Phage adsorption assay.

Phage adsorption was performed as described elsewhere (21, 22). Briefly, PAO1 cells were grown on LB agar plates at 37°C for 16 h, and the cells (10⁸ CFU) were resuspended in 500 μl of LB broth. The purified phages (3 × 10⁷ PFU) were added and allowed to adsorb to the bacterial cells at 37°C for 5 min. The phage-cell complex was pelleted at 500 × g, 4°C, for 10 min to remove the adsorbed phages, and the PFU of the recovered supernatant containing unbound phages was enumerated by plaque assay.