title: Growth and pigment production on D-tryptophan medium by Cryptococcus gattii, Cryptococcus neoformans, and Candida albicans.
abstract: Given the increasing prevalence of cryptococcosis caused by Cryptococcus gattii (serotypes B and C) strains, there is a need for rapid and reliable tests that discriminate C. gattii from Cryptococcus neoformans (serotypes A, D, and AD). Seventy-two C. neoformans strains, sixty-seven C. gattii strains, and five Candida albicans strains were analyzed for their ability to grow and produce pigment on minimal D-tryptophan D-proline (m-DTDP) medium, on yeast carbon base D-tryptophan D-proline (YCB-DTDP) medium, and on fructose D-tryptophan glycine (m-FDTG) medium. Of the C. gattii and C. neoformans isolates, 94% and 0% grew on m-DTDP agar, respectively, and 98% and 0% grew in YCB-DTDP medium, respectively. C. gattii produced large amounts of brown intracellular pigment(s) on m-DTDP agar and smaller amounts of yellow-brown (amber) extracellular pigment(s). C. albicans grew on both media and produced a pink photoactivated pigment on m-DTDP agar. C. gattii produced large amounts of brown intracellular pigments on the differential medium m-FDTG, whereas C. neoformans produced smaller amounts of the brown pigments and C. albicans produced a pink pigment. The pigments produced by C. gattii from D-tryptophan were distinct and were not related to melanin formation from 3,4-dihydroxyphenylalanine. Thin-layer chromatography of the methanol-extracted C. gattii cells detected four different pigments, including brown (two types), yellow, and pink-purple compounds. We conclude that tryptophan-derived pigments are not melanins and that growth on m-DTDP or YCB-DTDP agar can be used to rapidly differentiate C. gattii from C. neoformans.
authors.affiliation: Department of Biology, Farmingdale State College, 2350 Broadhollow Road, Farmingdale, NY 11735, USA. chaskesj@farmingdale.edu
authors.forename: Stuart
authors.initials: S
authors.lastname: Chaskes
authors.forename: Susana
authors.initials: S
authors.lastname: Frases
authors.forename: Michael
authors.initials: M
authors.lastname: Cammer
authors.forename: Gary
authors.initials: G
authors.lastname: Gerfen
authors.forename: Arturo
authors.initials: A
authors.lastname: Casadevall
mesh_terms: D002176:Candida albicans / Q000254:growth & development* / Q000378:metabolism*; D002855:Chromatography, Thin Layer; D003454:Cryptococcus / Q000737:chemistry / Q000254:growth & development* / Q000378:metabolism*; D003470:Culture Media / Q000737:chemistry*; D006801:Humans; D008027:Light; D016533:Mycological Typing Techniques; D010860:Pigments, Biological / Q000378:metabolism*; D011392:Proline / Q000378:metabolism; D014364:Tryptophan / Q000378:metabolism
chemical_list: D003470:Culture Media; D010860:Pigments, Biological; D014364:Tryptophan; D011392:Proline