Biodiversity and biotechnology of yeasts isolated from Patagonian freshwater environments

LIBKIND, DIEGO; BRIZZIO, SILVIA; MOLINÉ, MARTÍN; DE GARCÍA, VIRGINIA; RUSSO, GABRIEL; FONTENLA, SONIA; VAN BROOCK, MARÍA ROSA

Campinas-SP, Brazil

Workshop; Workshop Internacional sobre Microbiología Ambiental; 2005

Patagonia (Argentina) offers a great variety of glacially formed, ultra to oligothrophic, pristine water bodies which are in a microbiological point of view, scarcely known. Yeast occurrence in north-western Patagonia aquatic environs including high altitude lakes, sub-glacial ponds and volcanic hyper-acidic rivers and lakes was studied. Yeast isolates were identified and ocreened for their capability to: produce photoprotective compounds , (carotenoids and mycosporines), cold active extracellular enzymes and their ability to grow in acidic culture media, respectively. The identification of yeast isolates from 22 water bodies was performed by physiology, PCR fingerprinting and rDNA sequencing. Over 500 yeast strains were classified in 64 species and 19 genera including more than 14 novel species. Total carotenoid pigment synthesis by best producing strains reached 426 I-Ig/g and carotenoids identified were torularhodin, torulene and 8-carotene. UV light induced mycosporine production in yeast strains belonging to certain taxa. This photo-inducible metabolite with a maximum absorption in 310 nm was identified as mycosporine-glutaminol glucoside and some strains were found to accumulate up to 45 mg/g. Extracelullar enzymatic activity at 4°C was detected for amylase, protease, lipase, esterase and pectinase enzymes. Yeast strains with optimal growth pH near 3 were recovered and may be regarded as the first acidophilic yeast species. Patagonian natural unexplored habitats are a remarkable source of microbial biodiversity yet to be studied. Our investigations show that yeasts are common members of the patagonian freshwater microbial community and that many undescribed species may be found. These isolates are promising sources of metabolites with potential biotechnological applications.