Aislamiento e identificación de levaduras a partir de efluentes de curtiembres tungurahuenses y caracterización en función a la Tolerancia a cromo (Cr) VI.

Abstract

Tungurahua is an Ecuadorian province, which is considered one of the most important in terms of leather production and which owns on its territory 80% of the tanneries of the country. Tanneries represent a significant environmental problem due to the contamination they generate. These industries use Cr salts in the tanning process, which in turns generate effluents with high content of this material and once these get in contact with the environment, toxic effects are generated in the biota. This report evaluates the potential of native yeasts to tolerate Cr (VI). In order to achieve this, the yeasts of two tanneries effluents were isolated: a traditional and an industrialized one. There were established 1-9 test points depending on each case, starting from the reception phase until obtaining the final product, isolating in the process twenty five yeast strains. In terms of methodology, great emphasis was laid upon the molecular tools in order to identify the genera and specie of the isolated yeasts, which lead to identify eleven different species. The phylogenetic analysis classified them in three categories and in two families (Basidiomycota and Ascomycota). In order to determine stress tolerance to Cr (VI), triplicate assays were developed by using the drop plate method in presence of the metal. This allowed to observe that Candida parapsilosis, Candida zeylanoides, Rhodosporidium diobovatum, Candida humilis, Trichosporon otae y Zygowilliopsis califórnica were strains showed growth in the presence of Cr ( VI ), which in turn are suggested as a clean and autochthonous alternative to be used in the bioremediation processes for this kind of contamination.