Carotenogenic yeasts in northwestern Patagonia (Argentina) aquatic environments

LIBKIND FRATI, D; BRIZZIO, S; RUFFINI, A; GADANHO, M; VAN BROOCK, MR; SAMPAIO, JP

Faro, Portugal

Jornada; X Jornadas de Biología de Leveduras, “Prof. Nicolau van Uden”; 2002

Carotenoid producing yeasts or red yeasts, have both biotechnological and an emerging medical importance due to their ability to produce large amounts of commercially important pigments (b-carotene, torulene and torularhodine) or to their association with secondary infections of immunocompromised patients. Red yeasts have been scarcely studied in freshwater habitats, although they might comprise more than 50% of the recorded population. Low to non-polluted aquatic environments in Patagonia (Argentina) are mainly represented by ultra-oligothrophic lakes of glacial origin, small high elevation lakes and small lakes surrounded by dense forest. Here we present a yeast survey of eight different aquatic reservoirs. Water samples were collected from water subsurface using sterile bottles and filtrated for colony counting and yeast isolation. Unlike most yeast biodiversity studies, an accurate characterisation of 64 isolates was obtained, based on the mini/micro satellite-primed PCR (MSP-PCR) technique. 6 distinct groups were obtained using the (GTG)5 primer in MSP-PCR experiments (56% of total isolates) and primers M13 and (GAC)5 allowed a more detailed grouping in a selected number of cases. For species identification, representative fingerprints from each group were compared with the patterns of the various type strains. In some cases, sequence analysis of the 26S rDNA (D1/D2 domain) was performed. Rhodotorula mucilaginosa was found in almost all samples and represented more than 50% of total number of isolates. Less frequent yeast species were: Rhodosporidium kratochvilovae, R. babjevae, Sporidiobolus salmonicolor, Sporobolomyces ruberrimus, Sp. roseus, Cystofilobasidium capitatum, C. infirmo-miniatum, Rhodotorula slooffiae, and Rh. laryngis. Six isolates representing non described yeast species of the genera: Rhodotorula (2), Cryptococcus (1) and Sporobolomyces (2) were also found. Total viable pigmented and non pigmented yeasts and filamentous fungi rendered very low values of colony forming units (0-150 CFU l-1) when compared to data published for other aquatic locations. In our study, the highest counts were found in areas exposed to anthropic influence. This study represents the first preliminary report on the biodiversity and distribution of pigmented yeasts occurring in different aquatic environments of North-western Patagonia.