FIG. 2.

Assay for adsorption of phage 20422-1 on phage-susceptible and phage-resistant L. monocytogenes strains. Open and filled symbols indicate phage-susceptible and -resistant strains, respectively. Phage-susceptible strains 1845 (serotype 1/2a; open triangles) and 27 (serotype 1/2b; open squares) and phage-resistant strains 513 (serotype 1/2a; closed circles) and 597 (serotype 1/2b; closed triangles) were infected with phage 20422-1 propagated in L. monocytogenes DP-L862. L. monocytogenes F2365 (serotype 4b; open circles) was used as the reference strain. Phage titer (PFU/ml) in the supernatant was determined at the indicated times as described in Materials and Methods.