16S rDNA and ERIC(Enterobacteia Repetitive Intergenic Consensus Sequences) based on PCR method were tested for the effectiveness of the differentiation of B.thuringiensis and B.cereus.16S rDNA-PCR primers were designed based on the sequence difference in variable regions of B.cereus 16S rDNA and B.thuringiensis 16S rDNA.16S rDNA-PCR showed no obvious difference between B.cereus and B.thuringiensis.The only difference was that one 1600-bp amplificon could be obtained from all the three B.Cereus strains,and none amplificon from any B.thuringiensis strains.ERIC was optimized based on previous reports.The genomic DNA was used for the template of ERIC-PCR,and the following DNA fingerprints were analyzed by the agarose gel electrophoresis.The results showed that DNA fingerprint of three B.thuringiensis strains had a unique amplicon less than 100-bp,while DNA fingerprint of three B.cereus strains had none.Moreover,DNA fingerprint of B.cereus showed a 700-bp amplicon,but didn't have any DNA fingerprints of B.thuringiensis genome.Therefore,ERIC-PCR technique should be able to be used for the differentiation of B.thuringiensis and B.cereus.
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