ASCOMYCETOUS YEASTS ASSOCIATED WITH PHOEBE POPHYRIA AT THE PARK "SIERRA DE SAN JAVIER", TUCUMÁN, ARGENTINA. PHYSIOLOGICAL AND MOLECULAR CHARACTERIZATION

HIPÓLITO F. PAJOT; MARÍA ALEJANDRA MARTINEZ; SIÑERIZ, F.; LUCÍA I.C. DE FIGUEROA

Basel

Congreso; 11th European Congress on Biotechnology; 2003

Swiss Coordination Committee for Biotechnology

The ecology of yeasts is valuable specially for its practical importance and as fundamental basis of their evolution. New species of yeasts are formed due to selection pressures exerted by the environment. “Yungas Andinas” is a mountain forests area of northwest Argentina and south Bolivia. "Sierra de San Javier" nature reserve is located in this area and it belongs to Universidad Nacional de Tucumán. The aim of this study was to isolate thermo-tolerant yeasts from pods and exudates of Phoebe porphyria from Yungas Andinas, and to assess their phylogeny position. Samples were collected and carried into sterile plastic bags at room temperature. One or two grams were grounded and re-suspended in sterile water, serial dilutions were spread onto acidified malt extract plates; pH was adjusted to 3.7 in order to suppress bacterial growth. Plates were incubated at 37ºC and after 3 or 5 days, isolated colonies were re-stroked on yeast extract peptone-glucose agar. 17 different thermo-tolerant colonies were isolated. A preliminary identification of the isolates was carried out according to conventional procedures. On the other hand, sequencing of the 26S ribosomal DNA D1/D2 domain and ITS1-5.8S-ITS2 conserved regions as well as RFLP of ITS1-5.8S-ITS2 region were performed with phylogenetic purposes. By using these methodologies as the main basis of taxonomic determination 5 different groups were identified. The sequence data coupled with the Diazonium Blue B test, showing that all the species belong to ascomycetous yeasts. The highest identities were obtained with Hanseniaspora opuntiae, Kodamaea ohmerii (two different isolates), Candida haemulonii and Pichia rabaulensis. However, it is important to take into account that some of the isolated strains showed several physiological or molecular differences when they are compared with the reference strains. The results here reported, demonstrates the utility of using poly-phasic approaches in order to identify new isolates from natural environments.