INVESTIGADORES
VOLENTINI Sabrina Ines
congresos y reuniones científicas
Título:
Use of Escherichia coli strains as bioremediators of soil and water polluted with copper
Autor/es:
LORENZETTI Y; GRILLO PUERTAS, M; SCARAVAGLIO OR; CERIONI L; VOLENTINI SI; RODRÍGUEZ-MONTELONGO L
Lugar:
Tucuman
Reunión:
Congreso; VII CONGRESO ARGENTINO DE MICROBIOLOGÍA GENERAL SAMIGE DEL BICENTENARIO; 2011
Institución organizadora:
SAMIGE
Resumen:
Copper is an essential element for all living organisms, acting as a cofactor of several cellular enzymes. However, in excess, this metal becomes potentially toxic and because it is not degradable, their remediation turns complicated. Contamination of soils, rivers and deep waters with copper increased dangerously, especially from industrial effluents. On the other hand, when applied in the field as a fungicide (CuSO4, Bordeaux mixture, copper oxychloride, etc.) it acumulates in the soil, and when crops take it, copper may become toxic for animals and humans if it reaches certain level in those foods. The microorganisms have been studied as a tool for bioremediation of polluted environments. In our laboratory it was demonstrated that certain strains of Escherichia coli could detoxify liquid media with high copper levels. Additionally, we standardized a sequential oxidative treatment (SOT), which is able to eliminate postharvest citrus pathogens. In one step of SOT, CuSO4 is used combined with H2O2 for catalyze the formation of reactive oxygen species. In this process, H2O2 is transformed into a harmless compound, but the concentration of CuSO4 practically remains unchanged at the end of the processing. Because we are interested in protecting the environment, we explored ways to capture of copper from the SOT effluent. Here, we proposed: a) finding conditions suitable for extracting copper from soil by solubilising it to a liquid medium, b) finding appropriate conditions for copper capture by E. coli cells, both from liquid medium after the soil treatment and from SOT effluent. To perform this investigation, soil samples were contaminated with different amounts of copper and then we tried to solubilize it by using several types of acids and different extraction conditions, to obtain the most effective combination of them. Afterwards, supernatants of the extractions were treated with the E. coli strains studied. The SOT effluent was subjected to several procedures to degrade the residual H2O2 and subsequently treated with E. coli as well. Results shown that: 1) HCl, was the acid with which the better extraction was obtained; 2) three extractions of 30 min were capable of solubilize around 90% of the added copper; 3) when the solutions were treated with bacteria, the highest copper capture was at pH upper than 5, and with two bacterial extractions in a sequential manner, 90% of the metal was recovered; 4) the best condition to remove the residual H2O2 from the SOT effluent was irradiating with UV-B for 30 min; 5) the condition for the highest capture of copper from the SOT effluent was similar to that of the liquid medium from the soil treatment. These results suggest that the E. coli strains used in this study have the potential capability to detoxify soils and waters polluted with copper