Effect of the IncP-2 plasmids pMG1 and pMG2 on the pyocins of Pseudomonas aeruginosa.

Pyocin typing may be unstable under certain circumstances. In the early seventies, it was shown that the IncP-2 plasmids pMG1 and pMG2 interfered with the pyocin type of some Pseudomonas aeruginosa strains. Up to now, details of the influence of these plasmids on the pyocins are unknown. In this study, the effect of these plasmids on the R, F, and S pyocins, respectively, was examined. In distinct strains, S pyocin activity was detected in the presence of these plasmids, whereas R and F pyocin activities could not be observed. So the effect of the IncP-2 plasmids pMG1 and pMG2 may be limited to the R and/or F pyocins.