[Distribution, homology and cloning of cryptic Bacillus thuringiensis plasmids].

The 69-6 strain of Bacillus thuringiensis subsp. galleriae harbours at least 7 cryptic plasmids (pBTG1 - pBTG7) with molecular lengths 8,4 to 15,7 kb. According to hybridization analysis, the plasmid pBTG2 (8,7 kb) and other plasmids of the same host strain as well as cryptic plasmids of the strains belonging to 10 other serotypes of Bac. thuringiensis share detectable homology. As shown by the data of heteroduplex analysis, about 60% of pBTG1 and pBTG2 genomes have homologous DNA sequences. These data point out tht some plasmid genes are conserved in Bac. thuringiensis. BasmHI-, EcoRI- and HindIII-generated fragments of Bac. thuringiensis subsp. galleriae strain 69-6 are cloned on the pBR325 vehicle in the cells of Escherichia coli.