Resumo: Polímeros de impressão molecular (Molecularly Imprinted Polymers, MIPs) foram sintetizados e aplicados como adsorventes na técnica de extração em fase sólida (EFS). O método de polimerização por precipitação foi usado para sintetizar os polímeros, devido à simplicidade de preparo, altos rendimentos e obtenção de partículas mais uniformes uma vez que o polímero não é triturado. Os MIPs foram sintetizados com ácido metacrílico como monômero funcional, trimetacrilato de trimetilolpropano como agente de reticulação e cloridrato de amilorida como molécula molde. O solvente de elevada polaridade empregado na síntese (THF:MeOH:H2O) possibilita empregar a técnica para moléculas polares como o cloridrato de amilorida. O controle no volume de solvente permitiu obter partículas maiores, de modo que a EFS foi realizada nas condições usuais, o que confere um potencial para aplicação dessa técnica de polimerização na preparação de adsorventes para EFS. Palavras-chave: Polímeros de impressão molecular (MIP), extração em fase sólida (EFS), polimerização por precipitação, cloridrato de amilorida. Molecularly Imprinted Polymers Prepared by Precipitation Polymerization and their Application to Solid Phase ExtractionAbstract: Molecularly imprinted polymers (MIPs) were synthesized and applied as adsorbents in the solid-phase extraction (SPE) technique. The polymers were synthesized by precipitation polymerization because of its simplicity, high yields and good control of final particle size. MIPs were synthesized using methacrylic acid as functional monomer, trimethylolpropane trimethacrylate as crosslinker and amiloride hydrochloride as template. The polar solvent mixture used (THF:MeOH:H 2 O) permitted polar molecules such as amiloride hydrochloride to be used. The solvent volume control allowed bigger particles to be formed, so that the solid-phase extraction technique could be employed under usual conditions, and therefore this polymerization technique is promising for preparing adsorbents for SPE.

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SummaryIn this work, the production of antimicrobial substances by strains of Pseudomonas sp. isolated from pasteurized milk and their potential action against food-related bacteria were investigated. Samples of pasteurized milk were purchased from arbitrarily chosen commercial establishments in the city of Rio de Janeiro, Brazil. Of the four samples analyzed, three presented several typical colonies of Pseudomonas. About 100 colonies were chosen and subjected to biochemical tests for confirmation of their identity. Eighteen strains of the Pseudomonas genus were identified and submitted to tests for the production of antimicrobial substances. Twelve strains (66.7%) were identified as Pseudomonas fluorescens, four (22.2%) as P. aeruginosa, one (5.5%) as P. mendocina and one (5.5%) as P. pseudoalcaligenes. Only two P. fluorescens strains were unable to produce any antimicrobial substance against any of the indicator strains tested. Most of the strains presented a broad spectrum of action, inhibiting reference and food-related strains such as Proteus vulgaris, Proteus mirabilis, Hafnia alvei, Yersinia enterocolitica, Escherichia coli and Salmonella typhi. Five antimicrobial substance-producing strains, which presented the broadest spectrum of action, were also tested against Staphylococcus aureus reference strains and 26 Staphylococcus sp. strains isolated from foods, some of which were resistant to antibiotics. The producer strains 8.1 and 8.3, both P. aeruginosa, were able to inhibit all the staphylococcal strains tested. The antimicrobial substances produced by strains 8.1 and 8.3 did not seem to be typical bacteriocins, since they were resistant to the three proteolytic enzymes tested. Experiments involving the characterization of these substances are being carried out in order to evaluate their biotechnological application.