THE “TYROSINASE REACTION” OF THE ACTINOMYCETES

Abstract

Nearly 200 strains of Actinomyces were isolated from soil and planted on various media. A dark brown to black color was produced in 4 days or less in beef peptone agar, gelatin and water, Conn''s Na asparaginate agar + 0.1% tyrosine, and Conn''s agar + 1% casein or edestin, by 80 strains. All of these media contain tyrosine. The rest of the cultures did not produce this color in any of these media. None of the cultures produced the characteristic pigment in 4 days in Conn''s agar, Czapek''s agar, or Conn''s agar 0.1% tryptophane, phenylalanine, cystine, alanine, or glycine. These media are tyrosine free. A few cultures in a longer time produced, in tyrosine-free media, brownish pigments which were distinguished from the pigments mentioned above by solubilities in various liquids. Some strains which formed no dark pigment on any medium produced a red pigment which often turned dark on prolonged incubation, from media to which tyrosine, or phenylalanine was added. Work of others on the metabolism of actinomycetes is discussed.[long dash]The pigment production of the so-called "chromo-genus" actinomycetes is evidently an instance of the "tyrosinase reaction.".