Yeasts in Nonpolar Cold Habitats

The main terrestrial cold areas (outside Antarctica and the Arctic and subarctic regions, viz., the Earth strip running approximately between 60N and 60S) are those covered by glaciers and permafrost soil, primarily confined in the Himalayas, Andes, and European high mountains and only little portions in other parts of the globe. The study of microbial (prokaryotic and eukaryotic) biological diversity in nonpolar cold habitats represents a contribution to obtain a better defined picture of fungal diversity (including yeasts) inhabiting those ecosystems. The present chapter will provide an overview of both culturable and non-culturable yeast diversity found in nonpolar cold habitats. Yeasts found were identified as belonging to a number of ascomycetous and basidiomycetous species: among them, Basidiomycota dominated yeast diversity; in particular, species of the genera Cystofilobasidium, Dioszegia, Filobasidium, Holtermanniella, Leucosporidium, Mrakia, Naganishia, Rhodotorula, Saitozyma, Solicoccozyma, and Vishniacozyma were the most abundant. A number of new species were also found. Most of the yeast species are apparently ubiquitous in different geographical locations and exhibit some adaptation of their physiology and metabolism that increase cell protection against the damaging effects of low temperatures. Due to those physiological and metabolic adaptations, they could play an ecological role in nonpolar cold ecosystems, especially in relation to the in situ hydrolysis of complex organic macromolecules connected with the mineralization of organic matter.