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Search Results: 1 - 10 of 4753 matches for " Sonia Couri "
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Correlation between Agar Plate Screening and Solid-State Fermentation for the Prediction of Cellulase Production by Trichoderma Strains
Camila Florencio,Sonia Couri,Cristiane Sanchez Farinas
Enzyme Research , 2012, DOI: 10.1155/2012/793708
Abstract: The viability of converting biomass into biofuels and chemicals still requires further development towards the reduction of the enzyme production costs. Thus, there is a growing demand for the development of efficient procedures for selection of cellulase-producing microorganisms. This work correlates qualitative screening using agar plate assays with quantitative measurements of cellulase production during cultivation under solid-state fermentation (SSF). The initial screening step consisted of observation of the growth of 78 preselected strains of the genus Trichoderma on plates, using microcrystalline cellulose as carbon source. The 49 strains that were able to grow on this substrate were then subjected to a second screening step using the Congo red test. From this test it was possible to select 10 strains that presented the highest enzymatic indices (EI), with values ranging from 1.51 to 1.90. SSF cultivations using sugarcane bagasse and wheat bran as substrates were performed using selected strains. The CG 104NH strain presented the highest EGase activity (25.93?UI·g?1). The EI results obtained in the screening procedure using plates were compared with cellulase production under SSF. A correlation coefficient ( ) of 0.977 was obtained between the Congo red test and SSF, demonstrating that the two methodologies were in good agreement. 1. Introduction Cellulolytic microorganisms play an important role in the biosphere by recycling cellulose, the most abundant renewable carbohydrate produced by plants through the mechanism of photosynthesis [1]. In order to perform this task, these microorganisms have evolved a variety of strategies to attack the cell wall components, and therefore possess a comprehensive enzymatic arsenal that is able to degrade plant biomass. These enzymatic cocktails are often optimized according to the substrate and contain a mixture of cellulases, hemicellulases, pectinases, ligninases, and other accessory enzymes that act synchronously and synergistically in the degradation process [2]. Given the advantages of the enzymatic route in the bioconversion of biomass into fuels, there is an increasing demand for more effective enzymatic cocktails that could help to reduce the costs of cellulosic ethanol production. Among a large number of nonpathogenic microorganisms capable of producing useful enzymes, filamentous fungi are particularly interesting due to their high production of extracellular enzymes [3]. Members of the Trichoderma genus are especially notable for their high enzymatic productivity. Around 100 different Trichoderma
Purification and characterisation of an extracellular phytase from Aspergillus niger 11T53A9
Greiner, Ralf;Silva, Lucineia Gomes da;Couri, Sonia;
Brazilian Journal of Microbiology , 2009, DOI: 10.1590/S1517-83822009000400010
Abstract: an extracellular phytase from aspergillus niger 11t53a9 was purified about 51-fold to apparent homogeneity with a recovery of 20.3% referred to the phytase activity in the crude extract. purification was achieved by ammonium sulphate precipitation, ion chromataography and gel filtration. the purified enzyme behaved as a monomeric protein with a molecular mass of about 85 kda and exhibited maximal phytate-degrading activity at ph 5.0. optimum temperature for the degradation of phytate was 55°c. the kinetic parameters for the hydrolysis of sodium phytate were determined to be km = 54 μmol l-1 and kcat = 190 sec-1 at ph 5.0 and 37°c. the purified enzyme was rather specific for phytate dephosphorylation. it was shown that the phytase preferably dephosphorylates myo-inositol hexakisphosphate in a stereospecific way by sequential removal of phosphate groups via d-ins(1,2,4,5,6)p5, d-ins(1,2,5,6)p4, d-ins(1,2,6)p3, d-ins(1,2)p2 to finally ins(2)p.
Enzymatic technology to improve oil extraction from Caryocar brasiliense camb. (Pequi) Pulp.
Mariano, Renata Gomes de Brito;Couri, Sonia;Freitas, Suely Pereira;
Revista Brasileira de Fruticultura , 2009, DOI: 10.1590/S0100-29452009000300003
Abstract: the present study aims to compare yield and quality of pequi pulp oil when applying two distinct processes: in the first, pulp drying in a tray dryer at 60oc was combined with enzymatic treatment and pressing to oil extraction; in the second, a simple process was carried out by combining sun-drying pulp and pressing. in this study, raw pequi fruits were collected in mato grosso state, brazil. the fruits were autoclaved at 121oc and stored under refrigeration. an enzymatic extract with pectinase and cmcase activities was used for hydrolysis of pequi pulp, prior to oil extraction. the oil extractions were carried out by hydraulic pressing, with or without enzymatic incubation. the oil content in the pequi pulp (45% w/w) and the physicochemical characteristic of the oil was determined according to standard analytical methods. free fatty acids, peroxide values, iodine and saponification indices were respectively 1.46 mgkoh/g, 2.98 meq/kg, 49.13 and 189.40. the acidity and peroxide values were lower than the obtained values in commercial oil samples, respectively 2.48 mgkoh/g and 5.22 meq/kg. aqueous extraction has presented lower efficiency and higher oxidation of unsaturated fatty acids. on the other hand, pequi pulp pressing at room temperature has produced better quality oil. however its efficiency is still smaller than the combined enzymatic treatment and pressing process. this combined process promotes cellular wall hydrolysis and pulp viscosity reduction, contributing to at least 20% of oil yield increase by pressing.
Selection of tannase-producing Aspergillus niger strains
Pinto, Gustavo A.S.;Leite, Selma G.F.;Terzi, Selma C.;Couri, Sonia;
Brazilian Journal of Microbiology , 2001, DOI: 10.1590/S1517-83822001000100006
Abstract: the aim of this work was to select strains of aspergillus niger for tannase production. growth of colonies in plates with tannic acid-containing medium indicated their ability to synthesize tannase. tannase activity was also measured in solid-state fermentation. a. niger 11t25a5 was the best tannase producer (67.5 u.g-1/72 hours of fermentation).
Efeito de enzimas hidrolíticas no comportamento reológico do óleo de palma cru
FREITAS, Suely P.;SILVA, Fernando C.;LAGO, Regina C.A.;COURI, Sonia;
Ciência e Tecnologia de Alimentos , 1998, DOI: 10.1590/S0101-20611998000100026
Abstract: in conventional extraction of palm oil, a substantial loss of product occurs in the stages of the fruit pressing and clarification of the "crude" oil. the high viscosity of "crude" oil is the main factor that affects the separation of the oil from the other components in the mixture. this is usually overcome by the addition of water in the clarification stage. this work addresses the study of the influence of dilution and enzymatic treatments on the rheological behaviour of crude oil. data obtained were found to be useful for determining the separation velocities in the clarification and centrifugation stages. the palm oil employed in this work was supplied by a commercial plant and had the following composition: water (65%), oil (30%) and solids (5%). this feed was enzymatically hydrolysed at 60°c using a commercial enzyme (viscozyme) and a laboratory enzyme preparation. for a fix shear rate of 6s-1, the enzymatic treatment decreased the viscosity in about 29 % while with the addition of 20% of water the viscosity reduction was 35%. the combined effect of enzymatic and dilution treatments leads to viscosity reduction of 75 % approximately.
Composi??o em ácidos graxos do óleo da polpa de a?aí extraído com enzimas e com hexano
Nascimento, Rhutynéia Joana Silva do;Couri, Sonia;Antoniassi, Rosemar;Freitas, Suely Pereira;
Revista Brasileira de Fruticultura , 2008, DOI: 10.1590/S0100-29452008000200040
Abstract: a?aí (euterpe oleracea martius) is a typical palm tree from the amazon, growing spontaneously in states of pará, amazonas, amapá and maranh?o. it has been highlighted by the potential of its products, especially because of the economic importance for the regional fruit growing. the a?aí fruits are very appreciated by their pulp flavour. in the a?aí pulp, there is a significant amount of lipids, around 53%, in a dry basis, turning out to be an excellent source of essential fatty acids. the main purpose of the present work was to establish the fatty acid content in the lipid fraction of a?aí pulp using high resolution gaseous chromatography. the a?aí oil was obtained by enzymatic technology in water has been indicated as an alternative for vegetable oils extraction from pulp of fruits. a significant difference was not observed in the composition of the fatty acids present in a?aí oil obtained from either process. in both cases, the oil is high in monounsaturated fatty acids (68% to 71%) and in polyunsaturated fatty acids (7.8% to 10.6%).
Selection of tannase-producing Aspergillus niger strains
Pinto Gustavo A.S.,Leite Selma G.F.,Terzi Selma C.,Couri Sonia
Brazilian Journal of Microbiology , 2001,
Abstract: The aim of this work was to select strains of Aspergillus niger for tannase production. Growth of colonies in plates with tannic acid-containing medium indicated their ability to synthesize tannase. Tannase activity was also measured in solid-state fermentation. A. niger 11T25A5 was the best tannase producer (67.5 U.g-1/72 hours of fermentation).
Efeito de enzimas hidrolíticas no comportamento reológico do óleo de palma cru
FREITAS Suely P.,SILVA Fernando C.,LAGO Regina C.A.,COURI Sonia
Ciência e Tecnologia de Alimentos , 1998,
Abstract: No processamento tradicional de extra o de óleo de palma, uma quantidade substancial do produto é perdida na fibra - durante a etapa de prensagem do fruto - e na borra - durante a etapa de clarifica o do óleo cru. A viscosidade deste constitui a principal dificuldade de separa o do óleo dos demais componentes da mistura. A eficiência de recupera o do óleo é usualmente melhorada por adi o de água, no tanque de clarifica o. Neste trabalho avaliou-se os efeitos da dilui o e do tratamento enzimático no comportamento reológico do óleo de palma cru. Estes dados s o importantes para estimar a velocidade de separa o do óleo nos tanques de clarifica o e/ou nos decanters das usinas comerciais. O óleo cru utilizado neste estudo foi recolhido em uma unidade comercial sendo composto de 65% de água, 30% de óleo e 5% de sólidos. A hidrólise enzimática foi conduzida usando como agentes hidrolisantes uma enzima comercial (viscozyme) da Novo Nordisk e um preparado enzimático produzido no CTAA. Pode-se constatar que quanto mais diluída a amostra maior é a redu o na viscosidade após a hidrólise enzimática. Para uma taxa de deforma o fixa em 6s-1, o tratamento enzimático do óleo cru a 60°C reduziu a viscosidade do mesmo em cerca de 29% enquanto a adi o de 20% de água em cerca de 35%. A combina o da dilui o com 20% de água seguida de tratamento enzimático reduziu a viscosidade do óleo cru em cerca de 75%.
Produ??o de celulases por Aspergillus niger por fermenta??o em estado sólido
Rodríguez-Zú?iga, Ursula Fabiola;Farinas, Cristiane Sanchez;Bertucci Neto, Victor;Couri, Sonia;Crestana, Silvio;
Pesquisa Agropecuária Brasileira , 2011, DOI: 10.1590/S0100-204X2011000800018
Abstract: the objective of this work was to evaluate cellulase enzyme production by the filamentous fungus aspergillus niger by solid-state fermentation of different substrates. the solid substrates sugarcane bagasse, wheat bran, soybean meal, and their mixtures were evaluated. the effects of substrate moisture contents (60, 70, and 80% in humid basis) and of the supplementation with culture media: sucrose, basic mandels & weber, modified mandels & weber, with the addition of carboxymethyl cellulose, and czapeck dox, were evaluated in substrate with 90% bagasse and 10% soybean meal. the highest total cellulose and endoglucanase activities, in wheat bran, were obtained after 72 hours: 0.4 and 21.0 iu g-1, respectively. there was an expressive increase in enzymatic activities as the proportion of bran in the substrate increased, in comparison to fermentation with sugarcane bagasse only. the 50% moisture content was insufficient to fully hydrate sugarcane bagasse, and the ideal humidity varies according to the medium used for supplementation and is between 70 and 80%. the modified mandels &weber medium shows the best result as an inductor of enzymatic activity.
Discrimina??o entre estádios de matura??o e tipos de processamento de pós-colheita de cafés arábica por microextra??o em fase sólida e análise de componentes principais
Arruda, Neusa P.;Hovell, Ana M. C.;Rezende, Claudia M.;Freitas, Suely P.;Couri, Sonia;Bizzo, Humberto R.;
Química Nova , 2011, DOI: 10.1590/S0100-40422011000500017
Abstract: a fruit chemical composition reflects its maturation stage. for coffee, it is also the reflex of the post-harvesting processing type, dry, semi-wet and wet. the object of this work was to verify if headspace solid phase microextraction coupled to gas chromatography (hs-spme-gc) could be used to discriminate between samples harvested in different maturation stages and treated by different processes. with application of principal component analysis to the area of 117 compounds extracted by spme, using divinylbenzene/carboxen/polydimethylsiloxane fiber, it was possible to discriminate, in the roasted and ground coffee, the maturity stage and processing type used .
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