[Behavior of heterologous recombinant plasmid pCET in cells of Bacillus anthracis].

Recombinant plasmid pCET was constructed in vivo in cells of enteric and hay bacillus, on the basis of plasmids pC194, and pBC16. Plasmid pCET inherits marker genes of antibiotic resistance from parental plasmids. Anthrax cells were transformed by the recombinant plasmid developed. The behavior of this plasmid was studied in vegetative Bacillus anthracis cells, which did not pass through the sporulation stage and were cultivated at temperatures permissive for the replicon of plasmid pE194. Under these conditions, plasmid pCET was shown to replicate autonomously, regardless of the host chromosome, and to retain its structure, irrespective of the recipient strain. In this case, the phenotype of transformants fully corresponded to the genotype of plasmids inherited. Elevation of the cultivation temperature of strains Bac, anthracis (pCET) up to 44 degrees C led to the elimination of plasmid pCET from cells of anthrax microbe under conditions nonselective for plasmid pCET and its integration with the host chromosome under selective conditions. The frequency of plasmid pCET integration into the chromosome was approximately 10(-1) for all Bac. anthracis strains studied. In population of vegetative cells of strains Bac. anthracis (pCET), which passed through the sporulation stage under selective for plasmid pCET conditions, DNA of plasmid pCET was detected only in the state integrated with the chromosome. Irrespective of the reasons leading to the integration of plasmid pCET into the Bac. anthracis chromosome, all strains inheriting this DNA within their own genome lost the resistance to tetracycline observed in strains with the extrachromosomal plasmid location. Genome amplification of plasmid pCET in the chromosome of Bac. anthracis was detected.