RESUMO
We describe the preparation of a membrane composed of polypyrrole-polystyrene (PPy-PS) and its application in DNA extraction. We adopted the electrospinning technique to prepare polystyrene (PS) membranes, which we used as substrates for incorporating polypyrrole chains through an in situ chemical procedure. As a model system, we initially investigated the use of PPy-PS membranes for the extraction of salmon sperm DNA from aqueous solutions. These studies have shown that the PPy-PS membrane has a maximum adsorption capacity of 236.0 mg of DNA per gram of PPy after 30 min of exposure to a DNA solution (100 mg/L). We incorporated the PPy-PS membranes into centrifugation columns, which we used to carry out experiments for extracting and purification of DNA from curly lettuce leaves. The protocol was initially optimized by first examining the most appropriate concentration of the three components of the lysis buffer (Tris/HCl, NaCl, and EDTA-Na). We then investigated the most adequate volumes of the concentrated surfactant solution (SDS 20%) and that used in the protein and polysaccharide precipitation step (5 M potassium acetate, pH 6.3), factors that directly influence the quality and quantity of the fraction of DNA obtained. For curly lettuce leaves, both in their mature and young stages, the yield and purity of the DNA purified using the PPy-PS membrane were comparable to those obtained using a commercial kit. In both cases, the collected DNA samples presented excellent integrity and quality. These results are suggestive that these composite membranes are competitive with the commercial kits available for the extraction and purification of DNA from plants.
RESUMO
Existem poucas pesquisas sobre as práticas de fiscalização sanitária na cadeia de produção de hortaliças até o consumidor, especialmente os que são ingeridos crus, pois são passiveis de veicular microorganismo como bactérias, parasitos e fungos, contribuindo para possíveis malefícios à saúde. O objetivo deste trabalho foi verificar qualitativamente a contaminação por parasitos e/ou comensais de interesse médico em folhas de alface (Lactuca sativa) in natura comercializadas no município de Quatá, São Paulo. Um total de 15 amostras foi analisado aleatoriamente em dias alternados nos três diferentes locais que comercializam hortaliças (quitanda, supermercado e a horta comunitária) durante o mês de maio de 2011. Os parasitos e/ou comensais encontrados nas alfaces foram Entamoeba coli (67%), Entamoeba histolytica (20%), Giardia sp (13%) e Ascaris lumbricoides (7%). A análise mostrou a presença de parasitos e/ou comensais em todas as amostras, exceto nas cultivadas na horta o que evidenciou más condições sanitárias, provavelmente pela contaminação no transporte e manuseio por terceiros no supermercado e na quitanda. O monitoramento parasitário das condições higiênicas de hortaliças comercializadas em ambientes urbanos torna-se relevante para tomada de medidas preventivas evitando a continuidade do ciclo parasitário e possíveis complicações futuras à saúde.
There is little research on the practices of sanitary inspection in the chain of production of vegetables to the consumer, especially those eaten raw, they are liable to serve microorganism such as bacteria, fungi and parasites, contributing to possible health hazards. The aim of this study was to assess qualitatively contamination by parasites and / or commensals of medical interest in lettuce leaves (Lactuca sativa) "fresh" market in the municipality of Quatá, São Paulo. A total of 15 random samples were analyzed every other day of the three different places that sell vegetables a grocery store, a supermarket and a vegetable garden during the month of May 2011. The parasites and / or commensals found in lettuce were Entamoeba coli (67%), Entamoeba histolytica (20%), Giardia sp (13%) and Ascaris lumbricoides (7%). The analysis showed the presence of parasites and / or commensals in all samples, except in the cultivated garden which showed poor sanitary conditions, probably due to contamination in the shipping and handling by third parties in supermarket and grocery store. The parasite monitoring sanitary conditions of vegetables sold in urban environments becomes relevant for preventive measures to avoid the continued parasitic cycle and possible future health complications.