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Water quality of Mexican tropical lake Chapala was assessed through multivariate statistical techniques, cluster analysis (CA) and principal component analysis (PCA) at ten different monitoring sites for ten physicochemical variables and six metals. This study evaluated and interpreted complex water quality data sets and apportioned of pollution sources to get better information about water quality. From descriptive statistics results, the highest concentrations of metals occurred during the dry season, and this trend was explained by the fact that an unusual rainy event occurred during the month of February 2009 and brought metals into the lake by runoffs from nearby mountains. According to international criteria for water consumption by aquatic organisms [USEPA], only Zn concentration values were below these criteria whereas the values of Ni, Pb, Cd and Fe were above the corresponding values set in these criteria (Ni: 52 µg•L −1 , Pb: 2.5 µg•L −1 , Cd: 0.25 µg•L −1 , and Fe: 1000 µg•L −1). The correlations were observed by PCA, which were used to classify the samples by CA, based on the PCA scores. Seven significant cluster groups of sampling locations-(sites 4 and 5), (sites 3 and 9), (site 7), (site 10), (sites 2 and 6), (site 8) and (site 1)-* Corresponding author. J. Badillo-Camacho et al. 216 were detected on the basis of similarity of their water quality. The results revealed that the stress exerted on the lake caused by waste sources follows the order: domestic > agricultural > industrial.

Microbiological analyses of freshwater fish utilized in subsistence fisheries are relatively scarce. These fisheries are widespread throughout Latin America, and support numerous communities in rural, impoverished areas. We present the results of genetically-based microbiological analyses of river water samples and fish tissue samples obtained from specimens (n = 128) captured in the wild from three sites in the Ayuquila river, west central Mexico. The system is affected by numerous human activities. We identify 11 bacterial taxa of which Pseudomonas stutzeri, Shigella sonnei, Escherichia coli and Bacillus subtilis were isolated from the most fish. Citrobacter freundii and E. coli were present in water samples from all sites. Average taxa richness was similar among rainy and dry seasons. Enterobacteriaceae dominate the bacterial microbiota of water and fishes of the Ayuquila river, suggesting there is significant influence from anthropic activities in the basin. Our findings provide a baseline upon which to improve our understanding of the microbiology of the Ayuquila river and similar systems in west central Mexico, especially related to risks for biota and human populations dependent on rivers for sustenance. Palabras clave: Escherichia coli, contaminación, Manantlán, pesquería de subsistencia RESUMEN Los análisis microbiológicos en peces de agua dulce tomados directamente de hábitats naturales y que son utilizados en pesquerías de subsistencia son relativamente escasos. Estas pesquerías están muy extendidas en toda América Latina y son importantes para numerosas comunidades en áreas rurales empobrecidas. Presentamos los resultados de análisis microbiológicos y moleculares realizados en muestras de agua de río y muestras de tejido obtenidas de peces (n = 128) capturados en el medio silvestre de tres sitios en el río Ayuquila, en el centro oeste de México. El río es afectado por numerosas Short communication / Comunicación breve

The risk exposure to agents causing waterborne diseases (WBD), such as bacteria, parasites, and metals (Cr, Cd, Mn, and Pb) in a group of volunteers (« = 20) and an external group of three locations of the El Ahogado Basin, Mexico, is reported. A complete blood count (CBC) was made on the volunteers, and factor analysis was used for the CBC. Bacteria and parasitological agents were also monitored at the six sites of the El Ahogado Basin between 2008 and 2010. The measured blood concentrations of Cu, Mn, and Pb were 37.1, 4.6, and 7.1 |ig/g, indicating the lowest exposure of volunteers to Mn and Pb and the highest exposure to Cu. The volunteer groups of the El Ahogado Basin are more exposed to agents causing WBD compared to the volunteers of the external group. Water Environ. Res., 85, 2175Res., 85, (2013.

In this study, lignin was chemically modified to promote hydrogel degradation as a source of carbon and nitrogen for a bacterial consortium consisting of P. putida F1, B. cereus and, B. paramycoides. A hydrogel was synthesized using acrylic acid (AA), acrylamide (AM), and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and cross-linked with the modified lignin. The structural changes and mass loss in the hydrogel, as well as its final composition, were evaluated as functions of the growth of the selected strains in a culture broth with the powdered hydrogel. The average loss was 18.4% wt. The hydrogel was characterized using FTIR spectroscopy, scanning electronic microscopy (SEM), elemental analysis (EA), and thermogravimetric analysis (TGA) before and after bacterial treatment. FTIR showed that the carboxylic groups present in both the lignin and the acrylic acid of the hydrogel decreased during bacterial growth. The bacteria showed a preference for the biomaterial components of the hydrogel. SEM demonstrated superficial morphological changes in the hydrogel. The results reveal that the hydrogel was assimilated by the bacterial consortium while preserving the water retention capacity of the material and that the microorganisms carried out a partial biodegradation of the hydrogel. The results of the EA and TGA confirm that the bacterial consortium not only degraded the biopolymer (lignin), but also used the synthetic hydrogel as a carbon source to degrade its polymeric chains and modified original properties. This modification with lignin as a crosslinker (which is a waste product of the paper industry) is therefore proposed to promote hydrogel degradation.