Pigment formation for differentiating Cryptococcus neoformans from Candida albicans

When 2,3- or 3,4-dihydroxybenzoic acid, 3,4-dihydroxyphenylalanine, and 3,4-dihydroxycinnamic acid are added to growth media, they are converted to a characteristic brown pigment by Cryptococcus neoformans. This pigment formation has hitherto been encountered only when this microorganism was cultivated on media containing Guizotia abyssinica seed. This phenomenon can be used for differentiating Cryptococcus neoformans from Candida albicans. Possible precursors of these o-diphenols (quinic acid, aromatic monohydroxy acids, or tyrosine) do not give rise to the brown pigmentation.