38 research outputs found

    Parâmetros reacionais para a síntese enzimática do butirato de butila em solventes orgânicos Reactional parameters for enzymatic synthesis of butyl butyrate in organic solvent

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    A síntese orgânica catalisada por enzimas envolve um mecanismo complexo dependente do tipo de substrato, enzima, solvente orgânico e teor de água no meio reacional. Neste trabalho foi estudado a influência de alguns desses parâmetros no rendimento da esterificação do butanol com ácido butírico, utilizando uma preparação enzimática comercial de lipase. A polaridade e natureza do solvente, bem como a razão molar entre o butanol e ácido butírico, foram considerados os fatores que mais influenciaram o desenvolvimento dessa síntese enzimática.<br>The organic synthesis catalyzed by enzymes is a complex function of substrate concentration, water concentration in the liquid phase, enzyme and organic solvent properties. In this work the influence of some parameters on the esterification of butanol with butyric acid was investigated, using a commercial lipase preparation. The polarity and nature of the solvent and also the substrate mole ratios played an important role in the performance of this enzymatic synthesis

    USO DE SÍLICAS MODIFICADAS PARA IMOBILIZAÇÃO DE LIPASES

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    Enzyme-support strategies are increasingly replacing conventional chemical methods in both laboratories and industries with attributes including efficiency, higher performance and multifarious use, where silica surfaces show potential due to the chemical bonds based on the presence of hydroxyl groups which can be modified with different additives. Surface-modified silica is a novel class of materials capable of improving enzyme stability and reusability that can be applied to support several immobilization techniques. This review describes the use of innovative modified supports to improve the state of enzyme immobilization and provide the industrial sector with new perspectives

    Efeito do polietilenoglicol e da albumina na imobilização de lipase microbiana e na catálise em meio orgânico Effect of poly (ethylene) glycol and albumin on the immobilization of microbial lipase and catalysis and catalysis in organic media

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    <abstract language="eng">Poly (ethylene) glycol (PEG) and bovine serum albumin (BSA), as additive agents, were used to enhance the activity of immobilized microbial lipase in organic solvent. Controlled pore silica (CPS) was selected as matrix and different immobilization procedures were evaluated: directly lipase binding on CPS and simultaneous addition of lipase and additive agent on the same support. The highest coupling yield (59.6%) was attained when the immobilization procedure was performed at lipase loading of 150 U/g support in the presence of PEG-1.500. This immobilized system was used in esterification reactions under repeated batch cycles and the biocatalyst half-life was found to increase 2.7 times when compared with the control

    Sequential production of amylolytic and lipolytic enzymes by bacterium strain isolated from petroleum contaminated soil

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    Amylases and lipases are highly demanded industrial enzymes in various sectors such as food, pharmaceuticals, textiles, and detergents. Amylases are of ubiquitous occurrence and hold the maximum market share of enzyme sales. Lipases are the most versatile biocatalyst and bring about a range of bioconversion reactions such as hydrolysis, inter-esterification, esterification, alcoholysis, acidolysis, and aminolysis. The objective of this work was to study the feasibility for amylolitic and lipolytic production using a bacterium strain isolated from petroleum contaminated soil in the same submerged fermentation. This was a sequential process based on starch and vegetable oils feedstocks. Run were performed in batchwise using 2% starch supplemented with suitable nutrients and different vegetable oils as a lipase inducers. Fermentation conditions were pH 5.0; 30 degrees C, and stirred speed (200 rpm). Maxima activities for amyloglucosidase and lipase were, respectively, 0.18 and 1,150 U/ml. These results showed a promising methodology to obtain both enzymes using industrial waste resources containing vegetable oils

    Influence of gelation time on the morphological and physico-chemical properties of the sol-gel entrapped lipase

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    Different gelation times (4, 18, 24 and 48 h) were used for the preparation of silica sol-gel supports and encapsulated Candida rugosa lipase using tetraethoxysilane (TEOS) as precursor. The hydrophobic matrices and immobilized lipases produced were characterized with regard to pore volume and size by nitrogen adsorption (BJH method), weight loss upon heating (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), chemical composition (FTIR) and percentage of hydrolysis (POH%) of olive oil. These structural parameters were found to change with the gelation time, but no direct relation was found between the percentage of oil hydrolysis (POH%) and the gelation time. The best combination of high thermal stability and high POH% (99.5%) occurred for encapsulated lipase produced with 24 h gelation time. (C) 2007 Elsevier B.V. All rights reserved

    Simple screening method to identify toxic/non-toxic ionic liquids: agar diffusion test adaptation

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    A wide range of ionic liquids (ILs), containing a diverse set of cations, anions and alkyl chain lengths, was screened for their antimicrobial activity toward four microorganisms, Escherichia coli CCT-0355, Staphylococcus aureus ATCC-6533, Fusarium sp. LM03 and Candida albicans ATCC-76645. For that purpose an adaptation of the Agar Diffusion test was validated and successfully applied as a rapid screen method to identify toxic ILs, avoiding the use of more complex and expensive techniques. The effects of the cation alkyl chain length were studied, being observed both the "alkyl side chain" effect (increase in antimicrobial activity with the elongation of the alkyl chain) and "cut-off" effect (beyond a given chain length, the toxicity cannot be increased any further). Imidazolium-based ILs have in general, negative effects on the growth of these microorganisms dependent on the anion and alkyl chain length (growth inhibition halo from 1.98±0.04 mm for [C(2)mim]Cl to 39.53±0.81 mm for [C(10)mim]Cl). On the opposite, the phosphonium-based ILs do not seem to have negative effects for the longest alkyl chains (growth inhibition halos between 0.00±0.00 and 7.30±0.42 mm). It was also observed that the alkyl chain, cation family, and anion moiety all have significant effects on the antimicrobial activity these effects being well correlated with the lipophilicity of the ILs tested. The results also show that the microorganisms responses to the diverse ILs tested are dependent on their morphologic differences.publishe

    Lipase purification using ionic liquids as adjuvants in aqueous two-phase systems

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    Aqueous two-phase systems (ATPS) are efficient, environmentally friendly, an

    Aqueous two-phase systems based on cholinium salts and tetrahydrofuran and their use for lipase purification

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    Aqueous two phase systems (ATPS) formed with cholinium based ionic liquid ILs (or salts) are a novel, low cost, and high efficient technique for the recovery of biomolecules. This study examines the formation of ATPS based on cholinium based salts (cholinium chloride, cholinium bitartrate and cholinium dihydrogencitrate) and tetrahydrofuran (THF) for the purification of lipase from Bacillus sp. ITP 001, produced by submerged fermentation. The optimum conditions for this purification were determined to be 40 wt% of THF and 30 wt% of cholinium bitartrate at 25 C. A purification factor of 130.1 ± 11.7 fold, a lipase yield of 90.0 ± 0.7% and a partition coefficient of enzyme for IL rich phase (KE 0.11 ± 0.01) and protein contaminants for THF rich phase (KP 1.16 ± 0.1) were achieved

    Novel aqueous two-phase systems based on tetrahydrofuran and potassium phosphate buffer for purification of lipase

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    Aqueous two-phase systems (ATPS) based on tetrahydrofuran (THF) + potassium phosphate buffer (pH 7) were used in this work for the purification of lipases. Binodal curve, tie lines and critical point were obtained for the new THF-salt ATPS at 25 degrees C and the binodal curve were successfully correlated with the Merchuck and Hu equations. To optimize the extraction capability of this ATPS the effects of the concentration of components and temperature of equilibrium on the partition coefficients and extraction efficiencies were investigated using lipase from Burkholderia cepacia (commercially obtained) as a model compound. The optimum conditions for the purification of an extracellular lipase obtained by submerged fermentation were established through a surface response analysis by central composite rotational design applied allowing a purification factor (PF) of 103.9 +/- 0.9 and an enzyme recovery of 96.4 +/- 1.1 achieved using this process. Moreover, a commercial lipase by Candida antarctica B recombinant in Aspergillus niger was purified (PF= 4.84 +/- 0.24), confirming the potential of this new THF-based ATPS for purifying lipases. (C) 2015 Elsevier Ltd. All rights reserved
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