Effect of pheromone induction on transfer of the Enterococcus faecalis plasmid pCF10 in intestinal mucus ex vivo

The effect of synthetic sex pheromone on pheromone-inducible conjugation be tween the isogenic Enterococcus faecalis strains OG1RF and OG1SS was invest igated in (i) Todd-Hewitt broth medium and (ii) intestinal mucus isolated f rom germ-free rats. In broth, the presence of synthetic pheromone cCF10 had no detectable effect on the transfer kinetics observed for the tetracyclin e resistance encoding plasmid pCF10. In MUCUS, presence of the same pheromo ne significantly increased the transfer efficiency observed during the firs t 2 h of conjugation, while the effect was less pronounced later in the exp eriment. We suggest that due to differences in diffusion rates and medium-b inding of the pheromones, the effect of the synthetic cCF10 was immediately dominated by the effect of pheromones produced by the recipient E. faecali s strain in broth, while this happened later in mucus. (C) 2001 Federation of European Microbiological Societies. Published by Elsevier Science B.V. A ll rights reserved.