Isolation and molecular identification of Cry genes in Bacillus thuringiensis isolates from soil of West Mazandaran

Bacillus thuringiensis is a Gram-positive and endospore-forming bacterium. Soil is main habitat of this bacteria and it have capable of producing a wide variety of crystalline proteins with insecticide properties. The purpose of this study was isolation of Bacillus thuringiensis strains which carriers Cry gene through soil around the West Mazandaran province.Methods of research: 12 strains of Bacillus thuringiensis were isolated in minimal medium from 35 regions of west Mazandaran province, after soil screening by selective method of sodium acetate and L-Serine. After extracting DNA from all strains, confirming the strains including Cry genes as Bacillus thuringiensis, has been done through using 16S rDNA PCR Sequencing. Also relative molecular weight of crystal protein of the strain containing Cry gene were assessed by SDS-PAGE. Among 12 isolated strains, Cry gene in 1Aa class was recognized only just in one strain and through molecular method. Investigating rDNA sequence of isolated strain indicated a 99% homology with a Bacillus thuringiensis strain IBL 200(Accession No: ACNK01000211.1). Also, the approximate weight of it crystal protein was measured between 90-100 kDa. due to variety of crystal protein genes and lack of accurate phenotypic methods in detecting crystalline proteins, using semi-conserve PCR method identifies Bacillus species containing the crystal gene, through low cost and in quick form.