Characterization of two Salmonella newport bacteriophages

Abstract

Salmonella newport phages 16–19 and 7–11 have very long heads and are members of two rare and so far little-known phage groups. Both produce various morphological aberrations. Preparations of phage 7–11 contain numerous polyheads and about 0.4% short heads belonging to nine size classes. In addition, one giant phage particle was observed. The head of phage 7–11 seems to be an icosahedron which became elongated by adding successive rows of subunits. Phages 16–19 and 7–11 have buoyant densities in CsCl of 1.43 and 1.48 g/mL and particle weights of 103 and 204 × 106 respectively. Both viruses contain double-stranded DNA, internal proteins, and sugars. Phage 16–19 contains 46.5% DNA of 35 × 106 molecular weight, and glucose. Phage 7–11 contains 47.5% DNA of 108 × 106 molecular weight, and mannose. Base compositions of phage and S. newport DNAs were determined from buoyant densities, melting point, and acid hydrolysis. Phage 16–19 contains 5.4% 5-methylcytosine.