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Caracterização de lacase de Peniophora cinerea e estudo do potencial de aplicação biotecnológica; Characterization of Peniophora cinerea laccase and study of the potential for biotechnological applications

Moreira Neto, Sergio Luiz
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 16/03/2012 PT
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No presente estudo, fungos ligninolíticos isolados de ecossistemas brasileiros foram avaliados quanto a capacidade de descolorir corantes reativos e, a linhagem Peniophora cinerea, selecionada, teve seu sistema ligninolítico caracterizado. As lacases deste fungo foram avaliadas para duas aplicações: descoloração de efluentes têxteis e auxílio na hidrólise enzimática do bagaço de cana-de-açúcar. Lacase foi a única enzima ligninolítica extracelular detectada nos culivos de P. cinerea. A produção de lacase por P. cinerea foi avaliada em meios sintético e complexo, de forma a obter melhores níveis de produção da enzima. Em meio complexo (milhocina 0,5%, sacarose 0,5% e cobre como indutor de lacase) P. cinerea produziu cerca de aproximadamente 1000 U/l de lacase. Em meio sintético, contendo xilidina e tween 80, P. cinerea imobilizado (em esponja de poliuretano) produziu 3505 U/l de lacase em cultivo em Erlenmeyer e somente 150 U/l em reator de tanque com agitação por pás. Lacases produzidas por P. cinerea foram purificadas e caracterizadas. O sobrenadante do meio de cultivo foi aplicado em coluna de troca aniônica, DEAE-Sepharose CL-6B, e três picos com atividade de lacase foram observados e aplicados separadamente em Mono Q (coluna de troca aniônica). Oito isoenzimas de lacase...

Kinetic role of a histidine residue in the T1 copper site of the laccase from Rigidoporus lignosus

Vianello, Fabio; Miotto, Giovanni; Cambria, Maria Teresa; Lima, Giuseppina P. P.; Vanzani, Paola; Di Paolo, Maria Luisa
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 34-42
ENG
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Laccases (benzendiol:oxygen oxidoreductases; EC 1.10.3.2) catalyze the oxidation of a broad range of substrates, such as polyphenols, dyes and pollutants, and thus these enzymes are widely applied in industrial, biotechnological and environmental fields. In order to improve their biotechnological applications, a deep knowledge of structural factors involved in controlling their activity, in various experimental conditions and on different substrates, is required. In the present study, a laccase from the mushroom Rigidoporus lignosus was kinetically characterized. In particular, the stability, the effects of pH, ionic strength and fluoride ion concentration on the kinetic parameters were investigated, using three di-hydroxy-benzene isomers (1,2-dihydroxy-benzene, 1,3-dihydroxy-benzene and 1,4-dihydroxy-benzene) as substrates. The catalytic constant values of the laccase showed a bell-shaped pH profile, with the same optimum pH and pK(a) values for all tested substrates. This behavior appears to be due to the presence of an ionizable residue in the enzyme active site. To identify this residue, the enzyme was derivatized with diethylpyrocarbonate to modify accessible histidine residues, which, according to structural data, are present in the active site of this enzyme. The kinetic behavior of the derivatized laccase was compared with that of the native enzyme and the derivatized residues were identified by mass spectrometry. Mass spectrometry and kinetic results suggest the main role of His-457 in the control of the catalytic activity of laccase from R. lignosus. (C) 2013 Elsevier B.V. All rights reserved.

Caracterização da diversidade de fungos filamentosos associados a esponjas marinhas e avaliação da produção de lacase = : Diversity of filamentous fungi associated with marine sponges and evaluation of laccase production; Diversity of filamentous fungi associated with marine sponges and evaluation of laccase production

Michel Rodrigo Zambrano Passarini
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 06/09/2012 PT
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O oceano representa um habitat promissor na busca por novos micro-organismos, os quais podem apresentar capacidade de produzir enzimas de interesse industrial diferentes das produzidas por seus parceiros terrestres. Neste contexto, duas amostras da esponja marinha Dragmacidon reticulatum foram coletadas no litoral Norte do Estado de São Paulo, objetivando a caracterização da diversidade fúngica por métodos dependentes e independentes de cultivo, bem como a avaliação da produção, expressão da enzima e caracterização do gene da lacase. Com relação à parcela cultivada das amostras, 108 fungos filamentosos foram isolados. Destes, 64 ribotipos distintos foram submetidos aos experimentos de taxonomia polifásica e aos relacionados com a lacase. Análises macro- e microscópicas, moleculares (genes ribossomais ITS/28S) e pela técnica de MALDI TOF ICMS, resultaram na caracterização de 38 isolados distribuídos em 23 gêneros pertencentes ao Filo Ascomycota e um ao Filo Zygomycota. Este foram posteriormente depositados na Coleção Brasileira de Micro-organismos de Ambiente e Indústria (CBMAI). Dentre os isolados obtidos, uma potencial espécie nova de Penicillium foi identificada. Os resultados da triagem enzimática permitiram a seleção de dois isolados identificados como Nigrospora sp. CBMAI 1328 (0...

Laccase activity from the fungus trametes hirsuta using an air-lift bioreactor

Rodríguez Couto, S.; Rodríguez, A.; Paterson, R. R. M.; Lima, Nelson; Teixeira, J. A.
Fonte: The Society for Applied Microbiology Publicador: The Society for Applied Microbiology
Tipo: Artigo de Revista Científica
Publicado em //2006 ENG
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Aim: To produce high laccase activities from the white-rot fungus Trametes hirsuta in an in-house air-lift bioreactor (ALB). Methods and Results: Trametes hirsuta was grown in a 6-l ALB. A fed-batch strategy with glycerol as an addition resulted in maximum laccase activity of 19 400 U l)1, which was the highest reported from the fungus. Conclusion: The ALB configuration with additional glycerol resulted in high laccase activities. Significance and Impact of the Study: This study provides useful information on how to produce high concentrations of laccase.; University of Vigo (Spain; Department of Biological Engineering of the University of Minho, Portugal; Fundação para a Ciência e a Tecnologia (FCT)

Application of response surface methodological approach to optimise Reactive Black 5 decolouration by crude laccase from Trametes pubescens

Roriz, Margarida S.; Osma, Johann F.; Teixeira, J. A.; Rodríguez Couto, S.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em /09/2009 ENG
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Response surface methodology (RSM) was applied to optimise the decolouration of the diazo dye Reactive Black 5 (RB5) by crude laccase from the white-rot fungus Trametes pubescens. The presence of the redox mediator 1-hydroxybenzotriazole (HBT) greatly improved the decolouration levels of RB5 by crude laccase from T. pubescens. Central composite design (CCD) using RSM with three variables namely redox mediator (HBT), dye (RB5) and enzyme (laccase) concentrations was used in this study to optimise significant correlation between the effects of these variables on the decolouration of RB5. The optimum concentrations of HBT, RB5 and laccase were 1.17 mM, 150 mg/l and 500 U/l, respectively, for a maximum decolouration of RB5 (about 60% in 20 min). A quadratic model was obtained for dye decolouration through this design. The experimental values were in good agreement with the predicted ones and the model was highly significant, the correlation coefficient being 0.965. Interaction between HBT and RB5 concentrations, HBT and laccase concentrations and RB5 and laccase concentrations were negligible. In addition, when the kinetic parameters for RB5 decolouration were calculated according to Hannes–Wolf plot, the following values were obtained: KM of 260.11 mg/l and Vmax 37.59 mg/l min.; Spanish Ministry of Education and Science; Ramón y Cajal Programme and the European Social Fund; Erasmus Rovira i Virgili University (Tarragona...

Specificities of a chemically modified laccase from trametes

Schroeder, M.; Heumann, Sonja; Silva, Carla J. S. M.; Paulo, Artur Cavaco; Gübitz, Georg M.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em /05/2006 ENG
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Laccases could prevent fabrics and garments from re-deposition of dyes during washing and finishing processes by degrading the solubilized dye. However, laccase action must be restricted to solubilized dye molecules thereby avoiding decolorization of fabrics. Chemical modification of enzymes can provide a powerful tool to change the adsorption behaviour of enzymes on water insoluble polymers. Polyethylene glycol (PEG) was covalently attached onto a laccase from Trametes hirsuta. Different molecular weights of the synthetic polymer were tested in terms of adsorption behaviour and retained laccase activity. Covalent attachment of PEG onto the laccase resulted in enhanced enzyme stability while with increasing molecular weight of attached PEG the substrate affinity for the laccase conjugate decreased. The activity of the modified laccases on fibre bound dye was drastically reduced decreasing the adsorption of the enzyme on various fabrics. Compared to the 5 kDa PEG laccase conjugate (K/S value 47.60)

Polymerization study of the aromatic amines generated by the biodegradation of azo dyes using the laccase enzyme

Franciscon, E.; Piubeli, F.; Fantinatti-Garboggini, F.; Menezes, C. R.; Silva, I. S.; Paulo, Artur Cavaco; Grossman, M. J.; Durrant, L. R.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2010 ENG
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Four different azo dyes were decolorized (color reduction >90%) by bacteria isolated from a textile wastewater effluent. Dye decolorizing was carried out under microaerobic conditions until completion, after which the aromatic amine concentration was determined. A laccase from Myceliophthora thermophila was used to catalyze coupling reactions of the aromatic amines produced from decolorizing the dyes. The reaction was carried out with stirring (100 rpm) in a weak acidic buffer solution (pH 5.0) at 45 °C for 3 days. The presence of aromatic amines in the samples after bacterial decolorizing confirmed the azo bond was reduced in the process. In addition, the UV–vis spectrum was shifted significantly after the sequential bacterial-laccase treatment also indicating a chemical transformation of the dyes. After laccase treatment the solutions formed colored soluble and precipitated products. The particles sizes making up the precipitates formed after laccase treatment varied between 105 and 483 nm as determined by Photon Correlation Spectroscopy (PCS). The laccase treatment also reduced the COD of the dye solutions by ∼20%. We show that successive bacterial-laccase treatment is effective in decolorized azo dyes by reduction of the azo bonds...

Antimicrobial and antioxidant linen via laccase-assisted grafting

Silva, Carla Manuela Pereira Marinho da; Matamá, Maria Teresa; Padrão, Jorge; Kim, Suyeon; Prasetyo, E. N.; Kudanga, T.; Nyanhongo, Gibson S.; Guebitz, G. M.; Casal, Margarida; Paulo, Artur Cavaco
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em /07/2011 ENG
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A laccase from Ascomycetemyceliophthora thermophila was used to assist the binding of chitosan and catechin onto a previous enzymatically oxidized linen surface. The process consists of the pre-treatment of the linen with laccase followed by the application of chitosan in a first step and catechin plus laccase in a second step. The results presented here support the conclusion that laccase is able to oxidize phenols naturally existing in flax fibres, and that the o-quinones formed promote the attachment of chitosan or/and catechin. The pre-treatment of linen with laccase is therefore the key factor for the success of catechin and chitosan grafting. A multifunctional linen product with both antioxidant and antibacterial properties was obtained with an acceptable level of durability in terms of end user requirements.

Characterization and stability of free and immobilized laccase in the dyestar dyeing effluent

Zille, Andrea; Aixalá, Oriol; Basto, C.; Paulo, Artur Cavaco
Fonte: European Union, Fifth Framework Programme Publicador: European Union, Fifth Framework Programme
Tipo: Conferência ou Objeto de Conferência
Publicado em /03/2002 ENG
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In this study the stability (in terms of half-life time) and decolourisation efficiency of free and immobilised laccase was determined in four industrial dyeing effluents. The dyeing liquors composition and the chemical structure of the dyes influence significantly the stability and the decolourisation ability of the enzyme. The dyeing in enzymatically decolourised Reactive Black 5 effluent provided consistency of the colour with both bright and dark dyes. Additionally the number of washing cycles necessary to remove the hydrolyzed dyestuff from dyed textiles was reduced using an enzymatic pre-treatment. In decolourisation experiments with immobilised laccase, two phenomenons were observed - initial decolourisation due to adsorption on the support and dye degradation due to the enzyme action. This research focuses on the stability and decolourisation ability of free and immobilised laccase in industrial dyeing effluents and their reuse for dyeing. In our experiments the stability of the immobilised laccase in dyeing liquors was unexpectedly lower than the stability of the free enzyme. The stability of the laccase in dyeing effluents is a result of the additive effect of all components presented. The decrease of enzymatic activity could be associated with the potential protein – dyeing effluent components interactions. Azoaromatic sulfonate dye anions could provide enzyme stabilisation. However...

Laccase production by free and immobilized mycelia of Peniophora cinerea and Trametes versicolor : a comparative study

Silvério, Sara C.; Moreira, Sérgio; Milagres, Adriane M. F.; Macedo, Eugénia A.; Teixeira, J. A.; Mussatto, Solange I.
Fonte: Springer; Springer Verlag Publicador: Springer; Springer Verlag
Tipo: Artigo de Revista Científica
Publicado em //2013 ENG
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The production of laccase by immobilized mycelia of Peniophora cinerea and Trametes versicolor was studied. In an initial stage, experimental assays were performed in Erlenmeyer flasks using free and immobilized mycelium, and the performance of the fungal strains to produce the enzyme was compared. Both fungi adhered into the support material (a synthetic fiber), growing not only on the surface but also in the interspaces of the fibers. Immobilization of P. cinerea provided a 35-fold increase in laccase production when compared to the production obtained by using free mycelium. On the other hand, immobilization of T. versicolor caused a decrease in laccase activity. A comparison between the strains revealed that immobilized P. cinerea (3,500 U/L) surpassed the enzyme production by free T. versicolor (800 U/L). When the conditions that gave the best laccase production to each fungus were employed in a stirred tank bioreactor, very low laccase production was observed for both the cases, suggesting that shear stress and mycelia damage caused by the agitation impellers negatively affected the enzyme production.

Active bionanoconjugates of laccase and gold nanoparticles: kinetic and structural studies

Couto, Cláudia Alexandra Maia do
Fonte: Faculdade de Ciências e Tecnologia Publicador: Faculdade de Ciências e Tecnologia
Tipo: Dissertação de Mestrado
Publicado em //2012 ENG
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Thesis for the master degree in Structural and Functional Biochemistry; The work presented here had the objective of using gold nanoparticles (AuNPs) functionalized with mercaptoundecanoic acid (MUA), or the peptide CALNN, to develop bionanoconjugates (BNCs) with the enzyme Rhus vernicifera (Rv) laccase. Laccases are multi copper oxidases able to catalyze the oxidation of a variety of phenolic compounds with the reduction of molecular oxygen to water, and conjugating this enzyme with AuNPs could potentially contribute to enhance its catalytic activity. Spectroscopic, electrophoretic, kinetic, and computer modelling studies were carried out in order to characterize the enzyme structurally and investigate its stability and activity when conjugated with AuNPs. The studies performed revealed that Rv laccase is a monomer with 5.65 ± 0.83 nm in diameter and presents an optimal activity at pH 7.5, when syringaldazine was used as substrate. Laccase was successfully adsorbed to AuNP-CALNN but not to AuNP-MUA. BNCs with laccase and AuNP-CALNN remained active in the experimental conditions tested at pH from 6 – 8.5. Laccase followed a Michaelis-Menten kinetic model using syringaldazine as a substrate, in the pH range 6 – 8.5. Parallel studies with free laccase were conducted to evaluate the influence of AuNP-CALNN on laccase activity. These kinetic studies were performed by following substrate consumption and product formation. The kinetic results with less error were obtained when the reaction of product formation was followed. Therefore...

Additive effects of CuSO4 and aromatic compounds on laccase production by Pleurotus sajor-caju PS-2001 using sucrose as a carbon source

Bettin,F.; Montanari,Q.; Calloni,R.; Gaio,T. A.; Silveira,M. M.; Dillon,A. J. P.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2014 EN
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Laccase enzymes are now commercially available, and a laccase/mediator combination is currently marketed for indigo dye bleaching in textile manufacturing; replacing traditional chemical-based processes with enzymatic technology reduces the need for effluent treatment. However, an inexpensive source of these enzymes will be needed to enable wider application of this technology. In the present work, the main objective was to increase laccase production by the mushroom Pleurotus sajor-caju strain PS-2001 grown on sucrose derived from sugar cane, one of most economical carbon sources known, by the addition of compounds that are known to affect laccase production. High laccase activities (45-62 U mL-1) were obtained with additions of syringaldazine, benzoic acid, gallic acid, and vanillin. When CuSO4 was used in conjunction with these aromatic compounds, the levels of laccase activity were further improved, reaching 58-80 U mL-1. These laccase activities indicate the potential of this strain as an enzyme producer, which has also been detected in media containing glucose, but with activity lower than that observed with sucrose.

Validation of computationally predicted substrates for laccase

Reena,; Dhall,Purnima; Kumar,Rita; Kumar,Anil
Fonte: Instituto de Tecnologia do Paraná - Tecpar Publicador: Instituto de Tecnologia do Paraná - Tecpar
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2014 EN
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Present study reports the validation (oxidation) of computationally predicted oxidation of xenobiotic contaminants by commercially available pure laccase from Trametes versicolor. Selected contaminants were predicted as potential targets for laccase oxidation by using in-silico docking tool. The oxidation by laccase was measured by change in absorbance at specific λ max of each compound. Sinapic acid and tyrosine were taken as positive and negative controls, respectively. Oxidation was observed in m-chlorophenol, 2,4 di-chlorophenol, 2,4,6 tri-chlorophenol, captan, atrazine and thiodicarb, except malathion, which showed no activity. It could be speculated that the predicted substrates showing oxidation shared homology at structural and chemical level with positive control compounds. In case of malathion, structural non-homology with sinapic acid could be attributed to its inactivity towards laccase that required further structural analysis. Thus, a remediation tool proposing an advanced remediation approach combining the application of theoretical in-silico method and subsequent experimental validation using pure laccase could be proposed. As number and type of xenobiotics increase, the unfeasibility to screen them experimentally for bioremediation also rise. This approach would be useful to reduce the time and cost required in other screening methods.

Screening of inducers for laccase production by Lentinula edodes in liquid medium

Cavallazzi,José Renato P.; Kasuya,Catarina M.; Soares,Marcos A.
Fonte: Sociedade Brasileira de Microbiologia Publicador: Sociedade Brasileira de Microbiologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2005 EN
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Laccases are enzymes involved in lignin degradation and are produced by various organisms. Due to their low substrate specificity their potential to be used in biotechnological applications has received attention. The addition of laccase inducers to the culture medium of microorganisms can enhance laccase production and facilitate its purification and utilization. The aim of this study was to investigate the effect of some compounds as laccase inducers in cultures of Lentinula edodes (shiitake). First, it was selected a culture medium suitable for laccase production by shiitake using two levels of N (2.6 and 26 mM) and seven levels of Cu (0, 50, 100, 150, 200, 250 and 300 µM). The medium with 2.6 mM N and 250 µM Cu was found to provide the highest laccase activity. To the selected medium it were added gallic acid (1 mM), catechol (1 mM), ammonium tartrate (55 µM), hydroxybenzoic acid (1 mM) and vanillin (1 mM). The two first compounds completely inhibited laccase activity and a 30 day time course experiment was carried out with the remaining compounds. Only cultures with ammonium tartrate exhibited laccase activity higher than control cultures, reaching 251 U/mL of extract after 30 days. A native-PAGE was performed and showed only one band...

Copper induction and differential expression of laccase in Aspergillus flavus

Gomaa,Ola M.; Momtaz,Osama A.
Fonte: Sociedade Brasileira de Microbiologia Publicador: Sociedade Brasileira de Microbiologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/05/2015 EN
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Aspergillus flavus was isolated from soil and exhibited laccase activity under both constitutive and copper induced conditions. Spiking the medium with 1 mM copper sulfate resulted in an increase in the activity which reached 51.84 U/mL, a distinctive protein band was detected at 60 kDa. The extracellular enzyme was purified 81 fold using gel filtration chromatography and resulted in two different laccase fractions L1 and L2, the latter had a higher enzymatic activity which reached 79.57 U/mL and specific activity of 64.17 U/μg protein. The analysis of the spectrum of the L2 fraction showed a shoulder at 330 nm which is characteristic for T2/T3 copper centers; both copper and zinc were detected suggesting that this is an unconventional white laccase. Primers of laccase gene were designed and synthesized to recover specific gene from A. flavus. Sequence analysis indicated putative laccase (Genbank ID: JF683612) at the amino acid level suggesting a close identity to laccases from other genera containing the copper binding site. Decolorization of textile waste water under different conditions showed possible application in bioremediation within a short period of time. The effect of copper on A. flavus was concentration dependent.

Covalent immobilization of laccase in green coconut fiber and use in clarification of apple juice

Souza Bezerra, Thais Milena de; Bassan, Juliana Cristina; Oliveira Santos, Victor Tabosa de; Ferraz, Andre; Monti, Rubens
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 417-423
ENG
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Waste materials from agroindustry constituted from lignocellulose have been used in the immobilization process of technological interest enzymes to reduce costs, increasing the value of such products. In the present study, green coconut husk was used to obtain fibers (CF) that were treated through thermal decompression in combination with either acid or alkaline medium. A solid support for enzyme immobilization was prepared using the pretreated CF activated with glyoxyl or glutaraldehyde and was used to immobilize the laccase enzyme (EC 1.10.3.2) produced by Trametes versicolor. Immobilized enzyme retained up to 59 +/- 1% of the initial activity and showed maximum immobilization profile of 98 +/- 1%. The thermal stability was higher when laccase was immobilized on alkaline pretreated support with increments of 6.8-fold (laccase-glutaraldehyde-FC) up to 16.5-fold (laccase-glyoxyl-FC) of the soluble enzyme. The laccase-glutaraldehyde-CF achieved excellent results in the clarification of apple juice, reducing 61 +/- 1% of the original juice color and 29 +/- 1% of its turbidity...

Dye decolourization by immobilized laccase and impact of auxiliary chemicals on dye decolourization

Champagne, Paul-Philippe
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 1382542 bytes; application/pdf
EN; EN
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Textile dyes are molecules designed to impart a permanent colour to textile fabrics. They pose an environmental problem because they are toxic and they decrease the aesthetic value of rivers and lakes. Current technologies for dye removal cannot remove all classes of dyes and two or more technologies are usually combined to achieve statisfactory decolourization efficiencies. Lignin-degrading enzymes like laccases are potential technologies for dye decolourization and decolourization with immobilized laccase has been intensively investigated. The majority of those studies however have focused on dye disappearance and several reported that significant dye adsorption had occured during the dye removal, making the role of the enzyme unclear. Moreover, textile wastewaters contain auxiliary chemicals that can impact enzymatic dye decolourization and very few studies have evaluated the impact of those substances on laccase. This research evaluated the feasibility of treating dye-contaminated textile wastewaters with an immobilized laccase system. The first sub-objective was to examined the decolourization of Reactive blue 19 (an anthraquinone dye) by Trametes versicolor laccase immobilized on controlled porosity carrier (CPC) silica beads and the second was to analyze the kinetic effects of a non-ionic surfactant Merpol...

Cloning, characterization and expression of a novel laccase gene Pclac2 from Phytophthora capsici

Feng,Bao Zhen; Li,Peiqian
Fonte: Sociedade Brasileira de Microbiologia Publicador: Sociedade Brasileira de Microbiologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2014 EN
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Laccases are blue copper oxidases (E.C. 1.10.3.2) that catalyze the one-electron oxidation of phenolics, aromatic amines, and other electron-rich substrates with the concomitant reduction of O2 to H2O. A novel laccase gene pclac2 and its corresponding full-length cDNA were cloned and characterized from Phytophthora capsici for the first time. The 1683 bp full-length cDNA of pclac2 encoded a mature laccase protein containing 560 amino acids preceded by a signal peptide of 23 amino acids. The deduced protein sequence of PCLAC2 showed high similarity with other known fungal laccases and contained four copper-binding conserved domains of typical laccase protein. In order to achieve a high level secretion and full activity expression of PCLAC2, expression vector pPIC9K with the Pichia pastoris expression system was used. The recombinant PCLAC2 protein was purified and showed on SDS-PAGE as a single band with an apparent molecular weight ca. 68 kDa. The high activity of purified PCLAC2, 84 U/mL, at the seventh day induced with methanol, was observed with 2,2'-azino-di-(3-ethylbenzothialozin-6-sulfonic acid) (ABTS) as substrate. The optimum pH and temperature for ABTS were 4.0 and 30 ºC, respectively . The reported data add a new piece to the knowledge about P. Capsici laccase multigene family and shed light on potential function about biotechnological and industrial applications of the individual laccase isoforms in oomycetes.

Removal of lipophilic extractives from paper pulp by laccase and lignin-derived phenols as natural mediators

Gutiérrez Suárez, Ana; Rencoret, Jorge; Ibarra, David; Molina, Setefilla; Camarero, Susana; Romero Sánchez, Javier; Río Andrade, José Carlos del; Martínez, Ángel T.
Fonte: Conselho Superior de Investigações Científicas Publicador: Conselho Superior de Investigações Científicas
Tipo: Artículo Formato: 157265 bytes; application/pdf
ENG
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In this paper, we show for the first time that ligninderived phenols can act as laccase mediators for the removal of lipophilic compounds from paper pulp. These natural mediators represent an alternative to synthetic mediators, such as 1-hydroxybenzotriazole (HBT), that cause some economic and environmental concerns. Unbleached kraft pulp from eucalypt wood, which contained free and conjugated sterols responsible for pitch deposition in the manufacture of totally chlorine free paper, was treated with a fungal laccase in the presence of syringaldehyde, acetosyringone, and p-coumaric acid as mediators. The composition of lipophilic extractives in the pulps after the enzymatic treatment followed by a hydrogen peroxide stage was analyzed by gas chromatography and gas chromatography/mass spectrometry. The enzymatic treatment using syringaldehyde as laccase mediator caused the highest removal (over 90%) of free and conjugated sitosterol, similar to that attained with HBT, followed by acetosyringone (over 60% removal), whereas p-coumaric acid was barely effective. Moreover, recalcitrant oxidized steroids surviving laccase-HBT treatment could be removed when using these natural mediators. Pulp brightness was also improved (from 57% to 66% ISO brightness) by the laccase treatment in the presence of the above phenols followed by the peroxide stage due to the simultaneous removal of lignin.; Peer reviewed

Screening of Colletotrichum (Ascomycota) isolates, causal agents of Soybean Anthracnose, for Laccase production

Levin,L.; Ramos,A .M.; Parisi,M .; Gally,M.
Fonte: Boletín de la Sociedad Argentina de Botánica Publicador: Boletín de la Sociedad Argentina de Botánica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2007 EN
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Colletotrichum truncatum is the most common pathogen fungus associated with soybean anthracnose. Although the lignin-degrading enzyme laccase has been implicated in pathogenicity of a wide range of plant pathogenic fungi, its biological role in the Colletotrichum -soybean disease system is unknown. The extent of the infection in our country led us to examine laccase production in Argentinean Colletotrichum strains isolated from diseased soybean plants from different geographic locations. Ten strains (eight of them identified as C. truncatum) , were screened for in vitro laccase production. Only six of the isolates, all of them C. truncatum , produced laccase activity when cultured on a defined medium based on pectin and asparagine as carbon and nitrogen sources, respectively. Strain BAFC 3102 (isolated from Chaco province), yielded the highest laccase titers (44 U/L) in this medium. Denaturing polyacrylamide gel electrophoresis of extracellular culture fluids revealed one band with laccase activity (mol wt 67 kDa). CuSO 4 addition to media with either glucose or pectin as carbon sources increased up to 7-fold laccase production (280 U/L in the glucose medium), but the pattern of isoenzyme was not affected by culture age or medium composition. This is the first report on laccase production by C. truncatum.