[Recombinant plasmids carrying yersinia pestis fra-operon: specific features of genetic transmission, inheritance and expression in attenuated enterobacterial cells].

The study was undertaken to study the specific features of transformation of E. coli strains having different R-chemotypes, Y. pestis, S. minnesota R595, and S. typhi Ty21a by plasmids carrying Yersinia pestis Fra-operon which controls the formation of a plague microbe capsular F1 antigen in this microorganism. Calcium transformation was shown to be rather effective for the plasmids constructed on the basis of a cosmid vector (pFS1), rather than those designed by using the Y. pestis plasmid pPst I (pFSK3, pP3). The level of plasmid stability varied and failed to correlate with taxonomy fitting and the chemotype of a recipient strain. The cells of all recombinant strains produced F1 antigen, secreted it into the environment; the synthesis was temperature-regulated. F1 was identified both in the diffuse precipitation and serological tests. The levels of F1 antigen synthesis decreased whereas nutritious requirements for the maintenance of protein synthesis increased for bacterial strains with higher levels of LPS reduction.