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78 Bacillus from the Sichuan Ruoergai plateau of 37 soil samples were isolated using ERIC - PCR , 16S rDNA PCR - RFLP , 16S rRNA gene sequence analysis technique to study the genetic diversity of the test Bacillus initially identified phylogenetic and taxonomic status . Screened out three Bacillus thuringiensis , its Cry gene amplification and determination of the biological properties and toxicity , and the results are as follows : (1) ERIC-PCR technology to analyze the genetic diversity of 72 Bacillus the results show that the tested strains showed a rich zone type , have a greater genetic difference between the strains . Cluster analysis , the strains tested in the 81% similarity level of punishment for the eight genetic groups . ( 2) According to the ERIC-PCR analysis of results , select the 57 16S rDNA PCR - RFLP clustering analysis , the map in the level of 89% is divided into seven genetic groups , 16S rDNA PCR - RFLP pattern analysis and ERIC-PCR map The results are more consistent . Furthermore, on behalf of the strains 16SrDNA sequence 19 were determined to build a phylogenetic tree . The results showed that 19 distribution of representative strains of the genus Bacillus ( Bacillus ) , short Bacillus genus Brevibacillus , Paenibacillus spp ( Paneibacillus ) three phylogenetic branch , including Bacillus pumilus , Bacillus megaterium , Bacillus thuringiensis , Bacillus . (3 ) from the test Bacillus screened three Bacillus thuringiensis YB12 YB14 and YB19 , isolation rate was 3.85% , its Parasporal crystal diamond-shaped and spherical . 3 strains of Bt strains Cry gene amplification results show that the tested strains containing Cryl gene ; biological characteristics show that the tested Bt optimum growth temperature of 15-20 ° C , the optimum initial pH 7 and 8 ; virulence tests showed that the three bacteria silkworm insecticidal activity : 73.81% , 66.67% and 54.76% , higher insecticidal activity .
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