Navegando por Autor "Gallego, A."
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Ítem Acceso Abierto Biodegradation and detoxi cation of phenolic compounds by pure and mixed indigenous cultures in aerobic reactors.(2003) Gallego, A.; Fortunato, M.; Foglia, J.; Rossi, S.; Gemini, V.; Gómez, L.; Gómez, C.; Higa, L.; Korol, S.Degradation and detoxi!cation of a mixture of persistent compounds (2-chlorophenol, phenol and m-cresol) were studied by using pure and mixed indigenous cultures in aerobic reactors. Biodegradation assays were performed in batch and continuous 9ow reactors. Biodegradation was evaluated by determining total phenols, ultraviolet spectrophotometry and chemical oxygen demand (COD). Microbial growth was measured by the plate count method. Scanning electronic microscopy was employed to observe the microbial community in the reactor. Detoxi!cation was evaluated by using Daphnia magna toxicity tests. Individual compounds were degraded by pure bacteria cultures within 27 h. The mixture of 2-clorophenol (100 mg l−1), phenol (50 mg l−1) and m-cresol (50 mg l−1) was degraded by mixed bacteria cultures under batch conditions within 36 h: 99.8% of total phenols and 92.5% of COD were removed; under continuous 9ow conditions 99.8% of total phenols and 94.9% of COD were removed. Mineralization of phenolic compounds was assessed by gas chromatography performed at the end of the batch assays and in the eAuent of the continuous-9ow reactor. Toxicity was not detected in the eAuent of the continuous-9ow reactor.? 2003 Elsevier Ltd. All rights reserved.Ítem Acceso Abierto Biodegradation and detoxi!cation of phenolic compounds by pure and mixed indigenous cultures in aerobic reactors(2001) Gallego, A.; Fortunato, M.; Foglia, J.; Rossi, S.; Gemini, V.; Gomez, L.; Gomez, C.; Higa, L.; Korol, S.Degradation and detoxi!cation of a mixture of persistent compounds (2-chlorophenol, phenol and m-cresol) were studied by using pure and mixed indigenous cultures in aerobic reactors. Biodegradation assays were performed in batch and continuous 9ow reactors. Biodegradation was evaluated by determining total phenols, ultraviolet spectrophotometry and chemical oxygen demand (COD). Microbial growth was measured by the plate count method. Scanning electronic microscopy was employed to observe the microbial community in the reactor. Detoxi!cation was evaluated by using Daphnia magna toxicity tests. Individual compounds were degraded by pure bacteria cultures within 27 h. The mixture of 2-clorophenol (100 mg l−1), phenol (50 mg l−1) and m-cresol (50 mg l−1) was degraded by mixed bacteria cultures under batch conditions within 36 h: 99.8% of total phenols and 92.5% of COD were removed; under continuous 9ow conditions 99.8% of total phenols and 94.9% of COD were removed. Mineralization of phenolic compounds was assessed by gas chromatography performed at the end of the batch assays and in the eAuent of the continuous-9ow reactor. Toxicity was not detected in the eAuent of the continuous-9ow reactor.? 2003 Elsevier Ltd. All rights reserved.Ítem Acceso Abierto Biotransformation of chromium (VI) in liquid effluents by resistant bacteria isolated from the Matanza-Riachuelo Basin, in Argentina.(Taylor & Francis & Informa UK Limited, trading as Taylor & Francis Group, 2017) González, A.; Caimán, C. ; Gorino, N. ; Fortunato, M.; Radice, M. ; Gómez, C. ; Mujica, C.; Marquina, L. ; Gallego, A. ; Korol, S.The aims of this investigation were to evaluate the bacterial resistance to zinc, copper, chromium (VI) and lead in surface water streams from Buenos Aires, Argentina; to select a chromium-resistant strain able to remove the metal in batch process and to evaluate the potential of this strain to remove chromium (VI) in liquid effluents. Bacterial resistance to the metals was evaluated by determining the minimal inhibitory concentration. The kinetic of chromium (VI) removal by one of the resistant strains was studied in nutrient broth with 50 and 100 mg L−1 of the metal, as well as an effluent from an electroplating industry. High resistance to all the metals under study was observed in the bacterial communities of the Matanza-Riachuelo basin. A chromium-resistant strain was isolated and identified as Microbacterium sp. It was able to remove 50 and 100 mg L−1 of Cr (VI) in 36 and 66 h respectively, with efficiency higher than 99%. Experiments with liquid effluents showed the ability of the strain to transform 150 mg L−1 of the metal in 84 h, with efficiency higher than 99%. These results show the potential of this native strain for the treatment of liquid effluents that contain chromium (VI).Ítem Acceso Abierto Factors Affecting Biodegradation of 2-Chlorophenol by Alcaligenes sp. in Aerobic Reactors(2001) Gallego, A.; Gómez, C.; Fortunato, M.; Cenzano, L.; Rossi, S.; Paglilla, M.; Gómez Hermida, D.; Higa, L.; Korol, S.The influence of variations in carbon source concentration, cell inocula, pH, presence of other substrates, and other organisms on the biodegradation of 2-chlorophenol 2-CP was studied for ( ) Alcaligenes sp. isolated from natural sources. Assays of biodegradation were performed in batch and continuous-flow fluidized-bed aerobic reactors. Evaluation of biodegradation was performed by deter mining total phenols, chemical oxygen demand COD , and 2-CP by ultraviolet UV spectrophotometry. ( ) ()Measurement of microbial growth was carried out by the plate count method. Bioassays of acute toxicity were performed to evaluate detoxification by using Daphnia magna. Results obtained show that under batch conditions with initial inocula of 106 cells/mL the strain grew exponentially with 100, 200, and 300 ( 5 mg/L of 2-CP within 48 hr. A lag period was observed with low cell density inocula 10 cells/mL . The ) strain showed marked delay in the biodegradation of 2-CP at pH 5. Removal of target substrate from mixtures containing other carbon sources demonstrated the possibility of concurrent growth. Mineraliza tion of 2-CP was assessed by gas chromatography carried out at the end of the batch assays and at the exit of the continuous-flow reactor. The presence of other organisms bacteria, rotifers, ciliate, and ( algae that developed in the fluidized-bed reactor did not affect the efficacy of the biodegradation of )2-CP. The removal of 2-CP in the two assayed systems was over 97% in all cases. Toxicity was not detected at the exit of the continuous reactor.Ítem Acceso Abierto Resistencia y biodegradabilidad como complemento de estudios de la contaminación de aguas superficiales.(XXVI Congreso Nacional del Agua CONAGUA., 2017) Fortunato, M.; González, A.; Baroni, S. ; Gorino, N. ; Laurino Soulé, J. ; Gómez, C. ; Gallego, A. ; Korol, S.El objetivo de este trabajo fue estudiar los procesos de adaptación tales como la capacidad de biodegradación y resistencia a diferentes compuestos tóxicos, en las comunidades bacterianas autóctonas de las cuencas del Río Reconquista, Matanza-Riachuelo y del Río de la Plata, y su relación con el grado de contaminación; así como también determinar la utilidad del estudio de estos procesos en la caracterización de cursos de agua contaminados.Ítem Acceso Abierto Transformación de Cr (VI) a Cr (III) por una cepa bacteriana autóctona aislada de la Cuenca Matanza-Riachuelo(V Congreso Argentino de la Sociedad de Toxicología y Química Ambiental (SETAC), 2014) Rossi, S. ; Gorino, N.; Caimán, C. ; González, C. ; Fortunato, M. ; Mujica, C. ; Marquina, L. ; Gómez, C. ; Korol, S. ; Gallego, A.El Cr está presente en efluentes líquidos de múltiples actividades industriales, como ser las curtiembres o los procesos de acabados metálicos. El tratamiento de estos efluentes puede llevarse a cabo por procesos químicos o biológicos. Estos últimos pueden conseguir en algunos casos la transformación del Cr VI en Cr III, una especie menos móvil y tóxica. En un trabajo previo se seleccionó a partir de aguas superficiales de la Cuenca Matanza-Riachuelo una cepa autóctona tolerante a altas concentraciones de cromo. Los objetivos del presente trabajo fueron evaluar la capacidad de la cepa seleccionada para transformar Cr (VI) empleando diferentes fuentes de carbono y estudiar la cinética de remoción. Los ensayos de biotransformación se realizaron en Frascos Erlenmeyer incubados en un baño termostatizado (28 ºC) con agitación (200 rpm). El crecimiento bacteriano fue determinado por la técnica de recuento en placa. La concentración de Cr (VI) fue determinada por la técnica de la difenilcarbazida y la de Cr total por absorción atómica. Los ensayos fueron llevados a cabo en distintos medios de cultivo adicionados con 50 mg/L de Cr (VI), utilizando cromato o dicromato de potasio. Los medios de cultivo ensayados fueron Caldo tripteína soja (TSA), Caldo nutritivo (CN) y medio mínimo mineral adicionado de glucosa, lactosa, acetato de sodio, manitol o extracto de levadura como fuente de carbono. La cepa bacteriana solamente fue capaz de crecer y transformar Cr (VI) en medios complejos como el TSA, CN ó medio mínimo adicionado con extracto de levadura. Los ensayos de biotransformación en caldo nutritivo permitieron determinar que la cepa autóctona fue capaz de remover prácticamente en su totalidad 50 mg/L de Cr (VI) dentro de las 40 horas. No hubo diferencias en la remoción partiendo de cromato o dicromato como fuente de Cr (VI). El promisorio comportamiento de esta cepa permitiría su aplicación en la remediación de efluentes líquidos o aguas contaminadas con Cr (VI).