bacterial adsorption

The Entre Ríos Province, Argentina, is characterized by a high unequal land distribution, 62% of farms are less than 100 ha (17,000 cases) and just the 8.9 % has more than 500 ha (2,436 cases). This feature leads to an intensive and continuous agriculture in a region with high water erosion susceptibility (SAGYP, 1995). Forty percent of

The Entre Ríos Province, Argentina, is characterized by a high unequal land distribution, 62% of farms are less than 100 ha (17,000 cases) and just the 8.9 % has more than 500 ha (2,436 cases). This feature leads to an intensive and continuous agriculture in a region with high water erosion susceptibility (SAGYP, 1995). Forty percent of

The Entre Ríos Province, Argentina, is characterized by a high unequal land distribution, 62% of farms are less than 100 ha (17,000 cases) and just the 8.9 % has more than 500 ha (2,436 cases). This feature leads to an intensive and continuous agriculture in a region with high water erosion susceptibility (SAGYP, 1995). Forty percent of

Tout matériau immergé en milieu marin se recouvre de composés azotés, protéines, carbohydrates, sels, silice, puis de bactérie en quelques heures, et d'un biofilm mature en quelques jours. Cela altère ses propriétés physico-chimiques, entraîne un risque accru de corrosion localisée et de biodétérioration, avec pour conséquences des coûts d'entretien et de nettoyage importants. Les peintures contenant des sels de tributylétain (TBT) utilisées jusqu'à présent pour protéger ces surfaces se sont avérées toxiques pour le milieu marin [1]. Elles sont désormais soumises à des normes internationales, avec une interdiction d'application des sels TBT effective depuis 2003, et une interdiction totale en 2008. Il est donc aujourd'hui nécessaire de rechercher des alternatives à ces peintures. La solution ici proposée consiste à agir sur les premières étapes de formation du biofilm, à savoir la fixation de protéines et des premières bactéries sur la surface. Pour cela, la surface est modifiée chimiquement et fonctionnalisée par des enzymes, lesquelles vont agir localement sur la bactérie par hydrolyse de certains constituants de sa paroi, empêchant ainsi son adhésion à la surface. Les différentes étapes du greffage ont été contrôlées par Infra Rouge et par Spectroscopie de Photoélectrons X. Ces analyses ont permis de valider chaque étape du greffage. En parallèle, un nouveau test enzymatique pour tester l'activité de l'enzyme greffée a été mis en place et validé. Il a permis de vérifier l'efficacité de l'enzyme greffée vis-à-vis d'une suspension bactérienne modèle.

En el presente trabajo se evalúa la adhesión de Streptococcus mutans a hidroxiapatitas de diferente naturaleza en una solución oral sintética. La adhesión microbiana fue determinada indirectamente por recuento de los microorganismos viables en suspensiones equilibradas con los sustratos. Los resultados obtenidos mostraron que, a baja concentración de inóculo, la adhesión de Streptococcus mutans puede ser descripta, razonablemente, mediante una única isoterma de Langmuir, introduciendo una pequeña corrección en cada muestra para dar cuenta de las diferencias en la macrorugosidad. La constante de afinidad resultó ser aproximadamente igual a 0,25´10- 8 (bacterias/mL)-1. La falta de influencia del sustrato se interpreta en términos del mecanismo de adsorción del S. mutans, y el gran tamaño de la bacteria, que disimula diferencias químicas y morfológicas de la superficie en la dimensión nanométrica. Estos resultados sugieren que la derivatización de la superficie con grandes polímeros pu...

Bacterial adsorption on soils and sediments is one of the main factors that control bacterial transport to water bodies. In this work, 32 soil samples representative of the most important arable areas of the Rolling Pampa region (Argiudolls) and bottomlands devoted to livestock production (Natraqualfs) were analyzed in order to evaluate bacterial-soil adsorption. The first axis of a principal component analysis explained 45% of the total variation among soils in 11 physical and chemical properties, and was strongly and positively related to bacterial adsorption (r 2 =0.67). Soil bacterial adsorption presented a large range of values (25-73%), being those for Argiudolls significantly higher than those for Natraqualfs. For both soils, cation exchange capacity (CEC) (r 2 =0.67) and clay content (r 2 =0.55) were positively associated with bacterial adsorption; whereas exchangeable sodium percentage (ESP) showed a negative tendency (r 2 =0.42). It is concluded that in the basin studied, ...

El aumento de la carga animal vacuna en la Pampa Ondulada asociado a áreas frágiles supone un importante riesgo de contaminación biológica. Dicha contaminación está regulada por variables edáficas, como la textura, que controlan el transporte de contaminantes biológicos hacia los cuerpos de agua. En el presente trabajo se correlacionó la adsorción bacteriana del suelo con distintos tamaños de partículas individuales correspondientes a 27 suelos provenientes de una cuenca de la Pampa Ondulada. Para ello se utilizó una técnica de centrifugación lenta. Los valores de adsorción bacteriana, empleando en la determinación Escherichia coli ATCC 8739, variaron entre 25,3% y 73,3%, y el tamaño de partícula que mejor se correlacionó con esta propiedad fue el correspondiente a la fracción de arcillas (R 2 = 0,6). Esta correlación mejoró al considerar conjuntamente a todas las partículas menores de 3 μm (R 2 = 0,64), lo que resalta la capacidad de los limos muy finos en el fenómeno de adsorción. La curva de ajuste elaborada con los datos experimentales se comparó con la obtenida de acuerdo con el modelo propuesto por Ling et al. (2002). Se encontraron similitudes en la pendiente, no así en la ordenada al origen. Esta diferencia desapareció al emplear en la determinación una cepa autóctona aislada de deyecciones animales provenientes de la cuenca estudiada, dado que dicha cepa evidenció una adsorción 48% superior a la observada con la cepa de colección.

Bacterial adsorption on soils and sediments is one of the main factors that control bacterial transport to water bodies. In this work, 32 soil samples representative of the most important arable areas of the Rolling Pampa region (Argiudolls) and bottomlands devoted to livestock production (Natraqualfs) were analyzed in order to evaluate bacterial-soil adsorption. The first axis of a principal component analysis explained 45% of the total variation among soils in 11 physical and chemical properties, and was strongly and positively related to bacterial adsorption (r 2 =0.67). Soil bacterial adsorption presented a large range of values (25-73%), being those for Argiudolls significantly higher than those for Natraqualfs. For both soils, cation exchange capacity (CEC) (r 2 =0.67) and clay content (r 2 =0.55) were positively associated with bacterial adsorption; whereas exchangeable sodium percentage (ESP) showed a negative tendency (r 2 =0.42). It is concluded that in the basin studied, granulometry, CEC and ESP proved to be important properties to discriminate bacterial-soil adsorption, and the following equation to estimate mean soil bacterial adsorption in these soils is proposed: y=1.73×CEC-0.05×sand(50-250 μm)[g kg-1 ]-0.54×ESP (R 2 adjust=0.77). These results would help to monitor water quality of surface water bodies by the development of bacterial transport models using standard soil data. Palabras clave: contaminación hídrica, pastoreo, adsorción bacteriana, Argiudoles, Natracualfes RESUMEN La adsorción bacteriana a suelos y sedimentos es uno de los principales factores que controlan el transporte bacteriano hacia los cuerpos de agua. En este trabajo se analizó la adsorción bacteriana en 32 muestras de suelos representativas del área agrícola más

Bacterial adsorption on soils and sediments is one of the main factors that control bacterial transport to water bodies. In this work, 32 soil samples representative of the most important arable areas of the Rolling Pampa region (Argiudolls) and bottomlands devoted to livestock production (Natraqualfs) were analyzed in order to evaluate bacterial-soil adsorption. The first axis of a principal component analysis explained 45% of the total variation among soils in 11 physical and chemical properties, and was strongly and positively related to bacterial adsorption (r 2 =0.67). Soil bacterial adsorption presented a large range of values (25-73%), being those for Argiudolls significantly higher than those for Natraqualfs. For both soils, cation exchange capacity (CEC) (r 2 =0.67) and clay content (r 2 =0.55) were positively associated with bacterial adsorption; whereas exchangeable sodium percentage (ESP) showed a negative tendency (r 2 =0.42). It is concluded that in the basin studied, granulometry, CEC and ESP proved to be important properties to discriminate bacterial-soil adsorption, and the following equation to estimate mean soil bacterial adsorption in these soils is proposed: y=1.73×CEC-0.05×sand(50-250 μm)[g kg-1 ]-0.54×ESP (R 2 adjust=0.77). These results would help to monitor water quality of surface water bodies by the development of bacterial transport models using standard soil data. Palabras clave: contaminación hídrica, pastoreo, adsorción bacteriana, Argiudoles, Natracualfes RESUMEN La adsorción bacteriana a suelos y sedimentos es uno de los principales factores que controlan el transporte bacteriano hacia los cuerpos de agua. En este trabajo se analizó la adsorción bacteriana en 32 muestras de suelos representativas del área agrícola más

Bacterial adsorption on soils and sediments is one of the main factors that control bacterial transport to water bodies. In this work, 32 soil samples representative of the most important arable areas of the Rolling Pampa region (Argiudolls) and bottomlands devoted to livestock production (Natraqualfs) were analyzed in order to evaluate bacterial-soil adsorption. The first axis of a principal component analysis explained 45% of the total variation among soils in 11 physical and chemical properties, and was strongly and positively related to bacterial adsorption (r 2 =0.67). Soil bacterial adsorption presented a large range of values (25-73%), being those for Argiudolls significantly higher than those for Natraqualfs. For both soils, cation exchange capacity (CEC) (r 2 =0.67) and clay content (r 2 =0.55) were positively associated with bacterial adsorption; whereas exchangeable sodium percentage (ESP) showed a negative tendency (r 2 =0.42). It is concluded that in the basin studied, granulometry, CEC and ESP proved to be important properties to discriminate bacterial-soil adsorption, and the following equation to estimate mean soil bacterial adsorption in these soils is proposed: y=1.73×CEC-0.05×sand(50-250 μm)[g kg-1 ]-0.54×ESP (R 2 adjust=0.77). These results would help to monitor water quality of surface water bodies by the development of bacterial transport models using standard soil data. Palabras clave: contaminación hídrica, pastoreo, adsorción bacteriana, Argiudoles, Natracualfes RESUMEN La adsorción bacteriana a suelos y sedimentos es uno de los principales factores que controlan el transporte bacteriano hacia los cuerpos de agua. En este trabajo se analizó la adsorción bacteriana en 32 muestras de suelos representativas del área agrícola más Rev. Int. Contam. Ambie. 29 (1) 7-20, 2013