Partial Characterization of Coliphage WPK and a Comparison with Coliphage T3

Abstract

Coliphage WPK was originally isolated from sewage in Kiel, Germany, because its plaque diameter continued to expand for days. Electron microscopy revealed an isometric capsid with dimensions of 54 nm between opposite apices, and a short, noncontractile tail 16 nm long, placing phage WPK into morphogroup C1. The nucleic acid of phage WPK was linear double stranded DNA. The host ranges of phages WPK and T3 were identical. Of ten E. coli strains tested for host range, two were resistant and of eighteen other Enterobacteriaceae only four were susceptible. Seven gram‐negative species which are not members of the Enterobacteriaceae were refractory. However, there were differences in plaque morphology and plaque expansion between the two phages. Phage T3 plaques expanded for at least seven days on E. coli B only, while phage WPK plaques expanded for at least seven days on four strains of E. coli. The buoyant density of WPK, determined by isopycnic density gradient centrifugation in CsCl, was 1.508 g/ml which was significantly different than that of T3 at 1.493 g/ml (P<0.05). Phage‐encoded proteins were examined for each phage using [35S]methionine incorporation, SDS‐PAGE, and autoradiography. Of thirty proteins identified in phage WPK and twenty‐eight in' phage T3, only fourteen were of the same size in both. We concluded that phage WPK was distinct, but related to T3. © owned by Center for Academic Publications Japan (Publisher)