Expression of bacteriocin-like activity in batch cultures of Neisseria meningitidis and consequences for genetic recombination.

The bactericidal activity found in four strains of Neisseria meningitidis and the bacteriostatic effect observed in one were expressed in the exponential phase of batch cultures and continued during the stationary phase. The active material was stable for more than 50 hours in agar media. In mixed cultures a strain with inhibitory activity eradicated a sensitive strain, and dominated the culture in the latter part of the exponential phase. Recombination took place in mixed cultures when at least one of the strains had the genetic properties which determine competence in transformation. The presence of inhibitory activity increased the recombination frequency at least ten-fold. Genetic markers were introduced into a strain with inhibitory activity from sensitive strains of N. meningitidis and from N. cinerea.