[Transfer of the bacteriocinogenicity plasmid in mixed staphylococcal populations]

The capacity of the bactericinogenicity plasmid in S. epidermidis strain NI 17 to be transferred to nonbactericinogenic staphylococcal strains in mixed populations was studied. 3 out of 22 studied S. aureus strains and 3 out of 24 studied S. epidermidis strains were found to be capable of receiving the plasmid. No recombinants could be obtained with these recipients, which was seemingly due to the presence of the restriction and modification systems in plasmid DNA. The experiments, where the variants of S. epidermidis strain NI 17, having no plasmid, but resistant to antibiotics as the result of mutation, were used as recipients, revealed that the initial strain contained at least 2 plasmids, one of them controlling resistance to cadmium ions and the other responsible for the synthesis of bactericin.