A large transmissible plasmid is required for crystal toxin production in Bacillus thuringiensis variety israelensis

摘要: Bacillus thuringiensis var. israelensis (BTI), serotype 14, which produces parasporal crystals toxic to certain dipteran larvae, was analyzed by agarose gel electrophoresis and found contain a complex plasmid array. Eight plasmids were detected, with approximate sizes of 3.3, 4.2, 4.9, 10.6, 68, 75, 105, 135 MDa, as well plasmidlike linear DNA element approximately 10 MDa. Partially cured mutants BTI implicated the 75-MDa in crystal production. Fifteen independently isolated acrystalliferous (Cry-) lack this plasmid. In transfer experiments, several transferred into plasmid-free, Cry- recipient, but only converted recipient toxin The presence or absence mosquito-toxic activity all Cry+ variants confirmed bioassay sporulated cultures against larvae Aedes aegypti. Southern blot analyses revealed that one unusual variant no band detectable, sequences still present, possibly integrated chromosome. could also apparently recombine 68-MDa plasmid, it partially homologous.