Taxonomic Significance of Base Composition of Yeast Dna

The base composition of DNA (GC content) from 62 strains of yeasts and yeast-like fungi was studied. They are widely distributed from 26 to 64%. Most species of Saccharomycetaceae exhibited low GC content of 26-42.5%, but Lipomyces starkeyi and Naganishia globosus showed rather high values of 45.5% and 47.5%, respectively. In Cryptococcaceae, the GC content ranged from 30 to 64%. Yeasts belonging to Cryptococcus and Rhodotorulaexhibited high GC content of 46-56% and 47.5-64%, respectively. In the genera of Torulopsis, Candida and Trichosporon, GC contents were widely distributed, namely, 34.5-52.5% in Torulopsis, 30-60% in Candida, and 32.5-59% in Trichosporon. Brettanomyces bruxellensis and Kloeckera apiculata exhibited low GC content of 35% and 30%, respectively. Trigonopsis variabilis showed rather a high value of 44%. Sporobolomyces salmonicolor, a ballistosporous yeast, exhibited a high GC content (57%). Of the yeast-like fungi, Tremella fuciformis and Aureobasidium pullulans showed high GC content of 54.5% and 51.5%, respectively. Meanwhile, Dipodascus albidus and Geotrichum candidum exhibited low GC content of 33% and 40.5%, respectively.A phylogenetic relationship between the yeasts exhibiting a high GC content and Heterobasidiomycetes was discussed. A taxonomic significance of urease activity was found to be correlated to the GC content.