Aislamiento y caracterización de la microbiota nativa de muestras de efluentes de curtiembres.

Abstract

The objective was to isolate and characterize native bacterial microbiota that could present resistance to heavy metals, from the effluents of Quisapincha tannery company, Tungurahua province. Samples of wastewater from the company were collected and used for the isolation of bacteria using PCA agar with and without the addition of two types of selective pressure: potassium dichromate at 25 ppm (medium A) and the effluent of the process diluted in water distilled 1:10 (medium B). A total of 66 bacterial clones were isolated, which were subjected to chrome, lead and mercury resistance tests at different concentrations and temperatures (10, 20 and 35 C). As a result, variable levels of resistance were found for the isolated clones, of which, 3 showed resistance to 700 ppm of mercury, 5 to 2000 ppm of lead and one clone to 900 ppm of chromium; all were able to grow at the three temperatures evaluated, presenting slight growth variants for them. The biochemical analysis allowed identifying the resistant clones as microorganisms of the genera Micrococcus (11%), Enterobacter (11%), Moraxella (33%), Citrobacter (22%), Staphylococcus (11%) and Kurthia (11%.). It is concluded that extreme bacteria tolerant to heavy metals, were isolated from contaminated effluents, reason why the microorganisms analyzed have characteristics of adaptation to hostile environments. It is recommended to continue with the investigation of efficient bacteria in order to deepen the knowledge about the interaction of microorganism-metal and apply them in biotechnological treatments of environments contaminated with heavy metals.