Factors influencing the adsorption of bacteriophage 2 to cells of Pseudomonas aeruginosa.

Phage 2 adsorbed to Pseudomonas aeruginosa strain BI in 5 mM Tris buffer, providing that cations like Na(+), Mg(2+), or Ca(2+) were present. Adsorption was observed over a broad pH range, reaching a maximum level around pH 7.5, which coincided with the pH required for maximal activity of the phage 2-associated slime polysaccharide depolymerase. Mutants of strain BI and other strains of P. aeruginosa possessing slime layers that were devoid of phage 2 depolymerase substrate were incapable of adsorbing phage 2. On the other hand, those strains containing substrate for the phage 2 depolymerase in the slime layer were capable of adsorbing phage 2. The same relationship of phage depolymerase-substrate interaction to phage adsorption was observed with Pseudomonas phage 8, which possesses a depolymerase that differs in its specificity from the phage 2 depolymerase. The receptor-like activity of purified slime containing the specific substrate for the phage-associated depolymerase was demonstrable by its ability to inactivate phage. However, receptor-like activity or phage inactivation was not observed with those slimes that were devoid of the depolymerase substrate.