Estudio de la estructura dinámica de las comunidades microbianas del suelo durante un proceso de biorremediación : Efecto de la concentración de contaminante aplicado

Hipótesis: - La comunidad microbiana de un suelo limpio cambia debido a la contaminación con una mezcla compleja de hidrocarburos. - Dicho cambio esta relacionado con la carga inicial del contaminante. - La comunidad microbiana de sistemas contaminados se modifica durante un proceso de biorremediación. - La comunidad del suelo restablece sus condiciones originales al desaparecer el contaminante. Objetivo general: Estudiar los cambios producidos en la comunidad microbiana de un suelo limpio como consecuencia de la contaminación con un residuo petroquímico y durante el proceso de biorremediación. Evaluar la capacidad de biorestauración del suelo una vez finalizado el tratamiento. En forma particular, se plantearon los siguientes objetivos: a) Analizar la composición microbiológica del residuo petroquímico API, con el fin de determinar si los grupos microbianos predominantes intervienen en el proceso de biorremediación del residuo en suelo. b) Determinar la cinética de eliminación de los hidrocarburos durante el proceso de biorremediación, su influencia sobre la dinámica de las poblaciones microbianas cultivables y sobre la actividad de la comunidad microbiana completa, en suelo limpio y sistemas contaminados con distintas concentraciones del residuo petroquímico. c) Analizar los cambios en la estructura de las comunidades microbianas mediante técnicas convencionales de aislamiento e identificación de los grupos dominantes en puntos seleccionados durante el tratamiento, y mediante técnicas cultivo independiente. d) Evaluar el grado de restauración alcanzado comparando la estructura y función de las comunidades establecidas al finalizar el proceso de biorremediación con la comunidad del suelo limpio.Tesis digitalizada en SEDICI gracias a la Biblioteca Central de la Facultad de Ciencias Exactas (UNLP).Facultad de Ciencias Exacta

Effect of THPS on the structure and diversity of the microbial populations in a process of microbially influenced corrosion

The accumulation of water and sludge in oil storage tanks leads to microbial contamination. The study of these microbial communities is of particular interest, especially the sulfate reducing microorganisms (SRM) which are mainly responsible for microbiologically influenced corrosion (MIC). Usually, the development of those microorganisms is controlled by the addition of biocides. The objective of this work was to evaluate the effect of a biocide (THPS) on these communities in a batch fractionated assay.Centro de Investigación y Desarrollo en Tecnología de Pintura

Effect of THPS on the structure and diversity of the microbial populations in a process of microbially influenced corrosion

The accumulation of water and sludge in oil storage tanks leads to microbial contamination. The study of these microbial communities is of particular interest, especially the sulfate reducing microorganisms (SRM) which are mainly responsible for microbiologically influenced corrosion (MIC). Usually, the development of those microorganisms is controlled by the addition of biocides. The objective of this work was to evaluate the effect of a biocide (THPS) on these communities in a batch fractionated assay.Centro de Investigación y Desarrollo en Tecnología de Pintura

Effect of THPS on the structure and diversity of the microbial populations in a process of microbially influenced corrosion

The accumulation of water and sludge in oil storage tanks leads to microbial contamination. The study of these microbial communities is of particular interest, especially the sulfate reducing microorganisms (SRM) which are mainly responsible for microbiologically influenced corrosion (MIC). Usually, the development of those microorganisms is controlled by the addition of biocides. The objective of this work was to evaluate the effect of a biocide (THPS) on these communities in a batch fractionated assay.Centro de Investigación y Desarrollo en Tecnología de Pintura

Effect of petrochemical sludge concentrations on microbial communities during soil bioremediation

Qualitative and quantitative changes of microbial communities in soil microcosms during bioremediation were determined throughout one year. The soil was contaminated with 0%, 2.5%, 5%, 10% (wt/wt) of petrochemical sludge containing polynuclear aromatic hydrocarbons. We analyzed the hydrocarbon concentration in the microcosms, the number of cultivable bacteria using CFU and most probable number assays, the community structure using denaturing gradient gel electrophoresis, and the metabolic activity of soil using dehydrogenase activity and substrate-induced respiration assays. After one year of treatment, the chemical analysis suggested that the hydrocarbon elimination process was over. The biological analysis, however, showed that the contaminated microcosms suffered under long-term disturbance. The number of heterotrophic bacteria that increased after sludge addition (up to 108-109 cells ml-1) has not returned to the level of the control soil (2-6 × 107 cells ml-1). The community structure in the contaminated soils differed considerably from that in the control. The substrate-induced respiration of the contaminated soils was significantly lower (≈10-fold) and the dehydrogenase activity was significantly higher (20-40-fold) compared to the control. Changes in the community structure of soils depended on the amount of added sludge. The species, which were predominant in the sludge community, could not be detected in the contaminated soils.Facultad de Ciencias ExactasLaboratorio de Biodegradación Microbiológica de Hidrocarburo

Effect of petrochemical sludge concentrations on microbial communities during soil bioremediation

Qualitative and quantitative changes of microbial communities in soil microcosms during bioremediation were determined throughout one year. The soil was contaminated with 0%, 2.5%, 5%, 10% (wt/wt) of petrochemical sludge containing polynuclear aromatic hydrocarbons. We analyzed the hydrocarbon concentration in the microcosms, the number of cultivable bacteria using CFU and most probable number assays, the community structure using denaturing gradient gel electrophoresis, and the metabolic activity of soil using dehydrogenase activity and substrate-induced respiration assays. After one year of treatment, the chemical analysis suggested that the hydrocarbon elimination process was over. The biological analysis, however, showed that the contaminated microcosms suffered under long-term disturbance. The number of heterotrophic bacteria that increased after sludge addition (up to 108-109 cells ml-1) has not returned to the level of the control soil (2-6 × 107 cells ml-1). The community structure in the contaminated soils differed considerably from that in the control. The substrate-induced respiration of the contaminated soils was significantly lower (≈10-fold) and the dehydrogenase activity was significantly higher (20-40-fold) compared to the control. Changes in the community structure of soils depended on the amount of added sludge. The species, which were predominant in the sludge community, could not be detected in the contaminated soils.Facultad de Ciencias ExactasLaboratorio de Biodegradación Microbiológica de Hidrocarburo

Influencia de la técnica de extracción de ADN en el análisis de poblaciones bacterianas en plantas de almacenamiento de petróleo

El almacenamiento es un elemento de gran valor en la explotación de los servicios de hidrocarburos debido a que actúa como un pulmón entre producción y transporte para absorber las variaciones de consumo; permite la sedimentación de agua y barros del crudo antes de despacharlo por oleoducto o a destilación y brinda flexibilidad operativa a las refinerías que actúan como punto de referencia en la medición de despachos de producto.Centro de Investigación y Desarrollo en Tecnología de Pintura

Influencia de la técnica de extracción de ADN en el análisis de poblaciones bacterianas en plantas de almacenamiento de petróleo

El almacenamiento es un elemento de gran valor en la explotación de los servicios de hidrocarburos debido a que actúa como un pulmón entre producción y transporte para absorber las variaciones de consumo; permite la sedimentación de agua y barros del crudo antes de despacharlo por oleoducto o a destilación y brinda flexibilidad operativa a las refinerías que actúan como punto de referencia en la medición de despachos de producto.Centro de Investigación y Desarrollo en Tecnología de Pintura

Influencia de la técnica de extracción de ADN en el análisis de poblaciones bacterianas en plantas de almacenamiento de petróleo

El almacenamiento es un elemento de gran valor en la explotación de los servicios de hidrocarburos debido a que actúa como un pulmón entre producción y transporte para absorber las variaciones de consumo; permite la sedimentación de agua y barros del crudo antes de despacharlo por oleoducto o a destilación y brinda flexibilidad operativa a las refinerías que actúan como punto de referencia en la medición de despachos de producto.Centro de Investigación y Desarrollo en Tecnología de Pintura

Evaluation of biocides in oilfield environments using fluorescent <i>in-situ</i> hybridization

Microbiologically influenced corrosion and souring of oilfield reservoirs are process frequently provoked by the sulphate-reducing bacteria. The most common method applied in the industry for preventing or controlling the deleterious effect caused by the presence of microorganisms is the addition of chemical agents (biocides) aimed at killing the microorganisms or inhibiting the microbial growth. Traditionally, biocide selection and testing are based on NACE standard TM0194 which implies the use of culturing for enumerating the bacteria surviving the treatment. To overcome culturing limitations, we used Fluorescent in-situ Hybridization to assist in the evaluation of biocides applied in water production treatment plants. Biocides were based on THPS (40% (B1); 75% (B2)) and 40% of a mixture (1/1, v/v) of THPS and benzalkonium chloride (B3) applied at two concentrations: 50 and 400 mg/L. The relation between the number of cells visualized with the fluorescent probes Eub338 and SRB385 (for eubacteria and SRB populations respectively) and the DAPI-stained cells (PR%) was used as an indication of the biocide efficiency. B1 and B3 gave a high PR% indicating that the chemical induced the metabolic cell activity. Only the highest B2 concentration showed effectiveness on eubacteria and SRB populations. Thus, through the application of FISH we were able to distinguish concentration effects of the THPS, discriminating sublethal from net inhibitory effects. The possibility of including FISH into the protocols for the control of the biocides in water treatment plants could improve the biocide selection and the adjustment of their concentration in order to maintain the water system with a low density of metabolically active cells. This would avoid the misuse of chemicals with their consequent economic and ecological impacts.Centro de Investigación y Desarrollo en Fermentaciones IndustrialesCentro de Investigación y Desarrollo en Tecnología de Pintura