EFFECT OF SUPPLEMENTAL L-TYROSINE ON PIGMENT PRODUCTION IN CULTURES OF LEGIONNAIRES DISEASE BACTERIUM

The etiologic agent of Legionnaires' disease grows on certain agar media. Cultures of this organism on supplemented Mueller-Hinton agar are characterized by the appearance of brown pigment in and around areas of bacterial growth. The major peptone source in Mueller-Hinton agar is an acid hydrolysate of casein. Legionnaires' disease bacterium also grows on a medium in which the peptone source is 0.25% yeast extract, but no pigment is produced. If the yeast extract agar is enriched with l-tyrosine, pigment formation can occur. Pigmentation of cultures of Legionnaires' disease bacterium may be mediated by a phenol o-monooxygenase, or tyrosinase. © 1978 Springer-Verlag New York Inc.