Identificación de bacterias resistentes al mercurio aisladas de la microcuenca del río Gala

Abstract

The purpose of the research was to separate the microorganisms of Gala River micro-basin located in Camilo Ponce Enriquez County, Azuay Province in order to evaluate the mercury resistance. It was necessary to take three samples in triplicate from three different points of the micro-basin, the ones which were geo-referenced with the use of a Garmin brand Global Positioning System (GPS): sample 1. Lat. -2.987172, long.-79.725952; sample 2. Lat. -2.979343, Long -79.725684; sample 3. Lat. -2969681, Long. -79.771900. Bacteria were inoculated by using the surface seeding technique in two different types of media: Medium without selection pressure with sterile distilled water (PCA-) and medium with selection pressure (PCA+) supplemented with mercury acetate 25 ug/mL; then, it was necessary to continue with the counting and isolation of representative microorganisms, 170 clones were selected, adapted and stabilized. Gram Staining was carried out, in which it was possible to evidence the predominance of Gram-negative bacilli in the Gal (Gala) point with a 56%, 74% in the Chi (Chico) point and 67% in the SR (San Rafael) point. These clones were put under mercury-resistance tests with increasing concentrations (25, 50, 100, 200, 500, 750, 1000, 1500) ug/mL, resulting in different resistance levels, 7 clones in the Gal point, 17 in the Chi point, and 9 in the SR point resulting a total 33 clones which presented a mercury acetate resistance of 1500 ug/mL. By means of the characterization and resistance tests carried out as well as bibliography, it was possible to determine that Pseudomonas is the predominant type in areas with high concentrations of heavy metals.