Comparative Studies on Generalized Transducing Bacteriophages of Proteus mirabilis, φm and π1

抄録

Comparative studies were made on the generalized transducing bacteriophages of Proteus mirabilis φm (Nakaya and Rownd), π1 (Bohme), and a clear plaque-forming mutant φm-c, derived from φm. Electron microscopic observations revealed that these phages were morphologically identical, indicating that they belonged to the group C of Bradley's classification, or to the type Cl of Ackermann's classification. Phages φm and π1 formed characteristic turbid plaques different from each other, and the plaques of π1 were smaller in size than those of φm. The plaques of phage φm-c were clear and also were the largest in size among those studied. Average latent periods of φm and π1 were 70 and 60 min, respectively. Average burst size was found to be 30 and 10 plaque-forming units per infected cell for φm and π1, respectively. It was confirmed by cross neutralization tests that φm and π1 differed serologically from each other. The host range of the two phages also differed, and phage φm was more sensitive to heat than π1. These results indicate that phages φm and π1 are different types of phages. Majority of the properties of phage φm-c were nearly identical with those of phage φm except that the multiplication of φm-c was more strongly inhibited by methylene blue than that of φm and π1. Phage φm-c is considered to be a clear mutant of φm.