Pigmentation and autofluorescence of Cryptococcus species after growth on tryptophan and anthranilic acid media

Abstract

Cryptococcus neoformans and Candida albicans produced a pink pigment from media containing tryptophan. Approximately 30% of the C. neoformans strains produced large amounts of the pink (purple after 6 days) pigment in the absence of light whereas 70% of the Cryptococcus neoformans strains, as well as C. laurentii, C. albidus, C. diffluens, and C. albicans also produced the pink pigment with light being required for significant early production (2--6 days). Significant production did occur for Cryptococcus but not Candida species in the dark after extended incubation (10--25 days). C. terreus produced brown pigments from tryptophan and C. luteolus produced a trace of a buff pigment. Most Candida species produced either pink or brown pigments but not both. In contrast, many Cryptococcus species producing the pink pigment simultaneously produced brown pigments. C. terreus, C. albidus, and C. diffluens produced brown pigments from anthranilic acid whereas C. neoformans, C. laurentii, C. luteolus, and the medically important Candida species did not produce significant amounts of pigments from anthranilic acid. Cryptococcus and Candida species were autofluorescent when tryptophan was a major nitrogen source whereas yeast cell autofluorescence was not observed when anthranilic acid.