Yeasts from high altitude lakes: influence of UV radiation

LIBKIND, DIEGO; MOLINÉ, M; SAMPAIO, JP; VAN BROOCK, M.

FEMS MICROBIOLOGY ECOLOGY

FEMS

Año: 2009 vol. 69 p. 353 - 362

0168-6496

Mountain lakes located at high elevation are typically exposed to high UV radiation (UVR). Little is known about the ecology and diversity of yeasts inhabiting these extreme environments. We studied yeast occurrence (with special emphasis to those producing carotenoid pigments) at 5 high altitude (> 1400 m.a.s.l.) water bodies located in the Nahuel Huapi National Park (Bariloche, Argentina). Isolates were identified using a polyphasic approach. Production of photo-protective compounds (carotenoids and mycosporines) by yeast isolates, and UV-B resistance of selected species were studied. All water samples contained viable yeast cells in variable numbers, generally ranging from 49 to 209 cells l-1. A total of 24 yeast species was found; at least four represented novel species. Carotenogenic yeasts prevailed in lakes with low water conductivity and higher transparency and chlorophyll a levels. Apparently, the ability to produce photoprotective compounds in yeasts was related to the transparency of mountain lake waters, and strains from more transparent waters developed increased UV-B resistance. Our results indicate that UVR is an important environmental factor affecting yeast community structure in aquatic habitats.