Biodiversity of Yeasts in the Park "Sierras de San Javier", Tucumán, Argentina. Physiological and Molecular Characterization.

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

Salt Lake City

Encuentro; 102nd. General Meeting; 2002

American Society Microbiology

?Yungas Andinas? is the name of the mountain forests in northwest of Argentina and South of Bolivia. "Sierra de San Javier" Park belongs to the Tucumán National University and is located in this area, between 300 and 3000 meters of altitude in the west part of the city San Miguel de Tucumán. The present work is the first study reporting yeast diversity in this area. Yeasts are relatively easy to isolate from natural habitats, being necessary to weigh out a sample of the substrate, suspend it in sterile water, and spread a suitable dilution on either a nonselective medium (usually acidified malt extract agar to suppress bacterial growth) to obtain organisms of the total population or on a selective medium to obtain cultures of particular species. After the plates have been incubated and the colonies have developed, they are ready to study in order to identified them. Numerous samples of alive and dead parts of plants and different soil horizons as well as berries, roots and flowers were collected and transported in sterile plastic bags in order to isolate and identify yeasts in a first approach. A preliminary identification of isolated yeasts was made according to conventional techniques for studying its biochemical and physiological properties. These studies showed some limitations for identification of the new isolates, since there was not a 100% matching with reference strains profiles. The work was followed by using molecular genetic techniques based on amplification, restriction fragment length polymorphism analysis (RFLP) and sequence analysis of rDNA partial segments such as: intergenic transcribed spacer 1 (ITS1), rRNA 5.8S gene, and ITS2. Twenty isolated yeasts so far were differentiated by restriction fragment length polymorphism patterns of rDNA partial segments obtained by digestion of amplicons with the restriction enzymes HinfI, HaeIII and CfoI. Even though genetic molecular techniques do not replace physiological and biochemical tests, they do constitute a safe and reliable alternative for microbial identification. They have shown to be valuable tools to identify new isolations from nature.