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Isolation and Characterization of a Bacteriophage for the Identification of Corynebacterium michiganense. E. Echandi, Professor, Department of Plant Pathology, North Carolina State University, Raleigh 27607; M. Sun, Research Associate, Department of Plant Pathology, North Carolina State University, Raleigh 27607. Phytopathology 63:1398-1401. Accepted for publication 30 April 1973. DOI: 10.1094/Phyto-63-1398.

A bacteriophage designated CMP1, was isolated from overwintering tomato stems infected with Corynebacterium michiganense. CMP1 plaques are about 0.5- to 1.0-mm diam, clear, round, and entire, after 48 hr incubation. They are formed at 16, 20, and 24 C, but not at 28 C or above. CMP1 lysed virulent isolates of C. michiganense from western North Carolina and other parts of the country, but did not lyse species in Agrobacterium, Bacillus, Erwinia, Pseudomonas, Xanthomonas, and Corynebacterium other than C. michiganense. CMP1 was gradually inactivated at 45 C and inactivated in 10 min between 50 and 55 C. Antiserum neutralization of CMP1 required 20 min. About 82% of the phage particles were adsorbed to bacterial cells in 60 min. The latent period of CMP1 was 180 min, its rise period about 180 min and the average burst size 17 particles per cell. CMP1 has an hexagonal head about 68.3-nm wide and a thin tail about 244.9-nm long and 9-nm wide. This phage was found to be very useful for rapid diagnosis of C. michiganense.