Taxonomic and phenotypic characterization of yeasts isolated from worldwide cold rock-associated habitats.

Yeast strains isolated from rock samples collected from worldwide cold regions were identified by sequence analysis of the D1/D2 domains of the 26S rDNA gene and the ITS region followed by molecular phylogeny. Over 77% of yeasts isolates were Basidiomycota. Cryptococcus (orders Filobasidiales and Tremellales) and Rhodotorula (order Cystobasidiales) were the most frequent genera. About 40% of yeast isolates belonged to undescribed species. Almost all isolates were psychrotolerant. Urease and esterase were the most widely extracellular enzymatic activity at 4 °C and 20 °C. None of the strains exhibited extracellular protease, DNAse, cellulase, chitinase, and laccase activity. The taxonomic and ecological significance of yeasts associated to worldwide cold rocky habitats is discussed.