Summary
The complex ecology of free-living amoebae (FLA) and their role in spreading pathogenic microorganisms through water systems have recently raised considerable interest. In this study, we investigated the presence of FLA and amoebae-resisting bacteria (ARB) at various stages of a drinking water plant fed with river water. We isolated various amoebal species from the river and from several points within the plant, mostly at early steps of water treatment. Echinamoeba- and Hartmannella-related amoebae were mainly recovered in the drinking water plant whereas Acanthamoeba- and Naegleria-related amoebae were recovered from the river water and the sand filtration units. Some FLA isolates were recovered immediately after the ozonation step, thus suggesting resistance of these microorganisms to this disinfection procedure. A bacterial isolate related to Mycobacterium mucogenicum was recovered from an Echinamoeba-related amoeba isolated from ozone-treated water. Various other ARB were recovered using co-culture with axenic Acanthamoeba castellanii, including mycobacteria, legionella, Chlamydia-like organisms and various proteobacteria. Noteworthy, a new Parachlamydia acanthamoebae strain was recovered from river water and from granular activated carbon (GAC) biofilm. As amoebae mainly multiply in sand and GAC filters, optimization of filter backwash procedures probably offers a possibility to better control these protists and the risk associated with their intracellular hosts.

Biodiversity of amoebae and amoebae-resisting bacteria in a drinking water treatment plant.

Urbanization, land use, and water quality in Shanghai 1947-1996

This article reflects on the contrast between justice and the social contract in the globalized world of the 21st century, which faces increasing insecurity and the expectations of sustainable development. It exposes the causes for the widespread global distrust that has been growing since the middle of the last century and is affecting the prospects of a safe world headed to sustainable development. It presents the agreement of the post-modern social contract in the Objectives of Sustainable Development (ODS) as the last opportunity to redirect the egalitarian coexistence of humanity, without compromising the next generations, as John Rawls indicates. It also stresses the importance of certainty in the development and security set out in these objectives as an essential characteristic of post-modernity.

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Objetivos de Desarrollo Sostenible

Chemical quality of bottled waters from three cities in eastern Alabama.

Biology and pathogenesis of Naegleria fowleri

Pathogenic and free-living amoebae isolated from swimming pools and physiotherapy tubs in Mexico.

A survey of pathogenic and free-living amoebae inhabiting swimming pool water in Mexico City.

Bacteriological and physico-chemical parameters of 265 samples from 39 brands sold in 5-gallon plastic and glass bottles and 2-5 L plastic containers were analyzed to determine the quality of bottled water distributed in Mexico City. Tests included fecal and total coliform counts, alkalinity, total hardness, chloride, calcium and magnesium concentrations, pH and conductivity. Correlation and cluster analyses and ANOVA were carried out, and a comparison made of the averages with the maximum permissible levels established in the Official Mexican Norms. Concerning the investigated parameters no differences (p > 0.05) between the brands were found. Physico-chemical parameters were studied and all the samples were within the permissible limits. Most samples taken from the 5-gallon containers exceeded the maximum bacteriological limits. It was concluded that the bacteriological quality of the brands studied was extremely variable. Appropriate sanitary measures, should be established to control this aspect.

Bottled-Water Quality in Metropolitan Mexico City

http://www.scielo.org.mx/pdf/ecm/v43/v43a6.pdf

Actitudes de yucatecos bilingües de maya y español hacia la lengua maya y sus hablantes en mérida, yucatán

A protozoological survey was performed on a waste-stabilization pond to isolate, identify, and determine the incidence of ciliates present in these waters. The correlation between the species found and the physicochemical parameters was investigated. One hundred and eighty samples were analyzed from February 1983 to February 1984. Free-living ciliates isolated include:Carchesium polypinum Linnaeus,Vorticella microstoma Ehrenberg,Vorticella convallaria Linnaeus,Didinium balbiani Fabre-Domergue,Amphileptus claparedei Stein,Spathidium spathula Muller,Litonotus fasciola Ehrenberg,Paramecium caudatum Muller,Paramecium aurelia Ehrenberg,Tetrahymena vorax Kidder,Tetrahymena pyriformis Ehrenberg,Cyclidium glaucoma Muller,Aspidisca costata Ehrenberg, andStylonychia putrina Stokes. The performance of the pond was predominantly anaerobic. The temperature, total alkalinity, and nitrate concentration were the most variable parameters in the system studied.

Pedro Ramírez

Papers

Pathogenic and free-living amoebae isolated from swimming pools and physiotherapy tubs in Mexico.

A survey of pathogenic and free-living amoebae inhabiting swimming pool water in Mexico City.

Bottled-Water Quality in Metropolitan Mexico City

Actitudes de yucatecos bilingües de maya y español hacia la lengua maya y sus hablantes en mérida, yucatán

Ciliates in a waste stabilization pond system in Mexico