INIBIOMA   20415
INSTITUTO DE INVESTIGACIONES EN BIODIVERSIDAD Y MEDIOAMBIENTE
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Psychrotolerant yeasts from glacial environments of Patagonia, Argentina: biodiversity and extracellular enzyme production
Autor/es:
DE GARCÍA VIRGINIA; BRIZZIO SILVIA; VAN BROOCK MARÍA
Lugar:
Ljubljana
Reunión:
Congreso; 4th International Conference on Polar and Alpine Microbiology; 2011
Institución organizadora:
Ljubjana University, FEMS
Resumen:
Extremely cold environments (i.e. ice, snow, and sea
ice) are frequently colonized by extremophilic microorganisms known as psychrotolerant
and psychrophiles. They can use complex biopolymers as energy sources, synthesizing extracellular
enzymes active at low temperatures. Psychrophilic yeasts play an essential role
in nutrient cycling and biomass production processes in cold ecosystems. These
microorganisms have been isolated from cold environments in the entire world. Patagonian
Andes in Southwestern Argentina offer interesting and unexplored glacial
environments, such as Mount Tronador (Nahuel Huapi National Park) and Patagonian
icefields (Los Glaciares, National Park). The latter are the largest temperate
ice masses in the Southern Hemisphere accounting for more than 60% of the
Southern Hemispheres glacial area outside Antarctica. First studies on the
occurrence of cold-adapted yeasts in glacial environments in Patagonia are from
melt-water rivers of Mount Tronador. Occurrence of yeasts in ice from Frías
glacier (Mount Tronador) and Perito Moreno glacial (Patagonian icefields) has
been studied for the first time and are reported here. Ice samples were melted
aseptically at room temperature and then filtered; filters incubated at 10 ºC
in MYP agar for up to 1 month. Total of 115 strains were isolated, characterized
and identified by biochemical and molecular techniques. Isolates were tested for
their capability to produce extracellular enzymes (amylase, esterase, protease,
protease, pectatelyase, pectinase, cellulose) at 5 and 20 °C. Basidiomicetous
yeasts represented 90 % of the isolates, 16 genera and 33 species were identified,
21 % represent possible new species, 2 have been formally described (Cryptococcus spencermartinsiae sp. nov. and
Wickerhamomyces patagonicus sp. nov.). Psychrophilic yeasts accounted for
25 % of all isolates, while the rest 75 % were psychrotolerant; 85 % of all
isolated showed at least one enzymatic activity. Statistic analysis of multiple
correspondences and cluster classification allows finding a relationship among
isolated genera and enzymatic activities. Sporobolomyces
isolates produced amilases, Leucosporidiella and Udeniomyces produced proteases, cellulase, pectinase and
esterase, Cryptococcus cellulase, Dioszegia esterase, Mrakia
protease, esterase and pectinase at 5 °C, and
genera Rhodotorula and ascomycetous
yeasts did not showed any relation with enzymatic production. Results presented here showed all isolated
yeasts are adapted to cold environments and are able to hydrolyze natural compounds at low
temperatures. The above data suggest a significant ecological role, as organic
matter decomposers and nutrient cyclers; yeasts occurring in these extreme cold
habitats could be used for metabolic and ecological studies, and application in
biotechnological process at low temperatures.