Determinación de la biodiversidad y distribución geográfica de levaduras asociadas a frutos de mora de castilla (Rubus glaucus) de tres localidades de la provincia de Tungurahua

Abstract

Ecuador reports a few information about yeast biodiversity, most of the microbiological research are focused to bacteria. Fruits in their natural environment represent important habitats for yeasts. The target of this research was the determination of the diversity of yeasts as sociated to blackberry fruits from Salasaca, Cevallos and Tisaleo, where organic blackberries are cultivated. The sector with greater diversity was Tisaleo where 6 species were isolated, followed by Salasaca where 4 species were isolated and finally Cevallos, where only 2 species were isolated. A traditional characterization of the isolates was made, it consisted in macroscopic characterization where optical characteristic of colonies were evaluated such as: margin, elevation, surface, brightness, texture and color. A microscopic characterization in which was showed the morfology and the size of yeast cells. A physiologycal characterization with 8different carbon sources (dextrose, xylose, maltose, galactose, lactose, sucrose, cellobiose and soluble starch), assimilation and fermentations characteristics were evaluated for each of the yeast isolates. However, those techniques were not enough to achieve the identification of the isolates to the taxonomic level of genre or specie, the study of each isolated strain was complemented by the use of molecular techniques based on the restriction analysis of the gen rDNA 5.85S and the internal transcripted spacers (ITS1 and ITS2), getting 9 restriction profiles. The resultant profiles were compared with the ones from the data base of the Quito Católica Yeast Collection CLQCA (Acronym in Spanish). 5 profiles were identified by this technique as Meyerozyma guilliermondii, Hanseniaspora meyeri, Whickerhamomyces onychis,Galactomyces geotrichum and Pichia manshurica. The remaining yeasts were not identified bythis technique because they did not match similar band patterns with the ones from the CLQCA database. The taxonomic status of these cultures was determined by 26S rDNA sequencing giving as result: three isolates of Clavispora lusitaneae, two isolates of Metschnikowia pulcherrima one corresponding to Candida sorbosivorans and two corresponding to Pichia membranifaciens. The data obtained in this research demonstrate the great diversity of yeast associated to blackberry fruits, providing basic knowledge to find potential biotechnological applications.