BACTERIOPHAGES SPECIFICALLY RECOGNIZING THE LIPOPOLYSACCHARIDE ANTIGENS O4, O5, O6, AND O7 OF ESCHERICHIA-COLI

Four bacteriophages recognizing the Escherichia coli lipopolysaccharid e (LPS) antigens O4, O5, O6, and O7, respectively, were isolated from pooled sewage samples. Electron microscopic investigations revealed ic osahedral phage structures. Phages Phi O4, Phi O5, and Phi O7 belonged to Bradley's morphology group C, while Phi O6 had a tail and resemble s phages of group A of Bradley. The nucleic acid of the phages was ide ntified as double-stranded DNA of different genomic sizes. Host range studies showed that only E. coli strains with homologous O antigens we re attacked. No lysis of encapsulated and rough E. coli strains was ob served. The phages specifically depolymerized the homologous LPS of th eir host strains; they may be useful for detecting respective non-caps ulated E. coli strains in epidemiological studies as simple alternativ e to the laborious serological typing. Diagnostic application is restr icted, however, as strains carrying K antigens have not been detected. The high specificity of the phage-associated enzymes provides a mild method for the preparation of oligosaccharides from the LPS for struct ural studies.