This work aimed to study the partitioning of a lipase produced by Burkholderia cepacia in PEG/Phosphate aqueous two phase system (ATPS) and its characterization. Lipase was produced by B. cepacia strains in a fermenter. Enzyme partitioning occurred at pH 6.0 and 8.0, using PEG 1500 and 6000 on two tie lines. Metal ions, pH and temperature effects on enzyme activity were evaluated. Five milliliter of 7.5% olive oil emulsion with 2.5% gumarabic in 0.1M sodium phosphate buffer at pH 8.0 and 37ºC were used for the activity determinations. Results showed that crude stratum from B. cepacia was partitioned by PEG1500/phosphate ATPS at pH 6.0 or 8.0 for, which the partitioning coefficients were 108-and 209-folds. Lipase presented optimal activity conditions at 37 o C and pH 8.0; it showed pH-stability for 4 h of incubation at different pH values at 37 o C. Metal ions such as Mn 2+ , Co 2+ , Iand Ca 2+ sustained enzymatic activities; however, it was inhibited by the presence of Fe 2+ , Hg 2+ and Al 3+. K m and V max values were 0.258 U/mg and 43.90 g/L, respectively. A molecular weight of 33 kDa and an isoelectric point at pH 5.0 were determined by SDS-PAGE and IFS electrophoresis, respectively.

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Abstract:In this work, an investigation was made of the modification of film surface of Poly(methylmethacrylate) (PMMA) using the plasma polymerization technique. PMMA films 10 µm thick were obtained by Spin-Coating starting from a chloroform solution (15.36% w/w). The films were exposed to the plasma of CHF 3 at different gas pressures and exposure times to increase the thickness of fluorinated polymers onto PMMA films. The plasma fluorinated optical films were characterized by gravimetry, FTIR-ATR, contact angle of wetting, SEM and AFM. The surface fluorination of PMMA films can be inferred by the increase in contact angle under all experimental conditions, and confirmed with FTIR-ATR analysis. Gravimetry showed an increase of the fluorinated polymer layer over PMMA films, being 1.55 µm thick at 0.7 torr and 40 minutes of plasma exposure. The SEM analysis showed a well-defined layer of fluorinated polymer, with fluorine being detected in the EDS analysis. The film roughness for the fluorinated polymers was around of 200 Å, quite satisfactory for a 1.55 µm cladding.

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Sistemas bifásicos aquosos têm sido muito utilizados, em pesquisas, na separação e purificação de biomoléculas. São formados pela mistura de dois polímeros hidrofílicos, ou de um polímero e um sal. O objetivo principal deste trabalho foi caracterizar um sistema bifásico aquoso (SBA) a partir da preparação de soluções estoques de PEG com massas molares de 1500, 4000 e 6000 e tampões fosfato variando de 6 a 8, em condições normais. Nos diagramas de fases PEG/fosfato, foi observado um deslocamento da binodal para os valores de menores concentrações dos polímeros e com o aumento do peso molecular do PEG. Por outro lado, a variação do pH não mostrou um deslocamento significativo da binodal. Em relação às linhas de amarração, os valores das composições não se alteram muito, mesmo quando os polímeros são comparados entre si e a diferentes pHs.

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