Caracterización e identificación de microorganismos con resistencia a compuestos mercuriales

Abstract

RESUMEN: Los hidrocarburos recalcitrantes y metales pesados son considerados contaminantes de importancia por su impacto social y ambiental. Entre los segundos se encuentra el mercurio (Hg), siendo las actividades antropogénicas su principal fuente emisora. Los compuestos mercuriales son neurotóxicos y carcinogénicos y están presentes en 21 estados de la República Mexicana. A nivel nacional se liberan anualmente a la atmósfera alrededor de 30 toneladas que no reciben ningún tratamiento, siendo su efecto en el ambiente prácticamente desconocido. Algunos procesos biotecnológicos pueden ofrecer soluciones integrales a la contaminación de sitios por compuestos mercuriales de modo tal que se proteja tanto la salud humana como el medio ambiente. En el presente proyecto se llevó a cabo la caracterización macroscópica, microscópica, bioquímica, cinética y molecular de microorganismos aislados de sitios industriales contaminados con gasolina que fueron expuestos a cloruro de mercurio y cloruro de metil-mercurio, con el fin de identificar su potencial aplicación para futuros procesos de biorremediación. Se lograron caracterizar e identificar macroscópica, bioquímica, cinética y molecularmente cinco microorganismos resistentes a altas concentraciones de cloruro de metil-mercurio [10 ppm] y cloruro de mercurio [20-400 ppm]. Los resultados muestran que estos organismos pertenecen al taxa gamma-proteobacteria y firmicutes y estos se consideran como organismos potenciales para procesos de biorremediación de sitios industriales contaminados con compuestos mercuriales debido a las concentraciones mínimas inhibitorias que exhibieron y debido a su capacidad para formar biopelículas microbianas bajo las condiciones de estudio.

ABSTRACT: Recalcitrant compounds such as polycyclic aromatic hydrocarbons (PAH) and heavy metals are considered substances of high importance in both social and environmental affairs. Among the later, mercury (Hg) is one of the most studied heavy metals and its principal source of contamination is due to anthropogenic activities. Mercury compounds are neurotoxic and carcinogenic; these kind of compounds are present in twenty-one out of the thirty-one states of our country. Thirty tons of Hg are released to the atmosphere but besides this the worst part is that the effect in the environment is almost unknown. Biotechnological processes have shown to be an integral solution of sites contaminated with mercury, this processes have been used to reduce the damage and help in one way or another to the human health and the environment. In the present study macroscopic, microscopic, biochemical, kinetic and molecular characterization was carried out in order to study microorganisms isolated from industrial sites contaminated with gasoline or from where mercury was tought to be present. Five isolates were exposed to mercury chloride and methyl mercury chloride in experiments designed to identify the biotechnological potential of these organisms for bioremediation processes. We were able to characterize and identify five microorganisms using macroscopical, microscopical, biochemical, kinetical and molecular techniques, which were resistant to high concentrations of methyl mercury chloride (10 ppm) and mercury chloride (20-400 ppm). The results showed to the taxa gamma-proteobacteria and firmicute and thato our isolated have a clear potential in bioremediation processes particularly in places were mercury could be present in small o high concentration. It is important to highlight that some of the organisms formed distinct forms of biofilms that could give them a special attribute to survive in sites contaminated with heavy metals.