Green and brown colour effects in tremellaceous yeast fungi on Staib agar

Fifty-eight species of basidiomycetous yeast fungi were examined for green and brown colour effects (GCE, BCE) on Staib agar (Guizotia abyssinica crea tinine agar). In addition to 9% of Cryptococcus laurentii strains tested, o nly Cryptococcus podzolicus was GCE-positive. Out of 14 strains of this spe cies, 13 showed a GCE and four showed a BCE. All GCE-positive strains utili zed creatinine and creatine as a source of nitrogen but not of carbon. None of these strains could grow at 37 degrees C. Unlike Cr. laurentii, no stra ins of Cr. podzolicus assimilated glycine as a source of carbon. No associa tion was found to exist between GCE and killer activity. Some tremellaceous creatinine-negative species (Cryptococcus gastricus) showed a BCE whereas some sporidiobolaceous creatinine-positive yeasts (Leucosporidium, Rhodotor ula) produced neither GCE nor BCE.