Abstract
Two kinds of bacteriophage which attack Corynebacterium michiganense were isolated. The one named MiP1 was obtained from infected tomato stem, while the other, MiP1h, a host range mutant, was obtained from MiP1 culture. Seven out of 16 isolates of C. michiganense were resistant to MiP1, while, all of the isolates were susceptible to MiP1h. Neither MiP1 nor MiP1h phage was found to attack any other species of phytopathogenic bacteria used in this experiment.
For plaque formation, these phages require certain limited conditions concerning both the concentration of bacterial suspension to be used as the indicator and incubation temperature of the seeded plates. To ensure plaque counting, 2.7×107 to 4.4×108 cells per ml concentration of the bacterial suspension is required, and the plates must be incubated under a temperature from 21 to 23°C.
Both MiP1 and MiP1h phages has a head of 70mμ in diameter, with a tail of 160mμ in length and 20mμ in width. They are serologically closely related.
Both the phages are inactivated gradually over 45°C, and completely inactivated at 55°C, in 10min, in water.
One-step growth experiments at 22°C gave the latent period of the phages to be 240min. The average burst size appears to be somewhat different according to the phage strains: MiP1 phage produced more progenies than MiP1h.
