The application of whole-cell protein electrophoresis for the classification and identification of basidiomycetous yeast species

The relationships among 65 basidiomycetous yeast strains were determined by one-dimensional electrophoresis of SDS-solubilized whole-cell proteins. Protein profiles were compared by the Pearson product moment correlation coefficient (r). The strains investigated represented species from the genera Cystofilobasidium, Filobasidium, Filobasidiella, Kondoa, Leucosporidium, Mrakia and Rhodosporidium. Except for the genus Mrakia, all species constituted separate protein electrophoretic clusters. The species of the genus Mrakia (M. frigida, M. gelida, M. nivalis and M. stokesii) show highly similar protein patterns, suggesting that these four species may be synonymous. Strains of two varieties of Filobasidiella neoformans, F. neoformans var. neoformans and F. neoformans var. bacillispora, could not be differentiated by protein electrophoresis. For the delineation of the protein electrophoretic clusters of the yeasts studied, literature data relying on other criteria, such as DNA base composition, carbon source utilization patterns, enzymatic protein electrophoregrams, ubiquinone systems, DNA-DNA homology and rRNA sequence data were used. It was demonstrated that a database of SDS-protein patterns provides a valuable tool for the identification of yeasts.