Some species of pathogenic bacteria such as Salmonella, Escherichia coli, Shigella, among others, are a threat to the ichthyofauna that lives in freshwater rivers. This threat extends to the human population that develops various activities in this environment. Food products derived from these activities can affect consumers as well. Therefore, the objective of this research was to evaluate the microbiological quality of water in the middle basin of the Usumacinta River, Tabasco, Mexico. A total of 63 water samples were collected in 12 sampling sites: 36 in the dry season and 27 in the rainy season in 2013. The microbiological analysis was carried out according to Mexican standards. The highest concentration of CT was detected in Usumacinta (Usu) (130 NMP / 100mL) during the dry season and in Petunia (Pet) (240 NMP / 100mL) during the rainy season. The highest concentration of CF was detected in the water plant (Pa), Pet and Estapilla (Est) (34 NMP / 100mL), during the rainy season. The results of CT and CF registered significant differences in the Colony Forming Units (CFU), due to seasonality (p <0.05). Thus, they were not significant due to the effect of the sampling sites (p <0.05). Also, 284 putative strains of enterobacteria isolated and identified mainly Escherichia sp and Salmonella sp in the two studied seasons. These results are one of the first evidences of the microbiological quality of water in the middle basin of the river Usumacinta, Mexico.
Solanum marginatum L. f. (Solanaceae) is used in traditional Mexican medicine to treat infectious diseases and cancer, although lacks of the scientific validation. Consequently, we proposed a study of the enzymatic, antioxidant, antibacterial and toxic activities of an S. marginatum L. f. protein fraction previously characterized. For this, a protein extract from leaves of S. marginatum L. f. obtained and the protein fraction separated by FPLC. The protein content was quantified by the bicinchoninic acid (BCA) method and the enzymatic activity measured by the Kunitz method. Subsequently, protein subfractions were identified by SDS-PAGE. Additionally, the ability to capture radicals by the DPPH and ABTS methods was determined. The toxic effect was assessed with the A. salina test while cell viability in peripheral blood mononuclear cells (PBMC) tested by MTT method. Isolation of PF-FPLC was carried out at tr = 2.13 min, further, separated and identified seven subfractions with molecular weights ranging from 18-112 kDa, while the optimal conditions of enzymatic activity were 37°C, pH 7 and 120 min. The ABTS and DPPH methods showed a radical capture percentage of 20 and 62% respectively. The PF-FPLC proteins showed no toxicity in A. salina. However, the PF-FPLC showed a low antimicrobial effect (inhibition ≤ 35%), and decreases PBMC viability.
Background: Octopus is a fishery product of economic importance worldwide, the main species caught on the coast of the Gulf of Mexico and the Caribbean Sea are Octopus maya and O. vulgaris, the first represents up to 95 % of national production. Goals: Identify the bacterial flora associated with commercial Octopus maya captured in the Yucatan Peninsula, using PCR-DGGE. Methods: From the metagenomic DNAs (mDNAs) extracted from samples representative of the octopus muscle, PCR products were synthesized with universal primers for bacteria (gc338F and 518R) and specific primers for Phylum Firmicutes (FirF: 369 and gcFirR: 1244). They were separated by electrophoresis in denaturing gradient gels (DGGE). The fragmented DNAs were recovered by elution, amplified (338F / 518R and FirF: 369 / FirR: 1244), sequenced and analyzed phylogenetically. Results: The sequences amplified with universal primers, after the DNA fragmentation by DGGE were associated with Psychrobacter urativorans, Psychrobacter sp, Pseudomonas sp, Pseudoalteromonas sp, Shewanella sp, Shewanella baltica, Klebsiella oxytoca, Vibrio aestuarianus, Photobacterium sp, Flavobacterium sp, F. antarcticum, Bizionia sp, Flavobacteriaceae bacterium, Bacillus sp, C. divergens, Cetobacterium somerae, Psychrilyobacter atlanticus, Salinimicrobium sp as well as, Flavobacteriaceae not yet classified. In the sequences amplified with specific primers (Phylum Firmicutes) were identified: Carnobacterium sp, Lactococcus piscium Lactococcus sp, and Vagococcus sp Conclusion: The bacterial genus detected have been reported in samples from marine environments; therefore, can be part of the native microbial diversity associated with commercial O. maya captured in the Yucatan Peninsula, Mexico.
Por la situación climática de las últimas décadas, las normas internacionales que regulan a los materiales de construcción son cada vez más estrictas. Actualmente, el vidrio es uno de los materiales de construcción más utilizados a nivel global y existen normas para evaluar su rendimiento térmico y así conocer su eficiencia para ahorrar energía. El Coeficiente de Transferencia de Calor (U) y el Coeficiente de Ganancia de Calor Solar (CGCS) son los principales parámetros térmicos que se utilizan para verificar si el rendimiento del material es satisfactorio en función de las normas vigentes y el mercado de vidrios. Para determinar estos parámetros se hicieron pruebas al exterior con un calorímetro solar diseñado y desarrollado para este fin. En este trabajo se evaluaron cinco muestras de vidrio: una muestra de vidrio claro (referencia) y cuatro muestras con recubrimientos de ZnO:Cu y ZnO:Ag en distintas concentraciones y número de capas aplicadas, los cuales fueron desarrollados con el objetivo de reducir la ganancia de calor. Los resultados de la evaluación mostraron diferencias poco significativas entre la muestra de referencia y las muestras con recubrimientos. Por lo cual, se sugiere realizar modificaciones durante el desarrollo o la aplicación de los recubrimientos que permita mejorar las características de ganancia térmica. Due to the climatic situation of the last decades, the international standards that regulate construction materials are increasingly strict. Currently, glass is one of the most used building materials in the world, and there are standards to evaluate its thermal performance and thus know its efficiency to save energy. The Thermal Transmittance (U-value) and the Solar Heat Gain Coefficient (SHGC) are the main thermal parameters used to verify if the performance of the material is satisfactory according to current standards and the glass market. To determine these parameters, outdoor tests were carried out with a solar calorimeter designed and developed for this purpose. In this work, five glass samples were evaluated: one clear glass sample (reference) and four samples with ZnO: Cu and ZnO: Ag coatings in different concentrations and number of applied layers, which were developed to reduce heat gain. The results of the evaluation showed not very significant differences between the reference sample and the samples with coatings. Therefore, it is suggested to carry out modifications during the development or application of the coatings to improve the thermal gain characteristics.
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