Synthesis of fluorochromes and pigments in Malassezia furfur by use of tryptophan as the single nitrogen source

A new minimal medium consisting only of L-tryptophan (L-trp) and a lipid so urce 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 deriv atives with a broad spectrum of colors were detected by means of mass spect roscopy 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 versicolo r metabolic adaptation of Malassezia yeasts to altered nitrogen conditions on superficial skin might be of pathophysiological importance. Tryptophan a s inductor of pigmentogenesis probably cumulates during excessive sweating, a well known manifestation factor of pityriasis versicolor.