Some Characteristics of Virulent Bacteriophages Isolated from Pseudomonas solanacearum-Infested Soil

Virulent bacteriophages (phages) were isolated from a field soil infested with the host bacterium, Pseudomonas solanacearum (strain K-101) and examined for their physical and chemical properties. The phages were classified into two types on the basis of their plaque morphologies (small obscure or large clear plaques against the indicator bacterium K-101), and the phages were isolated and purified through a series of plaque isolation. An electron microsopic observation indicated that the phage isolate forming a small plaque had a polygonal head with three tails and the other a smaller head with two tails. The electrophoretic patterns of DNA fragments obtained by the digestion with some restriction endonucleases were completely different between these two types of isolated phages. The RFLP was detected among the small plaque-forming phage isolates, although there was no difference in morphology of phage particle and infectivity against some different strains of the host bacterium.