediated toxins - B. cereus has 3 toxins - B. anthracis has 1 toxin - B. thuringiensis has 1 insecticide • Plasmid-mediated toxin production creates an unstable classification • Plasmid may be lost or mobilized to another species Bacillus cereus • Most strains are unable to grow below 10 oC • Some are motile by peritrichous flagella Environmental Source • Widespread in nature • Associated with decaying matter • Isolated from soil and plants In soil - spores germinate upon favorable conditions - converge to filamentous multicellular forms that swarm in a coordinated direction Environmental Source • Easily spread from environment to foods • Problematic in dairy products - spores present in the soil 105 / g - spread to the cow udder - then to the raw milk - spores are hydrophobic and attach to pipelines and solid surfaces in the dairy - spores survive pasteurization - psychrotrophic strains can grow at refrigeration