Bacteriophage of Pseudomonas aeruginosa with unfamiliar head morphology.

P. aeruginosa (Kitasato strain) was used as host. Forty-three strains of P. aeruginosa from the culture collection of the Department of Bacteriology, School of Medicine, Kyushu University were used for determination of the lytic spectrum of the phage. A phage of P. aeruginosa with rod-shaped head was designated as K. The host cells were cultivated in nutrient broth with aeration for 3 hr. At this time the phage suspension was added to the culture and incubation with aeration was continued for an additional 3 hr. The lysate contained approximately 108 to 1010 phage particles per ml. Plaque counting and one step growth experiments were carried out according to Adams (1950). Antiphage serum was prepared in rabbits by injecting phage filtrates at 3 to 4-day intervals for 2 months. For electron microscopy, the phage suspension was placed on a collodion membrane overlying a copper mesh screen and was shadowed with chromium. The specimens were examined using a JENM-5 electron microscope.