Superinfection inhibition by prophage B3 of some R plasmids inPseudomonas aeruginosa

Abstract

SUMMARYThe prophage of the phage B3 ofP. aeruginosaexhibits superinfection inhibition towards certain R plasmids such as R18-1 or R18-3 as shown by a severe depression (c. 10−6) in the conjugal transfer of these plasmids into B3 lysogens. The transfer of other R plasmids into such lysogens and the transfer of R18-1 or R18-3 into bacteria lysogenic for unrelated phages was unimpaired. R18-1 or R18-3 was non-transducible into B3 lysogens although transducible into non-lysogens. The interaction appeared to be reciprocally expressed since B3 lysogenization of bacteria R+for R18-1 or R18-3 was also reduced. Consistent with the failure of co-existence of the prophage and the plasmids was the observation that when the transconjugants from the cross R18-1 donor ×B3 lysogenic recipients were tested, transfer-deficient plasmid derivatives were encountered (about 40%). Other transconjugants were cured of prophage, or carried mutant B3 prophage with lytic, lysogenization or superinfection inhibition functions impaired.