Study on genetic relationship between bacillus thuringiensis and bacillus cereus

Objective To study the genetic relationship between bacillus and bacillus cereus,and lay the foundation for identification and safety use of B.thuringiensis.Methods The genome DNA of 6 B.thuringiensis,3 B.cereus and other contrast strains was amplified by the enterobacteia repetitive intergenic consensus sequences-based PCR.DNA fingerprints were got and analyzed.Amplified fragments from B.thuringiensis were retrieved,cloned and marked as probes to hybridizate with tested DNA.Results DNA fingerprints were varied between B.thuringiensis and B.cereus.DNA fingerprints of B.thuringiensis were consistent comparatively and about a 250bp fragment could be amplified from all tested B.thuringiensis strains.DNA fingerprints of B.cereus varied from each other,but a 600bp fragment could be got both in B.thuringiensis and B.cereus strains.The hybridization result of 500bp fragment with the genome DNA of B.thuringiensis showed a great specificity.Conclusion Genetic relationship between B.thuringiensis and B.cereus can be obtained by enterobacteia repetitive intergenic consensus sequences-based PCR fingerprint,which can be used in the study on the genetic relationship of B.thuringiensis and B.cereus.B.thuringiensis can be identified according to 500bp amplified fragment.