BACTERIOCINS OF PHYTOPATHOGENIC CORYNEBACTERIUM SPECIES

The majority (85% of all strains tested) of 12 phytopathogenic Corynebacterium spp. produced bacteriocin(s) on nutrient broth-yeast extract (NBY) medium. All C. nebraskense, C. michiganense, C. insidiosum, C. oortii and C. iranicum strains produced bacteriocin(s). The optimal conditions for production of 23 distinct bacteriocins by 8 spp. of Corynebacterium generally were 20.degree. C and 4 days of incubation on NBY or on modified Burkholder''s agar that lacked peptone (MBAL). Production in liquid was marginal and not augmented by adding mitomycin C. Bacteriocins generally had little effect on other strains within a species but were inhibitory to other species. Most bacteriocins appeared to be bactericidal proteins resistant to heat (75-80.degree. C, 30 min) but sensitive to proteolytic enzymes. Some strains of C. nebraskense, C. michiganense, C. insidiosum and C. flaccumfaciens produced 2 bacteriocins which were clearly differentiated by varying or testing 1 or more of the following: conditions for production, the indicator, heat stability and susceptibility to proteolysis. Within certain limitations, a convenient and reproducible typing scheme was devised for strain and species differentiation of most phytopathogenic corynebacteria.