[Synthesis of fluorochromes and pigments in Malassezia furfur by using tryptophan as the single source of nitrogen].

A new minimal medium consisting only of L-tryptophan (L-trp) and a lipid source induced formation of brown pigmentation only in the species Malassezia furfur. Strains of the species M. sympodialis and M. pachydermatis failed to grow on this medium. Pigmentogenesis was already induced in M. furfur by 0.01 g% tryptophan, the pH optimum was pH = 5. Alternative amino nitrogen sources given concurrently with trp suppressed pigmentogenesis. The extract of the culture exhibited remarkable fluorescence, and several indole derivatives with a broad spectrum of colors were detected by means of mass spectroscopy and NMR. This finding may have an impact on the clinical appearance of pityriasis versicolor, a very common skin disease caused by lipophilic yeasts of the genus Malassezia. We hypothesize that in pityriasis versicolor metabolic adaptation of Malassezia yeasts to altered nitrogen conditions on superficial skin might be of pathophysiological importance. Tryptophan as inductor of pigmentogenesis probably cumulates during excessive sweating, a well known manifestation factor of pityriasis versicolor.