Aims:To compare the suitability of various bacterial and viral indicators to assess the removal of faecal microorganisms by primary and secondary wastewater treatment processes. Methods and Results: The numbers of several bacterial indicators [faecal coliforms (FC), enterococci (ENT) and sulphite-reducing clostridia (SRC)] and bacteriophages (somatic coliphages, F-specific RNA phages and bacteriophages infecting Bacteroides fragilis strain RYC2056) were determined in incoming raw sewage and effluents from various primary and secondary wastewater treatment processes in several geographical areas. Reductions in the numbers of indicators were calculated as log 10 reductions. Processes based on removal and mild disinfection, showed no significant differences in the elimination of any of the indicators tested or between geographical areas. In contrast, treatment processes that include strong microbial inactivation, such as lime-aided flocculation and lagooning, showed significant differences between the log 10 reductions of the various micro-organisms studied, FC showing the highest reduction and spores of SRC and phages infecting B. fragilis the lowest. Conclusions: The microbial elimination performance of treatment processes based principally on removal and mild disinfection can be evaluated with a single indicator. In contrast, processes with additional disinfecting capabilities require more than one indicator for accurate evaluation of the treatment; bacteriophages are good candidates for use as second indicators. Significance and Impact of the Study: Bacteriophages provide additional information for the evaluation of microbial elimination in some treatment plants. The easy, fast and cheap methods available for phage determination are feasible both in industrialized and developing countries.
Aims: To evaluate the feasibility of bacteriophages as a complementary tool for water quality assessment in surface waters from different parts of the globe. Methods and Results: Faecal coliform bacteria, enterococci, spores of sulphite-reducing clostridia, somatic coliphages, F-specific RNA bacteriophages and bacteriophages infecting Bacteroides fragilis were determined by standardized methods in raw sewage and in 392 samples of river water from 22 sampling sites in 10 rivers in Argentina, Colombia, France and Spain, which represent very different climatic and socio-economic conditions. The results showed that the indicators studied maintained the same relative densities in the raw sewage from the different areas. Classifying the river water samples according to the content of faecal coliform bacteria, it can be observed that the relative densities of the different bacterial indicators and bacteriophages changed according to the concentration of faecal coliform bacteria. There was a relative increase in the densities of all groups of bacteriophages and sulphite-reducing clostridia with respect to faecal coliforms and enterococci in the samples with low counts of faecal coliform bacteria. Conclusions: The numbers of bacterial indicators and bacteriophages were similar in the different geographical areas studied. Once released in rivers, the persistence of the different micro-organisms differed significantly. Bacteriophages and spores of sulphite-reducing clostridia persisted longer than faecal coliforms and enterococci. Significance and Impact of the Study: Bacteriophages in river water samples provide additional information to that provided by bacteria about the fate of faecal micro-organisms in river water. The easy, fast and cheap methods for phage determination are feasible both in industrialized and developing countries.
Aims: The aim of this research was to determine the suitability of coliphages (bacteriophages) for assessing the microbial quality of groundwater. Methods and Results: The number of several bacterial indicators (faecal coliforms, Escherichia coli, enterococci and spores of sulfite‐reducing clostridia) and bacteriophages (somatic coliphages, F‐specific RNA bacteriophages and bacteriophages infecting Bacteroides fragilis) were determined in groundwater of aquifers in various geographical areas. Results show that the relative abundance, determined as percentages of positive detections, of the bacterial indicators and bacteriophages varies depending on the aquifer. Conclusions: A single bacterial indicator may not be enough to assess microbiological quality in certain aquifers. One bacterial indicator and a bacteriophage parameter provide more information than two bacterial indicators. Significance and Impact of the Study: Coliphages (CPH) provide different information from that provided by bacterial indicators on the microbial quality of groundwater in different geographical areas. Easy, fast and inexpensive methods for the detection of CPH are feasible in both industrialized and developing countries.
The essentiality of chromium(III) has been the subject of much debate, particularly in healthy subjects. Chromium(III)-containing supplements are widely used for body mass loss, building of lean muscle mass, and improving glucose and lipid metabolism. [Cr3O(O2CCH2CH3)6(H2O)3]+, Cr3, is one of the most-studied chromium nutritional supplements. The current study evaluates the effects of long-term (15 months) supplementation with Cr3 on body mass and glucose metabolism in Wistar rats on traditional and cafeteria-style (high fat, high carbohydrate) diets. Male Wistar rats were randomly assigned to one of four treatment groups: 1) control diet (milled Harlan Teklad LM-485 rodent diet), 2) control diet + 1 mg Cr3/kg body mass/day, 3) a cafeteria-style (CAF) diet (high fat, high carbohydrate), or 4) CAF diet + 1 mg Cr3/kg/day. Cr3 supplementation had no effect on fasting blood glucose levels or blood glucose levels in response to glucose and insulin challenges. Rats consuming the CAF + Cr3 diet tended to have a significantly higher body mass than rats consuming the CAF diet, but necropsy results showed no difference in visceral fat or body wall thickness between groups. These data suggest that long-term Cr3 supplementation does not significantly affect body mass in rats consuming a normal diet or glucose levels or metabolism in rats consuming either diet.
Partiendo del supuesto de que las relaciones entre Estados Unidos y América Latina están fuertemente determinadas por la agenda de seguridad, este artículo propone examinar el vínculo cooperativo que establece Washington con Bogotá en función del combate contra el narcotráfico y el terrorismo como modo de aproximación al tipo de relacionamiento que propone el país del norte para la región latinoamericana en el siglo XXI. Consecuentemente, se intenta sustentar la observación de dos tendencias, por un lado, el afianzamiento de la militarización de la influencia norteamericana y de su conducción por parte del Departamento de Defensa y, por el otro, la participación militarizada de Estados Unidos en el conflicto armado colombiano mediante la inclusión de éste como parte de la lucha contra el terrorismo internacional. La metodología utilizada para la confección del escrito es cualitativa y se aplica a un proceso investigativo basado en fuentes primarias y, también, secundarias.
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