Differentiation of Candida stellatoidea from C. albicans and C. tropicalis by temperature-dependent growth responses on defined media.

C. stellatoidea differs from both C. albicans and C. tropicalis in its i) much greater growth differential on minimal and amino acid enriched media and ii) unique inability to grow on minimal medium containing glycerol as carbon source at 37C. The relative responses to amino acid enrichment occur on media containing either fermentative or oxidative carbon sources, at 25C or 37C. Under any given conditions of carbon source and temperature, different assortments of individual amino acids are stimulatory for each of the three species. All assortments include one or more members of the glutamic acid family. However, sulfur amino acids stimulate only C. stellatoidea on all three carbon sources. On minimal-glycerol medium, wild type strains of C. stellatoidea grow prototrophically at 25C but are auxotrophic for amino acids at 37C; the particular auxotrophies expressed vary from strain to strain. Slow growing, mycelial mutants, prototrophic on glycerol at 37C arise spontaneously in wild type strains at frequencies indicating nuclear gene mutation. Such mutants can be induced by both transition and frame shift mutagens. The implications of these observations for the taxonomic relationships between the three Candida species and for identification of C. stellatoidea in particular are discussed.