Comparison of biological characteristics between bacteriophage f_(2) and its broad host range phage

AIM: To investigate the difference of biological characteristics between a strain of E.coli bacteriophage with broad host range isolated from sewage and a wild standard strain (phage f 2). METHODS: The host range, bacteriolysis titer and antigenicity were detected, the plaque morphology and their ultrastructural characteristics were identified, and serological neutralization test, serological cross neutralization test as well as one step growth experiment were performed. RESULTS: The strain of E.coli bacteriophage with broad host range could lysis 4 strains of Escherichia coli belonging to the same genus but to different species. The plaque morphology of the phage with broad host range changed in accordance with its different host bacteria. The ultrastructure under electron microscope showed that the broad host range phage was different, to some extent, in size and shape from the wild standard strain. Their antiserum K values were also different and serological cross neutralization test showed that there was little correlation between them. One step growth experiment showed that it had a shorter latent period and higher lysis efficiency than the wild standard strain. CONCLUISON: The biological characteristics of broad host range phage may be significantly different from those of its wild standard strain. Therefore, it can be classified into a new serotype.