HETEROGENERIC CONJUGAL TRANSFER OF THE PHEROMONE-RESPONSIVE PLASMID PIP964 (INCHLYI) OF ENTEROCOCCUS-FAECALIS IN THE APPARENT ABSENCE OF PHEROMONE INDUCTION

Erythromycin-resistant derivatives of the pheromone-responsive plasmid pIP964 from Enterococcus faecalis were constructed to study its host range. This was done by inserting the integrative vector pAT112 and th e related replicon pTCR1 harboring oriR of the broad host range plasmi d pAM beta 1 into the hemolysin-bacteriocin operon of pIP964, to give pTCR2 and pTCR3, respectively. Plasmid pTCR2 was transferred by filter matings from E. faecalis to Enterococcus faecium and Listeria monocyl ogenes at frequencies of 2x10(-7) and 5x10(-7) per donor, respectively , in the apparent absence of pheromone induction and cellular aggregat ion. In these hosts, pTCR2 remained intact as a self-replicating eleme nt and maintained its transfer capabilities. Plasmid pTCR3, but not pT CR2, was transferred at similar frequencies from E. faecalis to Lactoc occus lactis and Streptococcus agalactiae. Thus, the transfer system o f pIP964 possesses a broader host-range than its replication system.