Genetic barcoding of Ecuadorian epilithic diatom species suitable as water quality bioindicators.

Diatom identification is a key step in using these microorganisms as water quality bioindicators. Morphological diagnosis is a difficult task due to the enormous number of species and their microscopic size. This can be overcome using molecular tools to complement the diagnosis. The main goal of this work was to obtain the DNA barcode of Ecuadorian epilithic diatoms with a wide geographical distribution, a well-defined ecological range and characteristics that allow them to be reliable indicator species. Unialgal diatom cultures were obtained from environmental samples of Ecuadorian Andean streams. Morphological characterization of cultures was carried out under SEM microscopy. For molecular characterization, 18SV4 and rbcL barcodes were sequenced from each strain and blasted against a GenBank database. A phylogenetic tree for each barcode was constructed using the ML method including sequences of strains of the studied species from different geographical locations. The results showed the following five species to be suitable as bioindicators and these were isolated. Sellaphora seminulum (strain JA01b, c), Nitzschia fonticola (strain SP02a) and N. palea (strain CA01a) are tolerant to eutrophication; Eolimna minima (strain CH02a) is a mesotrophic water bioindicator, and Achnanthidium minutissimum (strain JA01a) is an oligotrophic water bioindicator. The comparison with the GenBank database of the barcoding regions supported the morphological identification. The barcoding sequences of the strains showed a high percentage of identity with the sequences reported in INSDC databases for the same species. The topology of the phylogenetic trees demonstrates that epilithic diatoms from Ecuador are closely related to those of same species isolated from other geographical regions. This study is a first attempt to establish a morphological and molecular taxonomic reference library for neotropical diatoms. This study demonstrates that it would be feasible to use the existing barcoding data for diatoms to develop molecular tools for the bioassessment of aquatic ecosystems in the Ecuadorian Andean region.

L'identification des diatomées est une étape clé dans l'utilisation de ces microorganismes comme bioindicateurs de la qualité de l'eau. Le diagnostic morphologique est une tâche difficile en raison du nombre considérable d'espèces et de leur dimension microscopique. Il est possible de surmonter cette difficulté en utilisant des techniques moléculaires pour compléter le diagnostic. L'objectif principal de ce travail était d'obtenir le code-barre de l'ADN des diatomées épilithiques équatoriennes ayant une large distribution géographique, une niche écologique bien définie et des caractéristiques leur permettant d'être des espèces indicatrices fiables. Des cultures de diatomées unialgales ont été obtenues à partir d'échantillons environnementaux de cours d'eau des Andes équatoriennes. La caractérisation morphologique des cultures a été réalisée sous microscopie MEB. Pour la caractérisation moléculaire, les codes-barres 18SV4 et rbcL ont été séquencés à partir de chaque souche et comparés à la base de données GenBank. Pour chaque code-barres, un arbre phylogénétique a été construit à partir de la méthode ML comprenant des séquences de souches des espèces étudiées, provenant de différents lieux géographiques. Les résultats ayant montré que les cinq espèces suivantes étaient appropriées comme bioindicateurs, elles ont été isolées. Sellaphora seminulum (souche JA01b, c), Nitzschia fonticola (souche SP02a) et N. palea (souche CA01a) sont tolérantes à l'eutrophisation ; Eolimna minima (souche CH02a) est un bioindicateur d'eau mésotrophe, et Achnanthidium minutissimum (souche JA01a) est un bioindicateur d'eau oligotrophe. La comparaison avec la base de données GenBank des régions de code-barres a supporté leurs identifications morphologiques. Les séquences de code-barres des souches ont montré un pourcentage élevé d'identité génétique avec les séquences signalées dans les bases de données de l'INSDC pour la même espèce. La topologie des arbres phylogénétiques démontre que les diatomées épilithiques de l'Équateur sont étroitement liées à celles des mêmes espèces isolées d'autres régions géographiques. Cette étude est une première tentative d'établir une bibliothèque de référence morphologique et taxonomique moléculaire pour les diatomées néotropicales. Cette étude démontre qu'il serait possible d'utiliser les données de code-barres existantes pour les diatomées afin de développer des instruments moléculaires pour la bioévaluation des écosystèmes aquatiques dans la région andine équatorienne.

Acute ecotoxicity and genotoxicity assessment of two wastewater treatment units.

Water contamination by discharge of untreated or poorly treated wastewater into water bodies is a current issue that may cause harm to humans. Water quality assessment targets general parameters, which often misleads to underestimation of their implication in the environment. Acute and genotoxicity assays using Daphnia magna is a reliable tool for testing deleterious effects of wastewater exposure. This paper aimed at evaluating acute ecotoxicity as well as genotoxicity of a biological treatment system composed by an anaerobic bioreactor (AR), algal turf scrubber (ATS), followed by two downflow constructed wetlands (CW). The university's wastewater treatment plant (WWTP) composed by an equalization tank (ET), an upflow anaerobic sludge blanket (UASB), followed by an aerobic bioreactor (AB) was also assessed for acute and genotoxicity. Our results showed the acute ecotoxicity ranged from moderately to extremely toxic, and from nontoxic to moderately toxic for ET and AB. For AR, most samples were moderately toxic. The outflow from ATS and CW's tanks completely eliminated acute toxicity and genotoxicity evidencing that the proposed system combining ATS and vertical CWs is suitable for treating sanitary wastewater.

Algae turf scrubber and vertical constructed wetlands combined system for decentralized secondary wastewater treatment.

Water shortage is a current problem faced by many regions. The deterioration of water bodies driven by the directly discard of untreated wastewater worsens the water shortage and implies in more costly treatments to meet local standards for water quality. In rural areas, the problem is even worse, once conventional centralized treatment plants do not encompass them. Decentralized treatment systems must present low-cost, local availability, standards-meeting efficiency, and simplified operation. The present study examines the combined use of algae turf scrubber and down-flow vertical constructed wetlands for a University's sanitary wastewater treatment. After a hydraulic detention time of 21 days, the unit was able to reach 49%, 48%, 98%, 82%, 99.2%, 70.1%, 44%, 83%, 72%, 86%, 69%, 95%, and 99.9% for conductivity, total soluble solids, turbidity, apparent color, N-NH3, total nitrogen, P-soluble, total carbon, chemical oxygen demand, inorganic carbon, TOC, Escherichia coli, and total coliforms. In accord to the Brazilian standard ABNT 13969/97, the treated effluent is eligible for reuse in floor and sidewalks washing, garden irrigation, and landscaping purposes.

Prevalência de contaminação bacteriana em estetoscópios / Prevalence of bacteria contamination on stethoscopes

O estetoscópio é um dos instrumentos mais utilizados por médicos e enfermeiros para realizar exameclínico de pacientes e esse aparelho pode atuar como veículo de transmissão de micro-organismos. Nestetrabalho, foi avaliada a prevalência da contaminação bacteriana em estetoscópios utilizados em diferentesunidades de saúde em Santa Cruz do Sul - RS, nas práticas de limpeza utilizadas pelos usuários, bemcomo o grau de informação dos profissionais sobre os procedimentos de limpeza. Foi realizado estudoobservacional, transversal e analítico em 2011, foram analisados 81 estetoscópios usados em unidadesbásicas de saúde e unidades de terapia intensiva, pediátricos e adultos, e um questionário foi aplicado.Dos 81 estetoscópios, 96,2 % estavam contaminados e Staphylococcus aureus foi o micro-organismo maisfrequentemente detectado; 55,2 % dos profissionais afirmaram que realizam a desinfecção de estetoscópios,sendo 58,8 % médicos e 52,3 % profissionais de enfermagem. Ademais, 85,7 % dos funcionários daenfermagem e 64,7 % dos médicos afirmaram que não receberam orientação por parte de instituições emque trabalham sobre os procedimentos para a limpeza dos estetoscópios. A significativa prevalência decontaminação bacteriana detectada nos estetoscópios analisados (96,2 %) demonstra a existência de riscopotencial de contaminação cruzada de infecções nosocomiais.