This study represents the first analysis of the bacterioplankton community structure from a freshwater reservoir of Argentina using amplification of the entire 16S rDNA gene. It includes the description and the phylogenetic relationships of the bacterioplankton community from the photic and aphotic layers of the Río III Reservoir in Córdoba, Argentina. The classical ecological approach indicated that the photic layer had greater diversity whereas the aphotic layer had a better distribution of species and higher abundance. Nevertheless, when the microbial communities in both layers were compared using phylogenetic information, this analysis indicated that both environments were similar and that neither was enriched for any particular lineage. The phyla present in the Río III reservoir were Acidobacteria, Actinobacteria, and Proteobacteria and the 2 dominant species in both layers were "Candidatus Planktophila sp." (class Actinobacteria) and Polynucleobacter sp. (class Betaproteobacteria).

Este estudio constituye el primer análisis de la estructura de la comunidad del bacterioplancton en un reservorio de agua dulce de Argentina utilizando amplificación completa del gen ADNr 16S. Incluye las relaciones filogenéticas y una descripción del bacterioplacton de las zonas fótica y afótica del Embalse Río III, Córdoba, Argentina. El análisis ecológico clásico indicó que la zona fótica tenía mayor diversidad, mientras que la afótica tenía mayor abundancia y una distribución más uniforme de especies. Sin embargo, cuando se utilizó la información filogenética para comparar las comunidades microbianas de ambas zonas, este análisis indicó que ambos ambientes eran similares y que en ninguno predominaba algún linaje en particular. Los phyla identificados en el Embalse del Río III fueron Acidobacteria, Actinobacteria y Proteobacteria. Las especies dominantes en ambas zonas fueron "Candidatus Planktophila sp." (clase Actinobacteria) y Polynucleobacter sp. (clase Betaproteobacteria).

The purpose of this study was to investigate the genotypes of Giardia lamblia from human and animal feces and their epidemiological and clinical characteristics in Argentina, South America. Seventy isolates, 60 from humans (adults and children), eight from dogs and two from cows were processed by polymerase chain reaction-restriction fragment length polymorphism. Data corresponding to demographic, socio-cultural and environmental variables and presence/absence of signs/symptoms were collected. The triosephosphate isomerase gene was amplified from 43 (71.66%) of the 60 human fecal samples. Among these, 3/43 (6.98%) were genotype AII and 40/43 (93.02%) were genotype B. Assemblage AII was detected in three children who lived together in a shantytown and they were oligosymptomatic and none had diarrhea. This genotype was not found in animals. Genotype B showed a high prevalence in both adults and children. It was also found in polysymptomatic people, many of whom presented diarrhea. It was also found only in one dog. The present study represents the first contribution to the knowledge of G. lamblia genotypes in Argentina.

The efficiency of lysis procedures and DNA purification treatments of Giardia lamblia trophozoites were evaluated regarding the breaking-up efficiency, quantity and pureness of DNA, processing time and costs. Five lysis methods (distilled water and heating; distilled water, heating and proteinase K; buffer D Lysis; buffer E lysis, and commercial kit), and three DNA purification methods (phenol:chloroform:isoamilic, Chelex 100 and commercial kit) were tested. The obtained data were statistically analyzed. The buffer E lysis and Chelex combination was simple and economic method which produced high DNA performance with low pureness. Commercial kit was simple and expensive method which generated low yields of DNA with appropriate purity level for molecular analysis

Se evaluó la eficiencia de procedimientos de lisis y tratamientos de extracción de ADN de trofozoítos de Giardia lamblia respecto a la eficiencia de ruptura, cantidad y pureza de ADN, además de los tiempos de procesamiento y costos. Se testearon cinco métodos de lisis (agua destilada y calor; agua destilada, calor y proteinasa K; buffer de lisis D; buffer de lisis E y un kit comercial) y tres métodos de purificación de ADN (fenol:cloroformo: isoamílico; Chelex 100 y un kit comercial). Los datos obtenidos se analizaron estadísticamente. La combinación de buffer de lisis E y Chelex fue un método simple y económico, que produjo alto rendimiento de ADN con baja pureza. Ella técnica comercial fue un método simple, más costoso que produjo bajas cantidades de ADN con un nivel de pureza apropiado para estudios moleculares