Pathogenicity of Tyrosinase-Deficient Mutants of Streptomyces Scabies

Natural and X-ray induced mutations rendered strains of Streptomyces scabies simultaneously tyrosinase-deficient and unable to form a "brown-ring" in skim milk. These results and the presence of the tyrosinase reaction in each of 80 brown-ring positive streptomycetes tested were considered to indicate the identity of the brown-ring test and the tyrosinase reaction. All 12 tyrosinase-deficient mutants tested were virulent for Katahdin potatoes in controlled greenhouse tests.