Isolation and Characterization of Escherichia coli bacteriophage 8 specific for E. coli strains belonging to sero-group O 8

SUMMARY: A bacteriophage which is specific for Escherichia coli O8 strains was isolated from Freiburg sewage. It is designated as Ω8. Inhibition studies suggested that the O8 specific lipopolysaccharide (isolated from E. coli O8) may be the phage receptor or part of it. Bacteriophage Ω8 also causes clearing on lawns of E. coli O93 if added at high multiplicity but it does not multiply in this strain. Escherichia coli strains O8 and O93 cross-react serologically and their (O antigenic) lipopolysaccharides have similar structures. Electron microscopy revealed the following features of Ω8: icosahedric head, 48 to 50 nm. in diameter; base plate consisting of 6 units, total diameter 14 nm.; 6 spikes, 12·0 to 14·5 nm. long and 3·5 to 4·0 nm. thick; 6 fibres, 168 nm. long, bent at 56 nm., 1·5 nm. thick. The propagation characteristics of Ω8 are: burst size, 130; latent period, 19 min.; eclipse period, 13 min.