The adsorption of Pseudomonas aeruginosa pilus-dependent bacteriophages to a host mutant with nonretractile pili

Pseudomonas aeruginosa strain K is the host for two pilus-dependent bacteriophages (Pf, filamentous, and PO4, long noncontractile tail). This paper describes the isolation of a strain K mutant, which is resistant to both phages and yet bears many pili serologically similar to those of its parent. The efficiency of adsorption by the mutant was found to be close to that of strain K for each phage. The location of adsorbed P04 virions along the sides of the mutant's pili was consistent with the hypothesis that the pili were nonretractile. Pilus length measurements on strain K and the mutant showed no change in distribution before and after phage adsorption. This result is discussed in detail with reference to possible models for P04 penetration.