Aislamiento y caracterización de bacterias resistentes a metales pesados obtenidas de ambientes contaminados con derivados de hidrocarburos en la ciudad de Riobamba.

Abstract

The main purpose of this research was to isolate and characterize bacteria which are resistant to heavy metals, and coming from environments contaminated with hydrocarbon derivates in Riobamba city, and that can be considered as potential bio-remediating agents of environments contaminated with metals, mercury (Hg), Cadmium (Cd), Chromium (Cr) and lead (Pb). In order to carry out this process, bacteria were isolated from wastewater samples of the grease traps of the Riobamba Municipality workshops, and from the grease trap of the fuel station of the Polytechnic High School of Chimborazo by using 2 culture media: The first one, high in nutrients (TSA), and the another one minimum in nutrients (M9). These two media were used with and without the addition of a selective pressure, which was lead acetate at 25 ppm (parts per million). A total of 65 clones were isolated, 35 coming from TSA medium and 30 coming from minimal medium. Once isolated, purified and characterized macroscopically and microscopically, these clones were subjected to increasing concentrations of heavy metals, which showed that 3 clones were grew up to the concentration of 500 ppm, 5 clones in cadmium at 1500 ppm, 4 clones in chromium at 4000 ppm, and 5 clones in lead at 4500 ppm, these clones grew in TSA medium. In the other hand, in M9 medium; 1 clone in chromium at 800 ppm and 2 clones in lead at 4000 ppm. Biochemical tests identified a total of 12 clones, which showed resistance to heavy metals: Proteus vulgaris, Klebsiella ozaenae, Pseudomonas, Neisseria and Klebsiella oxytoca. It is concluded that in our environment it is possible to find bacteria resistant to heavy metals, which foster to the study of these bacteria as potential agents for bioremediation so that it is recommended to conduct researches in this area involving the bacteria found.