Laccase Enzymes in Inocula Pleurotus spp

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Nora García-Oduardo

2017-01-01

Full Text Available The cultivation of edible and medicinal mushrooms Pleurotus has been aimed at promoting alternative management for agricultural products. This basidiomicete has been the subject of numerous studies because of its fruiting body constitutes a food, being a producer of enzymes with industrial interest and for its ability of biotransformation of lignocellulosic substrates. Pleurotus inocula in the established technology for growing edible and medicinal mushrooms in the CEBI Research- Production Plant were performed using sorghum or wheat. However, it is possible to expand the possibilities with other substrates. In this paper, the results of laccase enzymes production in inocula prepared with sorghum, corn and coffee pulp with two strains Pleurotus ostreatus CCEBI 3021 and Pleurotus ostreatus CCEBI 3024 are presented. The period of preparation of seed reaches 15-21 days, the measurements of laccase activity were performed in periods of seven days. Extraction of crude enzyme was performed in aqueous phase, the determination of the laccase enzyme activity, using guaiacol as substrate. The results obtained in this work with studies in previous work using sorghum as inocula are compared. It is found that higher yields are obtained laccase in coffee pulp. This study contributes to the theoretical knowledge and to provide alternatives for securing the production process of the plant.

Laccase Enzymology in Relation to Lignocellulose Processing

DEFF Research Database (Denmark)

Sitarz, Anna Katarzyna

) and investigated for production of enzymes under such conditions (Paper I). G. lucidum was found to produce high amounts of laccase which corresponded to its exceptional growth on lignocellulosic substrate and lignin. This observation led to a hypothesis that this particular laccase might act in a synergistic way...... cocktail preparation. This discovery is significant considering the fact that the cellulase cocktail preparations, namely Cellic®CTec1 and Cellic®CTec2, are improved in respect to phenolic-derived, and end-substrate inhibitors. Additionally, the molecular dynamics simulations (MD) of the obtained amino...

Laccase engineering: from rational design to directed evolution.

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Mate, Diana M; Alcalde, Miguel

2015-01-01

Laccases are multicopper oxidoreductases considered by many in the biotechonology field as the ultimate "green catalysts". This is mainly due to their broad substrate specificity and relative autonomy (they use molecular oxygen from air as an electron acceptor and they only produce water as by-product), making them suitable for a wide array of applications: biofuel production, bioremediation, organic synthesis, pulp biobleaching, textiles, the beverage and food industries, biosensor and biofuel cell development. Since the beginning of the 21st century, specific features of bacterial and fungal laccases have been exhaustively adapted in order to reach the industrial demands for high catalytic activity and stability in conjunction with reduced production cost. Among the goals established for laccase engineering, heterologous functional expression, improved activity and thermostability, tolerance to non-natural media (organic solvents, ionic liquids, physiological fluids) and resistance to different types of inhibitors are all challenges that have been met, while obtaining a more comprehensive understanding of laccase structure-function relationships. In this review we examine the most significant advances in this exciting research area in which rational, semi-rational and directed evolution approaches have been employed to ultimately convert laccases into high value-added biocatalysts. Copyright © 2014 Elsevier Inc. All rights reserved.

Decolorization of the azo dye Acid Orange 51 by laccase produced in solid culture of a newly isolated Trametes trogii strain.

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Daâssi, Dalel; Zouari-Mechichi, Hela; Frikha, Fakher; Martinez, Maria Jesus; Nasri, Moncef; Mechichi, Tahar

2013-04-01

This study concerns the decolorization and detoxification of the azo dye Acid Orange 51 (AO51) by crude laccase from Trametes trogii produced in solid culture using sawdust as support media. A three-level Box-Behnken factorial design with four factors (enzyme concentration, 1-hydroxybenzotriazole (HBT) concentration, dye concentration and reaction time) combined with response surface methodology was applied to optimize AO51 decolorization. A mathematical model was developed showing the effect of each factor and their interactions on color removal. The model predicted that Acid Orange 51 decolorization above 87.87 ± 1.27 % could be obtained when enzyme concentration, HBT concentration, dye concentration and reaction time were set at 1 U/mL, 0.75 mM, 60 mg/L and 2 days, respectively. The experimental values were in good agreement with the predicted ones and the models were highly significant, the correlation coefficient (R 2 ) being 0.9. Then the desirability function was employed to determine the optimal decolorization condition for each dye and minimize the process cost simultaneously. In addition, germination index assay showed that laccase-treated dye was detoxified; however in the presence of HBT, the phytotoxicity of the treated dye was increased. By using cheap agro-industrial wastes, such as sawdust, a potential laccase was obtained. The low cost of laccase production may further broaden its application in textile wastewater treatment.

Hydrogen peroxide produced by glucose oxidase affects the performance of laccase cathodes in glucose/oxygen fuel cells: FAD-dependent glucose dehydrogenase as a replacement.

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Milton, Ross D; Giroud, Fabien; Thumser, Alfred E; Minteer, Shelley D; Slade, Robert C T

2013-11-28

Hydrogen peroxide production by glucose oxidase (GOx) and its negative effect on laccase performance have been studied. Simultaneously, FAD-dependent glucose dehydrogenase (FAD-GDH), an O2-insensitive enzyme, has been evaluated as a substitute. Experiments focused on determining the effect of the side reaction of GOx between its natural electron acceptor O2 (consumed) and hydrogen peroxide (produced) in the electrolyte. Firstly, oxygen consumption was investigated by both GOx and FAD-GDH in the presence of substrate. Relatively high electrocatalytic currents were obtained with both enzymes. O2 consumption was observed with immobilized GOx only, whilst O2 concentration remained stable for the FAD-GDH. Dissolved oxygen depletion effects on laccase electrode performances were investigated with both an oxidizing and a reducing electrode immersed in a single compartment. In the presence of glucose, dramatic decreases in cathodic currents were recorded when laccase electrodes were combined with a GOx-based electrode only. Furthermore, it appeared that the major loss of performance of the cathode was due to the increase of H2O2 concentration in the bulk solution induced laccase inhibition. 24 h stability experiments suggest that the use of O2-insensitive FAD-GDH as to obviate in situ peroxide production by GOx is effective. Open-circuit potentials of 0.66 ± 0.03 V and power densities of 122.2 ± 5.8 μW cm(-2) were observed for FAD-GDH/laccase biofuel cells.

A New Laccase Biosensor For Polyphenols Determination

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M. J.F. Rebelo

2003-06-01

Full Text Available The relevance of polyphenols in human health is a well known fact. Prompted by that, a very intensive research has been directed to get a method to detect them, wich will improve the current ones. Laccase (p-diphenol:dioxygen oxidoreductase EC 1.10.3.2 is a multi-copper oxidase, wich couples catalytic oxidation of phenolic substrates with four electron reduction of dioxygen to water [1]. A maximum catalytic response in oxigenated electrolyte was observed between 4.5 and 5.5 [2], while for pH > 6.9 the laccase was found to be inactive [3]. We prepared a biosensor with laccase immobilised on a polyether sulphone membrane, at pH 4.5, wich was applied at Universal Sensors base electrode. Reduction of the product of oxidation of several polyphenols, catalysed by laccase, was done at a potential for wich the polyphenol of interest was found to respond. Reduction of catechol was found to occur at a potential of -200mV, wich is often referred to in the literature for polyphenolic biosensors. However other polyphenols did not respond at that potential. It was observed that (+- catechin produced a very large cathodic current when +100mV were applied to the laccase biosensor, both in aqueous acetate and 12% ethanol acetate buffer, whereas caffeic acid responded at -50mV. Other polyphenols tested were gallic acid, malvidin, quercetin, rutin, trans-resveratrol

A Sequential Combination of Laccase Pretreatment and Enzymatic Hydrolysis for Glucose Production from Furfural Residues

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Hailong Yu

2014-06-01

Full Text Available Furfural residues (FRs were pretreated with laccase or a laccase-mediator (1-hydroxybenzotriazole, HBT system to produce fermentable sugar for bioethanol production. Compared to laccase-only pretreatment, laccase-mediator pretreatment dissolved more lignin. Approximately 10.5% of the initially present lignin was removed when FRs were treated with a laccase loading of 100 U/g of dry substrate in 1% (w/w HBT at 48 °C for 24 h in an acetate buffer (pH 4.8. The enzymatic saccharification process was carried out by a combined laccase or laccase-mediator pretreatment without washing of the treated solids. The results showed that active laccase had a negative effect on the rate and yield of enzymatic hydrolysis. Laccase-oxidized HBT seriously reduced glucose yield. However, non-oxidized HBT increased glucose yield when laccase was deactivated at 121 °C for 20 min prior to enzymatic hydrolysis. The highest glucose yield, 80.9%, was obtained from the substrate pretreated with 100 U/g of dry substrate laccase and 1% (w/w HBT at 48 °C for 24 h in an acetate buffer (pH 4.8. Furthermore, the structures of FRs before and after laccase-mediator pretreatment were characterized by scanning electron microscopy (SEM and Fourier Transform Infrared spectroscopy (FT-IR.

Gram-scale production of a basidiomycetous laccase in Aspergillus niger.

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Mekmouche, Yasmina; Zhou, Simeng; Cusano, Angela M; Record, Eric; Lomascolo, Anne; Robert, Viviane; Simaan, A Jalila; Rousselot-Pailley, Pierre; Ullah, Sana; Chaspoul, Florence; Tron, Thierry

2014-01-01

We report on the expression in Aspergillus niger of a laccase gene we used to produce variants in Saccharomyces cerevisiae. Grams of recombinant enzyme can be easily obtained. This highlights the potential of combining this generic laccase sequence to the yeast and fungal expression systems for large-scale productions of variants. Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Characterization and cloning of laccase gene from Hericium coralloides NBRC 7716 suitable for production of epitheaflagallin 3-O-gallate.

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Itoh, Nobuya; Takagi, Shinya; Miki, Asami; Kurokawa, Junji

2016-01-01

Epitheaflagallin 3-O-gallate (ETFGg) is a minor polyphenol found in black tea extract, which has good physiological functions. It is synthesized from epigallocatechin gallate (EGCg) with gallic acid via laccase oxidation. Various basidiomycetes and fungi were screened to find a suitable laccase for the production of ETFGg. A basidiomycete, Hericium coralloides NBRC 7716, produced an appropriate extracellular laccase. The purified laccase produced twice the level of ETFGg compared with commercially available laccase from Trametes sp. The enzyme, termed Lcc2, is a monomeric protein with an apparent molecular mass of 67.2 kDa. The N-terminal amino acid sequence of Lcc2 is quite different from laccase isolated from the fruiting bodies of Hericium. Lcc2 showed similar substrate specificity to known laccases and could oxidize various phenolic substrates, including pyrogallol, gallic acid, and 2,6-dimethoxyphenol. The full-length lcc2 gene was obtained by PCR using degenerate primers, which were designed based on the N-terminal amino acid sequence of Lcc2 and conserved copper-binding sites of laccases, and 5'-, and 3'-RACE PCR with mRNA. The Lcc2 gene showed homology with Lentinula edodes laccase (sharing 77% amino acid identity with Lcc6). We successfully produced extracellular Lcc2 using a heterologous expression system with Saccharomyces cerevisiae. Moreover, it was confirmed that the recombinant laccase generates similar levels of ETFGg as the native enzyme. Copyright © 2015 Elsevier Inc. All rights reserved.

Characterization of C-terminally engineered laccases.

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Liu, Yingli; Cusano, Angela Maria; Wallace, Erin C; Mekmouche, Yasmina; Ullah, Sana; Robert, Viviane; Tron, Thierry

2014-08-01

Extremities of proteins are potent sites for functionalization. Carboxy terminus variants of the Trametes sp. strain C30 LAC3 laccase were generated and produced in Saccharomyces cerevisiae. A variant deleted of the last 13 residues (CΔ) and its 6 His tagged counterpart (CΔ6H) were found active enzymes. The production of CΔ6H resulted in the synthesis of a unusually high proportion of highly glycosylated forms of the enzyme therefore allowing the additional purification of a hyper-glycosylated form of CΔ6H noted CΔ6Hh. Properties of CΔ, CΔ6H and CΔ6Hh were compared. Globally, LAC3 catalytic efficiency was moderately affected by terminal modifications except in CΔ for which the kcat/KM ratio decreased 4 fold (with syringaldazine as substrate) and 10 fold (with ABTS as substrate) respectively. The catalytic parameters kcat and KM of CΔ6H and CΔ6Hh were found to be strictly comparable revealing that over glycosylation does not affect the enzyme catalytic efficiency. To the contrary, in vitro deglycosylation of laccase drastically reduced its activity. So, despite a complex glycosylated pattern observed for some of the variant enzymes, terminal sequences of laccases appear to be appropriate sites for the functionalization/immobilization of laccase. Copyright © 2014 Elsevier B.V. All rights reserved.

Sonochemical and hydrodynamic cavitation reactors for laccase/hydrogen peroxide cotton bleaching.

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Gonçalves, Idalina; Martins, Madalena; Loureiro, Ana; Gomes, Andreia; Cavaco-Paulo, Artur; Silva, Carla

2014-03-01

The main goal of this work is to develop a novel and environmental-friendly technology for cotton bleaching with reduced processing costs. This work exploits a combined laccase-hydrogen peroxide process assisted by ultrasound. For this purpose, specific reactors were studied, namely ultrasonic power generator type K8 (850 kHz) and ultrasonic bath equipment Ultrasonic cleaner USC600TH (45 kHz). The optimal operating conditions for bleaching were chosen considering the highest levels of hydroxyl radical production and the lowest energy input. The capacity to produce hydroxyl radicals by hydrodynamic cavitation was also assessed in two homogenizers, EmulsiFlex®-C3 and APV-2000. Laccase nanoemulsions were produced by high pressure homogenization using BSA (bovine serum albumin) as emulsifier. The bleaching efficiency of these formulations was tested and the results showed higher whiteness values when compared to free laccase. The combination of laccase-hydrogen peroxide process with ultrasound energy produced higher whiteness levels than those obtained by conventional methods. The amount of hydrogen peroxide was reduced 50% as well as the energy consumption in terms of temperature (reduction of 40 °C) and operating time (reduction of 90 min). Copyright © 2013 Elsevier Inc. All rights reserved.

Heterologous expression of trametes versicolor laccase in pichia pastoris and aspergillus niger

CSIR Research Space (South Africa)

Bohlin, C

2006-09-01

Full Text Available primarily for screening purposes. With A. niger, high levels of laccase (2700 U/L) were produced using a min- imal medium containing sucrose and yeast extract. Recombinant laccase from A. niger harboring the lcc2 cDNA was purified to homogeneity...). Methods Microbial Strains and Recombinant DNA The lcc1 and lcc2 cDNA genes from T. (Coriolus, Polyporus) versicolor (9–11) were used in the construction of plasmids for expression of laccases in P. pastoris and A. niger. For the expression in P...

Zinc-Laccase Biofuel Cell

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Abdul Aziz Ahmad

2011-12-01

Full Text Available A zinc-laccase biofuel cell adapting the zinc-air cell design features is investigated. A simple cell design configuration is employed: a membraneless single chamber and a freely suspended laccase in a quasi-neutral buffer electrolyte. The cell is characterised according to its open-circuit voltage, polarization profile, power density plot and discharge capacity at constant current. The biocatalytic role of laccase is evident from the polarization profile and power output plot. Performance comparison between a single chamber and dual chamber cell design is also presented. The biofuel cell possessed an open-circuit voltage of 1.2 V and delivered a maximum power density of 0.9 mW/cm2 at current density of 2.5 mA/cm2. These characteristics are comparable to biofuel cell utilising a much more complex system design.KEY WORDS (keyword:  Biofuel cell, Bioelectrochemical cell, Zinc anode, Laccase and Oxidoreductase.ABSTRAK: Sel bio-bahan api zink-laccase dengan adaptasi daripada ciri-ciri rekabentuk sel zink-udara telah dikaji. Sel dengan konfigurasi rekabentuk yang mudah digunapakai: ruangan tunggal tanpa membran dan laccase diampaikan secara bebas di dalam elektrolit pemampan quasi-neutral. Sel dicirikan berdasarkan voltan litar terbuka, profil polarisasi, plot ketumpatan kuasa dan kapasiti discas pada arus malar. Peranan laccase sebagai bio-pemangkin adalah amat ketara daripada profil polarisasi dan plot ketumpatan kuasa. Perbandingan prestasi di antara sel dengan rekabentuk ruangan tunggal and dwi-ruangan turut diketengahkan. Seperti dijangkakan, sel dengan rekabentuk ruangan tunggal menunjukkan kuasa keluaran yang lebih rendah jika dibandingkan dengan rekabentuk dwi-ruangan kemungkinan disebabkan fenomena cas bocor. Sel bio-bahan api ini mempunyai voltan litar terbuka 1.2 V dan memberikan ketumpatan kuasa maksima 0.9 mW/cm2 pada ketumpatan arus 2.5 mA/cm2. Ciri-ciri ini adalah sebanding dengan sel bio-bahan api yang menggunapakai rekabentuk sel

β-Carotene from Yeasts Enhances Laccase Production of Pleurotus eryngii var. ferulae in Co-culture.

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Guo, Chaolin; Zhao, Liting; Wang, Feng; Lu, Jian; Ding, Zhongyang; Shi, Guiyang

2017-01-01

Laccase is widely used in several industrial applications and co-culture is a common method for enhancing laccase production in submerged fermentation. In this study, the co-culture of four yeasts with Pleurotus eryngii var. ferulae was found to enhance laccase production. An analysis of sterilization temperatures and extraction conditions revealed that the stimulatory compound in yeasts was temperature-sensitive, and that it was fat-soluble. An LC-MS analysis revealed that the possible stimulatory compound for laccase production in the four yeast extracts was β-carotene. Moreover, the addition of 4 mg β-carotene to 150 mL of P. eryngii var. ferulae culture broth improved laccase production by 2.2-fold compared with the control (i.e., a monoculture), and was similar to laccase production in co-culture. In addition, the enhanced laccase production was accompanied by an increase of lac gene transcription, which was 6.2-time higher than the control on the fifth day. Therefore, it was concluded that β-carotene from the co-cultured yeasts enhanced laccase production in P. eryngii var. ferulae , and strains that produce β-carotene could be selected to enhance fungal laccase production in a co-culture. Alternatively, β-carotene or crude extracts of β-carotene could be used to induce high laccase production in large scale.

Effect of mediator added to modified paste carbon electrodes with immobilized laccase from Aspergillus oryzae

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Marcelo Silva Ferreira

2015-05-01

Full Text Available Carbon paste electrodes based on the immobilization of laccase from Aspergillus oryzae were developed and voltammetric measurements were performed to evaluate the amperometric response. The 2,2′-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid diammonium salt  (ABTS functions as substrate and mediator for the laccase enzyme. Electrodes were modified  in two different conditions: without mediator (EPC/laccase and with mediator (EPC/laccase/ABTS. The addition of ABTS as a mediator increased eight-fold the amperometric response. The electrode was sensitive to pH variation with best response at pH 4.0. Studies on different concentrations of laccase and ABTS at different pH rates revealed that the composition 187 U mL-1 in laccase and 200 µL of ABTS obtained the highest amperometric response. The carbon paste electrode modified with ABTS proved to be a good base for the immobilization of the laccase enzyme. Moreover, it is easy to manufacture and inexpensive to produce a modified electrode with potential application in biosensors.

Effects and interactions of medium components on laccase from a marine-derived fungus using response surface methodology

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DeSouza-Ticlo, D.; Garg, S.; Raghukumar, C.

The effects of various synthetic medium components and their interactions with each other ultimately impact laccase production in fungi. This was studied using a laccase-hyper-producing marine-derived basidiomycete, Cerrena unicolor MTCC 5159...

Media optimization for laccase production by Trichoderma harzianum ZF-2 using response surface methodology.

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Gao, Huiju; Chu, Xiang; Wang, Yanwen; Zhou, Fei; Zhao, Kai; Mu, Zhimei; Liu, Qingxin

2013-12-01

Trichoderma harzianum ZF-2 producing laccase was isolated from decaying samples from Shandong, China, and showed dye decolorization activities. The objective of this study was to optimize its culture conditions using a statistical analysis of its laccase production. The interactions between different fermentation parameters for laccase production were characterized using a Plackett-Burman design and the response surface methodology. The different media components were initially optimized using the conventional one-factor-at-a-time method and an orthogonal test design, and a Plackett-Burman experiment was then performed to evaluate the effects on laccase production. Wheat straw powder, soybean meal, and CuSO4 were all found to have a significant influence on laccase production, and the optimal concentrations of these three factors were then sequentially investigated using the response surface methodology with a central composite design. The resulting optimal medium components for laccase production were determined as follows: wheat straw powder 7.63 g/l, soybean meal 23.07 g/l, (NH4)2SO4 1 g/l, CuSO4 0.51 g/l, Tween-20 1 g/l, MgSO4 1 g/l, and KH2PO4 0.6 g/l. Using this optimized fermentation method, the yield of laccase was increased 59.68 times to 67.258 U/ml compared with the laccase production with an unoptimized medium. This is the first report on the statistical optimization of laccase production by Trichoderma harzianum ZF-2.

Preparation of Laccase Immobilized Cryogels and Usage for Decolorization

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Murat Uygun

2013-01-01

Full Text Available Poly(methyl methacrylate-co-glycidyl methacrylate (poly(MMA-co-GMA cryogels were synthesized by radical cryopolymerization technique. Then, laccase enzyme was covalently attached to the cryogel and characterized by using swelling studies and SEM and EDX analyses. Kinetic properties and optimum conditions of the immobilized and free laccase were studied and it was found that of the immobilized laccase was lower than that of free laccase. of the immobilized laccase was increased upon immobilization. Optimum pH was found to be 4.0 for each type of laccase, while optimum temperature was shifted to the warmer region after the immobilization. It was also found that thermal stability of the immobilized laccase was higher than that of free laccase. Immobilized laccase could be used for 10 times successive reuse with no significant decrease in its activity. Also, these laccase immobilized cryogels were successfully used for the decolorization of seven different dyes.

Construction and direct electrochemistry of orientation controlled laccase electrode.

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Li, Ying; Zhang, Jiwei; Huang, Xirong; Wang, Tianhong

2014-03-28

A laccase has multiple redox centres. Chemisorption of laccases on a gold electrode through a polypeptide tag introduced at the protein surface provides an isotropic orientation of laccases on the Au surface, which allows the orientation dependent study of the direct electrochemistry of laccase. In this paper, using genetic engineering technology, two forms of recombinant laccase which has Cys-6×His tag at the N or C terminus were generated. Via the Au-S linkage, the recombinant laccase was assembled orientationally on gold electrode. A direct electron transfer and a bioelectrocatalytic activity toward oxygen reduction were observed on the two orientation controlled laccase electrodes, but their electrochemical behaviors were found to be quite different. The orientation of laccase on the gold electrode affects both the electron transfer pathway and the electron transfer efficiency of O2 reduction. The present study is helpful not only to the in-depth understanding of the direct electrochemistry of laccase, but also to the development of laccase-based biofuel cells. Copyright © 2014 Elsevier Inc. All rights reserved.

Optimization of laccase production by two strains of Ganoderma lucidum using phenolic and metallic inducers

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Francisco Kuhar

Full Text Available Ganoderma lucidum (Curtis P. Karst is a white rot fungus that is able to degrade the lignin component in wood. The ability of two strains of this species to produce the ligninolytic enzyme laccase was assessed. After the evaluation of induction with heavy metals and phenolic compounds, it was found that among the tested substances, copper and ferulic acid are the best laccase inducers. It was also observed that the two types of inducers (phenolic and metallic produce different electrophoretic patterns of laccase activity. Optimized concentrations of inducers were obtained through a factorial design and the thermal stability of optimized supernatants was studied at a wide range of acidic pH. We found that the enzyme is more thermostable at higher pH values.

Structure and Biochemestry of Laccases from the Lignin-Degrading Basidiomycete, Ganoderma lucidum

Energy Technology Data Exchange (ETDEWEB)

C.A.Reddy, PI

2005-06-30

G. lucidum is one of the most important and widely distributed ligninolytic white rot fungi from habitats such as forest soils, agricultural soils, and tropical mangrove ecosystems and produce laccases as an important family of lignin modifying enzymes. Biochemically, laccases are blue multi copper oxidases that couple four electron reduction of molecular oxygen to water. There is a growing interest in the use of laccases for a variety of industrial applications such as bio-pulping and biobleaching as well as in their ability to detoxify a wide variety of toxic environmental pollutants. These key oxidative enzymes are found in all the three domains of life: Eukaryota. Prokarya, and Archaea. Ganoderma lucidum (strain no.103561) produces laccase with some of the highest activity (17,000 micro katals per mg of protein) reported for any laccases to date. Our results showed that this organism produces at least 11 different isoforms of laccase based on variation in mol. weight and/or PI. Our Studies showed that the presence of copper in the medium yields 15- to 20-fold greater levels of enzyme by G. lucidum. Dialysation of extra cellular fluid of G. lucidum against 10mM sodium tartrate (pH5.5) gave an additional 15 to 17 fold stimulation of activity with an observed specific activity of 17,000 {micro}katals/mg protein. Dialysis against acetate buffer gave five fold increase in activity while dialysis against glycine showed inhibition of activity. Purification by FPLC and preparative gel electrophoresis gave purified fractions that resolved into eleven isoforms as separated by isoelectric focusing, and the PI,s were 4.7, 4.6, 4.5, 4.3, 4.2, 4.1, 3.8, 3.7, 3.5, 3.4 and 3.3. Genomic clones of laccase were isolated using G. lucidum DNA as a template and using inverse PCR and forward/reverse primers corresponding to the sequences of the conserved copper binding region in the N-terminal domain of one of the laccases of this organism. Inverse PCR amplication of HindIII digested

Comparison of the efficiency of bacterial and fungal laccases in delignification and detoxification of steam-pretreated lignocellulosic biomass for bioethanol production.

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De La Torre, María; Martín-Sampedro, Raquel; Fillat, Úrsula; Eugenio, María E; Blánquez, Alba; Hernández, Manuel; Arias, María E; Ibarra, David

2017-11-01

This study evaluates the potential of a bacterial laccase from Streptomyces ipomoeae (SilA) for delignification and detoxification of steam-exploded wheat straw, in comparison with a commercial fungal laccase from Trametes villosa. When alkali extraction followed by SilA laccase treatment was applied to the water insoluble solids fraction, a slight reduction in lignin content was detected, and after a saccharification step, an increase in both glucose and xylose production (16 and 6%, respectively) was observed. These effects were not produced with T. villosa laccase. Concerning to the fermentation process, the treatment of the steam-exploded whole slurry with both laccases produced a decrease in the phenol content by up to 35 and 71% with bacterial and fungal laccases, respectively. The phenols reduction resulted in an improved performance of Saccharomyces cerevisiae during a simultaneous saccharification and fermentation (SSF) process, improving ethanol production rate. This enhancement was more marked with a presaccharification step prior to the SSF process.

Laccase/Mediator Systems: Their Reactivity toward Phenolic Lignin Structures.

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Hilgers, Roelant; Vincken, Jean-Paul; Gruppen, Harry; Kabel, Mirjam A

2018-02-05

Laccase-mediator systems (LMS) have been widely studied for their capacity to oxidize the nonphenolic subunits of lignin (70-90% of the polymer). The phenolic subunits (10-30% of the polymer), which can also be oxidized without mediators, have received considerably less attention. Consequently, it remains unclear to what extent the presence of a mediator influences the reactions of the phenolic subunits of lignin. To get more insight in this, UHPLC-MS was used to study the reactions of a phenolic lignin dimer (GBG), initiated by a laccase from Trametes versicolor , alone or in combination with the mediators HBT and ABTS. The role of HBT was negligible, as its oxidation by laccase occurred slowly in comparison to that of GBG. Laccase and laccase/HBT oxidized GBG at a comparable rate, resulting in extensive polymerization of GBG. In contrast, laccase/ABTS converted GBG at a higher rate, as GBG was oxidized both directly by laccase but also by ABTS radical cations, which were rapidly formed by laccase. The laccase/ABTS system resulted in Cα oxidation of GBG and coupling of ABTS to GBG, rather than polymerization of GBG. Based on these results, we propose reaction pathways of phenolic lignin model compounds with laccase/HBT and laccase/ABTS.

Formation of hydroxylated polybrominated diphenyl ethers from laccase-catalyzed oxidation of bromophenols.

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Lin, Kunde; Zhou, Shiyang; Chen, Xi; Ding, Jiafeng; Kong, Xiaoyan; Gan, Jay

2015-11-01

Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) have been frequently found in the marine biosphere as emerging organic contaminants. Studies to date have suggested that OH-PBDEs in marine biota are natural products. However, the mechanisms leading to the biogenesis of OH-PBDEs are still far from clear. In this study, using a laccase isolated from Trametes versicolor as the model enzyme, we explored the formation of OH-PBDEs from the laccase-catalyzed oxidation of simple bromophenols (e.g., 2,4-DBP and 2,4,6-TBP). Experiments under ambient conditions clearly showed that OH-PBDEs were produced from 2,4-DBP and 2,4,6-TBP in presence of laccase. Polybrominated compounds 2'-OH-BDE68, 2,2'-diOH-BB80, and 1,3,8-TrBDD were identified as the products from 2,4-DBP, and 2'-OH-BDE121 and 4'-OH-BDE121 from 2,4,6-TBP. The production of OH-PBDEs was likely a result of the coupling of bromophenoxy radicals, generated from the laccase-catalyzed oxidation of 2,4-DBP or 2,4,6-TBP. The transformation of bromophenols by laccase was pH-dependant, and was also influenced by enzymatic activity. In view of the abundance of 2,4-DBP and 2,4,6-TBP and the phylogenetic distribution of laccases in the environment, laccase-catalyzed conversion of bromophenols may be potentially an important route for the natural biosynthesis of OH-PBDEs. Copyright © 2015 Elsevier Ltd. All rights reserved.

How Truncating Are 'Truncating Languages'? Evidence from Russian and German.

Science.gov (United States)

Rathcke, Tamara V

Russian and German have pr eviously been described as 'truncating', or cutting off target frequencies of the phrase-final pitch trajectories when the time available for voicing is compromised. However, supporting evidence is rare and limited to only a few pitch categories. This paper reports a production study conducted to document pitch adjustments to linguistic materials, in which the amount of voicing available for the realization of a pitch pattern varies from relatively long to extremely short. Productions of nuclear H+L*, H* and L*+H pitch accents followed by a low boundary tone were investigated in the two languages. The results of the study show that speakers of both 'truncating languages' do not utilize truncation exclusively when accommodating to different segmental environments. On the contrary, they employ several strategies - among them is truncation but also compression and temporal re-alignment - to produce the target pitch categories under increasing time pressure. Given that speakers can systematically apply all three adjustment strategies to produce some pitch patterns (H* L% in German and Russian) while not using truncation in others (H+L* L% particularly in Russian), we question the effectiveness of the typological classification of these two languages as 'truncating'. Moreover, the phonetic detail of truncation varies considerably, both across and within the two languages, indicating that truncation cannot be easily modeled as a unified phenomenon. The results further suggest that the phrase-final pitch adjustments are sensitive to the phonological composition of the tonal string and the status of a particular tonal event (associated vs. boundary tone), and do not apply to falling vs. rising pitch contours across the board, as previously put forward for German. Implications for the intonational phonology and prosodic typology are addressed in the discussion. © 2017 S. Karger AG, Basel.

Separation of phenolic acids from monosaccharides by low-pressure nanofiltration integrated with laccase pre-treatments

DEFF Research Database (Denmark)

Luo, Jianquan; Zeuner, Birgitte; Morthensen, Sofie Thage

2015-01-01

(e.g. dimers and trimers) were mainly responsible for the adsorption fouling. Free laccase treatment was preferred since it was prone to produce large polymeric products while the biocatalytic membrane with immobilized laccase was not suitable as it generated smaller polymers by in-situ product...... monosaccharides (xylose, arabinose, glucose). Four commercial NF membranes (NF270, NP030, NTR7450 and NP010) were evaluated at different pH values and with various laccase pre-treatments (for polymerization of phenolic acids). The results showed that with increasing pH, the retentions of phenolic acids by NF...... could be polymerized by laccase and then completely retained by the NF membranes via size exclusion at pH 5.15. The formation of large polymeric products by laccase could alleviate the irreversible fouling in/on a NF membrane and decrease the monosaccharide retention, while the small polymeric products...

Secretory expression of the non-secretory-type Lentinula edodes laccase by Aspergillus oryzae.

Science.gov (United States)

Yano, Akira; Kikuchi, Sayaka; Nakagawa, Yuko; Sakamoto, Yuichi; Sato, Toshitsugu

2009-01-01

The shiitake mushroom, Lentinula edodes, has an extracelluar secretory-type laccase, Lcc1, and a fruiting-body-accumulation-type laccase, Lcc4. We previously reported the production of Lcc1 by plant cells, but had difficulty producing Lcc4. Here, we report the production of Lcc1 and Lcc4 by Aspergillus oryzae and the extracellular secretory production of Lcc4 using a modified secretion signal peptide (SP) from Lcc1. Sp-Lcc4 produced by A. oryzae had biochemical activities similar to Lcc4 produced by L. edodes. Lcc1 did not react with beta-(3,4-dihydroxyphenol) alanine (DOPA), but Lcc4 from L. edodes and A. oryzae could oxidize DOPA. K(M) values for the substrates 2,2'-azino-di-(3-ethylbenzthiazolinsulfonate), 2,6-dimethoxyphenol, guaiacol, pyrogallol, and catechol were similar for Lcc4 and Sp-Lcc4. In conclusion, a non-secretory-type fungal laccase is secreted into the culture media with its original enzymatic properties by exploiting modified secretory signal peptide. 2008 Elsevier GmbH.

Decolorization of the azo dye Acid Orange 51 by laccase produced in solid culture of a newly isolated Trametes trogii strain

OpenAIRE

Daâssi, Dalel; Zouari-Mechichi, Héla; Frikha, Fakher; Martínez, María Jesús; Nasri, M.; Mechichi, Tahar

2013-01-01

This study concerns the decolorization and detoxification of the azo dye Acid Orange 51 (AO51) by crude laccase from Trametes trogii produced in solid culture using sawdust as support media. A three-level Box?Behnken factorial design with four factors (enzyme concentration, 1-hydroxybenzotriazole (HBT) concentration, dye concentration and reaction time) combined with response surface methodology was applied to optimize AO51 decolorization. A mathematical model was developed showing the effect...

Multiple Reaction Monitoring for quantitative laccase kinetics by LC-MS

DEFF Research Database (Denmark)

Perna, Valentina; Agger, Jane W.; Holck, Jesper

2018-01-01

as substrates to assess enzyme kinetics by HPLC-MS on two fungal laccases Trametes versicolor laccase, Tv and Ganoderma lucidum laccase, Gl. The method allowed accurate kinetic measurements and detailed insight into the product profiles of both laccases. Both Tv and Gl laccase are active...

Purification and characterization of laccase from Trametes hirsuta ...

African Journals Online (AJOL)

oem

2012-02-21

Feb 21, 2012 ... wine, and in beer stabilization (Minussi et al., 2002), paper pulp .... Laccase was incubated with ethanol and acetonitrile 20% at room temperature for 24 h. ... Apparent kinetic constants (Km, Vmax) were calculated using ..... from Trametes versicolor produced by solid-substrate fermentation. Adv. Biosci.

Isolation and Physicochemical Characterization of Laccase from Ganoderma lucidum-CDBT1 Isolated from Its Native Habitat in Nepal

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Prabin Shrestha

2016-01-01

Full Text Available At present, few organisms are known to and capable of naturally producing laccases and white rot fungi are one such group. In the present study, three fungal species, namely, Ganoderma lucidum-CDBT1, Ganoderma japonicum, and Lentinula edodes, isolated from their native habitat in Nepal were screened for laccase production, and G. lucidum-CDBT1 was found to express highest levels of enzyme (day 10 culture media showed 0.92 IU/mg total protein or 92 IU/mL laccase activity with ABTS as substrate. Lignin extracted from rice straw was used in Olga medium for laccase production and isolation from G. lucidum-CDBT1. Presence of lignin (5 g/L and copper sulfate (30 μM in the media increased the extracellular laccase content by 111% and 114%, respectively. The laccase enzyme produced by G. lucidum-CDBT1 was fractionated by ammonium sulfate and purified by DEAE Sepharose anion exchange chromatography. The purified enzyme was found to have a molecular mass of 43 kDa and exhibits optimal activity at pH 5.0 and 30°C. The isolated laccase was thermally stable for up to 70°C for 1 h and exhibited broad pH stability. The kinetic constants, Km, Vmax, and Kcat, determined using 2,2′-azinobis-(-3-ethylbenzothiazoline-6-sulfonic acid as substrate were found to be 110 μM, 36 μmol/min/mg, and 246 min−1, respectively. The isolated thermostable laccase will be used in future experiments for delignification process.

Isolation and Physicochemical Characterization of Laccase from Ganoderma lucidum-CDBT1 Isolated from Its Native Habitat in Nepal.

Science.gov (United States)

Shrestha, Prabin; Joshi, Bishnu; Joshi, Jarina; Malla, Rajani; Sreerama, Lakshmaiah

2016-01-01

At present, few organisms are known to and capable of naturally producing laccases and white rot fungi are one such group. In the present study, three fungal species, namely, Ganoderma lucidum -CDBT1 , Ganoderma japonicum, and Lentinula edodes , isolated from their native habitat in Nepal were screened for laccase production, and G. lucidum -CDBT1 was found to express highest levels of enzyme (day 10 culture media showed 0.92 IU/mg total protein or 92 IU/mL laccase activity with ABTS as substrate). Lignin extracted from rice straw was used in Olga medium for laccase production and isolation from G. lucidum -CDBT1. Presence of lignin (5 g/L) and copper sulfate (30  μ M) in the media increased the extracellular laccase content by 111% and 114%, respectively. The laccase enzyme produced by G. lucidum -CDBT1 was fractionated by ammonium sulfate and purified by DEAE Sepharose anion exchange chromatography. The purified enzyme was found to have a molecular mass of 43 kDa and exhibits optimal activity at pH 5.0 and 30°C. The isolated laccase was thermally stable for up to 70°C for 1 h and exhibited broad pH stability. The kinetic constants, K m , V max , and K cat , determined using 2,2'-azinobis-(-3-ethylbenzothiazoline-6-sulfonic acid) as substrate were found to be 110  μ M, 36  μ mol/min/mg, and 246 min -1 , respectively. The isolated thermostable laccase will be used in future experiments for delignification process.

Direct rate assessment of laccase catalysed radical formation in lignin by electron paramagnetic resonance spectroscopy

DEFF Research Database (Denmark)

Munk, Line; Andersen, Mogens Larsen; Meyer, Anne S.

2017-01-01

Laccases (EC 1.10.3.2) catalyse removal of an electron and a proton from phenolic hydroxyl groups, including phenolic hydroxyls in lignins, to form phenoxy radicals during reduction of O2. We employed electron paramagnetic resonance spectroscopy (EPR) for real time measurement of such catalytic...... to suspensions of the individual lignin samples produced immediate time and enzyme dose dependent increases in intensity in the EPR signal with g-values in the range 2.0047–2.0050 allowing a direct quantitative monitoring of the radical formation and thus allowed laccase enzyme kinetics assessment on lignin...... for the radical formation rate in organosolv lignin was determined by response surface methodology to pH 4.8, 33 °C and pH 5.8, 33 °C for the Tv laccase and the Mt laccase, respectively. The results verify direct radical formation action of fungal laccases on lignin without addition of mediators and the EPR...

Automated chromatographic laccase-mediator-system activity assay.

Science.gov (United States)

Anders, Nico; Schelden, Maximilian; Roth, Simon; Spiess, Antje C

2017-08-01

To study the interaction of laccases, mediators, and substrates in laccase-mediator systems (LMS), an on-line measurement was developed using high performance anion exchange chromatography equipped with a CarboPac™ PA 100 column coupled to pulsed amperometric detection (HPAEC-PAD). The developed method was optimized for overall chromatographic run time (45 to 120 min) and automated sample drawing. As an example, the Trametes versicolor laccase induced oxidation of 1-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)-1,3-dihydroxypropane (adlerol) using 1-hydroxybenzotriazole (HBT) as mediator was measured and analyzed on-line. Since the Au electrode of the PAD detects only hydroxyl group containing substances with a limit of detection being in the milligram/liter range, not all products are measureable. Therefore, this method was applied for the quantification of adlerol, and-based on adlerol conversion-for the quantification of the LMS activity at a specific T. versicolor laccase/HBT ratio. The automated chromatographic activity assay allowed for a defined reaction start of all laccase-mediator-system reactions mixtures, and the LMS reaction progress was automatically monitored for 48 h. The automatization enabled an integrated monitoring overnight and over-weekend and minimized all manual errors such as pipetting of solutions accordingly. The activity of the LMS based on adlerol consumption was determined to 0.47 U/mg protein for a laccase/mediator ratio of 1.75 U laccase/g HBT. In the future, the automated method will allow for a fast screening of combinations of laccases, mediators, and substrates which are efficient for lignin modification. In particular, it allows for a fast and easy quantification of the oxidizing activity of an LMS on a lignin-related substrate which is not covered by typical colorimetric laccase assays. ᅟ.

Fungal Laccases Degradation of Endocrine Disrupting Compounds

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Gemma Macellaro

2014-01-01

Full Text Available Over the past decades, water pollution by trace organic compounds (ng/L has become one of the key environmental issues in developed countries. This is the case of the emerging contaminants called endocrine disrupting compounds (EDCs. EDCs are a new class of environmental pollutants able to mimic or antagonize the effects of endogenous hormones, and are recently drawing scientific and public attention. Their widespread presence in the environment solicits the need of their removal from the contaminated sites. One promising approach to face this challenge consists in the use of enzymatic systems able to react with these molecules. Among the possible enzymes, oxidative enzymes are attracting increasing attention because of their versatility, the possibility to produce them on large scale, and to modify their properties. In this study five different EDCs were treated with four different fungal laccases, also in the presence of both synthetic and natural mediators. Mediators significantly increased the efficiency of the enzymatic treatment, promoting the degradation of substrates recalcitrant to laccase oxidation. The laccase showing the best performances was chosen to further investigate its oxidative capabilities against micropollutant mixtures. Improvement of enzyme performances in nonylphenol degradation rate was achieved through immobilization on glass beads.

Cross-linking proteins by laccase: Effects on the droplet size and rheology of emulsions stabilized by sodium caseinate.

Science.gov (United States)

Sato, A C K; Perrechil, F A; Costa, A A S; Santana, R C; Cunha, R L

2015-09-01

The aim of this work was to evaluate the influence of laccase and ferulic acid on the characteristics of oil-in-water emulsions stabilized by sodium caseinate at different pH (3, 5 and 7). Emulsions were prepared by high pressure homogenization of soybean oil with sodium caseinate solution containing varied concentrations of laccase (0, 1 and 5mg/mL) and ferulic acid (5 and 10mM). Laccase treatment and pH exerted a strong influence on the properties with a consequent effect on stability, structure and rheology of emulsions stabilized by Na-caseinate. At pH7, O/W emulsions were kinetically stable due to the negative protein charge which enabled electrostatic repulsion between oil droplets resulting in an emulsion with small droplet size, low viscosity, pseudoplasticity and viscoelastic properties. The laccase treatment led to emulsions showing shear-thinning behavior as a result of a more structured system. O/W emulsions at pH5 and 3 showed phase separation due to the proximity to protein pI, but the laccase treatment improved their stability of emulsions especially at pH3. At pH3, the addition of ferulic acid and laccase produced emulsions with larger droplet size but with narrower droplet size distribution, increased viscosity, pseudoplasticity and viscoelastic properties (gel-like behavior). Comparing laccase treatments, the combined addition of laccase and ferulic acid generally produced emulsions with lower stability (pH5), larger droplet size (pH3, 5 and 7) and higher pseudoplasticity (pH5 and 7) than emulsion with only ferulic acid. The results suggested that the cross-linking of proteins by laccase and ferulic acid improved protein emulsifying properties by changing functional mechanisms of the protein on emulsion structure and rheology, showing that sodium caseinate can be successfully used in acid products when treated with laccase. Copyright © 2015 Elsevier Ltd. All rights reserved.

Isolation and Physicochemical Characterization of Laccase from Ganoderma lucidum-CDBT1 Isolated from Its Native Habitat in Nepal

Science.gov (United States)

Joshi, Jarina; Malla, Rajani

2016-01-01

At present, few organisms are known to and capable of naturally producing laccases and white rot fungi are one such group. In the present study, three fungal species, namely, Ganoderma lucidum-CDBT1, Ganoderma japonicum, and Lentinula edodes, isolated from their native habitat in Nepal were screened for laccase production, and G. lucidum-CDBT1 was found to express highest levels of enzyme (day 10 culture media showed 0.92 IU/mg total protein or 92 IU/mL laccase activity with ABTS as substrate). Lignin extracted from rice straw was used in Olga medium for laccase production and isolation from G. lucidum-CDBT1. Presence of lignin (5 g/L) and copper sulfate (30 μM) in the media increased the extracellular laccase content by 111% and 114%, respectively. The laccase enzyme produced by G. lucidum-CDBT1 was fractionated by ammonium sulfate and purified by DEAE Sepharose anion exchange chromatography. The purified enzyme was found to have a molecular mass of 43 kDa and exhibits optimal activity at pH 5.0 and 30°C. The isolated laccase was thermally stable for up to 70°C for 1 h and exhibited broad pH stability. The kinetic constants, K m, V max, and K cat, determined using 2,2′-azinobis-(-3-ethylbenzothiazoline-6-sulfonic acid) as substrate were found to be 110 μM, 36 μmol/min/mg, and 246 min−1, respectively. The isolated thermostable laccase will be used in future experiments for delignification process. PMID:27822471

Effect of inducers and culturing processes on laccase synthesis in Phanerochaete chrysosporium NCIM 1197 and the constitutive expression of laccase isozymes

DEFF Research Database (Denmark)

Manavalan, Arulmani

2006-01-01

Phanerochaete chrysosporium NCIM 1197 constitutively secretes considerable level of extracellular enzyme laccase in defined growth medium. Effect of several inducers on laccase production was attempted and found that copper sulphate alone at 30 mM concentration accelerate the laccase production...

Simultaneous production of laccase and decolouration of the diazo dye Reactive Black 5 in a fixed-bed bioreactor

International Nuclear Information System (INIS)

Enayatzamir, Kheirghadam; Alikhani, Hossein A.; Rodriguez Couto, Susana

2009-01-01

In this paper the production of laccase and the decolouration of the recalcitrant diazo dye Reactive Black 5 (RB5) by the white-rot fungus Trametes pubescens immobilised on stainless steel sponges in a fixed-bed reactor were studied. Laccase production was increased by 10-fold in the presence of RB5 and reached a maximum value of 1025 U/l. Enhanced laccase production in the presence of RB5 in this fungus is an added advantage during biodegradation of RB5-containing effluents. The decolouration of RB5 was due to two processes: dye adsorption onto the fungal mycelium and dye degradation by the laccase enzymes produced by the fungus. RB5 decolouration was performed during four successive batches obtaining high decolouration percentages (74%, 43% and 52% in 24 h for the first, third and four batch, respectively) without addition of redox mediators. Also, the in vitro decolouration of RB5 by the concentrated culture extract, containing mainly laccase, produced in the above bioreactor was studied. The decolouration percentages obtained were considerably lower (around 20% in 24 h) than that attained with the whole culture

Simultaneous production of laccase and decolouration of the diazo dye Reactive Black 5 in a fixed-bed bioreactor

Energy Technology Data Exchange (ETDEWEB)

Enayatzamir, Kheirghadam [Department of Chemical Engineering, Rovira i Virgili University, Av. Paisos Catalans 26, 43007 Tarragona (Spain); Department of Soil Science Engineering, University of Tehran, Karaj (Iran, Islamic Republic of); Alikhani, Hossein A. [Department of Soil Science Engineering, University of Tehran, Karaj (Iran, Islamic Republic of); Rodriguez Couto, Susana [Department of Chemical Engineering, Rovira i Virgili University, Av. Paisos Catalans 26, 43007 Tarragona (Spain)], E-mail: susana.rodriguez@urv.cat

2009-05-15

In this paper the production of laccase and the decolouration of the recalcitrant diazo dye Reactive Black 5 (RB5) by the white-rot fungus Trametes pubescens immobilised on stainless steel sponges in a fixed-bed reactor were studied. Laccase production was increased by 10-fold in the presence of RB5 and reached a maximum value of 1025 U/l. Enhanced laccase production in the presence of RB5 in this fungus is an added advantage during biodegradation of RB5-containing effluents. The decolouration of RB5 was due to two processes: dye adsorption onto the fungal mycelium and dye degradation by the laccase enzymes produced by the fungus. RB5 decolouration was performed during four successive batches obtaining high decolouration percentages (74%, 43% and 52% in 24 h for the first, third and four batch, respectively) without addition of redox mediators. Also, the in vitro decolouration of RB5 by the concentrated culture extract, containing mainly laccase, produced in the above bioreactor was studied. The decolouration percentages obtained were considerably lower (around 20% in 24 h) than that attained with the whole culture.

Laccase from a non-melanogenic, alkalotolerant gamma-proteobacterium JB isolated from industrial wastewater drained soil.

Science.gov (United States)

Bains, Jasleen; Capalash, Neena; Sharma, Prince

2003-07-01

A gram-negative, alkalotolerant bacterium, isolated from the soil continually drained with industrial wastewater and identified as gamma-proteobacterium by partial 16S rRNA sequence analysis, produced a polyphenol oxidase, which showed laccase but not tyrosinase activity. The organism grew well from pH 6 to 10 and produced laccase maximally at pH 10. The enzyme was stable from pH 3 to 10.6 for at least 24 h and was optimally active at 55 degrees C and pH 6.5 in a 5 min assay.

Structural and Phylogenetic Analysis of Laccases from Trichoderma: A Bioinformatic Approach

Science.gov (United States)

Cázares-García, Saila Viridiana; Vázquez-Garcidueñas, Ma. Soledad; Vázquez-Marrufo, Gerardo

2013-01-01

The genus Trichoderma includes species of great biotechnological value, both for their mycoparasitic activities and for their ability to produce extracellular hydrolytic enzymes. Although activity of extracellular laccase has previously been reported in Trichoderma spp., the possible number of isoenzymes is still unknown, as are the structural and functional characteristics of both the genes and the putative proteins. In this study, the system of laccases sensu stricto in the Trichoderma species, the genomes of which are publicly available, were analyzed using bioinformatic tools. The intron/exon structure of the genes and the identification of specific motifs in the sequence of amino acids of the proteins generated in silico allow for clear differentiation between extracellular and intracellular enzymes. Phylogenetic analysis suggests that the common ancestor of the genus possessed a functional gene for each one of these enzymes, which is a characteristic preserved in T. atroviride and T. virens. This analysis also reveals that T. harzianum and T. reesei only retained the intracellular activity, whereas T. asperellum added an extracellular isoenzyme acquired through horizontal gene transfer during the mycoparasitic process. The evolutionary analysis shows that in general, extracellular laccases are subjected to purifying selection, and intracellular laccases show neutral evolution. The data provided by the present study will enable the generation of experimental approximations to better understand the physiological role of laccases in the genus Trichoderma and to increase their biotechnological potential. PMID:23383142

Optimization of Laccase Production using White Rot Fungi and Agriculture Wastes in Solid State Fermentation

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Hendro Risdianto

2012-07-01

Full Text Available Laccase has been produced in a solid state fermentation (SSF using white rot fungi and various lignocellulosic based substrates. White rot fungi used were Marasmius sp, Trametes hirsuta, Trametes versicolor and Phanerochaete crysosporium. The solid substrates employed in this research were collected from agriculture waste which were empty fruit bunches (EFB, rice straw, corn cob, and rice husk. The objective of this research was to determine the most promising fungus, the best solid substrate and the optimal conditions for the production of laccase. The results showed that Marasmius sp. on all solid substrates displayed higher laccase activity than that of any other strain of white rot fungi. Marasmius sp. and solid substrate of rice straw demonstrated the highest laccase activity of 1116.11 U/L on day 10. Three significant factors, i.e. pH, temperature and yeast extract concentration were studied by response surface method on laccase production using Marasmius sp and rice straw. The optimized conditions were pH, temperature and yeast extract concentration of 4.9, 31ºC and 0.36 g/L respectively. The fermentation of Marasmius sp. in SSF on agricultural waste shows a great potential for the production of laccase.

Laccase detoxification mediates the nutritional alliance between leaf-cutting ants and fungus-garden symbionts.

Science.gov (United States)

De Fine Licht, Henrik H; Schiøtt, Morten; Rogowska-Wrzesinska, Adelina; Nygaard, Sanne; Roepstorff, Peter; Boomsma, Jacobus J

2013-01-08

Leaf-cutting ants combine large-scale herbivory with fungus farming to sustain advanced societies. Their stratified colonies are major evolutionary achievements and serious agricultural pests, but the crucial adaptations that allowed this mutualism to become the prime herbivorous component of neotropical ecosystems has remained elusive. Here we show how coevolutionary adaptation of a specific enzyme in the fungal symbiont has helped leaf-cutting ants overcome plant defensive phenolic compounds. We identify nine putative laccase-coding genes in the fungal genome of Leucocoprinus gongylophorus cultivated by the leaf-cutting ant Acromyrmex echinatior. One of these laccases (LgLcc1) is highly expressed in the specialized hyphal tips (gongylidia) that the ants preferentially eat, and we confirm that these ingested laccase molecules pass through the ant guts and remain active when defecated on the leaf pulp that the ants add to their gardens. This accurate deposition ensures that laccase activity is highest where new leaf material enters the fungus garden, but where fungal mycelium is too sparse to produce extracellular enzymes in sufficient quantities to detoxify phenolic compounds. Phylogenetic analysis of LgLcc1 ortholog sequences from symbiotic and free-living fungi revealed significant positive selection in the ancestral lineage that gave rise to the gongylidia-producing symbionts of leaf-cutting ants and their non-leaf-cutting ant sister group. Our results are consistent with fungal preadaptation and subsequent modification of a particular laccase enzyme for the detoxification of secondary plant compounds during the transition to active herbivory in the ancestor of leaf-cutting ants between 8 and 12 Mya.

Synthesis of novel laccase-biotitania biocatalysts for malachite green decolorization.

Science.gov (United States)

Zhang, Xinying; Wang, Meiyin; Lin, Linlin; Xiao, Gao; Tang, Zhenping; Zhu, Xuefeng

2018-07-01

Biomimetic mineralization has emerged as a novel tool for generating excellent supports for enzyme stabilization. In this work, protamine was used to induce titanium (IV) bis(ammonium lactato) dihydroxide (Ti-BALDH) into titania nanoparticles. This biomimetic titanification process was adopted for laccase immobilization. Laccase-biotitania biocatalyst was prepared and the effect of different parameters (buffer solution, titania precursor concentration, protamine concentration, and enzyme loading) on the encapsulation efficiency and recovery of laccase were evaluated. Compared with free laccase, the thermal and pH stability of immobilized laccase were improved significantly. In addition, laccase loaded on titania was effective at enhancing its storage stability. After seven consecutive cycles, the immobilized laccase still retained 51% of its original activity. Finally, laccase-biotitania biocatalysts showed good performance on decolorization of malachite green (MG), which can be attributed to an adsorption and degradation effect. The intermediates of the MG degradation were identified by gas chromatography-mass spectrometry (GC-MS) analysis, and the most probable degradation pathway was proposed. This study provides deeper understanding of the laccase-biotitania particles as a fast biocatalyst for MG decolorization. Copyright © 2018 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

A chloride tolerant laccase from the plant pathogen ascomycete Botrytis aclada expressed at high levels in Pichia pastoris.

Science.gov (United States)

Kittl, Roman; Mueangtoom, Kitti; Gonaus, Christoph; Khazaneh, Shima Tahvilda; Sygmund, Christoph; Haltrich, Dietmar; Ludwig, Roland

2012-01-20

Fungal laccases from basidiomycetous fungi are thoroughly investigated in respect of catalytic mechanism and industrial applications, but the number of reported and well characterized ascomycetous laccases is much smaller although they exhibit interesting catalytic properties. We report on a highly chloride tolerant laccase produced by the plant pathogen ascomycete Botrytis aclada, which was recombinantly expressed in Pichia pastoris with an extremely high yield and purified to homogeneity. In a fed-batch fermentation, 495 mg L(-1) of laccase was measured in the medium, which is the highest concentration obtained for a laccase by a yeast expression system. The recombinant B. aclada laccase has a typical molecular mass of 61,565 Da for the amino acid chain. The pI is approximately 2.4, a very low value for a laccase. Glycosyl residues attached to the recombinant protein make up for approximately 27% of the total protein mass. B. aclada laccase exhibits very low K(M) values and high substrate turnover numbers for phenolic and non-phenolic substrates at acidic and near neutral pH. The enzyme's stability increases in the presence of chloride ions and, even more important, its substrate turnover is only weakly inhibited by chloride ions (I(50)=1.4M), which is in sharp contrast to most other described laccases. This high chloride tolerance is mandatory for some applications such as implantable biofuel cells and laccase catalyzed reactions, which suffer from the presence of chloride ions. The high expression yield permits fast and easy production for further basic and applied research. Copyright © 2011 Elsevier B.V. All rights reserved.

Engineering laccases: in search for novel catalysts.

Science.gov (United States)

Robert, Viviane; Mekmouche, Yasmina; Pailley, Pierre R; Tron, Thierry

2011-04-01

Laccases (p-diphenol oxidase, EC 1.10.3.2) are blue multicopper oxidases that catalyze the reduction of dioxygen to water, with a concomitant oxidation of small organic substrates. Since the description at the end of the nineteenth century of a factor catalyzing the rapid hardening of the latex of the Japanese lacquer trees (Rhus sp.) exposed to air laccases from different origins (plants, fungi bacteria) have been continuously discovered and extensively studied. Nowadays, molecular evolution and other powerful protein modification techniques offer possibilities to develop tailored laccases for a wide array of applications including drug synthesis, biosensors or biofuel cells. Here, we give an overview on strategies and results of our laboratory in the design of new biocatalysts based on laccases.

Fungal Laccases and Their Applications in Bioremediation

Directory of Open Access Journals (Sweden)

Buddolla Viswanath

2014-01-01

Full Text Available Laccases are blue multicopper oxidases, which catalyze the monoelectronic oxidation of a broad spectrum of substrates, for example, ortho- and para-diphenols, polyphenols, aminophenols, and aromatic or aliphatic amines, coupled with a full, four-electron reduction of O2 to H2O. Hence, they are capable of degrading lignin and are present abundantly in many white-rot fungi. Laccases decolorize and detoxify the industrial effluents and help in wastewater treatment. They act on both phenolic and nonphenolic lignin-related compounds as well as highly recalcitrant environmental pollutants, and they can be effectively used in paper and pulp industries, textile industries, xenobiotic degradation, and bioremediation and act as biosensors. Recently, laccase has been applied to nanobiotechnology, which is an increasing research field, and catalyzes electron transfer reactions without additional cofactors. Several techniques have been developed for the immobilization of biomolecule such as micropatterning, self-assembled monolayer, and layer-by-layer techniques, which immobilize laccase and preserve their enzymatic activity. In this review, we describe the fungal source of laccases and their application in environment protection.

Expression of a thermotolerant laccase from Pycnoporus sanguineus in Trichoderma reesei and its application in the degradation of bisphenol A.

Science.gov (United States)

Zhao, Jie; Zeng, Shengquan; Xia, Ying; Xia, Liming

2018-04-01

The laccase gene from Pycnoporus sanguineus was cloned and inserted between the strong Pcbh1 promoter and the Tcbh1 terminator from Trichoderma reesei to form the recombinant plasmid pCH-lac. Using Agrobacterium-mediated technique, the pCH-lac was integrated into the chromosomes of T. reesei. Twenty positive transformants were obtained by employing hygromycin B as a selective agent. PCR was used to confirm that the laccase gene was integrated into the chromosomal DNA of T. reesei. Laccase production by recombinant transformants was performed in shaking flasks, and the activity of laccase reached 8.8 IU/mL after 96-h fermentation under a batch process, and 17.7 IU/mL after 144-h fermentation using a fed-batch process. SDS-PAGE analysis of the fermentation broth showed that the molecular mass of the protein was about 68 kDa, almost the same as that of the laccase produced by P. sanguineus, which indicated that laccase was successfully expressed in T. reesei and secreted out of the cells. The laccase produced by the recombinant T. reesei showed good thermal stability, and could degrade the toxic phenolic material bisphenol A efficiently, after 1-h reaction with 0.06 IU/mL laccase and 0.5 mmol/L ABTS as the mediator at 60 °C and pH 4.5, the degradation rate reached 95%, which demonstrated that it had great potential value in treating the household garbage and wastewater containing the bisphenol A. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Bioinspired production of magnetic laccase-biotitania particles for the removal of endocrine disrupting chemicals.

Science.gov (United States)

Ardao, Inés; Magnin, Delphine; Agathos, Spiros N

2015-10-01

Microbial laccases are powerful enzymes capable of degrading lignin and other recalcitrant compounds including endocrine disrupting chemicals (EDCs). Efficient EDC removal on an industrial scale requires robust, stable, easy to handle and cost-effective immobilized biocatalysts. In this direction, magnetic biocatalysts are attractive due to their easy separation through an external magnetic field. Recently, a bioinspired immobilization technique that mimics the natural biomineralization reactions in diatoms has emerged as a fast and versatile tool for generating robust, cheap, and highly stable (nano) biocatalysts. In this work, bioinspired formation of a biotitania matrix is triggered on the surface of magnetic particles in the presence of laccase in order to produce laccase-biotitania (lac-bioTiO2 ) biocatalysts suitable for environmental applications using a novel, fast and versatile enzyme entrapment technique. Highly active lac-bioTiO2 particles have been produced and the effect of different parameters (enzyme loading, titania precursor concentration, pH, duration of the biotitania formation, and laccase adsorption steps) on the apparent activity yield of these biocatalysts were evaluated, the concentration of the titania precursor being the most influential. The lac-bioTiO2 particles were able to catalyze the removal of bisphenol A, 17α-ethinylestradiol and diclofenac in a mixture of six model EDCs and retained 90% of activity after five reaction cycles and 60% after 10 cycles. © 2015 Wiley Periodicals, Inc.

Isolation of laccase gene-specific sequences from white rot and brown rot fungi by PCR.

Science.gov (United States)

D'Souza, T M; Boominathan, K; Reddy, C A

1996-01-01

Degenerate primers corresponding to the consensus sequences of the copper-binding regions in the N-terminal domains of known basidiomycete laccases were used to isolate laccase gene-specific sequences from strains representing nine genera of wood rot fungi. All except three gave the expected PCR product of about 200 bp. Computer searches of the databases identified the sequence of each of the PCR products analyzed as a laccase gene sequence, suggesting the specificity of the primers. PCR products of the white rot fungi Ganoderma lucidum, Phlebia brevispora, and Trametes versicolor showed 65 to 74% nucleotide sequence similarity to each other; the similarity in deduced amino acid sequences was 83 to 91%. The PCR products of Lentinula edodes and Lentinus tigrinus, on the other hand, showed relatively low nucleotide and amino acid similarities (58 to 64 and 62 to 81%, respectively); however, these similarities were still much higher than when compared with the corresponding regions in the laccases of the ascomycete fungi Aspergillus nidulans and Neurospora crassa. A few of the white rot fungi, as well as Gloeophyllum trabeum, a brown rot fungus, gave a 144-bp PCR fragment which had a nucleotide sequence similarity of 60 to 71%. Demonstration of laccase activity in G. trabeum and several other brown rot fungi was of particular interest because these organisms were not previously shown to produce laccases. PMID:8837429

In silico Analysis for Laccase-mediated Bioremediation of the Emerging Pharmaceutical Pollutants

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Anjali Singh

2015-12-01

Full Text Available Laccases, a copper oxidase enzyme, has been employed for bioremediation of anthropogenic pollutants in the recent past. Laccase has a broad range of substrate specificity which offers the prospect for screening in numerable xenobiotics. The present study was aimed to use protein-ligand docking as a tool for prediction of biodegradation of selected pharmaceutical pollutants. A comparative study was also done to determine the binding efficacy of bacterial and fungal laccase for those selected pollutants. The laccase-pollutant docking was carried out using HEX software. The docking scores of bacterial and fungal laccase for predefined pollutants were comparable to ABTS, a substrate for laccase, which suggested that laccase might be able to degrade emerging pharmaceutical pollutants. The docking analysis approach can be useful in prediction of binding competence of pharmaceutical pollutants with laccase for in situ laccase-mediated bioremediation.

Modification of Lignans by Trametes Hirsuta Laccase

NARCIS (Netherlands)

Mattinen, M.L.; Struijs, K.; Suortti, T.; Mattila, I.; Kruus, K.; Willfor, S.; Tamminen, T.; Vincken, J.P.

2009-01-01

Oxidative polymerization of two isolated lignans, secoisolariciresinol, and secoisolariciresinol diglucoside, as well as the lignan macromolecule, by a high redox potential Trametes hirsuta laccase was studied with different analytical methods. The reactivity of laccase with the different compounds

Evolved α-factor prepro-leaders for directed laccase evolution in Saccharomyces cerevisiae.

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Mateljak, Ivan; Tron, Thierry; Alcalde, Miguel

2017-11-01

Although the functional expression of fungal laccases in Saccharomyces cerevisiae has proven to be complicated, the replacement of signal peptides appears to be a suitable approach to enhance secretion in directed evolution experiments. In this study, twelve constructs were prepared by fusing native and evolved α-factor prepro-leaders from S. cerevisiae to four different laccases with low-, medium- and high-redox potential (PM1L from basidiomycete PM1; PcL from Pycnoporus cinnabarinus; TspC30L from Trametes sp. strain C30; and MtL from Myceliophthora thermophila). Microcultures of the prepro-leader:laccase fusions were grown in selective expression medium that used galactose as both the sole carbon source and as the inducer of expression so that the secretion and activity were assessed with low- and high-redox potential mediators in a high-throughput screening context. With total activity improvements as high as sevenfold over those obtained with the native α-factor prepro-leader, the evolved prepro-leader from PcL (α PcL ) most strongly enhanced secretion of the high- and medium-redox potential laccases PcL, PM1L and TspC30L in the microtiter format with an expression pattern driven by prepro-leaders in the order α PcL  > α PM 1L  ~ α native . By contrast, the pattern of the low-redox potential MtL was α native  > α PcL  > α PM 1L . When produced in flask with rich medium, the evolved prepro-leaders outperformed the α native signal peptide irrespective of the laccase attached, enhancing secretion over 50-fold. Together, these results highlight the importance of using evolved α-factor prepro-leaders for functional expression of fungal laccases in directed evolution campaigns. © 2017 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

Can laccases catalyze bond cleavage in lignin?

DEFF Research Database (Denmark)

Munk, Line; Sitarz, Anna Katarzyna; Kalyani, Dayanand

2015-01-01

illustrations of the putative laccase catalyzed reactions, including the possible reactions of the reactive radical intermediates taking place after the initial oxidation of the phenol-hydroxyl groups, we show that i) Laccase activity is able to catalyze bond cleavage in low molecular weight phenolic lignin......-substituted phenols, benzenethiols, polyphenols, and polyamines, which may be oxidized. In addition, the currently available analytical methods that can be used to detect enzyme catalyzed changes in lignin are summarized, and an improved nomenclature for unequivocal interpretation of the action of laccases on lignin...

Aldehyde PEGylation of laccase from Trametes versicolor in route to increase its stability: effect on enzymatic activity.

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Mayolo-Deloisa, Karla; González-González, Mirna; Simental-Martínez, Jesús; Rito-Palomares, Marco

2015-03-01

Laccase is a multicopper oxidase that catalyzes the oxidation of phenolic compounds. Laccase can be used in bioremediation, beverage (wine, fruit juice, and beer) processing, ascorbic acid determination, sugar beet pectin gelation baking, and as a biosensor. Recently, the antiproliferative activity of laccase toward tumor cells has been reported. Because of the potential applications of this enzyme, the efforts for enhancing and stabilizing its activity have increased. Thus, the PEGylation of laccase can be an alternative. PEGylation is the covalent attachment of one or more molecules of methoxy poly(ethylene glycol) (mPEG) to a protein. Normally, during the PEGylation reaction, the activity is reduced but the stability increases; thus, it is important to minimize the loss of activity. In this work, the effects of molar ratio (1:4, 1:8, and 1:12), concentration of laccase (6 and 12 mg/ml), reaction time (4 and 17 h), molecular weight, and type of mPEG (20, 30, 40 kDa and 40 kDa-branched) were analyzed. The activity was measured using three substrates: ABTS, 2,6-dimethoxyphenol, and syringaldazine. The best conditions for laccase PEGylation were 12 mg/ml of laccase, molar ratio 1:4, and 4 h reaction time. Under these conditions, the enzyme was able to maintain nearly 100% of its enzymatic activity with ABTS. The PEGylation of laccase has not been extensively explored, so it is important to analyze the effects of this bioconjugation in route to produce a robust modified enzyme. Copyright © 2015 John Wiley & Sons, Ltd.

Bioinformatic analysis reveals high diversity of bacterial genes for laccase-like enzymes.

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Luka Ausec

Full Text Available Fungal laccases have been used in various fields ranging from processes in wood and paper industries to environmental applications. Although a few bacterial laccases have been characterized in recent years, prokaryotes have largely been neglected as a source of novel enzymes, in part due to the lack of knowledge about the diversity and distribution of laccases within Bacteria. In this work genes for laccase-like enzymes were searched for in over 2,200 complete and draft bacterial genomes and four metagenomic datasets, using the custom profile Hidden Markov Models for two- and three-domain laccases. More than 1,200 putative genes for laccase-like enzymes were retrieved from chromosomes and plasmids of diverse bacteria. In 76% of the genes, signal peptides were predicted, indicating that these bacterial laccases may be exported from the cytoplasm, which contrasts with the current belief. Moreover, several examples of putatively horizontally transferred bacterial laccase genes were described. Many metagenomic sequences encoding fragments of laccase-like enzymes could not be phylogenetically assigned, indicating considerable novelty. Laccase-like genes were also found in anaerobic bacteria, autotrophs and alkaliphiles, thus opening new hypotheses regarding their ecological functions. Bacteria identified as carrying laccase genes represent potential sources for future biotechnological applications.

Fungal laccase: copper induction, semi-purification, immobilization ...

African Journals Online (AJOL)

Fungal laccase: copper induction, semi-purification, immobilization, phenolic effluent treatment and electrochemical measurement. ... In order to apply in an effluent treatment, laccase was immobilized on different vitroceramics supports, pyrolytic graphite and also on a carbon fiber electrode as biosensor. The maximum ...

Production of Trametes pubescens Laccase under Submerged and Semi-Solid Culture Conditions on Agro-Industrial Wastes

Science.gov (United States)

Rodriguez, Alexander; Osma, Johann F.; Alméciga-Díaz, Carlos J.; Sánchez, Oscar F.

2013-01-01

Laccases are copper-containing enzymes involved in the degradation of lignocellulosic materials and used in the treatment of phenol-containing wastewater. In this study we investigated the effect of culture conditions, i.e. submerged or semi-solid, and copper supplementation on laccase production by Trametes pubescens grown on coffee husk, soybean pod husk, or cedar sawdust. The highest specific laccase activity was achieved when the culture was conducted under submerged conditions supplemented with copper (5 mM), and using coffee husk as substrate. The crude extracts presented two laccase isoforms with molecular mass of 120 (Lac1) and 60 kDa (Lac2). Regardless of the substrate, enzymatic crude extract and purified fractions behaved similarly at different temperatures and pHs, most of them presented the maximum activity at 55 °C and a pH range between 2 and 3. In addition, they showed similar stability and electro-chemical properties. At optimal culture conditions laccase activity was 7.69±0.28 U mg-1 of protein for the crude extract, and 0.08±0.001 and 2.86±0.05 U mg-1 of protein for Lac1 and Lac2, respectively. In summary, these results show the potential of coffee husk as an important and economical growth medium to produce laccase, offering a new alternative use for this common agro-industrial byproduct. PMID:24019936

Production of Trametes pubescens laccase under submerged and semi-solid culture conditions on agro-industrial wastes.

Science.gov (United States)

Gonzalez, Juan C; Medina, Sandra C; Rodriguez, Alexander; Osma, Johann F; Alméciga-Díaz, Carlos J; Sánchez, Oscar F

2013-01-01

Laccases are copper-containing enzymes involved in the degradation of lignocellulosic materials and used in the treatment of phenol-containing wastewater. In this study we investigated the effect of culture conditions, i.e. submerged or semi-solid, and copper supplementation on laccase production by Trametespubescens grown on coffee husk, soybean pod husk, or cedar sawdust. The highest specific laccase activity was achieved when the culture was conducted under submerged conditions supplemented with copper (5 mM), and using coffee husk as substrate. The crude extracts presented two laccase isoforms with molecular mass of 120 (Lac1) and 60 kDa (Lac2). Regardless of the substrate, enzymatic crude extract and purified fractions behaved similarly at different temperatures and pHs, most of them presented the maximum activity at 55 °C and a pH range between 2 and 3. In addition, they showed similar stability and electro-chemical properties. At optimal culture conditions laccase activity was 7.69 ± 0.28 U mg(-1) of protein for the crude extract, and 0.08 ± 0.001 and 2.86 ± 0.05 U mg(-1) of protein for Lac1 and Lac2, respectively. In summary, these results show the potential of coffee husk as an important and economical growth medium to produce laccase, offering a new alternative use for this common agro-industrial byproduct.

Production of Trametes pubescens laccase under submerged and semi-solid culture conditions on agro-industrial wastes.

Directory of Open Access Journals (Sweden)

Juan C Gonzalez

Full Text Available Laccases are copper-containing enzymes involved in the degradation of lignocellulosic materials and used in the treatment of phenol-containing wastewater. In this study we investigated the effect of culture conditions, i.e. submerged or semi-solid, and copper supplementation on laccase production by Trametespubescens grown on coffee husk, soybean pod husk, or cedar sawdust. The highest specific laccase activity was achieved when the culture was conducted under submerged conditions supplemented with copper (5 mM, and using coffee husk as substrate. The crude extracts presented two laccase isoforms with molecular mass of 120 (Lac1 and 60 kDa (Lac2. Regardless of the substrate, enzymatic crude extract and purified fractions behaved similarly at different temperatures and pHs, most of them presented the maximum activity at 55 °C and a pH range between 2 and 3. In addition, they showed similar stability and electro-chemical properties. At optimal culture conditions laccase activity was 7.69 ± 0.28 U mg(-1 of protein for the crude extract, and 0.08 ± 0.001 and 2.86 ± 0.05 U mg(-1 of protein for Lac1 and Lac2, respectively. In summary, these results show the potential of coffee husk as an important and economical growth medium to produce laccase, offering a new alternative use for this common agro-industrial byproduct.

Oxygen cathode based on a layer-by-layer self-assembled laccase and osmium redox mediator

Energy Technology Data Exchange (ETDEWEB)

Szamocki, R.; Flexer, V. [INQUIMAE-DQIAyQF, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, 1428 Buenos Aires (Argentina); Levin, L.; Forchiasin, F. [Micologia Experimental, Departamento de Biodiversidad y Biologia Experimental. Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, 1428 Buenos Aires (Argentina); Calvo, E.J. [INQUIMAE-DQIAyQF, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, 1428 Buenos Aires (Argentina)], E-mail: calvo@qi.fcen.uba.ar

2009-02-28

Trametes trogii laccase has been studied as biocatalyst for the oxygen electro-reduction in three different systems: (i) soluble laccase was studied in solution; (ii) an enzyme monolayer was tethered to a gold surface by dithiobis N-succinimidyl propionate (DTSP), with a soluble osmium pyridine-bipyridine redox mediator in both cases. The third case (iii) consisted in the sequential immobilization of laccase and the osmium complex derivatized poly(allylamine) self-assembled layer-by-layer (LbL) on mercaptopropane sulfonate modified gold to produce an all integrated and wired enzymatic oxygen cathode. The polycation was the same osmium complex covalently bound to poly-(ally-lamine) backbone (PAH-Os), the polyanion was the enzyme adsorbed from a solution of a suitable pH so that the protein carries a net negative charge. The adsorption of laccase was studied by monitoring the mass uptake with a quartz crystal microbalance and the oxygen reduction electrocatalysis was studied by linear scan voltammetry. While for the three cases, oxygen electrocatalysis mediated by the osmium complex was observed, for tethered laccase direct electron transfer in the absence of redox mediator was also apparent but no electrocatalysis for the oxygen reduction was recorded in the absence of mediator in solution. For the fully integrated LbL self-assembled laccase and redox mediator (case iii) a catalytic reduction of oxygen could be recorded at different oxygen partial pressures and different electrolyte pH. The tolerance of the reaction to methanol and chloride was also investigated.

Oxygen cathode based on a layer-by-layer self-assembled laccase and osmium redox mediator

International Nuclear Information System (INIS)

Szamocki, R.; Flexer, V.; Levin, L.; Forchiasin, F.; Calvo, E.J.

2009-01-01

Trametes trogii laccase has been studied as biocatalyst for the oxygen electro-reduction in three different systems: (i) soluble laccase was studied in solution; (ii) an enzyme monolayer was tethered to a gold surface by dithiobis N-succinimidyl propionate (DTSP), with a soluble osmium pyridine-bipyridine redox mediator in both cases. The third case (iii) consisted in the sequential immobilization of laccase and the osmium complex derivatized poly(allylamine) self-assembled layer-by-layer (LbL) on mercaptopropane sulfonate modified gold to produce an all integrated and wired enzymatic oxygen cathode. The polycation was the same osmium complex covalently bound to poly-(ally-lamine) backbone (PAH-Os), the polyanion was the enzyme adsorbed from a solution of a suitable pH so that the protein carries a net negative charge. The adsorption of laccase was studied by monitoring the mass uptake with a quartz crystal microbalance and the oxygen reduction electrocatalysis was studied by linear scan voltammetry. While for the three cases, oxygen electrocatalysis mediated by the osmium complex was observed, for tethered laccase direct electron transfer in the absence of redox mediator was also apparent but no electrocatalysis for the oxygen reduction was recorded in the absence of mediator in solution. For the fully integrated LbL self-assembled laccase and redox mediator (case iii) a catalytic reduction of oxygen could be recorded at different oxygen partial pressures and different electrolyte pH. The tolerance of the reaction to methanol and chloride was also investigated

Biochemical characterization and molecular evidence of a laccase from the bird's nest fungus Cyathus bulleri.

Science.gov (United States)

Vasdev, Kavita; Dhawan, Shikha; Kapoor, Rajeev Kumar; Kuhad, Ramesh Chander

2005-08-01

Cyathus bulleri, a bird's nest fungus, known to decolorize polymeric dye Poly R-478, was found to produce 8 U ml(-1) of laccase in malt extract broth. Laccase activity appeared as a single band on non-denaturing gel. Laccase was purified to homogeneity by anion exchange chromatography and gel filtration. The enzyme was a monomer with an apparent molecular mass of 60 kD, pI of 3.7 and was stable in the pH range of 2-6 with an optimum pH of 5.2. The optimal reaction temperature was 45 degrees C and the enzyme lost its activity above 70 degrees C. Enzyme could oxidize a broad range of various phenolic substrates. K(m) values for ABTS, 2,6-dimethoxyphenol, guaiacol, and ferulic acid were found to be 48.6, 56, 22, and 14 mM while K(cat) values were 204, 180, 95.6, and 5.2, respectively. It was completely inhibited by KCN, NaN(3), beta-mercaptoethanol, HgCl(2), and SDS, while EDTA had no effect on enzyme activity. The N-terminal amino acid sequence of C. bulleri laccase showed close homology to N-terminal sequences of laccase from other white-rot fungi. A 150 bp gene sequence encoding copper-binding domains I and II was most similar to the sequence encoding a laccase from Pycnoporus cinnabarinus with 74.8% level of similarity.

Characterization Of Laccase T-DNA Mutants In Arabidopsis thaliana

DEFF Research Database (Denmark)

Andersen, Jeppe Reitan; Asp, Torben; Mansfield, Shawn

2009-01-01

Laccases (P-diphenol:O2 oxidoreductase; EC 1.10.3.2), also termed laccase-like multicopper oxidases, are blue copper-containing oxidases which comprise multigene families in plants. In the Arabidopsis thaliana genome, 17 laccase genes (LAC1 to LAC17) have been annotated. To identify laccases...... for LAC15 T-DNA mutant seeds and an approximate 24 hour delay in germination was observed for these seeds. An approximate 20% reduction in glucose, galactose, and xylose was observed in primary stem cell walls of the LAC2 T-DNA mutants while similar relative increases in xylose were observed for LAC8...

Glycosylated yellow laccases of the basidiomycete Stropharia aeruginosa.

Science.gov (United States)

Daroch, Maurycy; Houghton, Catharine A; Moore, Jonathan K; Wilkinson, Mark C; Carnell, Andrew J; Bates, Andrew D; Iwanejko, Lesley A

2014-05-10

Here we describe the identification, purification and characterisation of glycosylated yellow laccase proteins from the basidiomycete fungus Stropharia aeruginosa. Biochemical characterisation of two yellow laccases, Yel1p and Yel3p, show that they are both secreted, monomeric, N-glycosylated proteins of molecular weight around 55kDa with substrate specificities typical of laccases, but lacking the absorption band at 612nm typical of the blue laccase proteins. Low coverage, high throughput 454 transcriptome sequencing in combination with inverse-PCR was used to identify cDNA sequences. One of the cDNA sequences has been assigned to the Yel1p protein on the basis of identity between the translated protein sequence and the peptide data from the purified protein, and the full length gene sequence has been obtained. Biochemical properties, substrate specificities and protein sequence data have been used to discuss the unusual spectroscopic properties of S. aeruginosa proteins in the context of recent theories about the differences between yellow and blue laccases. Copyright © 2014 Elsevier Inc. All rights reserved.

Exploiting the oxidizing capabilities of laccases exploiting the oxidizing capabilities of laccases for sustainable chemistry

Energy Technology Data Exchange (ETDEWEB)

Cannatelli, Mark D. [Georgia Inst. of Technology, Atlanta, GA (United States)

2017-05-01

Part one of this dissertation research has focused on harnessing the ability of laccases to generate reactive para-quinones in situ from the corresponding hydroquinones, followed by reaction with a variety of nucleophiles to perform novel carbon-carbon, carbon-nitrogen, and carbon-sulfur bond forming reactions for the synthesis of new and existing compounds. In part two of this dissertation, the fundamental laccase-catalyzed coupling chemistry developed in part one was applied to functionalize the surface of kraft lignin.

Nuclear track-based biosensors with the enzyme laccase

Energy Technology Data Exchange (ETDEWEB)

García-Arellano, H. [Departamento de Ciencias Ambientales, División de Ciencias Biológicas y de la Salud, Universidad Autónoma Metropolitana-Lerma, Av. de las Garzas No. 10, Col. El Panteón, Lerma de Villada, Municipio de Lerma, Estado de México, C.P. 52005 (Mexico); Fink, D., E-mail: fink@xanum.uam.mx [Division de Ciencias Naturales e Ingeneria, Universidad Autónoma Metropolitana-Cuajimalpa, Artificios 40, Col. Hidalgo, Del. Álvaro Obregón C.P. 01120, México, D.F. (Mexico); Nuclear Physics Institute, 25068 Řež (Czech Republic); Muñoz Hernández, G. [Division de Ciencias Naturales e Ingeneria, Universidad Autónoma Metropolitana-Cuajimalpa, Artificios 40, Col. Hidalgo, Del. Álvaro Obregón C.P. 01120, México, D.F. (Mexico); Departamento de Fisica, Universidad Autónoma Metropolitana-Iztapalapa, PO Box 55-534, 09340 México, D.F. (Mexico); Vacík, J.; Hnatowicz, V. [Nuclear Physics Institute, 25068 Řež (Czech Republic); Alfonta, L. [Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben-Gurion University of the Negev, PO Box 653, Beer-Sheva 84105 (Israel)

2014-08-15

Highlights: • We construct a biosensor using polymer foils with laccase-clad etched nuclear tracks. • We use the biosensor for quantitation of phenolic compounds. • The biosensor can detect picomolar concentrations for some phenolic compounds. - Abstract: A new type of biosensors for detecting phenolic compounds is presented here. These sensors consist of thin polymer foils with laccase-clad etched nuclear tracks. The presence of suitable phenolic compounds in the sensors leads to the formation of enzymatic reaction products in the tracks, which differ in their electrical conductivities from their precursor materials. These differences correlate with the concentrations of the phenolic compounds. Corresponding calibration curves have been established for a number of compounds. The sensors thus produced are capable to cover between 5 and 9 orders of magnitude in concentration – in the best case down to some picomoles. The sensor's detection sensitivity strongly depends on the specific compound. It is highest for caffeic acid and acid blue 74, followed by ABTS and ferulic acid.

Screening of Lignocellulose-Degrading Superior Mushroom Strains and Determination of Their CMCase and Laccase Activity

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Li Fen

2014-01-01

Full Text Available In order to screen lignocellulose-degrading superior mushroom strains ten strains of mushrooms (Lentinus edodes939, Pholiota nameko, Lentinus edodes868, Coprinus comatus, Macrolepiota procera, Auricularia auricula, Hericium erinaceus, Grifola frondosa, Pleurotus nebrodensis, and Shiraia bambusicola were inoculated onto carboxymethylcellulose agar-Congo red plates to evaluate their ability to produce carbomethyl cellulase (CMCase. The results showed that the ratio of transparent circle to mycelium circle of Hericium erinaceus was 8.16 (P<0.01 higher than other strains. The filter paper culture screening test showed that Hericium erinaceus and Macrolepiota procera grew well and showed extreme decomposition of the filter paper. When cultivated in guaiacol culture medium to detect their abilities to secrete laccase, Hericium erinaceus showed the highest ability with the largest reddish brown circles of 4.330 cm. CMCase activity determination indicated that Coprinus comatus and Hericium erinaceus had the ability to produce CMCase with 33.92 U/L on the 9th day and 22.58 U/L on the 10th day, respectively, while Coprinus comatus and Pleurotus nebrodensis had the ability to produce laccase with 496.67 U/L and 489.17 U/L on the 16th day and 18th day. Based on the results, Coprinus comatus might be the most promising lignocellulose-degrading strain to produce both CMCase and laccase at high levels.

Lignin Biodegradation with Laccase-Mediator Systems

International Nuclear Information System (INIS)

Christopher, Lew Paul; Yao, Bin; Ji, Yun

2014-01-01

Lignin has a significant and largely unrealized potential as a source for the sustainable production of fuels and bulk high-value chemicals. It can replace fossil-based oil as a renewable feedstock that would bring about socio-economic and environmental benefits in our transition to a biobased economy. The efficient utilization of lignin however requires its depolymerization to low-molecular weight phenolics and aromatics that can then serve as the building blocks for chemical syntheses of high-value products. The ability of laccase to attack and degrade lignin in conjunction with laccase mediators is currently viewed as one of the potential “breakthrough” applications for lignin valorization. Here, we review the recent progress in lignin biodegradation with laccase-mediator systems, and research needs that need to be addressed in this field.

Lignin Biodegradation with Laccase-Mediator Systems

Energy Technology Data Exchange (ETDEWEB)

Christopher, Lew Paul, E-mail: lew.christopher@sdsmt.edu [Center for Bioprocessing Research and Development, South Dakota School of Mines & Technology, Rapid City, SD (United States); Department of Civil and Environmental Engineering, South Dakota School of Mines & Technology, Rapid City, SD (United States); Yao, Bin [Center for Bioprocessing Research and Development, South Dakota School of Mines & Technology, Rapid City, SD (United States); Ji, Yun [Department of Chemical Engineering, University of North Dakota, Grand Forks, ND (United States)

2014-03-31

Lignin has a significant and largely unrealized potential as a source for the sustainable production of fuels and bulk high-value chemicals. It can replace fossil-based oil as a renewable feedstock that would bring about socio-economic and environmental benefits in our transition to a biobased economy. The efficient utilization of lignin however requires its depolymerization to low-molecular weight phenolics and aromatics that can then serve as the building blocks for chemical syntheses of high-value products. The ability of laccase to attack and degrade lignin in conjunction with laccase mediators is currently viewed as one of the potential “breakthrough” applications for lignin valorization. Here, we review the recent progress in lignin biodegradation with laccase-mediator systems, and research needs that need to be addressed in this field.

Isolation of laccase gene-specific sequences from white rot and brown rot fungi by PCR

Energy Technology Data Exchange (ETDEWEB)

D`Souza, T.M.; Boominathan, K.; Reddy, C.A. [Michigan State Univ., East Lansing, MI (United States)

1996-10-01

Degenerate primers corresponding to the consensus sequences of the copper-binding regions in the N-terminal domains of known basidiomycete laccases were used to isolate laccase gene-specific sequences from strains representing nine genera of wood rot fungi. All except three gave the expected PCR product of about 200 bp. Computer searches of the databases identified the sequences of each of the PCR product of about 200 bp. Computer searches of the databases identified the sequence of each of the PCR products analyzed as a laccase gene sequence, suggesting the specificity of the primers. PCR products of the white rot fungi Ganoderma lucidum, Phlebia brevispora, and Trametes versicolor showed 65 to 74% nucleotide sequence similarity to each other; the similarity in deduced amino acid sequences was 83 to 91%. The PCR products of Lentinula edodes and Lentinus tigrinus, on the other hand, showed relatively low nucleotide and amino acid similarities (58 to 64 and 62 to 81%, respectively); however, these similarities were still much higher than when compared with the corresponding regions in the laccases of the ascomycete fungi Aspergillus nidulans and Neurospora crassa. A few of the white rot fungi, as well as Gloeophyllum trabeum, a brown rot fungus, gave a 144-bp PCR fragment which had a nucleotide sequence similarity of 60 to 71%. Demonstration of laccase activity in G. trabeum and several other brown rot fungi was of particular interest because these organisms were not previously shown to produce laccases. 36 refs., 6 figs., 2 tabs.

Reactivity of bacterial and fungal laccases with lignin under alkaline conditions.

Science.gov (United States)

Moya, Raquel; Saastamoinen, Päivi; Hernández, Manuel; Suurnäkki, Anna; Arias, Enriqueta; Mattinen, Maija-Liisa

2011-11-01

The ability of Streptomyces ipomoea laccase to polymerize secoisolariciresinol lignan and technical lignins was assessed. The reactivity of S. ipomoea laccase was also compared to that of low redox fungal laccase from Melanocarpus albomyces using low molecular mass p-coumaric, ferulic and sinapic acid as well as natural (acetosyringone) and synthetic 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) mediators as substrates. Oxygen consumption measurement, MALDI-TOF MS and SEC were used to follow the enzymatic reactions at pH 7, 8, 9 and 10 at 30°C and 50°C. Polymerization of lignins and lignan by S. ipomoea laccase under alkaline reaction conditions was observed, and was enhanced in the presence of acetosyringone almost to the level obtained with M. albomyces laccase without mediator. Reactivities of the enzymes towards acetosyringone and TEMPO were similar, suggesting exploitation of the compounds and low redox laccase in lignin valorization under alkaline conditions. The results have scientific impact on basic research of laccases. Copyright © 2011 Elsevier Ltd. All rights reserved.

Functional analysis of truncated and site-directed mutagenesis dextransucrases to produce different type dextrans.

Science.gov (United States)

Wang, Chao; Zhang, Hong-Bin; Li, Meng-Qi; Hu, Xue-Qin; Li, Yao

2017-07-01

Dextrans with distinct molecular size and structure are increasingly being used in the food and pharmaceutical industries. Dextran is produced by dextransucrase (DSR, EC2.4.5.1), which is produced by Leuconostoc mesenteroides. DSR belongs to glycosyl hydrolase family (GH70) and synthesizes branched α-glucan (dextran) with both 5% α(1-3) and 95% α(1-6) glycosidic linkages. The DSR gene dex-YG (Genebank, Accession No. DQ345760) was cloned from the wild strain Leuconostoc mesenteroides 0326. This study generated a series of C-terminally truncated variants of dextransucrase and substituting the amino-acid residues in the active site of DSR. With shorter length of DSR, its polysaccharide-synthesizing capability was impaired heavily, whereas oligosaccharide (acting as prebiotics)-synthesizing capability increased significantly, efficiently producing special sizes of dextran. All truncated mutant enzymes were active. Results demonstrated that the catalytic domain dextransucrase was likely in 800 aa or less. Based on the three-dimensional structure model of dextransucrase built through homology modeling methods, the DSR and its mutants with the acceptor substrate of maltose and donor substrate of sucrose were studied by molecular-docking method. Substituting these amino-acid residues significantly affected enzyme activities. Compared with the wild-type dextran, mutant enzymes catalyzed the synthesis of a-glucan with 1-9% α(1-3) and 90-98% α(1-6) branching linkages. Some mutants introduced a small amount of α(1-4) linkages and α(1-2) linkages. This strategy can be effectively used for the rational protein design of dextransucrase. Copyright © 2017 Elsevier Inc. All rights reserved.

Degradation of Synthetic Dyes by Laccases – A Mini-Review

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Legerská Barbora

2016-06-01

Full Text Available Laccases provide a promising future as a tool to be used in the field of biodegradation of synthetic dyes with different chemical structures. These enzymes are able to oxidize a wide range of phenolic substrates without the presence of additional co-factors. Laccases have been confirmed for their potential of synthetic dye degradation from wastewater and degradation products of these enzymatic reactions become less toxic than selected dyes. This study discusses the potential of laccase enzymes as agents for laccase-catalyzed degradation in terms of biodegradation efficiency of synthetic dyes, specifically: azo dyes, triphenylmethane, indigo and anthraquinone dyes. Review also summarizes the laccase-catalyzed degradation mechanisms of the selected synthetic dyes, as well as the degradation products and the toxicity of the dyes and their degradation products.

Fluorescent nanocellulosic hydrogels based on graphene quantum dots for sensing laccase

International Nuclear Information System (INIS)

Ruiz-Palomero, Celia; Benítez-Martínez, Sandra; Soriano, M. Laura; Valcárcel, Miguel

2017-01-01

A novel low-cost fluorimetric platform based on sulfur, nitrogen-codoped graphene quantum dots immersed into nanocellulosic hydrogels is designed and applied in detecting the laccase enzyme. Although most of methods for detecting laccase are based on their catalytic activity, which is strongly dependent on environmental parameters, we report a sensitive and selective method based on the fluorescence response of hydrogels containing graphene quantum dots (GQDs) acting as luminophore towards laccase. The easily-prepared gel matrix not only improves the fluorescence signal of GQDs by avoiding their self-quenching but also stabilizes their fluorescence signal and improves their sensitivity towards laccase. Noncovalent interactions between the sensor and the analyte are believed to be causing this significant quenching without peak-shifts of GQD fluorescence via energy transfer. The selective extraction of laccase was proved in different shampoos as complex matrices achieving a detection limit of 0.048 U mL −1 and recoveries of 86.2–94.1%. As the unusual properties of nanocellulose and GQDs, the fluorescent sensor is simple, eco-friendly and cost-efficient. This straightforward strategy is able to detect and stabilize laccase, being an added-value for storage and recycling enzymes. - Highlights: • Fluorescent hydrogels were constructed by combining nanocellulose and graphene quantum dots. • The resulting hydrogels exhibited fluorescence quenching in presence of laccase. • Equilibrium in the optical signal of S,N-graphene quantum dots in presence of laccase was achieved faster within hydrogels. • The proposed method to determine laccase using fluorescent hydrogels was successfully applied in shampoo.

Laccase production by Monotospora sp., an endophytic fungus in Cynodon dactylon.

Science.gov (United States)

Wang, J W; Wu, J H; Huang, W Y; Tan, R X

2006-03-01

The effects of the carbon and nitrogen sources, initial pH and incubation temperature on laccase production by the endophytic fungus Monotospora sp. were evaluated. The optimal temperature and initial pH for laccase production by Monotospora sp. in submerged culture were found to be 30 degrees C and 8.5, respectively. Maltose (2 g l(-1)) and ammonium tartrate (10 g l(-1)) were the most suitable carbon and nitrogen source for laccase production. Under optimal culture medium, the maximum laccase activity was determined to be 13.55 U ml(-1), which was approximately four times higher than that in basal medium. This is the first report on laccase production by an endophytic fungus.

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

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F. Bettin

2014-06-01

Full Text Available 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.

Laccase Gene Family in Cerrena sp. HYB07: Sequences, Heterologous Expression and Transcriptional Analysis

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Jie Yang

2016-08-01

Full Text Available Laccases are a class of multi-copper oxidases with industrial potential. In this study, eight laccases (Lac1–8 from Cerrena sp. strain HYB07, a white-rot fungus with high laccase yields, were analyzed. The laccases showed moderate identities to each other as well as with other fungal laccases and were predicted to have high redox potentials except for Lac6. Selected laccase isozymes were heterologously expressed in the yeast Pichia pastoris, and different enzymatic properties were observed. Transcription of the eight laccase genes was differentially regulated during submerged and solid state fermentation, as shown by quantitative real-time polymerase chain reaction and validated reference genes. During 6-day submerged fermentation, Lac7 and 2 were successively the predominantly expressed laccase gene, accounting for over 95% of all laccase transcripts. Interestingly, accompanying Lac7 downregulation, Lac2 transcription was drastically upregulated on days 3 and 5 to 9958-fold of the level on day 1. Consistent with high mRNA abundance, Lac2 and 7, but not other laccases, were identified in the fermentation broth by LC-MS/MS. In solid state fermentation, less dramatic differences in transcript abundance were observed, and Lac3, 7 and 8 were more highly expressed than other laccase genes. Elucidating the properties and expression profiles of the laccase gene family will facilitate understanding, production and commercialization of the fungal strain and its laccases.

Induction of fungal laccase production under solid state bioprocessing of new agroindustrial waste and its application on dye decolorization.

Science.gov (United States)

Akpinar, Merve; Ozturk Urek, Raziye

2017-06-01

Lignocellulosic wastes are generally produced in huge amounts worldwide. Peach waste of these obtained from fruit juice industry was utilized as the substrate for laccase production by Pleurotus eryngii under solid state bioprocessing (SSB). Its chemical composition was determined and this bioprocess was carried out under stationary conditions at 28 °C. The effects of different compounds; copper, iron, Tween 80, ammonium nitrate and manganese, and their variable concentrations on laccase production were investigated in detail. The optimum production of laccase (43,761.33 ± 3845 U L -1 ) was achieved on the day of 20 by employing peach waste of 5.0 g and 70 µM Cu 2+ , 18 µM Fe 2+ , 0.025% (v/v) Tween 80, 4.0 g L -1 ammonium nitrate, 750 µM Mn 2+ as the inducers. The dye decolorization also researched to determine the degrading capability of laccase produced from peach culture under the above-mentioned conditions. Within this scope of the study, methyl orange, tartrazine, reactive red 2 and reactive black dyes were treated with this enzyme. The highest decolorization was performed with methyl orange as 43 ± 2.8% after 5 min of treatment when compared to other dyes. Up to now, this is the first report on the induction of laccase production by P. eryngii under SSB using peach waste as the substrate.

Laccase-mediator catalyzed conversion of model lignin compounds

Science.gov (United States)

Laccases play an important role in the biological breakdown of lignin and have great potential in the deconstruction of lignocellulosic feedstocks. We examined a variety of laccases, both commercially prepared and crude extracts, for their ability to oxidize three model lignol compounds (p-coumaryl...

Improved Laccase Production by Trametes pubescens MB89 in Distillery Wastewaters

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P. J. Strong

2011-01-01

Full Text Available Various culture parameters were optimised for laccase synthesis by Trametes pubescens MB89, including pH, carbon source, nitrogen source, lignocellulosic supplements, and reported inducers. Glucose, in conjunction with a complex nitrogen source at pH 5.0, resulted in the highest laccase yield. Adding ethanol, copper, or 2,5-xylidine prior to inoculation further improved laccase concentrations. The addition of 2,5-xylidine was further investigated with multiple additions applied at varying times. This novel application substantially improved laccase production when applied regularly from inoculation and during the growth phase, and also countered glucose repression of laccase synthesis. Single and multiple factor changes were studied in three distillery wastewaters and a wine lees. A synergistic increase in laccase synthesis was observed with the addition of glucose, copper, and 2,5-xylidine. Single addition of 2,5-xylidine proved most beneficial with distillery wastewaters, while copper addition was most beneficial when using the wine lees as a culture medium.

Laccase mediated transformation of 17β-estradiol in soil

International Nuclear Information System (INIS)

Singh, Rashmi; Cabrera, Miguel L.; Radcliffe, David E.; Zhang, Hao; Huang, Qingguo

2015-01-01

It is known that 17β-estradiol (E2) can be transformed by reactions mediated by some oxidoreductases such as laccase in water. Whether or how such reactions can happen in soil is however unknown although they may significantly impact the environmental fate of E2 that is introduced to soil by land application of animal wastes. We herein studied the reaction of E2 in a model soil mediated by laccase, and found that the reaction behaviors differ significantly from those in water partly because of the dramatic difference in laccase stability. We also examined E2 transformation in soil using 14 C-labeling in combination with soil organic matter extraction and size exclusion chromatography, which indicated that applied 14 C radioactivity was preferably bound to humic acids. The study provides useful information for understanding the environmental fate of E2 and for developing a novel soil remediation strategy via enzyme-enhanced humification reactions. - Highlights: • E2 was effectively transformed in soil through reactions mediated by laccase. • The reaction behaviors in soil differ significantly from those in water. • E2 was preferably bound to the humic acids in soil. • Laccase treatment resulted in changes in the structures of the humic acids. - E2 was effectively transformed in soil by preferably binding to the humic acids through reactions mediated by laccase

Production and characterization of laccase from Cyathus bulleri and its use in decolourization of recalcitrant textile dyes.

Science.gov (United States)

Salony; Mishra, S; Bisaria, V S

2006-08-01

Many fungi (particularly the white rot) are well suited for treatment of a broad range of textile dye effluents due to the versatility of the lignin-degrading enzymes produced by them. We have investigated decolourization of a number of recalcitrant reactive azo and acid dyes using the culture filtrate and purified laccase from the fungus Cyathus bulleri. For this, the enzyme was purified from the culture filtrate to a high specific activity of 4,022 IU mg(-1) protein, produced under optimized carbon, nitrogen and C/N ratio with induction by 2,6-dimethylaniline. The protein was characterized as a monomer of 58+/-5.0 kDa with carbohydrate content of 16% and was found to contain all three Cu(II) centres. The three internal peptide sequences showed sequence identity (80-92%) with laccases of a number of white rot fungi. Substrate specificity indicated highest catalytic efficiency (k(cat)/K(M)) on guaiacol followed by 2,2'-azino-bis(3-ethylthiazoline-6-sulfonic acid) (ABTS). Decolourization of a number of reactive azo and acid dyes was seen with the culture filtrate of the fungus containing predominantly laccase. In spite of no observable effect of purified laccase on other dyes, the ability to decolourize these was achieved in the presence of the redox mediator ABTS, with 50% decolourization in 0.5-5.4 days.

Ethanol induction of laccase depends on nitrogen conditions of Pycnoporus sanguineus

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Christian A. Hernández

2015-07-01

Conclusions: We suggest that laccase in P. sanguineus is regulated by a catabolic nitrogen repression mechanism; laccase activity is strongly inhibited by urea used as nitrogen source and it decreases when the amount of urea increases; contrarily, a synergic positive effect was observed between yeast extract and ethanol on laccase production.

A New Laccase Based Biosensor for Tartrazine

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Siti Zulaikha Mazlan

2017-12-01

Full Text Available Laccase enzyme, a commonly used enzyme for the construction of biosensors for phenolic compounds was used for the first time to develop a new biosensor for the determination of the azo-dye tartrazine. The electrochemical biosensor was based on the immobilization of laccase on functionalized methacrylate-acrylate microspheres. The biosensor membrane is a composite of the laccase conjugated microspheres and gold nanoparticles (AuNPs coated on a carbon-paste screen-printed electrode. The reaction involving tartrazine can be catalyzed by laccase enzyme, where the current change was measured by differential pulse voltammetry (DPV at 1.1 V. The anodic peak current was linear within the tartrazine concentration range of 0.2 to 14 μM (R2 = 0.979 and the detection limit was 0.04 μM. Common food ingredients or additives such as glucose, sucrose, ascorbic acid, phenol and sunset yellow did not interfere with the biosensor response. Furthermore, the biosensor response was stable up to 30 days of storage period at 4 °C. Foods and beverage were used as real samples for the biosensor validation. The biosensor response to tartrazine showed no significant difference with a standard HPLC method for tartrazine analysis.

A New Laccase Based Biosensor for Tartrazine.

Science.gov (United States)

Mazlan, Siti Zulaikha; Lee, Yook Heng; Hanifah, Sharina Abu

2017-12-09

Laccase enzyme, a commonly used enzyme for the construction of biosensors for phenolic compounds was used for the first time to develop a new biosensor for the determination of the azo-dye tartrazine. The electrochemical biosensor was based on the immobilization of laccase on functionalized methacrylate-acrylate microspheres. The biosensor membrane is a composite of the laccase conjugated microspheres and gold nanoparticles (AuNPs) coated on a carbon-paste screen-printed electrode. The reaction involving tartrazine can be catalyzed by laccase enzyme, where the current change was measured by differential pulse voltammetry (DPV) at 1.1 V. The anodic peak current was linear within the tartrazine concentration range of 0.2 to 14 μM ( R ² = 0.979) and the detection limit was 0.04 μM. Common food ingredients or additives such as glucose, sucrose, ascorbic acid, phenol and sunset yellow did not interfere with the biosensor response. Furthermore, the biosensor response was stable up to 30 days of storage period at 4 °C. Foods and beverage were used as real samples for the biosensor validation. The biosensor response to tartrazine showed no significant difference with a standard HPLC method for tartrazine analysis.

Optimization of Laccase-Aided Chlorine Dioxide Bleaching of Bagasse Pulp

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Yong Pei

2015-11-01

Full Text Available The laccase-mediator system in laccase-aided chlorine dioxide bleaching of bagasse pulp was optimized using response surface methodology (RSM. The effects and interactions of the laccase enzyme dosage, the dosage of the mediator 1-hydroxybenzotriazole (HBT, and the reaction time on the adsorbed organic halogen (AOX content of the wastewater as well as the brightness and kappa number of the pulp were examined. The optimal reaction conditions to achieve a balance of lower AOX content, higher brightness, and lower kappa number were as follows: laccase enzyme dosage of 20.3 U/g, HBT dosage of 1.51%, and reaction time of 154.5 min. Under these conditions, an AOX content of 20.67 mg/L, brightness of 58.94% ISO, and kappa number of 2.71 were observed. These results will offer a favorable option for pulp and paper mills as well as the natural environment and therefore provide a theoretical foundation for the industrial application of laccase in bleaching processes.

Laccase/Mediator Systems

NARCIS (Netherlands)

Hilgers, Roelant; Vincken, Jean Paul; Gruppen, Harry; Kabel, Mirjam A.

2018-01-01

Laccase-mediator systems (LMS) have been widely studied for their capacity to oxidize the nonphenolic subunits of lignin (70-90% of the polymer). The phenolic subunits (10-30% of the polymer), which can also be oxidized without mediators, have received considerably less attention. Consequently, it

Maltose binding protein-fusion enhances the bioactivity of truncated forms of pig myostatin propeptide produced in E. coli.

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Sang Beum Lee

Full Text Available Myostatin (MSTN is a potent negative regulator of skeletal muscle growth. MSTN propeptide (MSTNpro inhibits MSTN binding to its receptor through complex formation with MSTN, implying that MSTNpro can be a useful agent to improve skeletal muscle growth in meat-producing animals. Four different truncated forms of pig MSTNpro containing N-terminal maltose binding protein (MBP as a fusion partner were expressed in E. coli, and purified by the combination of affinity chromatography and gel filtration. The MSTN-inhibitory capacities of these proteins were examined in an in vitro gene reporter assay. A MBP-fused, truncated MSTNpro containing residues 42-175 (MBP-Pro42-175 exhibited the same MSTN-inhibitory potency as the full sequence MSTNpro. Truncated MSTNpro proteins containing either residues 42-115 (MBP-Pro42-115 or 42-98 (MBP-Pro42-98 also exhibited MSTN-inhibitory capacity even though the potencies were significantly lower than that of full sequence MSTNpro. In pull-down assays, MBP-Pro42-175, MBP-Pro42-115, and MBP-Pro42-98 demonstrated their binding to MSTN. MBP was removed from the truncated MSTNpro proteins by incubation with factor Xa to examine the potential role of MBP on MSTN-inhibitory capacity of those proteins. Removal of MBP from MBP-Pro42-175 and MBP-Pro42-98 resulted in 20-fold decrease in MSTN-inhibitory capacity of Pro42-175 and abolition of MSTN-inhibitory capacity of Pro42-98, indicating that MBP as fusion partner enhanced the MSTN-inhibitory capacity of those truncated MSTNpro proteins. In summary, this study shows that MBP is a very useful fusion partner in enhancing MSTN-inhibitory potency of truncated forms of MSTNpro proteins, and MBP-fused pig MSTNpro consisting of amino acid residues 42-175 is sufficient to maintain the full MSTN-inhibitory capacity.

EFFECT OF POTENTIAL INDUCTORS ON LACCASE PRODUCTION BY WHITE-ROT FUNGUS CERIPORIOPSIS SUBVERMISPORA

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Daniela Chmelová

2014-02-01

Full Text Available In this work, the influence of selected inorganic ions (Cu2+ and Mn2+ and aromatic amino acids (tryptophan and tyrosine on laccase production by white-rot fungus Ceriporiopsis subvermispora was investigated. This aim was realized by monitoring laccase production during cultivation of C. subvermispora. Secondary, we been evaluated glucose concentration in medium and biomass growth after cultivation. Extracellular laccase formation can stimulated by the addition of Cu2+ (3.0 mmol/L. The higher laccase activity reached maximum at 7th day (63 U/L, equivalent to 3.7-fold higher than the laccase production without copper (17.2 U/L. Higher concentration of copper ions had a negative effect on laccase production. The addition of copper ions inhibited the biomass growth. Mn2+ ions similarly stimulated laccase activity (3.0 and 7.0 mmol/L; 79.6 and 63.8 U/L, respectively and maximum activities were reached at 6th day. Manganese ions also stimulated fungal biomass of C. subvermispora. The addition of aromatic amino acids did not cause an increase laccase production. The highest laccase production was observed in cultivation media without aromatic amino acids (16.0 U/L at 8th day.

The Type 3 copper site is intact but labile in Type 2-depleted laccase

DEFF Research Database (Denmark)

Frank, P; Farver, O; Pecht, I

1983-01-01

We report results of experiments designed to characterize the Type 1 and Type 3 copper sites in Rhus laccase depleted of Type 2 copper (T2D). Use of the Lowry method for determining protein concentration yielded the value 5620 +/- 570 M-1 cm-1 for the extinction of the 615-nm absorption band...... as intensity perturbations at 280 and 615 nm. Comparison of difference spectra show that this 330-nm band derives from a Type 3 copper-bound peroxide and not from a reoxidized Type 3 site. Dioxygen reoxidation of ascorbate-reduced T2D laccase produced new difference bands at 330 nm (delta epsilon = 770 M-1 cm...

Characterisation of a novel white laccase from the deuteromycete fungus Myrothecium verrucaria NF-05 and its decolourisation of dyes.

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Dan Zhao

Full Text Available A novel 'white' laccase was purified from the deuteromycete fungus, Myrothecium verrucaria NF-05, which was a high laccase-producing strain (40.2 U·ml(-1 on the thirteenth day during fermentation. SDS-PAGE and native-PAGE revealed a single band with laccase activity corresponding to a molecular weight of approximately 66 kDa. The enzyme had three copper and one iron atoms per protein molecule determined by ICP-AES. Furthermore, both UV/visible and EPR spectroscopy remained silence, indicating the enzyme a novel laccase with new metal compositions of active centre and spectral properties. The N-terminal amino acid sequence of the purified protein was APQISPQYPM. Together with MALDI-TOF analysis, the protein revealed a high homology of the protein with that from reported M. verrucaria. The highest activity was detected at pH 4.0 and at 30°C. The enzyme activity was significantly enhanced by Na(+, Mn(2+, Cu(2+ and Zn(2+ while inhibited by DTT, NaN(3 and halogen anions. The kinetic constant (Km showed the enzyme was more affinitive to ABTS than other tested aromatic substrates. Twelve structurally different dyes could be effectively decolourised by the laccase within 10 min. The high production of the strain and novel properties of the laccase suggested its potential for biotechnological applications.

Immobilization in polyvinyl alcohol hydrogel enhances yeast storage stability and reusability of recombinant laccase-producing S-cerevisiae

Czech Academy of Sciences Publication Activity Database

Herkommerová, Klára; Zemančíková, Jana; Sychrová, Hana; Antošová, Zuzana

2018-01-01

Roč. 40, č. 2 (2018), s. 405-411 ISSN 0141-5492 R&D Projects: GA TA ČR(CZ) TA01011461 Institutional support: RVO:67985823 Keywords : immobilization * laccase * LentiKats * polyvinyl alcohol hydrogel * reusability * storage stability * yeasts Subject RIV: EI - Biotechnology ; Bionics OBOR OECD: Industrial biotechnology Impact factor: 1.730, year: 2016

Identification of a laccase from Ganoderma lucidum CBS 229.93 having potential for enhancing cellulase catalyzed lignocellulose degradation.

Science.gov (United States)

Sitarz, Anna K; Mikkelsen, Jørn D; Højrup, Peter; Meyer, Anne S

2013-12-10

Based on a differential pre-screening of 44 white-rot fungi on a lignocellulose-supplemented minimal medium, four basidiomycetes were selected for further study: Ganoderma lucidum, Polyporus brumalis, Polyporus ciliatus and Trametes versicolor. Only G. lucidum was able to grow vividly on malt extract or minimal media supplemented with alkali lignin. When grown on malt extract or minimal medium supplemented with lignocellulose (sugar cane bagasse), the crude G. lucidum protein extract exhibited high laccase activity, ∼3U/mL toward syringaldazine. This activity was 13-17 fold higher than the corresponding activities of the crude protein extracts of P. brumalis, P. ciliatus and T. versicolor. Native PAGE electrophoresis of the crude G. lucidum extract confirmed the presence of an active laccase. The G. lucidum laccase had a molecular weight of ∼62.5kDa, and a Km value of 0.107mM (determined on ABTS). A partial amino acid sequence analysis of four short de novo sequenced peptides, defined after trypsin digest analysis using MALDI-TOF MS/MS analysis, revealed 64-100% homology to sequences in related laccases in the UniProt database, but also indicated that certain sequence stretches had low homology. Addition of the laccase-rich G. lucidum broth to lignocellulosic biomass (pretreated sugar cane bagasse) together with a state-of-the-art cellulase enzyme preparation (Cellic™CTec1) produced significantly increased cellulolytic yields, which were also better than those obtained with a T. versicolor laccase addition, indicating that the laccase from G. lucidum has unique properties that may be momentous in lignocellulosic biomass conversion. Copyright © 2013 Elsevier Inc. All rights reserved.

Natural and recombinant fungal laccases for paper pulp bleaching

NARCIS (Netherlands)

Sigoillot, C.; Record, E.; Belle, V.; Robert, J.L.; Levasseur, A.; Punt, P.J.; Hondel, C.A.M.J.J. van den; Fournel, A.; Sigoillot, J.C.; Asther, M.

2004-01-01

Three laccases, a natural form and two recombinant forms obtained from two different expression hosts, were characterized and compared for paper pulp bleaching. Laccase from Pycnoporus cinnabarinus, a well known lignolytic fungus, was selected as a reference for this study. The corresponding

Phenol oxidation of petrol refinery wastewater catalyzed by Laccase

International Nuclear Information System (INIS)

Vargas, Maria Carolina; Ramirez, Nubia E.

2002-01-01

Laccase has been obtained through two different production systems, the first using Pleurotus ostreatus in solid-state fermentation, the second one using Trametes versicolor in submerged culture. Different substrates (by products from yeast, flour and beverage industries) have been evaluated in both systems. Maximum laccase yield with Pleurotus ostreatus (25 u/ml) was obtained in a wheat bran medium. The maximum enzyme concentration level using Trametes versicolor (25 u/ml) was achieved in a submerged system, containing 10% vinasse, 4,5% wheat bran and 0,2% molasses per liter of waste. Culture filtrate extracted from Pleurotus ostreatus was used to remove phenol from wastewater. The enzymatic treatment is effective over a wide pH and temperature range. The Laccase treatment has been successfully used to dephenolize industrial petrol refinery wastewater. The advantage of Laccase dephenolization is that this enzyme uses molecular oxygen as an oxidant

Isolation, Purification, and Characterization of Fungal Laccase from Pleurotus sp.

Directory of Open Access Journals (Sweden)

Sunil S. More

2011-01-01

Full Text Available Laccases are blue copper oxidases (E.C. 1.10.3.2 benzenediol: oxygen oxidoreductase that catalyze the one-electron oxidation of phenolics, aromatic amines, and other electron-rich substrates with the concomitant reduction of O2 to H2O. They are currently seen as highly interesting industrial enzymes because of their broad substrate specificity. A positive strain was isolated and characterized as nonspore forming Basidiomycetes Pleurotus sp. Laccase activity was determined using ABTS as substrate. Laccase was purified by ionexchange and gel filtration chromatography. The purified laccase was a monomer showed a molecular mass of 40±1 kDa as estimated by SDS-PAGE and a 72-fold purification with a 22% yield. The optimal pH and temperature were 4.5 and 65°C, respectively. The Km and Vmax⁡ values are 250 (mM and 0.33 (μmol/min, respectively, for ABTS as substrate. Metal ions like CuSO4, BaCl2, MgCl2, FeCl2, ZnCl2 have no effect on purified laccase whereas HgCl2 and MnCl2 moderately decrease enzyme activity. SDS and sodium azide inhibited enzyme activity, whereas Urea, PCMB, DTT, and mercaptoethanol have no effect on enzyme activity. The isolated laccase can be used in development of biosensor for detecting the phenolic compounds from the effluents of paper industries.

Laccase: microbial sources, production, purification, and potential biotechnological applications.

Science.gov (United States)

Shraddha; Shekher, Ravi; Sehgal, Simran; Kamthania, Mohit; Kumar, Ajay

2011-01-01

Laccase belongs to the blue multicopper oxidases and participates in cross-linking of monomers, degradation of polymers, and ring cleavage of aromatic compounds. It is widely distributed in higher plants and fungi. It is present in Ascomycetes, Deuteromycetes and Basidiomycetes and abundant in lignin-degrading white-rot fungi. It is also used in the synthesis of organic substance, where typical substrates are amines and phenols, the reaction products are dimers and oligomers derived from the coupling of reactive radical intermediates. In the recent years, these enzymes have gained application in the field of textile, pulp and paper, and food industry. Recently, it is also used in the design of biosensors, biofuel cells, as a medical diagnostics tool and bioremediation agent to clean up herbicides, pesticides and certain explosives in soil. Laccases have received attention of researchers in the last few decades due to their ability to oxidize both phenolic and nonphenolic lignin-related compounds as well as highly recalcitrant environmental pollutants. It has been identified as the principal enzyme associated with cuticular hardening in insects. Two main forms have been found: laccase-1 and laccase-2. This paper reviews the occurrence, mode of action, general properties, production, applications, and immobilization of laccases within different industrial fields.

Laccase: Microbial Sources, Production, Purification, and Potential Biotechnological Applications

Directory of Open Access Journals (Sweden)

Shraddha

2011-01-01

Full Text Available Laccase belongs to the blue multicopper oxidases and participates in cross-linking of monomers, degradation of polymers, and ring cleavage of aromatic compounds. It is widely distributed in higher plants and fungi. It is present in Ascomycetes, Deuteromycetes and Basidiomycetes and abundant in lignin-degrading white-rot fungi. It is also used in the synthesis of organic substance, where typical substrates are amines and phenols, the reaction products are dimers and oligomers derived from the coupling of reactive radical intermediates. In the recent years, these enzymes have gained application in the field of textile, pulp and paper, and food industry. Recently, it is also used in the design of biosensors, biofuel cells, as a medical diagnostics tool and bioremediation agent to clean up herbicides, pesticides and certain explosives in soil. Laccases have received attention of researchers in the last few decades due to their ability to oxidize both phenolic and nonphenolic lignin-related compounds as well as highly recalcitrant environmental pollutants. It has been identified as the principal enzyme associated with cuticular hardening in insects. Two main forms have been found: laccase-1 and laccase-2. This paper reviews the occurrence, mode of action, general properties, production, applications, and immobilization of laccases within different industrial fields.

Structure, functionality and tuning up of laccases for lignocellulose and other industrial applications

DEFF Research Database (Denmark)

Sitarz, Anna K.; Mikkelsen, Jørn D.; Meyer, Anne S.

2016-01-01

Laccases (EC 1.10.3.2) are copper-containing oxidoreductases that have a relatively high redox potential which enables them to catalyze oxidation of phenolic compounds, including lignin-derived phenolics. The laccase-catalyzed oxidation of phenolics is accompanied by concomitant reduction of diox...... but differences in loop conformations. We also evaluate the features and regions of laccases in relation to modification and evolution of laccases for various industrial applications including lignocellulosic biomass processing....

Laccases as palladium oxidases.

Science.gov (United States)

Mekmouche, Yasmina; Schneider, Ludovic; Rousselot-Pailley, Pierre; Faure, Bruno; Simaan, A Jalila; Bochot, Constance; Réglier, Marius; Tron, Thierry

2015-02-01

The first example of a coupled catalytic system involving an enzyme and a palladium(ii) catalyst competent for the aerobic oxidation of alcohol in mild conditions is described. In the absence of dioxygen, the fungal laccase LAC3 is reduced by a palladium(0) species as evidenced by the UV/VIS and ESR spectra of the enzyme. During the oxidation of veratryl alcohol performed in water, at room temperature and atmospheric pressure, LAC3 regenerates the palladium catalyst, is reduced and catalyzes the four-electron reduction of dioxygen into water with no loss of enzyme activity. The association of a laccase with a water-soluble palladium complex results in a 7-fold increase in the catalytic efficiency of the complex. This is the first step in the design of a family of renewable palladium catalysts for aerobic oxidation.

Adsorption of Trametes versicolor laccase to soil iron and aluminum minerals: enzyme activity, kinetics and stability studies.

Science.gov (United States)

Wu, Yue; Jiang, Ying; Jiao, Jiaguo; Liu, Manqiang; Hu, Feng; Griffiths, Bryan S; Li, Huixin

2014-02-01

Laccases play an important role in the degradation of soil phenol or phenol-like substance and can be potentially used in soil remediation through immobilization. Iron and aluminum minerals can adsorb extracellular enzymes in soil environment. In the present study, we investigated the adsorptive interaction of laccase, from the white-rot fungus Trametes versicolor, with soil iron and aluminum minerals and characterized the properties of the enzyme after adsorption to minerals. Results showed that both soil iron and aluminum minerals adsorbed great amount of laccase, independent of the mineral specific surface areas. Adsorbed laccases retained 26-64% of the activity of the free enzyme. Compared to the free laccase, all adsorbed laccases showed higher Km values and lower Vmax values, indicating a reduced enzyme-substrate affinity and a lower rate of substrate conversion in reactions catalyzed by the adsorbed laccase. Adsorbed laccases exhibited increased catalytic activities compared to the free laccase at low pH, implying the suitable application of iron and aluminum mineral-adsorbed T. versicolor laccase in soil bioremediation, especially in acid soils. In terms of the thermal profiles, adsorbed laccases showed decreased thermal stability and higher temperature sensitivity relative to the free laccase. Moreover, adsorption improved the resistance of laccase to proteolysis and extended the lifespan of laccase. Our results implied that adsorbed T. versicolor laccase on soil iron and aluminum minerals had promising potential in soil remediation. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

Purification and characterization of three laccase isozymes from the ...

African Journals Online (AJOL)

2012-04-17

Apr 17, 2012 ... improve wine quality by removing fermentation inhibitors so as to increase yield of ethanol (Baldrian, 2006). They have also been used .... Summary of purification of laccase isozymes from Trametes sp. HS-03a. Purification .... and kinetics of a thermostable laccase from Pycnoporus sanguineus. (SCC 108).

Inactivation of Laccase by the Attack of As (III) Reaction in Water.

Science.gov (United States)

Hu, Jinyuan; Lu, Kun; Dong, Shipeng; Huang, Qingguo; Mao, Liang

2018-03-06

Laccase is a multicopper oxidase containing four coppers as reaction sites, including one type 1, one type 2, and two type 3. We here provide the first experimental data showing that As (III) can be effectively removed from water and transformed to As (V) through reactions mediated by laccase with the presence of oxygen. To this end, the As (III) removal, As (V) yields, total protein, active laccase, and copper concentrations in the aqueous phase were determined, respectively. Additionally, electron paramagnetic resonance spectra and UV-vis spectra were applied to probe possible structural changes of the laccase during the reaction. The data offer the first evidence that laccase can be inactivated by As (III) attack thus leading to the release of type 2 copper. The released copper has no reactivity with the As (III). These findings provide new ideas into a significant pathway likely to master the environmental transformation of arsenite, and advance the understanding of laccase inactivation mechanisms, thus providing a foundation for optimization of enzyme-based processes and potential development for removal and remediation of arsenite contamination in the environment.

Laccase-Based CLEAs: Chitosan as a Novel Cross-Linking Agent

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Alexandre Arsenault

2011-01-01

Full Text Available Laccase from Coriolopsis Polyzona was insolubilized as cross-linked enzyme aggregates (CLEAs for the first time with chitosan as the cross-linking agent. Concentrations between 0.01 and 1.867 g/L of chitosan were used and between 0.05 and 600 mM of 1-ethyl-3-(3-dimethylaminopropylcarbodiimide hydrochloride. The laccase was precipitated using ammonium sulphate and cross-linked simultaneously. Specific activity and thermal stability of these biocatalysts were measured. Activities of up to 737 U/g were obtained when 2,2-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid (ABTS was used as a substrate. Moreover, the stability of these biocatalysts was improved with regards to thermal degradation compared to free laccase when exposed to denaturing conditions of high temperature and low pH. The CLEAs stability against chemical denaturants was also tested but no significant improvement was detected. The total amount of ABTS to be oxidized during thermal degradation by CLEAs and free laccase was calculated and the insolubilized enzymes were reported to oxidize more substrate than free laccase. The formation conditions were analyzed by response surface methodology in order to determine an optimal environment for the production of efficient laccase-based CLEAs using chitosan as the cross-linking agent. After 24 hours of formation at pH 3 and at 4°C without agitation, the CLEAs exhibit the best specific activity.

Laccase-catalyzed oxidation and intramolecular cyclization of dopamine: A new method for selective determination of dopamine with laccase/carbon nanotube-based electrochemical biosensors

International Nuclear Information System (INIS)

Xiang, Ling; Lin, Yuqing; Yu, Ping; Su, Lei; Mao, Lanqun

2007-01-01

This study demonstrates a new electrochemical method for the selective determination of dopamine (DA) with the coexistence of ascorbic acid (AA) and 3,4-dihydroxyphenylacetic acid (DOPAC) with laccase/multi-walled carbon nanotube (MWNT)-based biosensors prepared by cross-linking laccase into MWNT layer confined onto glassy carbon electrodes. The method described here is essentially based on the chemical reaction properties of DA including oxidation, intramolecular cyclization and disproportionation reactions to finally give 5,6-dihydroxyindoline quinone and on the uses of the two-electron and two-proton reduction of the formed 5,6-dihydroxyindoline quinone to constitute a method for the selective determination of DA at a negative potential that is totally separated from those for the redox processes of AA and DOPAC. Instead of the ECE reactions of DA with the first oxidation of DA being driven electrochemically, laccase is used here as the biocatalyst to drive the first oxidation of DA into its quinone form and thus initialize the sequential reactions of DA finally into 5,6-dihydroxyindoline quinone. In addition, laccase also catalyzes the oxidation of AA and DOPAC into electroinactive species with the concomitant reduction of O 2 . As a consequence, a combinational exploitation of the chemical properties inherent in DA and the multifunctional catalytic properties of laccase as well as the excellent electrochemical properties of carbon nanotubes substantially enables the prepared laccase/MWNT-based biosensors to be well competent for the selective determination of DA with the coexistence of physiological levels of AA and DOPAC. This demonstration offers a new method for the selective determination of DA, which could be potentially employed for the determination of DA in biological systems

Biobleaching chemistry of laccase-mediator systems on high-lignin-content kraft pulps

International Nuclear Information System (INIS)

Chakar, F.S.; Ragauskas, A.J.

2004-01-01

A high-lignin-content softwood kraft pulp was reacted with laccase in the presence of 1-hydroxybenzotriazole (HBT), N-acetyl-N-phenylhydroxylamine (NHA), and violuric acid (VA). The biodelignification response with violuric acid was superior to both 1-hydroxybenzotriazole and N-acetyl-N-phenylhydroxylamine. NMR analysis of residual lignins isolated before and after the biobleaching treatments revealed that the latter material was highly oxidized and that the magnitude of structural changes was most pronounced with the laccase - violuric acid biobleaching system. An increase in the content of carboxylic acid groups and a decrease in methoxyl groups were noted with all three laccase-mediator systems. The oxidation biobleaching pathway is directed primarily towards noncondensed C5 phenolic lignin functional structures for all three laccase-mediated systems. The laccase - violuric acid system was also reactive towards C5-condensed phenolic lignin structures. (author)

Biocatalytic potential of laccase-like multicopper oxidases from Aspergillus niger

NARCIS (Netherlands)

Tamayo Ramos, J.A.; Berkel, van W.J.H.; Graaff, de L.H.

2012-01-01

BACKGROUND: Laccase-like multicopper oxidases have been reported in several Aspergillus species but they remain uncharacterized. The biocatalytic potential of the Aspergillus niger fungal pigment multicopper oxidases McoA and McoB and ascomycete laccase McoG was investigated. RESULTS: The

Cloning and expression of Icc1 Laccase gene promoter in Aspergillus niger

International Nuclear Information System (INIS)

Marqueda-Galvez, A. P.; Loera Carrol, O.; Xaconostle cazares, B.; Tellez-Jurado, A.; Arana-Cuenca, A.

2009-01-01

The white rot fungus Trametes sp. I-62 is a strain with laccase activity and a great potential for biotechnological applications given its ability to detoxify distillery effluents. The Icc1, Icc2 and Icc3 laccase genes of this basidiomycetes have been cloned and sequenced. The promoter region of Icc1 laccase gene contains a putative site for xenobiotics (XRE). (Author)

Stellar Disk Truncations: HI Density and Dynamics

Science.gov (United States)

Trujillo, Ignacio; Bakos, Judit

2010-06-01

Using HI Nearby Galaxy Survey (THINGS) 21-cm observations of a sample of nearby (nearly face-on) galaxies we explore whether the stellar disk truncation phenomenon produces any signature either in the HI gas density and/or in the gas dynamics. Recent cosmological simulations suggest that the origin of the break on the surface brightness distribution is produced by the appearance of a warp at the truncation position. This warp should produce a flaring on the gas distribution increasing the velocity dispersion of the HI component beyond the break. We do not find, however, any evidence of this increase in the gas velocity dispersion profile.

Upgrading Laccase Production and Biochemical Properties: Strategies and Challenges.

Science.gov (United States)

Bertrand, Brandt; Martínez-Morales, Fernando; Trejo-Hernández, María R

2017-07-01

Improving laccases continues to be crucial in novel biotechnological developments and industrial applications, where they are concerned. This review breaks down and explores the potential of the strategies (conventional and modern) that can be used for laccase enhancement (increased production and upgraded biochemical properties such as stability and catalytic efficiency). The challenges faced with these approaches are briefly discussed. We also shed light on how these strategies merge and give rise to new options and advances in this field of work. Additionally, this article seeks to serve as a guide for students and academic researchers interested in laccases. This document not only gives basic information on laccases, but also provides updated information on the state of the art of various technologies that are used in this line of investigation. It also gives the readers an idea of the areas extensively studied and the areas where there is still much left to be done. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1015-1034, 2017. © 2017 American Institute of Chemical Engineers.

Laccase/mediator assisted degradation of triarylmethane dyes in a continuous membrane reactor.

Science.gov (United States)

Chhabra, Meenu; Mishra, Saroj; Sreekrishnan, Trichur Ramaswamy

2009-08-10

Laccase/mediator systems are important bioremediation agents as the rates of reactions can be enhanced in the presence of the mediators. The decolorization mechanism of two triarylmethane dyes, namely, Basic Green 4 and Acid Violet 17 is reported using Cyathus bulleri laccase. Basic Green 4 was decolorized through N-demethylation by laccase alone, while in mediator assisted reactions, dye breakdown was initiated from oxidation of carbinol form of the dye. Benzaldehyde and N,N-dimethyl aniline were the major end products. With Acid Violet 17, laccase carried out N-deethylation and in mediator assisted reactions, oxidation of the carbinol form of the dye occurred resulting in formation of formyl benzene sulfonic acid, carboxy benzene sulfonic acid and benzene sulfonic acid. Toxicity analysis revealed that Basic Green 4 was toxic and treatment with laccase/mediators resulted in 80-100% detoxification. The treatment of the textile dye solution using laccase and 2,2'-azino-di-(-ethylbenzothiazoline-6-sulfonic acid) (ABTS) was demonstrated in an enzyme membrane reactor. At a hydraulic retention time of 6h, the process was operated for a period of 15 days with nearly 95% decolorization, 10% reduction in flux and 70% recovery of active ABTS.

Thermokinetic comparison of trypan blue decolorization by free laccase and fungal biomass.

Science.gov (United States)

Razak, N N A; Annuar, M S M

2014-03-01

Free laccase and fungal biomass from white-rot fungi were compared in the thermokinetics study of the laccase-catalyzed decolorization of an azo dye, i.e., Trypan Blue. The decolorization in both systems followed a first-order kinetics. The apparent first-order rate constant, k1', value increases with temperature. Apparent activation energy of decolorization was similar for both systems at ∼ 22 kJ mol(-1), while energy for laccase inactivation was 18 kJ mol(-1). Although both systems were endothermic, fungal biomass showed higher enthalpy, entropy, and Gibbs free energy changes for the decolorization compared to free laccase. On the other hand, free laccase showed reaction spontaneity over a wider range of temperature (ΔT = 40 K) as opposed to fungal biomass (ΔT = 15 K). Comparison of entropy change (ΔS) values indicated metabolism of the dye by the biomass.

Analysis of truncation limit in probabilistic safety assessment

International Nuclear Information System (INIS)

Cepin, Marko

2005-01-01

A truncation limit defines the boundaries of what is considered in the probabilistic safety assessment and what is neglected. The truncation limit that is the focus here is the truncation limit on the size of the minimal cut set contribution at which to cut off. A new method was developed, which defines truncation limit in probabilistic safety assessment. The method specifies truncation limits with more stringency than presenting existing documents dealing with truncation criteria in probabilistic safety assessment do. The results of this paper indicate that the truncation limits for more complex probabilistic safety assessments, which consist of larger number of basic events, should be more severe than presently recommended in existing documents if more accuracy is desired. The truncation limits defined by the new method reduce the relative errors of importance measures and produce more accurate results for probabilistic safety assessment applications. The reduced relative errors of importance measures can prevent situations, where the acceptability of change of equipment under investigation according to RG 1.174 would be shifted from region, where changes can be accepted, to region, where changes cannot be accepted, if the results would be calculated with smaller truncation limit

Laccase-catalyzed oxidation of iodide and formation of organically bound iodine in soils.

Science.gov (United States)

Seki, Miharu; Oikawa, Jun-ichi; Taguchi, Taro; Ohnuki, Toshihiko; Muramatsu, Yasuyuki; Sakamoto, Kazunori; Amachi, Seigo

2013-01-02

Laccase oxidizes iodide to molecular iodine or hypoiodous acid, both of which are easily incorporated into natural soil organic matter. In this study, iodide sorption and laccase activity in 2 types of Japanese soil were determined under various experimental conditions to evaluate possible involvement of this enzyme in the sorption of iodide. Batch sorption experiment using radioactive iodide tracer ((125)I(-)) revealed that the sorption was significantly inhibited by autoclaving (121 °C, 40 min), heat treatment (80 and 100 °C, 10 min), γ-irradiation (30 kGy), N(2) gas flushing, and addition of reducing agents and general laccase inhibitors (KCN and NaN(3)). Interestingly, very similar tendency of inhibition was observed in soil laccase activity, which was determined using 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) as a substrate. The partition coefficient (K(d): mL g(-1)) for iodide and specific activity of laccase in soils (Unit g(-1)) showed significant positive correlation in both soil samples. Addition of a bacterial laccase with an iodide-oxidizing activity to the soils strongly enhanced the sorption of iodide. Furthermore, the enzyme addition partially restored iodide sorption capacity of the autoclaved soil samples. These results suggest that microbial laccase is involved in iodide sorption on soils through the oxidation of iodide.

Plants increase laccase activity in soil with long-term elevated CO2 legacy

DEFF Research Database (Denmark)

Partavian, Asrin; Mikkelsen, Teis Nørgaard; Vestergård, Mette

2015-01-01

[CO2] stimulate laccase activity. We incubated soil exposed to seven years of elevated or ambient field [CO2] in ambient or elevated [CO2] chambers for six months either with or without plants (Deschampsia flexuosa). Elevated chamber [CO2] increased D. flexuosa production and belowground respiration....... Interestingly, plants also grew larger in soil with an elevated [CO2] legacy. Plants stimulated soil microbial biomass, belowground respiration and laccase activity, and the plant-induced laccase stimulation was particularly apparent in soil exposed to long-term elevated [CO2] in the field, whereas laccase......Actively growing plants can stimulate mineralization of recalcitrant soil organic matter (SOM), and increased atmospheric [CO2] can further enhance such plant-mediated SOM degradation. Laccases are central for recalcitrant SOM decomposition, and we therefore hypothesized that plants and elevated...

Improved immobilization of laccase on a glassy carbon electrode by oriented covalent attachment

Directory of Open Access Journals (Sweden)

Liu Xin

2014-01-01

Full Text Available A laccase from Thermus thermophilus HB27 was reported to be potentially useful in the design of a temperature controlled biofuel cell. For enhancing its application in different thermal conditions, we engineered a laccase-oriented immobilized electrode. A site-directed mutant N323C of the laccase was constructed. A photometric assay was employed in order to compare the catalytic properties of wild-type laccase and mutant. The mutant was attached to a glass carbon electrode by covalent cross-linking. The electrochemical properties of the immobilized laccase were investigated by cyclic voltammetry. This immobilization allowed the active electrode to function at temperatures up to 95°C. The thermal and pH dependence profiles were similar to those of the soluble enzyme investigated by spectrophotometry.

Recovery of laccase from processed Hericium erinaceus (Bull.:Fr) Pers. fruiting bodies in aqueous two-phase system.

Science.gov (United States)

Rajagopalu, Devamalini; Show, Pau Loke; Tan, Yee Shin; Muniandy, Sekaran; Sabaratnam, Vikineswary; Ling, Tau Chuan

2016-09-01

The feasible use of aqueous two-phase systems (ATPSs) to establish a viable protocol for the recovery of laccase from processed Hericium erinaceus (Bull.:Fr.) Pers. fruiting bodies was evaluated. Cold-stored (4.00±1.00°C) H. erinaceus recorded the highest laccase activities of 2.02±0.04 U/mL among all the processed techniques. The evaluation was carried out in twenty-five ATPSs, which composed of polyethylene glycol (PEG) with various molecular weights and potassium phosphate salt solution to purify the protein from H. erinaceus. Optimum recovery condition was observed in the ATPS which contained 17% (w/w) PEG with a molecular weight of 8000 and 12.2% (w/w) potassium phosphate solution, at a volume ratio (VR) of 1.0. The use of ATPS resulted in one-single primary recovery stage process that produced an overall yield of 99% with a purification factor of 8.03±0.46. The molecular mass of laccases purified from the bottom phase was in the range of 55-66 kDa. The purity of the partitioned laccase was confirmed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Effect of antibiotics on growth and laccase production from Cyathus bulleri and Pycnoporus cinnabarinus.

Science.gov (United States)

Dhawan, Shikha; Lal, Rup; Hanspal, Manjit; Kuhad, Ramesh Chander

2005-08-01

The effect of nine different antibiotics (chloramphenicol, ampicillin trihydrate, kanamycin A monosulfate, neomycin sulfate, erythromycin, thiostrepton, tetracycline, apramycin sulfate and streptomycin sulfate) on growth and laccase production from Cyathus bulleri and Pycnoporus cinnabarinus has been investigated. All the antibiotics tested at a concentration of 200 mg/l affected the fungal growth, release of protein and laccase production to different extent. Inhibition in fungal growth was found to be positively correlated with increase in laccase production. Interestingly, apramycin sulfate inhibited biomass production (14.9-26.2%), nevertheless, it stimulated maximum laccase production (18.2 U/ml) in both the fungi. Increasing concentrations of apramycin sulfate enhanced laccase production from P. cinnabarinus but not from C. bulleri.

Biosensor based on laccase immobilized on plasma polymerized allylamine/carbon electrode

Energy Technology Data Exchange (ETDEWEB)

Ardhaoui, Malika, E-mail: malika.ardhaoui@ucd.ie [Laboratoire de Génie des Procédés Plasma et Traitements de Surface, Université Pierre et Marie Curie-Chimie ParisTech, 11 rue Pierre et Marie Curie, 75231 Paris (France); Laboratoire Charles Friedel, CNRS UMR 7223, Chimie ParisTech, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Surface Engineering Research Group, School of Electrical, Electronic and Mechanical Engineering, University College Dublin, Belfield, Dublin 4 (Ireland); Bhatt, Sudhir [Laboratoire de Génie des Procédés Plasma et Traitements de Surface, Université Pierre et Marie Curie-Chimie ParisTech, 11 rue Pierre et Marie Curie, 75231 Paris (France); Zheng, Meihui [Laboratoire Charles Friedel, CNRS UMR 7223, Chimie ParisTech, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Dowling, Denis [Surface Engineering Research Group, School of Electrical, Electronic and Mechanical Engineering, University College Dublin, Belfield, Dublin 4 (Ireland); Jolivalt, Claude [Laboratoire Charles Friedel, CNRS UMR 7223, Chimie ParisTech, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Khonsari, Farzaneh Arefi [Laboratoire de Génie des Procédés Plasma et Traitements de Surface, Université Pierre et Marie Curie-Chimie ParisTech, 11 rue Pierre et Marie Curie, 75231 Paris (France)

2013-08-01

In this work, a simple and rapid method was used to functionalize carbon electrode in order to efficiently immobilize laccase for biosensor application. A stable allylamine coating was deposited using a low pressure inductively excited RF tubular plasma reactor under mild plasma conditions (low plasma power (10 W), few minutes) to generate high density amine groups (N/C ratio up to 0.18) on rough carbon surface electrodes. The longer was the allylamine plasma deposition time; the better was the surface coverage. Laccase from Trametes versicolor was physisorbed and covalently bound to these allylamine modified carbon surfaces. The laccase activities and current outputs measured in the presence of 2,2′-azinobis-(3-ethylbenzothiazole-6-sulfonic acid) (ABTS) showed that the best efficiency was obtained for electrode plasma coated during 30 min. They showed also that for all the tested electrodes, the activities and current outputs of the covalently immobilized laccases were twice higher than the physically adsorbed ones. The sensitivity of these biocompatible bioelectrodes was evaluated by measuring their catalytic efficiency for oxygen reduction in the presence of ABTS as non-phenolic redox substrate and 2,6-dimethoxyphenol (DMP) as phenolic one. Sensitivities of around 4.8 μA mg{sup −1} L and 2.7 μA mg{sup −1} L were attained for ABTS and DMP respectively. An excellent stability of this laccase biosensor was observed for over 6 months. - Highlights: • Low pressure plasma was used to generate stable allylamine coating. • Laccase from Trametes versicolor was physisorbed and covalently immobilized. • Best biosensor efficiency obtained for the covalently immobilized laccases • Sensitivities of 4.8 μA mg{sup −1} L and 2.7 μA mg{sup −1} L for ABTS and DMP respectively.

Adsorption and transformation of PAHs from water by a laccase-loading spider-type reactor

Energy Technology Data Exchange (ETDEWEB)

Niu, Junfeng, E-mail: junfengn@bnu.edu.cn [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875 (China); Dai, Yunrong, E-mail: daiyunrong@mail.bnu.edu.cn [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875 (China); Guo, Huiyuan, E-mail: hyguo0216@163.com [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875 (China); Xu, Jiangjie, E-mail: 1993120hb@163.com [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875 (China); Shen, Zhenyao, E-mail: zyshen@bnu.edu.cn [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875 (China)

2013-03-15

Highlights: ► Laccase-loading spider-type reactor (LSTR) is got by emulsion electrospinning. ► LSTR consists of beads-in-string fibers with more laccase and higher activity. ► LSTR can achieve the rapid and efficient removal of PAHs from water. ► Aquatic environmental factors have little influence on the PAH removal by LSTR. ► A synergetic mechanism includes adsorption, directional migration and degradation. -- Abstract: The remediation of polycyclic aromatic hydrocarbons (PAHs) polluted waters has become a concern as a result of the widespread use of PAHs and their adverse impacts on water ecosystems and human health. To remove PAHs rapidly and efficiently in situ, an active fibrous membrane, laccase-loading spider-type reactor (LSTR) was fabricated by electrospinning a poly(D,L-lactide-co-glycolide) (PDLGA)/laccase emulsion. The LSTR is composed of beads-in-string structural core–shell fibers, with active laccase encapsulated inside the beads and nanoscale pores on the surface of the beads. This structure can load more laccase and retains higher activity than do linear structural core–shell fibers. The LSTR achieves the efficient removal/degradation of PAHs in water, which is attributed to not only the protection of the laccase activity by the core–shell structure but also the pre-concentration (adsorption) of PAHs on the surface of the LSTR and the concentration of laccase in the beads. Moreover, the effects of pH, temperature and dissolved organic matter (DOM) concentration on the removal of PAHs by the LSTR, in comparison with that by free laccase, have been taken into account. A synergetic mechanism including adsorption, directional migration and degradation for PAH removal is proposed.

Laccase catalyzed grafting of-N-OH type mediators to lignin via radical-radical coupling

DEFF Research Database (Denmark)

Munk, Line; Punt, A. M.; Kabel, M. A.

2017-01-01

Lignin is an underexploited resource in biomass refining. Laccases (EC 1.10.3.2) catalyze oxidation of phenolic hydroxyls using O2 as electron acceptor and may facilitate lignin modification in the presence of mediators. This study assessed the reactivity of four different synthetic mediators...... better than HBT (1-hydroxybenzotriazole). Three different mechanisms are suggested to explain the grafting of HPI and HBT, all involving radical-radical coupling to produce covalent bonding to lignin. Lignin from exhaustive cellulase treatment of wheat straw was more susceptible to grafting than beech...... organosolv lignin with the relative abundance of grafting being 35% vs. 11% for HPI and 5% vs. 1% for HBT on these lignin substrates. The data imply that lignin can be functionalized via laccase catalysis with-N-OH type mediators....

Effect of pretreatment of hydrothermally processed rice straw with laccase-displaying yeast on ethanol fermentation

Energy Technology Data Exchange (ETDEWEB)

Nakanishi, Akihito; Bae, Jun Gu; Fukai, Kotaro; Tokumoto, Naoki; Kuroda, Kouichi; Ogawa, Jun; Shimizu, Sakayu; Ueda, Mitsuyoshi [Kyoto Univ. (Japan). Div. of Applied Life Sciences; Nakatani, Masato [Daiwa Kasei, Shiga (Japan)

2012-05-15

A gene encoding laccase I was identified and cloned from the white-rot fungus Trametes sp. Ha1. Laccase I contained 10 introns and an original secretion signal sequence. After laccase I without introns was prepared by overlapping polymerase chain reaction, it was inserted into expression vector pULD1 for yeast cell surface display. The oxidation activity of a laccase-I-displaying yeast as a whole-cell biocatalyst was examined with 2,2{sup '}-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS), and the constructed yeast showed a high oxidation activity. After the pretreatment of hydrothermally processed rice straw (HPRS) with laccase-I-displaying yeast with ABTS, fermentation was conducted with yeast codisplaying endoglucanase, cellobiohydrolase, and {beta}-glucosidase with HPRS. Fermentation of HPRS treated with laccase-I-displaying yeast was performed with 1.21-fold higher activities than those of HPRS treated with control yeast. The results indicated that pretreatment with laccase-I-displaying yeast with ABTS was effective for direct fermentation of cellulosic materials by yeast codisplaying endoglucanase, cellobiohydrolase, and {beta}-glucosidase. (orig.)

Effect Of Metal Ions On Triphenylmethane Dye Decolorization By Laccase From Trametes Versicolor

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Chmelová Daniela

2015-12-01

Full Text Available The aim of this study was investigate the influence of different metal ions on laccase activity and triphenylmethane dye decolorization by laccase from white-rot fungus Trametes versicolor. Laccase activity was inhibited by monovalent ions (Li+, Na+, K+ and Ag+ but the presence of divalent ions increased laccase activity at the concentration of 10 mmol/l. The effect of metal ions on decolorization of triphenylmethane dyes with different structures namely Bromochlorophenol Blue, Bromophenol Blue, Bromocresol Blue and Phenol Red was tested. The presence of metal ions (Na+, K+, Mg2+, Ca2+, Ba2+, Mn2+, Zn2+ slightly decreased triphenylmethane dye decolorization by laccase from T. versicolor except Na+ and Mg2+, which caused the increase of decolorization for all tested dyes. Decolorization of selected dyes showed that the presence of low-molecular-weight compounds is necessary for effective decolorization. Hydroxybenzotriazole (HBT is the most frequently used. Although HBT belongs to most frequently used redox mediator and generally increase decolorization efficiency, so its presence decreased decolorization percentage of Bromophenol Blue and Bromochlorophenol Blue, the influence of metal ions to dye decolorization by laccase has the similar course with or without presence of redox mediator HBT.

Laccase Immobilization by Chelated Metal Ion Coordination Chemistry

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Qingqing Wang

2014-09-01

Full Text Available In this work, amidoxime polyacrylonitrile (AOPAN nanofibrous membrane was prepared by a reaction between PAN nanofibers and hydroxylamine hydrochloride. The AOPAN nanofibrous membranes were used for four metal ions (Fe3+, Cu2+, Ni2+, Cd2+ chelation under different conditions. Further, the competition of different metal ions coordinating with AOPAN nanofibrous membrane was also studied. The AOPAN chelated with individual metal ion (Fe3+, Cu2+, Ni2+, Cd2+ and also the four mixed metal ions were further used for laccase (Lac immobilization. Compared with free laccase, the immobilized laccase showed better resistance to pH and temperature changes as well as improved storage stability. Among the four individual metal ion chelated membranes, the stability of the immobilized enzymes generally followed the order as Fe–AOPAN–Lac > Cu–AOPAN–Lac > Ni–AOPAN–Lac > Cd–AOPAN–Lac. In addition, the immobilized enzyme on the carrier of AOPAN chelated with four mixed metal ions showed the best properties.

Laccase treatment of recycled blue dyed paper: Physical properties and fiber charge

Digital Repository Service at National Institute of Oceanography (India)

Mohandass, C.; Knutson, K.; Ragauskas, A.J.

Recycled blue colored paper was treated with laccase under various combinations of physical and chemical parameters including enzyme concentration, temperature, oxygen, and reaction time. Laccase treatment of recycled dyed pulp increased acid group...

Heterologous expression and characterization of a laccase from Laccaria bicolor in Pichia pastoris

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Bo Wang

2016-01-01

Full Text Available Synthetic dyes are known to be highly toxic to mammalian cells and mutagenic and carcinogenic to humans and, therefore, should be detoxified and removed from industrial effluents. Different approaches for removal and detoxication are extensively sought. Biochemical methods are considered the most economical and effective method of dye decolourization. In this research, the laccase gene from Laccaria bicolor was modified and expressed in Pichia pastoris. The properties of the recombinant laccase and its ability to degrade synthetic dyes were studied. The laccase activity was optimal at pH 2.2 and 50 °C. Its Km value was 0.187 mmol/L for ABTS [2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid]. The laccase obtained was shown to decolorize the synthetic dyes, malachite green, crystal violet and orange G, with ABTS as a mediator. These results indicated that the laccase obtained may be used to treat industrial effluents containing artificial dyes.

A step forward in laccase exploitation: Recombinant production and evaluation of techno-economic feasibility of the process.

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Pezzella, Cinzia; Giacobelli, Valerio Guido; Lettera, Vincenzo; Olivieri, Giuseppe; Cicatiello, Paola; Sannia, Giovanni; Piscitelli, Alessandra

2017-10-10

Protein heterologous production offers viable opportunities to tailor laccase properties to specific industrial needs. The high redox potential laccase POXA1b from Pleurotus ostreatus was chosen as case study of marketable enzyme, due to its desirable properties in terms of activity/stability profile, and already assessed applicability. POXA1b was heterologously produced in Pichia pastoris by investigating the effect of inducible and constitutive expression systems on both the yield and the cost of its production. System performances were first assessed in shaken-flasks and then scaled-up in bioreactor. The production level obtained in the inducible system is 42U/mL, while the activity value achieved with the constitutive one is 60U/mL, the highest obtained in constitutive systems so far. The economic feasibility of recombinant laccase production was simulated, describing the case of an Italian small-medium enterprise. Two scenarios were evaluated: Scenario (I) production based on methanol inducible system; Scenario (II) production based on the constitutive system, fed with glycerol. At all the scales the glycerol-based fermentation is more economic than the methanol-based one. The price forecast for rPOXA1b production is 0.34€kU -1 for glycerol-based process, and is very competitive with the current price of commercial laccase. Copyright © 2017 Elsevier B.V. All rights reserved.

Expression of a new laccase from Moniliophthora roreri at high levels in Pichia pastoris and its potential application in micropollutant degradation.

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Bronikowski, Agathe; Hagedoorn, Peter-Leon; Koschorreck, Katja; Urlacher, Vlada B

2017-12-01

Laccases have gained significant attention due to their emerging applications including bioremediation, biomass degradation and biofuel cells. One of the prerequisites for the industrial application of laccases is their sufficient availability. However, expression levels of recombinantly expressed laccases are often low. In this study Mrl2, a new laccase from the basidiomycete Moniliophthora roreri, was cloned in Pichia pastoris and produced in an optimized fed-batch process at an exceptionally high yield of 1.05 g l -1 . With a redox potential of 0.58 V, Mrl2 belongs to mid-redox potential laccases. However, Mrl2 demonstrated high k cat values of 316, 20, 74, and 36 s -1 towards 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), syringaldazine (SGZ), 2,6-dimethoxyphenol (2,6-DMP) and guaiacol, respectively. Mrl2 remained stable above pH 6 and in the presence of many metal ions, which is important for application in bioremediation. Mrl2 was investigated for the ability to degrade endocrine disrupting chemicals (EDCs) and non-steroidal anti-inflammatory drugs (NSDAIs) at neutral pH value. The enzyme accepted and converted estrone, 17β-estradiol, estriol, the synthetic contraceptive 17α-ethinyl estradiol and bisphenol A at pH 7 faster than high-potential laccases from Trametes versicolor. For example, within 30 min Mrl2 removed more than 90% bisphenol A, 17ß-estradiol, 17α-ethinyl estradiol and estriol, respectively. The concentration of the recalcitrant drug diclofenac dropped by 56% after 20 h incubation with Mrl2.

Protection of Wood from Microorganisms by Laccase-Catalyzed Iodination

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Engel, J.; Thöny-Meyer, L.; Schwarze, F. W. M. R.; Ihssen, J.

2012-01-01

In the present work, Norway spruce wood (Picea abies L.) was reacted with a commercial Trametes versicolor laccase in the presence of potassium iodide salt or the phenolic compounds thymol and isoeugenol to impart an antimicrobial property to the wood surface. In order to assess the efficacy of the wood treatment, a leaching of the iodinated and polymerized wood and two biotests including bacteria, a yeast, blue stain fungi, and wood decay fungi were performed. After laccase-catalyzed oxidation of the phenols, the antimicrobial effect was significantly reduced. In contrast, the enzymatic oxidation of iodide (I−) to iodine (I2) in the presence of wood led to an enhanced resistance of the wood surface against all microorganisms, even after exposure to leaching. The efficiency of the enzymatic wood iodination was comparable to that of a chemical wood preservative, VP 7/260a. The modification of the lignocellulose by the laccase-catalyzed iodination was assessed by the Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) technique. The intensities of the selected lignin-associated bands and carbohydrate reference bands were analyzed, and the results indicated a structural change in the lignin matrix. The results suggest that the laccase-catalyzed iodination of the wood surface presents an efficient and ecofriendly method for wood protection. PMID:22865075

Mechanism of salt-induced activity enhancement of a marine-derived laccase, Lac15.

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Li, Jie; Xie, Yanan; Wang, Rui; Fang, Zemin; Fang, Wei; Zhang, Xuecheng; Xiao, Yazhong

2018-04-01

Laccase (benzenediol: oxygen oxidoreductases, EC1.10.3.2) is a multi-copper oxidase capable of oxidizing a variety of phenolic and other aromatic organic compounds. The catalytic power of laccase makes it an attractive candidate for potential applications in many areas of industry including biodegradation of organic pollutants and synthesis of novel drugs. Most laccases are vulnerable to high salt and have limited applications. However, some laccases are not only tolerant to but also activated by certain concentrations of salt and thus have great application potential. The mechanisms of salt-induced activity enhancement of laccases are unclear as yet. In this study, we used dynamic light scattering, size exclusion chromatography, analytical ultracentrifugation, intrinsic fluorescence emission, circular dichroism, ultraviolet-visible light absorption, and an enzymatic assay to investigate the potential correlation between the structure and activity of the marine-derived laccase, Lac15, whose activity is promoted by low concentrations of NaCl. The results showed that low concentrations of NaCl exert little influence on the protein structure, which was partially folded in the absence of the salt; moreover, the partially folded rather than the fully folded state seemed to be favorable for enzyme activity, and this partially folded state was distinctive from the so-called 'molten globule' occasionally observed in active enzymes. More data indicated that salt might promote laccase activity through mechanisms involving perturbation of specific local sites rather than a change in global structure. Potential binding sites for chloride ions and their roles in enzyme activity promotion are proposed.

Continuous adsorption and biotransformation of micropollutants by granular activated carbon-bound laccase in a packed-bed enzyme reactor.

Science.gov (United States)

Nguyen, Luong N; Hai, Faisal I; Dosseto, Anthony; Richardson, Christopher; Price, William E; Nghiem, Long D

2016-06-01

Laccase was immobilized on granular activated carbon (GAC) and the resulting GAC-bound laccase was used to degrade four micropollutants in a packed-bed column. Compared to the free enzyme, the immobilized laccase showed high residual activities over a broad range of pH and temperature. The GAC-bound laccase efficiently removed four micropollutants, namely, sulfamethoxazole, carbamazepine, diclofenac and bisphenol A, commonly detected in raw wastewater and wastewater-impacted water sources. Mass balance analysis showed that these micropollutants were enzymatically degraded following adsorption onto GAC. Higher degradation efficiency of micropollutants by the immobilized compared to free laccase was possibly due to better electron transfer between laccase and substrate molecules once they have adsorbed onto the GAC surface. Results here highlight the complementary effects of adsorption and enzymatic degradation on micropollutant removal by GAC-bound laccase. Indeed laccase-immobilized GAC outperformed regular GAC during continuous operation of packed-bed columns over two months (a throughput of 12,000 bed volumes). Copyright © 2016 Elsevier Ltd. All rights reserved.

Extraction and Application of Laccases from Shimeji Mushrooms (Pleurotus ostreatus Residues in Decolourisation of Reactive Dyes and a Comparative Study Using Commercial Laccase from Aspergillus oryzae

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Ricardo Sposina S. Teixeira

2010-01-01

Full Text Available Oxidases are able to degrade organic pollutants; however, high costs associated with biocatalysts production still hinder their use in environmental biocatalysis. Our study compared the action of a commercial laccase from Aspergillus oryzae and a rich extract from Pleurotus ostreatus cultivation residues in decolourisation of reactive dyes: Drimaren Blue X-3LR (DMBLR, Drimaren Blue X-BLN (DMBBLN, Drimaren Rubinol X-3LR (DMR, and Drimaren Blue C-R (RBBR. The colour removal was evaluated by considering dye concentration, reaction time, absence or presence of the mediator ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid, and the source of laccase. The presence of ABTS was essential for decolourisation of DMR (80–90%, 1 h and RBBR (80–90%, 24 h with both laccases. The use of ABTS was not necessary in reactions containing DMBLR (85–97%, 1 h and DMBBLN (63–84%, 24 h. The decolourisation of DMBBLN by commercial laccase showed levels near 60% while the crude extract presented 80% in 24 h.

Electron Beam-Induced Immobilization of Laccase on Porous Supports for Waste Water Treatment Applications

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Elham Jahangiri

2014-08-01

Full Text Available The versatile oxidase enzyme laccase was immobilized on porous supports such as polymer membranes and cryogels with a view of using such biocatalysts in bioreactors aiming at the degradation of environmental pollutants in wastewater. Besides a large surface area for supporting the biocatalyst, the aforementioned porous systems also offer the possibility for simultaneous filtration applications in wastewater treatment. Herein a “green” water-based, initiator-free, and straightforward route to highly reactive membrane and cryogel-based bioreactors is presented, where laccase was immobilized onto the porous polymer supports using a water-based electron beam-initiated grafting reaction. In a second approach, the laccase redox mediators 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS and syringaldehyde were cross-linked instead of the enzyme via electron irradiation in a frozen aqueous poly(acrylate mixture in a one pot set-up, yielding a mechanical stable macroporous cryogel with interconnected pores ranging from 10 to 50 µm in size. The membranes as well as the cryogels were characterized regarding their morphology, chemical composition, and catalytic activity. The reactivity towards waste- water pollutants was demonstrated by the degradation of the model compound bisphenol A (BPA. Both membrane- and cryogel-immobilized laccase remained highly active after electron beam irradiation. Apparent specific BPA removal rates were higher for cryogel- than for membrane-immobilized and free laccase, whereas membrane-immobilized laccase was more stable with respect to maintenance of enzymatic activity and prevention of enzyme leakage from the carrier than cryogel-immobilized laccase. Cryogel-immobilized redox mediators remained functional in accelerating the laccase-catalyzed BPA degradation, and especially ABTS was found to act more efficiently in immobilized than in freely dissolved state.

Immobilized laccase mediated dye decolorization and transformation pathway of azo dye acid red 27.

Science.gov (United States)

Chhabra, Meenu; Mishra, Saroj; Sreekrishnan, Trichur Ramaswamy

2015-01-01

Laccases have good potential as bioremediating agents and can be used continuously in the immobilized form like many other enzymes. In the present study, laccase from Cyathus bulleri was immobilized by entrapment in Poly Vinyl Alcohol (PVA) beads cross-linked with either nitrate or boric acid. Immobilized laccase was used for dye decolorization in both batch and continuous mode employing a packed bed column. The products of degradation of dye Acid Red 27 were identified by LC MS/MS analysis. The method led to very effective (90%) laccase immobilization and also imparted significant stability to the enzyme (more than 70% after 5 months of storage at 4°C). In batch decolorization, 90-95% decolorization was achieved of the simulated dye effluent for up to 10-20 cycles. Continuous decolorization in a packed bed bioreactor led to nearly 90% decolorization for up to 5 days. The immobilized laccase was also effective in decolorization and degradation of Acid Red 27 in the presence of a mediator. Four products of degradation were identified by LC-MS/MS analysis. The immobilized laccase in PVA-nitrate was concluded to be an effective agent in treatment of textile dye effluents.

Evaluation of fungal laccase immobilized on natural nanostructured bacterial cellulose

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Lin eChen

2015-11-01

Full Text Available The aim of this work was to assess the possibility of using native bacterial nanocellulose (BC as a carrier for laccase immobilization. BC was synthesized by Gluconacetobacter xylinus, which was statically cultivated in a mannitol-based medium and was freeze-dried to form BC sponge after purification. For the first time, fungal laccase from Trametes versicolor was immobilized on the native nanofibril network-structured BC sponge through physical adsorption and cross-linking with glutaraldehyde. The properties including morphologic and structural features of the BC as well as the immobilized enzyme were thoroughly investigated. It was found that enzyme immobilized by cross-linking exhibited broader pH operation range of high catalytic activity as well as higher running stability compared to free and adsorbed enzyme. Using ABTS as substrate, the optimum pH value was 3.5 for the adsorption-immobilized laccase and 4.0 for the crosslinking-immobilized laccase. The immobilized enzyme retained 69% of the original activity after being recycled 7 times. Novel applications of the BC-immobilized enzyme tentatively include active packaging, construction of biosensors, and establishment of bioreactors.

Purification, crystallization and preliminary X-ray study of the fungal laccase from Cerrena maxima

International Nuclear Information System (INIS)

Lyashenko, Andrey V.; Zhukhlistova, Nadegda E.; Gabdoulkhakov, Azat G.; Zhukova, Yuliya N.; Voelter, Wolfang; Zaitsev, Viatcheslav N.; Bento, Isabel; Stepanova, Elena V.; Kachalova, Galina S.; Koroleva, Ol’ga V.; Cherkashyn, Evgeniy A.; Tishkov, Vladimir I.; Lamzin, Victor S.; Schirwitz, Katja; Morgunova, Ekaterina Yu.; Betzel, Christian; Lindley, Peter F.; Mikhailov, Al’bert M.

2006-01-01

The crystallization and preliminary X-ray structure at 1.9 Å resolution of the fungal laccase from C. maxima are presented. Laccases are members of the blue multi-copper oxidase family that oxidize substrate molecules by accepting electrons at a mononuclear copper centre and transferring them to a trinuclear centre. Dioxygen binds to the trinuclear centre and, following the transfer of four electrons, is reduced to two molecules of water. Crystals of the laccase from Cerrena maxima have been obtained and X-ray data were collected to 1.9 Å resolution using synchrotron radiation. A preliminary analysis shows that the enzyme has the typical laccase structure and several carbohydrate sites have been identified. The carbohydrate chains appear to be involved in stabilization of the intermolecular contacts in the crystal structure, thus promoting the formation of well ordered crystals of the enzyme. Here, the results of an X-ray crystallographic study on the laccase from the fungus Cerrena maxima are reported. Crystals that diffract well to a resolution of at least 1.9 Å (R factor = 18.953%; R free = 23.835; r.m.s.d. bond lengths, 0.06 Å; r.m.s.d. bond angles, 1.07°) have been obtained despite the presence of glycan moieties. The overall spatial organization of C. maxima laccase and the structure of its copper-containing active centre have been determined by the molecular-replacement method using the laccase from Trametes versicolor (Piontek et al., 2002 ▶) as a structural template. In addition, four glycan-binding sites were identified and the 1.9 Å X-ray data were used to determine the previously unknown primary structure of this protein. The identity (calculated from sequence alignment) between the C. maxima laccase and the T. versicolor laccase is about 87%. Tyr196 and Tyr372 show significant extra density at the ortho positions and this has been interpreted in terms of NO 2 substituents

Laccase Production from a Temperature and pH Tolerant Fungal Strain of Trametes hirsuta (MTCC 11397

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Kusum Dhakar

2013-01-01

Full Text Available Laccase production by a temperature and pH tolerant fungal strain (GBPI-CDF-03 isolated from a glacial site in Indian Himalayan Region (IHR has been investigated. The fungus developed white cottony mass on potato dextrose agar and revealed thread-like mycelium under microscope. ITS region analysis of fungus showed its 100% similarity with Trametes hirsuta. The fungus tolerated temperature from 4 to 48°C ± 2 (25°C opt. and pH 3–13 (5–7 opt.. Molecular weight of laccase was determined approximately 45 kDa by native PAGE. Amplification of laccase gene fragment (corresponding to the copper-binding conserved domain contained 200 bp. The optimum pH for laccase production, at optimum growth temperature, was determined between 5.5 and 7.5. In optimization experiments, fructose and ammonium sulfate were found to be the best carbon and nitrogen sources, respectively, for enhancing the laccase production. Production of laccase was favored by high carbon/nitrogen ratio. Addition of CuSO4 (up to 1.0 mM induced laccase production up to 2-fold, in case of 0.4 mM concentration. Addition of organic solvents also induced the production of laccase; acetone showed the highest (2-fold induction. The study has implications in bioprospecting of ecologically resilient microbial strains.

Site-directed mutation of a laccase from Thermus thermophilus: Effect on the activity profile

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Liu Xin

2012-01-01

Full Text Available A site-directed mutant R453T of a laccase from Thermus thermophilus HB27 (Tth-laccase was constructed in order to investigate the effect on laccase catalytic properties. The mutated gene was cloned and overexpressed in Escherichia coli. Nickel-affinity purification was achieved and followed by copper ion incorporation. The mature mutated enzyme was quantitatively equal to the wild type. A photometric assay based on the oxidation of the substrate 2,2-azino-bis-(3- ethylbenzthiazoline-6-sulfonate (ABTS was employed in comparison with the wild-type Tth-laccase on catalytic properties. The R453T mutant exhibited improvement in substrate affinity and specific activity at room temperature, whereas those parameters were not significantly influenced when the temperature increased up to 65°C or higher. The mutant had better catalytic activity than that of the wild type at acidic pH. Investigated by circular dichroism spectroscopy, the mutant Tth-laccase displayed similar profiles at low and high temperatures.

Electroenzymatic Reactions With Oxygen on Laccase-Modified Electrodes in Anhydrous (Pure) Organic Solvent

DEFF Research Database (Denmark)

Yarapolov, A.; Shleev, S.; Zaitseva, E.

2007-01-01

in two different ways: (i) by studying the electroreduction of oxygen in anhydrous DMSO via a direct electron transfer mechanism without proton donors and (ii) by doing the same experiments in the presence of laccase substrates, which display in pure organic solvents both the properties of electron......The electroenzymatic reactions of Trametes hirsuta laccase in the pure organic solvent dimethyl sulfoxide (DMSO) have been investigated within the framework for potential use as a catalytic reaction scheme for oxygen reduction. The bioelectrochemical characteristics of laccase were investigated...... donors as well as the properties of weak acids. The results obtained with laccase in anhydrous DMSO were compared with those obtained previously in aqueous buffer. It was shown that in the absence of proton donors under oxygenated conditions, formation of superoxide anion radicals is prevented at bare...

Substrate Specificity and Enzyme Recycling Using Chitosan Immobilized Laccase

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Everton Skoronski

2014-10-01

Full Text Available The immobilization of laccase (Aspergillus sp. on chitosan by cross-linking and its application in bioconversion of phenolic compounds in batch reactors were studied. Investigation was performed using laccase immobilized via chemical cross-linking due to the higher enzymatic operational stability of this method as compared to immobilization via physical adsorption. To assess the influence of different substrate functional groups on the enzyme’s catalytic efficiency, substrate specificity was investigated using chitosan-immobilized laccase and eighteen different phenol derivatives. It was observed that 4-nitrophenol was not oxidized, while 2,5-xylenol, 2,6-xylenol, 2,3,5-trimethylphenol, syringaldazine, 2,6-dimetoxyphenol and ethylphenol showed reaction yields up 90% at 40 °C. The kinetic of process, enzyme recyclability and operational stability were studied. In batch reactors, it was not possible to reuse the enzyme when it was applied to syringaldazne bioconversion. However, when the enzyme was applied to bioconversion of 2,6-DMP, the activity was stable for eight reaction batches.

Role of Laccase and Low Molecular Weight Metabolites from Trametes versicolor in Dye Decolorization

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Diego Moldes

2012-01-01

Full Text Available The studies regarding decolorization of dyes by laccase may not only inform about the possible application of this enzyme for environmental purposes, but also may provide important information about its reaction mechanism and the influence of several factors that could be involved. In this paper, decolorization of crystal violet and phenol red was carried out with different fractions of extracellular liquids from Trametes versicolor cultures, in order to describe the role of laccase in this reaction. Moreover, the possible role of the low molecular weight metabolites (LMWMs also produced by the fungus was evaluated. The results confirm the existence of a nonenzymatic decolorization factor, since the nonprotein fraction of the extracellular liquids from cultures of T. versicolor has shown decolorization capability. Several experiments were performed in order to identify the main compounds related to this ability, which are probably low molecular weight peroxide compounds.

Elimination of estrogenic activity of thermal paper using laccase from Trichoderma sp NFCCI-2745.

Science.gov (United States)

Divya, L M; Prasanth, G K; Sadasivan, C

2013-02-01

In thermal printing, bisphenol A (BPA) functions chemically as a developer and reacts with white or colorless dyes in the presence of heat, converting them to a dark color. BPA can transfer readily to skin in small amounts from these papers. Its damage to environment and organisms has caused an extensive concern. In the present study, thermal paper used at the local automated teller machine counters of India were analyzed for the presence of BPA, and the capability of the paper to produce estrogenicity were assessed using a yeast two-hybrid assay experimental system. The study also focused on eliminating the endocrine-disrupting properties with partially purified laccase from newly isolated ascomycete fungi. The results indicate that these papers can produce estrogen hormone-like effect on experimental systems. It should be noted that on a daily basis, tons of such receipts are being dumped in the environment. Estrogenic properties of thermal paper were effectively removed from the reaction mixture within 3 h of incubation with the partially purified enzyme. We propose the utilization of waste thermal paper as a cheap substrate for laccase production for a safer and cleaner environment.

Gel-Based Purification and Biochemical Study of Laccase Isozymes from Ganoderma sp. and Its Role in Enhanced Cotton Callogenesis

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Krishna K. Sharma

2017-04-01

Full Text Available Basidiomycetous fungi, Ganoderma lucidum MDU-7 and Ganoderma sp. kk-02 secreted multiple laccase isozymes under diverse growth condition. Aromatic compounds and metal salts were also found to regulate the differential expression of laccase isozymes from both the Ganoderma sp. Laccase isozymes induced in the presence of copper from G. lucidum MDU-7 were purified by gel-based (native-PAGE purification method. The purity of laccase isozymes was checked by zymogram and SDS-PAGE. The SDS-PAGE of purified proteins confirmed the multimeric nature of laccase isozymes. The molecular mass of isozymes was found to be in the range of 40–66 kDa. Further, the purified laccase isozymes and their peptides were confirmed with the help of MALDI-TOF peptide fingerprinting. The biochemical characterization of laccase isozymes viz. Glac L2, Glac L3, Glac L4, and Glac L5 have shown the optimum temperature in the range of 30°–45°C and pH 3.0. The Km values of all the laccase isozymes determined for guaiacol were (96–281 μM, ABTS (15–83 μM and O-tolidine (78–724 μM. Further, laccase isozymes from G. lucidum whole genome were studied using bioinformatics tools. The molecular modeling and docking of laccase isozymes with different substrates showed a significant binding affinity, which further validates our experimental results. Interestingly, copper induced laccase of 40 U/ml in culture medium was found to significantly induce cotton callogenesis. Interestingly, all the laccase isozymes were found to have an antioxidative role and therefore capable in free radicals scavenging during callogenesis. This is the first detailed study on the biochemical characterization of all the laccase isozymes purified by a gel-based novel method.

Production of cellobionate from cellulose using an engineered Neurospora crassa strain with laccase and redox mediator addition

Science.gov (United States)

We report a novel production process for cellobionic acid from cellulose using an engineered fungal strain with the exogenous addition of laccase and a redox mediator. A previously engineered strain of Neurospora crassa (F5'ace-1'cre-1'ndvB) was shown to produce cellobionate directly from cellulose ...

Laccase-catalyzed dimerization of glycosylated lignols

Czech Academy of Sciences Publication Activity Database

Bassanini, I.; Gavezzotti, P.; Monti, D.; Krejzová, Jana; Křen, Vladimír; Riva, S.

2016-01-01

Roč. 134, SI (2016), s. 295-301 ISSN 1381-1177 R&D Projects: GA MŠk(CZ) LD15085 Institutional support: RVO:61388971 Keywords : Biocatalysis * Biooxidation * Laccase Subject RIV: CE - Biochemistry Impact factor: 2.269, year: 2016

Rice (Oryza sativa) Laccases Involved in Modification and Detoxification of Herbicides Atrazine and Isoproturon Residues in Plants.

Science.gov (United States)

Huang, Meng Tian; Lu, Yi Chen; Zhang, Shuang; Luo, Fang; Yang, Hong

2016-08-24

Atrazine (ATR) and isoproturon (IPU) as herbicides have become serious environmental contaminants due to their overuse in crop production. Although ATR and IPU in soils are easily absorbed by many crops, the mechanisms for their degradation or detoxification in plants are poorly understood. This study identified a group of novel genes encoding laccases (EC 1.10.3.2) that are possibly involved in catabolism or detoxification of ATR and IPU residues in rice. Transcriptome profiling shows at least 22 differentially expressed laccase genes in ATR/IPU-exposed rice. Some of the laccase genes were validated by RT-PCR analysis. The biochemical properties of the laccases were analyzed, and their activities in rice were induced under ATR/IPU exposure. To investigate the roles of laccases in degrading or detoxifying ATR/IPU in rice, transgenic yeast cells (Pichia pastoris X-33) expressing two rice laccase genes (LOC_Os01g63180 and LOC_Os12g15680) were generated. Both transformants were found to accumulate less ATR/IPU compared to the control. The ATR/IPU-degraded products in the transformed yeast cells using UPLC-TOF-MS/MS were further characterized. Two metabolites, hydroxy-dehydrogenated atrazine (HDHA) and 2-OH-isopropyl-IPU, catalyzed by laccases were detected in the eukaryotic cells. These results indicate that the laccase-coding genes identified here could confer degradation or detoxification of the herbicides and suggest that the laccases could be one of the important enzymatic pathways responsible for ATR/IPU degradation/detoxification in rice.

Laccase immobilized on methylene blue modified mesoporous silica MCM-41/PVA

International Nuclear Information System (INIS)

Xu Xinhua; Lu Ping; Zhou Yumei; Zhao Zhenzhen; Guo Meiqing

2009-01-01

The mesoporous silica sieve MCM-41 containing methylene blue (MB) provides a suitable immobilization of biomolecule matrix due to its uniform pore structure, high surface areas, good biocompatibility and nice conductivity. Based on this, a facilely fabricated amperometric biosensor by entrapping laccase into the MB modified MCM-41/PVA composite film has been developed. Laccase from Trametes versicolor is assembled on a composite film of MCM-41 containing MB/PVA modified Au electrode and the electrode is characterized with respect to transmission electron microscopy (TEM) and scanning electron microscopic (SEM), Cyclic voltammetry (CV), response time, detection limit, linear range and activity of laccase. The laccase modified electrode remains good redox behavior in pH 4.95 acetate buffer solution, at room temperature in present of 0.1 mM catechol. The response time (t 90% ) of the modified electrode is less than 4 s for catechol. The detection limit is 0.331 μM and the linear detect range is about from 4.0 μM to 87.98 μM for catechol with a correlation coefficient of 0.99913(S/N = 3). The apparent Michaelis-Menten (K M app ) is estimated using the Lineweaver-Burk equation and the K M app value is about 0.256 mM. This work demonstrated that the mesoporous silica MCM-41 containing MB provides a novel support for laccase immobilization and the construction of biosensors with a faster response and better bioactivity.

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

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Bao Zhen Feng

2014-01-01

Full Text Available 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.

Two-domain laccase from Streptomyces coelicolor: a link between laccases and nitrite reductases

Czech Academy of Sciences Publication Activity Database

Skálová, Tereza; Dohnálek, Jan; Ostergaard, L. H.; Ostergaard, P. R.; Kolenko, Petr; Dušková, Jarmila; Štěpánková, Andrea; Hašek, Jindřich

2009-01-01

Roč. 16, 3a - Special Issue (2009), s. 3-4 ISSN 1211-5894. [Heart of European Crystallographic Meeting /12./. 24.09.2009-26.09.2009, Třešt´] R&D Projects: GA AV ČR IAA500500701; GA ČR GA305/07/1073 Institutional research plan: CEZ:AV0Z40500505 Keywords : laccase * oxidoreductase * multicopper blue protein Subject RIV: CD - Macromolecular Chemistry

Immobilized laccase mediated dye decolorization and transformation pathway of azo dye acid red 27

OpenAIRE

Chhabra, Meenu; Mishra, Saroj; Sreekrishnan, Trichur Ramaswamy

2015-01-01

Background Laccases have good potential as bioremediating agents and can be used continuously in the immobilized form like many other enzymes. Methods In the present study, laccase from Cyathus bulleri was immobilized by entrapment in Poly Vinyl Alcohol (PVA) beads cross-linked with either nitrate or boric acid. Immobilized laccase was used for dye decolorization in both batch and continuous mode employing a packed bed column. The products of degradation of dye Acid Red 27 were identified by ...

Chemical reactivity of alkali lignin modified with laccase

International Nuclear Information System (INIS)

Sun, Yong; Qiu, Xueqing; Liu, Yunquan

2013-01-01

The modification of alkali lignin with laccase was investigated. The structural change of lignin was analyzed. The sulfonation reactivity was measured by the content of sulfonic group. The results showed the sulfonation reactivity increased to some extent under the condition of atmosphere pressure, but decreased under the condition of 0.3 MPa oxygen pressure. The analysis of Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC) showed the cleavage of various ether linkages and demethylation took place in the structure of lignin to certain extent during modification with laccase, which contributed to the improvement of sulfonation reactivity. Under the condition of 0.3 MPa oxygen pressure, the ratio of s/g (guaiacyl/syringyl) increased after modification, which reduced the sulfonation reactivity of lignin. Simultaneously partial polymerization reaction, such as 4-O-5′, β-5, 5-5 and other reaction in the aromatic ring decreased the activity sites of C 2 , C 5 and C 6 . Abundant polymerization reaction of α-O increased steric hindrance of C 2 and C 6 in aromatic ring, resulting in low sulfonation reactivity of lignin. -- Highlights: ► The modification of alkali lignin with laccase was investigated. ► The sulfonation reactivity increased under the condition of atmosphere pressure. ► More content of guaiacyl and hydroxy, the less content of methoxyl, syringyl can enhance the sulfonation reactivity of lignin. ► Partial moieties polymerized each other with α-O linkgages during treatment with laccase under oxygen pressure. ► The steric hindrance on C 2 and C 6 in aromatic ring resulted in low sulfonation reaction reactivity of lignin

Effect of amino acids and vitamins on laccase production by the bird's nest fungus Cyathus bulleri.

Science.gov (United States)

Dhawan, Shikha; Kuhad, Ramesh Chander

2002-08-01

Various amino acids, their analogues and vitamins have shown stimulatory as well as inhibitory effects on laccase production by Cyathus bulleri. DL-methionine, DL-tryptophan, glycine and DL-valine stimulated laccase production, while L-cysteine monohydrochloride completely inhibited the enzyme production. Among vitamins tested biotin, riboflavin and pyridoxine hydrochloride were found to induce laccase production.

Xenobiotic Compounds Degradation by Heterologous Expression of a Trametes sanguineus Laccase in Trichoderma atroviride.

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Edgar Balcázar-López

Full Text Available Fungal laccases are enzymes that have been studied because of their ability to decolorize and detoxify effluents; they are also used in paper bleaching, synthesis of polymers, bioremediation, etc. In this work we were able to express a laccase from Trametes (Pycnoporus sanguineus in the filamentous fungus Trichoderma atroviride. For this purpose, a transformation vector was designed to integrate the gene of interest in an intergenic locus near the blu17 terminator region. Although monosporic selection was still necessary, stable integration at the desired locus was achieved. The native signal peptide from T. sanguineus laccase was successful to secrete the recombinant protein into the culture medium. The purified, heterologously expressed laccase maintained similar properties to those observed in the native enzyme (Km and kcat and kcat/km values for ABTS, thermostability, substrate range, pH optimum, etc. To determine the bioremediation potential of this modified strain, the laccase-overexpressing Trichoderma strain was used to remove xenobiotic compounds. Phenolic compounds present in industrial wastewater and bisphenol A (an endocrine disruptor from the culture medium were more efficiently removed by this modified strain than with the wild type. In addition, the heterologously expressed laccase was able to decolorize different dyes as well as remove benzo[α]pyrene and phenanthrene in vitro, showing its potential for xenobiotic compound degradation.

Polymerization of different lignins by laccase

NARCIS (Netherlands)

Mattinen, M.L.; Suortti, T.; Gosselink, R.J.A.; Argyropoulos, D.S.; Evtuguin, D.; Suurnäkki, A.; Jong, de E.; Tamminen, T.

2008-01-01

In this study the oxidative polymerization of different lignins, i.e. Flax Soda lignin, Spruce EMAL, and Eucalyptus Dioxane lignin by Trametes hirsuta laccase was compared. Initially the structures of the different lignins were compared by Fourier transform infrared spectroscopy. The reactivity of

Studies on Possible Activation of Microbial Laccase Production Using Gamma Irradiation

International Nuclear Information System (INIS)

ElKenawy, N.M.A.

2013-01-01

Enzyme production is an essential discipline in biotechnology. Laccase enzyme is an oxidoreductase that catalyzes the oxidation of various aromatic compounds, with the simultaneous reduction of oxygen into water. Although the enzyme is present in plants, insects and bacteria, the most important source is fungi and particularly the Basidiomycetes. In fungi, the enzyme plays a role in the removal of potentially toxic phenols arising during fungal morphogenesis, sporulation, phytopathogensis and virulence. In this work, the production of fungal laccase was optimized from a local isolate of Pleurotus ostreatus using solid state fermentation. Factorial design was used to study the effect of several nutrients and inducer on enzyme activity. Purification, characterization of the enzyme, the effect of temperature and ph were studied. The effect of gamma radiation on fungal growth and enzyme production was investigated. The optimization of the production conditions yielded an enzyme with activity over 32,054 IU/gram of fermented substrate. Factorial design was capable of establishing the conditions that multiplied the activity of the enzyme several folds and consequently, reducing the cost of production. The enzyme was capable of decolorizing several dyes with over 80 % reduction in color in case of methyl orange and trypan blue. The decolorisation of dyes is a simple method to assess the aromatic degrading capability of laccase. The enzyme was also used in the synthesis of gold nanoparticles, proving that laccase from Pleurotus ostreatus has a strong potential in several industrial applications, which opens a door towards using of fungal laccase in further biotechnological processes.

Incorporation of copper ions into crystals of T2 copper-depleted laccase from Botrytis aclada

International Nuclear Information System (INIS)

Osipov, E. M.; Polyakov, K. M.; Tikhonova, T. V.; Kittl, R.; Dorovatovskii, P.V.; Shleev, S. V.; Popov, V. O.; Ludwig, R.

2015-01-01

The restoration of the native form of laccase from B. aclada from the type 2 copper-depleted form of the enzyme was investigated. Copper ions were found to be incorporated into the active site after soaking the depleted enzyme in a Cu + -containing solution. Laccases belong to the class of multicopper oxidases catalyzing the oxidation of phenols accompanied by the reduction of molecular oxygen to water without the formation of hydrogen peroxide. The activity of laccases depends on the number of Cu atoms per enzyme molecule. The structure of type 2 copper-depleted laccase from Botrytis aclada has been solved previously. With the aim of obtaining the structure of the native form of the enzyme, crystals of the depleted laccase were soaked in Cu + - and Cu 2+ -containing solutions. Copper ions were found to be incorporated into the active site only when Cu + was used. A comparative analysis of the native and depleted forms of the enzymes was performed

Induction of Laccase, Lignin Peroxidase and Manganese Peroxidase Activities in White-Rot Fungi Using Copper Complexes

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Martina Vrsanska

2016-11-01

Full Text Available Ligninolytic enzymes, such as laccase, lignin peroxidase and manganese peroxidase, are biotechnologically-important enzymes. The ability of five white-rot fungal strains Daedaleopsis confragosa, Fomes fomentarius, Trametes gibbosa, Trametes suaveolens and Trametes versicolor to produce these enzymes has been studied. Three different copper(II complexes have been prepared ((Him[Cu(im4(H2O2](btc·3H2O, where im = imidazole, H3btc = 1,3,5-benzenetricarboxylic acid, [Cu3(pmdien3(btc](ClO43·6H2O and [Cu3(mdpta3(btc](ClO43·4H2O, where pmdien = N,N,N′,N′′,N′′-pentamethyl-diethylenetriamine and mdpta = N,N-bis-(3-aminopropylmethyl- amine, and their potential application for laccase and peroxidases induction have been tested. The enzyme-inducing activities of the complexes were compared with that of copper sulfate, and it has been found that all of the complexes are suitable for the induction of laccase and peroxidase activities in white-rot fungi; however, the newly-synthesized complex M1 showed the greatest potential for the induction. With respect to the different copper inducers, this parameter seems to be important for enzyme activity, which depends also on the fungal strains.

Oxidative polymerization of lignins by laccase in water-acetone mixture.

Science.gov (United States)

Fiţigău, Ionița Firuța; Peter, Francisc; Boeriu, Carmen Gabriela

2013-01-01

The enzymatic oxidative polymerization of five technical lignins with different molecular properties, i.e. Soda Grass/Wheat straw Lignin, Organosolv Hardwood Lignin, Soda Wheat straw Lignin, Alkali pretreated Wheat straw Lignin, and Kraft Softwood was studied. All lignins were previously fractionated by acetone/water 50:50 (v/v) and the laccase-catalyzed polymerization of the low molecular weight fractions (Mw Reactivity of lignin substrates in laccase-catalyzed reactions was determined by monitoring the oxygen consumption. The oxidation reactions in 50% acetone in water mixture proceed with high rate for all tested lignins. Polymerization products were analyzed by size exclusion chromatography, FT-IR, and (31)P-NMR and evidence of important lignin modifications after incubation with laccase. Lignin polymers with higher molecular weight (Mw up to 17500 g/mol) were obtained. The obtained polymers have potential for applications in bioplastics, adhesives and as polymeric dispersants.

A high effective NADH-ferricyanide dehydrogenase coupled with laccase for NAD(+) regeneration.

Science.gov (United States)

Wang, Jizhong; Yang, Chengli; Chen, Xing; Bao, Bingxin; Zhang, Xuan; Li, Dali; Du, Xingfan; Shi, Ruofu; Yang, Junfang; Zhu, Ronghui

2016-08-01

To find an efficient and cheap system for NAD(+) regeneration A NADH-ferricyanide dehydrogenase was obtained from an isolate of Escherichia coli. Optimal activity of the NADH dehydrogenase was at 45 °C and pH 7.5, with a K m value for NADH of 10 μM. By combining the NADH dehydrogenase, potassium ferricyanide and laccase, a bi-enzyme system for NAD(+) regeneration was established. The system is attractive in that the O2 consumed by laccase is from air and the sole byproduct of the reaction is water. During the reaction process, 10 mM NAD(+) was transformed from NADH in less than 2 h under the condition of 0.5 U NADH dehydrogenase, 0.5 U laccase, 0.1 mM potassium ferricyanide at pH 5.6, 30 °C CONCLUSION: The bi-enzyme system employed the NADH-ferricyanide dehydrogenase and laccase as catalysts, and potassium ferricyanide as redox mediator, is a promising alternative for NAD(+) regeneration.

Modeling of growth and laccase production by Pycnoporus sanguineus.

Science.gov (United States)

Saat, Muhammad Naziz; Annuar, Mohamad Suffian Mohamad; Alias, Zazali; Chuan, Ling Tau; Chisti, Yusuf

2014-05-01

Production of extracellular laccase by the white-rot fungus Pycnoporus sanguineus was examined in batch submerged cultures in shake flasks, baffled shake flasks and a stirred tank bioreactor. The biomass growth in the various culture systems closely followed a logistic growth model. The production of laccase followed a Luedeking-Piret model. A modified Luedeking-Piret model incorporating logistic growth effectively described the consumption of glucose. Biomass productivity, enzyme productivity and substrate consumption were enhanced in baffled shake flasks relative to the cases for the conventional shake flasks. This was associated with improved oxygen transfer in the presence of the baffles. The best results were obtained in the stirred tank bioreactor. At 28 °C, pH 4.5, an agitation speed of 600 rpm and a dissolved oxygen concentration of ~25 % of air saturation, the laccase productivity in the bioreactor exceeded 19 U L(-1 )days(-1), or 1.5-fold better than the best case for the baffled shake flask. The final concentration of the enzyme was about 325 U L(-1).

Bio-coloration of bacterial cellulose assisted by immobilized laccase.

Science.gov (United States)

Song, Ji Eun; Su, Jing; Noro, Jennifer; Cavaco-Paulo, Artur; Silva, Carla; Kim, Hye Rim

2018-02-13

In this work a process for the bio-coloration of bacterial cellulose (BC) membranes was developed. Laccase from Myceliophthora thermophila was immobilized onto BC membranes and retained up to 88% of residual activity after immobilization. Four compounds belonging to the flavonoids family were chosen to test the in situ polymerase activity of immobilized laccase. All the flavonoids were successfully polymerized by laccase giving rise to yellow, orange and dark brown oligomers which conferred color to the BC support. The optimal bio-coloration conditions were studied for two of the tested flavonoids, catechol and catechin, by varying the concentration and time of incubation. High color depth and resistance to washing were obtained for both compounds. The highly porous bacterial cellulose material demonstrated great performance as a bio-coloration support, in contrast to other materials cited in literature, like cotton or wool. The process developed is presented as an environmentally friendly alternative for bacterial cellulose bio-coloration and will contribute deeply for the development of new fashionable products within this material.

Plasticity of laccase generated by homeologous recombination in yeast.

Science.gov (United States)

Cusano, Angela M; Mekmouche, Yasmina; Meglecz, Emese; Tron, Thierry

2009-10-01

Laccase-encoding sequences sharing 65-71% identity were shuffledin vivo by homeologous recombination. Yeast efficiently repaired linearized plasmids containing clac1, clac2 or clac5 Trametes sp. C30 cDNAs using a clac3 PCR fragment. From transformants secreting active variants, three chimeric laccases (LAC131, LAC232 and LAC535), each resulting from double crossovers, were purified, and their apparent kinetic parameters were determined using 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) and syringaldazine (SGZ) as substrates. At acidic pH, the apparent kinetic parameters of the chimera were not distinguishable from each other or from those obtained for the LAC3 enzyme used as reference. On the other hand, the pH tolerance of the variants was visibly extended towards alkaline pH values. Compared to the parental LAC3, a 31-fold increase in apparent k(cat) was observed for LAC131 at pH 8. This factor is one of the highest ever observed for laccase in a single mutagenesis step.

Stabilized Laccases as Heterogeneous Bioelectrocatalysts (Postprint)

Science.gov (United States)

2012-10-01

Reference Rhus vernificera catechin (anticancer flavonoid ) • covalent binding (amide chemistry) to Au Nps in dendrimers [82] Rigidoporus lignosis phenolic...proper· tiesP· 391 An interesting extension to the application of laccases in biosensors is the medically relevant detection of catechins and flavonoids

Copper and dyes enhance laccase production in gamma-proteobacterium JB.

Science.gov (United States)

Malhotra, Kanam; Sharma, Prince; Capalash, Neena

2004-07-01

Laccase production in gamma-proteobacterium JB was enhanced 13-fold by adding 0.1 mM CuSO(4) 24 h after the onset of growth. Ethidium bromide (2.5 microM), Malachite Green, Phenol Red and Thymol Blue (10 microM each) enhanced laccase production 17-, 19-, 4- and 2-fold, respectively. Among the fourteen aromatic/organic compounds tried, p-aminobenzoic acid and an industrial effluent, from where the organism was isolated, showed 1.2- and 1.26-fold increases in production.

A Post-Truncation Parameterization of Truncated Normal Technical Inefficiency

OpenAIRE

Christine Amsler; Peter Schmidt; Wen-Jen Tsay

2013-01-01

In this paper we consider a stochastic frontier model in which the distribution of technical inefficiency is truncated normal. In standard notation, technical inefficiency u is distributed as N^+ (μ,σ^2). This distribution is affected by some environmental variables z that may or may not affect the level of the frontier but that do affect the shortfall of output from the frontier. We will distinguish the pre-truncation mean (μ) and variance (σ^2) from the post-truncation mean μ_*=E(u) and var...

Catalytic Efficiency of Basidiomycete Laccases: Redox Potential versus Substrate-Binding Pocket Structure

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Olga A. Glazunova

2018-04-01

Full Text Available Laccases are copper-containing oxidases that catalyze a one-electron abstraction from various phenolic and non-phenolic compounds with concomitant reduction of molecular oxygen to water. It is well-known that laccases from various sources have different substrate specificities, but it is not completely clear what exactly provides these differences. The purpose of this work was to study the features of the substrate specificity of four laccases from basidiomycete fungi Trametes hirsuta, Coriolopsis caperata, Antrodiella faginea, and Steccherinum murashkinskyi, which have different redox potentials of the T1 copper center and a different structure of substrate-binding pockets. Enzyme activity toward 20 monophenolic substances and 4 phenolic dyes was measured spectrophotometrically. The kinetic parameters of oxidation of four lignans and lignan-like substrates were determined by monitoring of the oxygen consumption. For the oxidation of the high redox potential (>700 mV monophenolic substrates and almost all large substrates, such as phenolic dyes and lignans, the redox potential difference between the enzyme and the substrate (ΔE played the defining role. For the low redox potential monophenolic substrates, ΔE did not directly influence the laccase activity. Also, in the special cases, the structure of the large substrates, such as dyes and lignans, as well as some structural features of the laccases (flexibility of the substrate-binding pocket loops and some amino acid residues in the key positions affected the resulting catalytic efficiency.

Purification and Characterization of a White Laccase with Pronounced Dye Decolorizing Ability and HIV-1 Reverse Transcriptase Inhibitory Activity from Lepista nuda

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Mengjuan Zhu

2016-03-01

Full Text Available A strain LN07 with high laccase yield was identified as basidiomycete fungus Lepista nuda from which a white laccase without type I copper was purified and characterized. The laccase was a monomeric protein with a molecular mass of 56 kDa. Its N-terminal amino acid sequence was AIGPAADLHIVNKDISPDGF. Besides, eight inner peptide sequences were determined and lac4, lac5 and lac6 sequences were in the Cu2+ combination and conservation zones of laccases. HIV-1 reverse transcriptase was inhibited by the laccase with a half-inhibitory concentration of 0.65 μM. Cu2+ ions (1.5 mM enhanced the laccase production and the optimal pH and temperature of the laccase were pH 3.0 and 50 °C, respectively. The Km and Vmax of the laccase using ABTS as substrate were respectively 0.19 mM and 195 μM. Several dyes including laboratory dyes and textile dyes used in this study, such as Methyl red, Coomassie brilliant blue, Reactive brilliant blue and so on, were decolorized in different degrees by the purified laccase. By LC-MS analysis, Methyl red was structurally degraded by the laccase. Moreover, the laccase affected the absorbance at the maximum wavelength of many pesticides. Thus, the white laccase had potential commercial value for textile finishing and wastewater treatment.

Equivalence of truncated count mixture distributions and mixtures of truncated count distributions.

Science.gov (United States)

Böhning, Dankmar; Kuhnert, Ronny

2006-12-01

This article is about modeling count data with zero truncation. A parametric count density family is considered. The truncated mixture of densities from this family is different from the mixture of truncated densities from the same family. Whereas the former model is more natural to formulate and to interpret, the latter model is theoretically easier to treat. It is shown that for any mixing distribution leading to a truncated mixture, a (usually different) mixing distribution can be found so that the associated mixture of truncated densities equals the truncated mixture, and vice versa. This implies that the likelihood surfaces for both situations agree, and in this sense both models are equivalent. Zero-truncated count data models are used frequently in the capture-recapture setting to estimate population size, and it can be shown that the two Horvitz-Thompson estimators, associated with the two models, agree. In particular, it is possible to achieve strong results for mixtures of truncated Poisson densities, including reliable, global construction of the unique NPMLE (nonparametric maximum likelihood estimator) of the mixing distribution, implying a unique estimator for the population size. The benefit of these results lies in the fact that it is valid to work with the mixture of truncated count densities, which is less appealing for the practitioner but theoretically easier. Mixtures of truncated count densities form a convex linear model, for which a developed theory exists, including global maximum likelihood theory as well as algorithmic approaches. Once the problem has been solved in this class, it might readily be transformed back to the original problem by means of an explicitly given mapping. Applications of these ideas are given, particularly in the case of the truncated Poisson family.

Kinetics of Adsorbable Organic Halides (AOX Reduction in Laccase-Aided Chlorine Dioxide Bleaching of Bagasse Pulp

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Xueping Song

2016-07-01

Full Text Available This paper presents a kinetic model of the laccase-aided chlorine dioxide bleaching of bagasse pulp. The kinetic model was based on the rate of reduction of adsorbed organic halogen (AOX. The effects of the laccase enzyme dosage, the mediator 1-hydroxybenzotriazole (HBT dosage, and the reaction temperature on the AOX content of the bleaching effluent are discussed. Good fits were obtained for the experimental data obtained from the different laccase enzyme dosages, HBT dosages, and reaction temperatures, indicating the feasibility of the kinetic model as a means of predicting the optimal operation conditions for the laccase-aided chlorine dioxide bleaching of bagasse pulp in the future.

First evidence of a potential antibacterial activity involving a laccase-type enzyme of the phenoloxidase system in Pacific oyster Crassostrea gigas haemocytes.

Science.gov (United States)

Luna-Acosta, Andrea; Saulnier, Denis; Pommier, Mylène; Haffner, Philippe; De Decker, Sophie; Renault, Tristan; Thomas-Guyon, Hélène

2011-12-01

Phenoloxidases (POs) are a group of copper proteins including tyrosinase, catecholase and laccase. In several insects and crustaceans, antibacterial substances are produced through the PO cascade, participating in the direct killing of invading microorganisms. However, although POs are widely recognised as an integral part of the invertebrate immune defence system, experimental evidence is lacking that these properties are conserved in molluscs, and more particularly in the Pacific oyster Crassostrea gigas. In the present study, Vibrio splendidus LGP32 and Vibrio aestuarianus 02/041 growths were affected, after being treated with C. gigas haemocyte lysate supernatant (HLS), and either a common substrate of POs, l-3,4-dihydroxyphenylalanine (L-DOPA), to detect catecholase-type PO activity, or a specific substrate of laccase, p-phenylenediamine (PPD), to detect laccase-type PO activity. Interestingly, a higher bacterial growth inhibition was observed in the presence of PPD than in the presence of L-DOPA. These effects were suppressed when the specific PO inhibitor, phenylthiourea (PTU), was added to the medium. Results of the present study suggest, for the first time in a mollusc species, that antibacterial activities of HLS from C. gigas potentially involve POs, and more particularly laccase catalysed reactions. Copyright © 2011 Elsevier Ltd. All rights reserved.

Stability mechanisms of a thermophilic laccase probed by molecular dynamics

DEFF Research Database (Denmark)

Christensen, Niels Johan; Kepp, Kasper Planeta

2013-01-01

Laccases are highly stable, industrially important enzymes capable of oxidizing a large range of substrates. Causes for their stability are, as for other proteins, poorly understood. In this work, multiple-seed molecular dynamics (MD) was applied to a Trametes versicolor laccase in response...... integrity by increasing persistent backbone hydrogen bonds by ∼4 across simulations, mainly via prevention of F(-) intrusion. Hydrogen-bond loss in distinct loop regions and ends of critical β-sheets suggest potential strategies for laboratory optimization of these industrially important enzymes....

Ecofriendly laccase-hydrogen peroxide/ultrasound-assisted bleaching of linen fabrics and its influence on dyeing efficiency.

Science.gov (United States)

Abou-Okeil, A; El-Shafie, A; El Zawahry, M M

2010-02-01

This study evaluates the bleaching efficiency of enzymatically scoured linen fabrics using a combined laccase-hydrogen peroxide bleaching process with and without ultrasonic energy, with the goal of obtaining fabrics with high whiteness levels, well preserved tensile strength and higher dye uptake. The effect of the laccase enzyme and the combined laccase-hydrogen peroxide bleaching process with and without ultrasound has been investigated with regard to whiteness value, tensile strength, dyeing efficiency and dyeing kinetics using both reactive and cationic dyes. The bleached linen fabrics were characterized using X-ray diffraction and by measuring tensile strength and lightness. The dyeing efficiency and kinetics were characterized by measuring dye uptake and colour fastness. The results indicated that ultrasound was an effective technique in the combined laccase-hydrogen peroxide bleaching process of linen fabrics. The whiteness values expressed as lightness of linen fabrics is enhanced by using ultrasonic energy. The measured colour strength values were found to be slightly better for combined laccase-hydrogen peroxide/ultrasound-assisted bleached fabrics than for combined laccase-hydrogen peroxide for both reactive and cationic dyes. The fastness properties of the fabrics dyed with reactive dye were better than those obtained when using cationic dye. The time/dye uptake isotherms were also enhanced when using combined laccase-hydrogen peroxide/ultrasound-assisted bleached fabric, which confirms the efficiency of ultrasound in the combined oxidative bleaching process. The dyeing rate constant, half-time of dyeing and dyeing efficiency have been calculated and discussed.

Cloning and expression of Icc1 Laccase gene promoter in Aspergillus niger

Energy Technology Data Exchange (ETDEWEB)

Marqueda-Galvez, A. P.; Loera Carrol, O.; Xaconostle cazares, B.; Tellez-Jurado, A.; Arana-Cuenca, A.

2009-07-01

The white rot fungus Trametes sp. I-62 is a strain with laccase activity and a great potential for biotechnological applications given its ability to detoxify distillery effluents. The Icc1, Icc2 and Icc3 laccase genes of this basidiomycetes have been cloned and sequenced. The promoter region of Icc1 kaccase gene contains a putative site for xenobiotics (XRE). (Author)

Crystallization and preliminary X-ray crystallographic analysis of the small subunit of the heterodimeric laccase POXA3b from Pleurotus ostreatus

Science.gov (United States)

Ferraroni, Marta; Scozzafava, Andrea; Ullah, Sana; Tron, Thierry; Piscitelli, Alessandra; Sannia, Giovanni

2014-01-01

Laccases are multicopper oxidases of great biotechnological potential. While laccases are generally monomeric glycoproteins, the white-rot fungus Pleurotus ostreatus produces two closely related heterodimeric isoenzymes composed of a large subunit, homologous to the other fungal laccases, and a small subunit. The sequence of the small subunit does not show significant homology to any other protein or domain of known function and consequently its function is unknown. The highest similarity to proteins of known structure is to a putative enoyl-CoA hydratase/isomerase from Acinetobacter baumannii, which shows an identity of 27.8%. Diffraction-quality crystals of the small subunit of the heterodimeric laccase POXA3b (sPOXA3b) from P. ostreatus were obtained using the sitting-drop vapour-diffusion method at 294 K from a solution consisting of 1.8 M sodium formate, 0.1 M Tris–HCl pH 8.5. The crystals belonged to the tetragonal space group P41212 or P43212, with unit-cell parameters a = 126.6, c = 53.9 Å. The asymmetric unit contains two molecules related by a noncrystallographic twofold axis. A complete data set extending to a maximum resolution of 2.5 Å was collected at 100 K using a wavelength of 1.140 Å. PMID:24419623

A Novel Laccase from Ganoderma Lucidum Capable of Enhancing Enzymatic Degradation of Lignocellulolytic Biomass

DEFF Research Database (Denmark)

2014-01-01

for the hydrolysis of biomass using a laccase derived from Ganoderma lucidum. Further, the invention provides an enzyme composition comprising a laccase derived from Ganoderma lucidum which may be combined with one or more cellulases, and for its use in enhancing lignocellulose biomass hydrolysis....

EXTRACTION AND PURIFICATION OF EXTRACELLULAR LACCASE FROM WILD, MUTANTS AND HYBRID STRAINS OF TWO WHITE-ROT FUNGUS AND ITS APPLICATIONS IN DECOLOURIZATION AND LIGNINOLYSIS

Directory of Open Access Journals (Sweden)

Olusola Majolagbe

2012-12-01

Full Text Available Extracellular laccases were extracted from a 5-day old submerge cultures of the wild, mutants and hybrid of Lentinus subnudus. Mutants were generated by exposure of the wild strain of L. subnudus to ultraviolet radiation (ג = 280 nm at specific time intervals while the hybrid was produced by cross-breeding L. subnudus with L. edodes. The crude enzyme was fractionated with 80% ammonium sulphate and further purified on DEAE column. The laccase has a molecular weight of about 45 KDa. Purification yield on DEAE column gave the highest purification yield of 23.25% in SWT and least in SHT (5.29%. Its potentials in decolourization of 2, 6-dichlorophenol-indophenol dye at different pH conditions were investigated. Five out of the six fungal strains tested gave significant (P<0.05 percentage decolourization (≥43.94% at pH 8. The fungus was further studied for their ability in degrading wheat and paddy straws. The solid substrate fermentation was inoculated with two pieces (0.6cm diameter mycelial agar blocks of each of the fungal strains, supplemented with 30mg/100g sucrose, 24mg/100g KNO3 and 60mg/100g CaCO3. The periodic reduction in weight of the solid substrate medium and enzymatic activity of laccase for each of the fungal strains was assessed. Therefore, the ability of the wild, mutants and hybrid of L subnudus strains to produce laccase enzyme shows their significant potential in textile industry, especially in decolourization of dye and bioconversion of lignocellulosic wastes.

Bacterial exopolysaccharides as a modern biotechnological tool for modification of fungal laccase properties and metal ion binding.

Science.gov (United States)

Osińska-Jaroszuk, Monika; Jaszek, Magdalena; Starosielec, Magdalena; Sulej, Justyna; Matuszewska, Anna; Janczarek, Monika; Bancerz, Renata; Wydrych, Jerzy; Wiater, Adrian; Jarosz-Wilkołazka, Anna

2018-03-26

Four bacterial EPSs extracted from Rhizobium leguminosarum bv. trifolii Rt24.2, Sinorhizobium meliloti Rm1021, Bradyrhizobium japonicum USDA110, and Bradyrhizobium elkanii USDA76 were determined towards their metal ion adsorption properties and possible modification of Cerrena unicolor laccase properties. The highest magnesium and iron ion-sorption capacity (~ 42 and ~ 14.5%, respectively) was observed for EPS isolated from B. japonicum USDA110. An evident influence of EPSs on the stability of laccase compared to the control values (without EPSs) was shown after 30-day incubation at 25 °C. The residual activity of laccases was obtained in the presence of Rh76EPS and Rh1021EPS, i.e., 49.5 and 41.5% of the initial catalytic activity, respectively. This result was confirmed by native PAGE electrophoresis. The EPS effect on laccase stability at different pH (from 3.8 to 7.0) was also estimated. The most significant changes at the optimum pH value (pH 5.8) was observed in samples of laccase stabilized by Rh76EPS and Rh1021EPS. Cyclic voltamperometry was used for analysis of electrochemical parameters of laccase stabilized by bacterial EPS and immobilized on single-walled carbon nanotubes (SWCNTs) with aryl residues. Laccases with Rh76EPS and Rh1021EPS had an evident shift of the value of the redox potential compared to the control without EPS addition. In conclusion, the results obtained in this work present a new potential use of bacterial EPSs as a metal-binding component and a modulator of laccase properties especially stability of enzyme activity, which can be a very effective tool in biotechnology and industrial applications.

Biochemical and molecular characterization of Coriolopsis rigida laccases involved in transformation of the solid waste from olive oil production.

Science.gov (United States)

Díaz, Rosario; Saparrat, Mario C N; Jurado, Miguel; García-Romera, Inmaculada; Ocampo, Juan Antonio; Martínez, María Jesús

2010-09-01

Two laccase isoenzymes were purified and characterized from the basidiomycete Coriolopsis rigida during transformation of the water-soluble fraction of "alpeorujo" (WSFA), a solid residue derived from the olive oil production containing high levels of toxic compounds. Zymogram assays of laccases secreted by the fungus growing on WSFA and WSFA supplemented with glucose showed two bands with isoelectric points of 3.3 and 3.4. The kinetic studies of the two purified isoenzymes showed similar affinity on 2,6-dimethoxyphenol and 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulfonic acid), used as phenolic and non-phenolic model substrate, respectively. The molecular mass of both proteins was 66 kDa with 9% N-linked carbohydrate. Physico-chemical properties of the purified laccases from media containing WSFA were similar to those obtained from medium with glucose as the main carbon source. In-vitro studies performed with the purified laccases revealed a 42% phenol reduction of WSFA, as well as changes in the molecular mass distribution. These findings indicate that these laccases are involved in the process of transformation, via polymerization by the oxidation of phenolic compounds present in WSFA. A single laccase gene, containing an open reading frame of 1,488 bp, was obtained in PCR amplifications performed with cDNA extracted from mycelia grown on WSFA. The product of the gene shares 90% identity (95% similarity) with a laccase from Trametes trogii and 89% identity (95% similarity) with a laccase from Coriolopsis gallica. This is the first report on purification and molecular characterization of laccases directly involved in the transformation of olive oil residues.

Family Therapy for the "Truncated" Nuclear Family.

Science.gov (United States)

Zuk, Gerald H.

1980-01-01

The truncated nuclear family consists of a two-generation group in which conflict has produced a polarization of values. The single-parent family is at special risk. Go-between process enables the therapist to depolarize sharply conflicted values and reduce pathogenic relating. (Author)

R Programs for Truncated Distributions

Directory of Open Access Journals (Sweden)

Saralees Nadarajah

2006-08-01

Full Text Available Truncated distributions arise naturally in many practical situations. In this note, we provide programs for computing six quantities of interest (probability density function, mean, variance, cumulative distribution function, quantile function and random numbers for any truncated distribution: whether it is left truncated, right truncated or doubly truncated. The programs are written in R: a freely downloadable statistical software.

Effect of amino acids and vitamins on laccase production by the bird's nest fungus Cyathus bulleri

Energy Technology Data Exchange (ETDEWEB)

Shikha Dhawan; Ramesh Chander Kuhad [University of Delhi, New Delhi (India). Dept. of Microbiology

2002-08-01

Various amino acids, their analogues and vitamins have shown stimulatory as well as inhibitory effects on laccase production by Cyathus bulleri. DL-methionine, DL-tryptophan, glycine and DL-valine stimulated laccase production, while L-cysteine monohydrochloride completely inhibited the enzyme production. Among vitamins tested biotin, riboflavin and pyridoxine hydrochloride were found to induce laccase production. (author)

Green Synthesis and Antibacterial Activities of Silver Nanoparticles Using Extracellular Laccase of Lentinus edodes

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Agbaje LATEEF

2015-12-01

Full Text Available This study reports the multi-step mutagenesis of Lentinus edodes towards optimization of the production of laccase and novel application of laccase in the biosynthesis of silver nanoparticles (AgNPs which could be used to develop an eco-friendly method for the rapid biosynthesis of AgNPs. The wild strain of L. edodes was subjected to UV irradiation at 254 nm and the resultant viable mutant was further treated with acridine orange, a chemical mutagen. The strains were evaluated for the production of laccase and the crude laccase of the UV mutant (UV10 was used for the green synthesis of AgNPs. The particles were characterized by UV-Visible spectroscopy, Fourier transform infrared (FTIR spectroscopy and scanning electron microscopy (SEM. Laccase activities of wild, UV10 and UV10ACR8 strains of L. edodes were obtained as 2.6, 10.6 and 2.8 U/ml/min respectively after 7 days of fermentation, showing laccase yield improvement of 4.08-fold for UV10 mutant. UV-Visible spectroscopy indicated the formation of AgNPs at absorption band of 430 nm. FTIR result indicated that proteins were responsible for AgNP synthesis, while SEM analysis confirmed the formation of walnut-shaped nanoparticles with size range of 50-100 nm. The biosynthesized nanoparticles revealed effective inhibition against clinical isolates of Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae. To the best of the authors’ knowledge, this result represents the first report on the biosynthesis of AgNPs using L. edodes metabolite. The report adds to the growing relevance of L. edodes as potential industrially viable organism, used for diverse biotechnological applications.

Potentiality of a ceramic membrane reactor for the laccase-catalyzed removal of bisphenol A from secondary effluents.

Science.gov (United States)

Arca-Ramos, A; Eibes, G; Feijoo, G; Lema, J M; Moreira, M T

2015-11-01

In this study, the removal of bisphenol A (BPA) by laccase in a continuous enzymatic membrane reactor (EMR) was investigated. The effects of key parameters, namely, type of laccase, pH, and enzyme activity, were initially evaluated. Once optimal conditions were determined, the continuous removal of the pollutant in an EMR was assessed in synthetic and real biologically treated wastewaters. The reactor configuration consisted of a stirred tank reactor coupled to a ceramic membrane, which prevented the sorption of the pollutant and allowed the recovery and recycling of laccase. Nearly complete removal of BPA was attained under both operation regimes with removal yields above 94.5 %. In experiments with real wastewater, the removal of BPA remained high while the presence of colloids and certain ions and the formation of precipitates on the membrane potentially affected enzyme stability and made necessary the periodic addition of laccase. Polymerization and degradation were observed as probable mechanisms of BPA transformation by laccase.

Radical Scavenging by Acetone: A New Perspective to Understand Laccase/ABTS Inactivation and to Recover Redox Mediator.

Science.gov (United States)

Liu, Hao; Zhou, Pandeng; Wu, Xing; Sun, Jianliang; Chen, Shicheng

2015-11-04

The biosynthetic utilization of laccase/mediator system is problematic because the use of organic cosolvent causes significant inhibition of laccase activity. This work explored how the organic cosolvent impacts on the laccase catalytic capacity towards 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) in aqueous solution. Effects of acetone on the kinetic constants of laccase were determined and the results showed Km and Vmax varied exponentially with increasing acetone content. Acetone as well as some other cosolvents could transform ABTS radicals into its reductive form. The content of acetone in media significantly affected the radical scavenging rates. Up to 95% of the oxidized ABTS was successfully recovered in 80% (v/v) acetone in 60 min. This allows ABTS recycles at least six times with 70%-75% of active radicals recovered after each cycle. This solvent-based recovery strategy may help improve the economic feasibility of laccase/ABTS system in biosynthesis.

Squeezing in multi-mode nonlinear optical state truncation

International Nuclear Information System (INIS)

Said, R.S.; Wahiddin, M.R.B.; Umarov, B.A.

2007-01-01

In this Letter, we show that multi-mode qubit states produced via nonlinear optical state truncation driven by classical external pumpings exhibit squeezing condition. We restrict our discussions to the two- and three-mode cases

Laccases stabilization with phosphatidylcholine liposomes

OpenAIRE

Martí, M.; Zille, Andrea; Paulo, Artur Cavaco; Parra, J. L.; Coderch, L.

2012-01-01

In recent years, there has been an upsurge of interest in enzyme treatment of textile fibres. Enzymes are globular proteins whose catalytic function is due to their three dimensional structure. For this reason, stability strategies make use of compounds that avoid dismantling or distorting protein 3D structures. This study is concerned with the use of microencapsulation techniques to optimize enzyme stabilization. Laccases were embedded in phophatidylcholine liposomes and their encaps...

Crystal structures of E. coli laccase CueO at different copper concentrations

International Nuclear Information System (INIS)

Li Xu; Wei Zhiyi; Zhang Min; Peng Xiaohui; Yu Guangzhe; Teng Maikun; Gong Weimin

2007-01-01

CueO protein is a hypothetical bacterial laccase and a good laccase candidate for large scale industrial application. Four CueO crystal structures were determined at different copper concentrations. Low copper occupancy in apo-CueO and slow copper reconstitution process in CueO with exogenous copper were demonstrated. These observations well explain the copper dependence of CueO oxidase activity. Structural comparison between CueO and other three fungal laccase proteins indicates that Glu106 in CueO constitutes the primary counter-work for reconstitution of the trinuclear copper site. Mutation of Glu106 to a Phe enhanced CueO oxidation activity and supported this hypothesis. In addition, an extra α-helix from Leu351 to Gly378 covers substrate biding pocket of CueO and might compromises the electron transfer from substrate to type I copper

Effects of laccase on lignin depolymerization and enzymatic hydrolysis of ensiled corn stover.

Science.gov (United States)

Chen, Qin; Marshall, Megan N; Geib, Scott M; Tien, Ming; Richard, Tom L

2012-08-01

The aim of this study was to explore the synergies of laccase, a ligninolytic enzyme, with cellulose and hemicellulase amendments on ensiled corn stover. Molecular signals of lignin decomposition were observed by tetramethylammonium hydroxide thermochemolysis and gas chromatography-mass spectroscopy (TMAH-GC-MS) analysis. The significant findings suggest that ensilage might provide a platform for biological pretreatment. By partially hydrolyzing cellulose and hemicellulose into soluble sugars, ensilage facilitates laccase penetration into the lignocellulose complex to enhance lignin degradation. Downstream cellulose hydrolysis was improved 7% with increasing laccase loading rate. These results demonstrate the potential of enzymes, either directly amended or expressed by microbes during ensilage, to maximize utilization of corn stover for cellulosic biofuels and other downstream fermentations. Copyright © 2012. Published by Elsevier Ltd.

The small laccase from Streptomyces coelicolor

Czech Academy of Sciences Publication Activity Database

Dohnálek, Jan; Skálová, Tereza; Ostergaard, L. H.; Ostergaard, P. R.; Hašek, Jindřich

2009-01-01

Roč. 16, 1a (2009), b4-b5 ISSN 1211-5894. [Discussions in Structural Molecular Biology /7./. 12.03.2009-14.03.2009, Nové Hrady] R&D Projects: GA ČR GA305/07/1073 Institutional research plan: CEZ:AV0Z40500505 Keywords : laccase * Streptomyces coelicolor * enzymer Subject RIV: CD - Macromolecular Chemistry

Laccase aided modification of nanofibrillated cellulose with dodecyl gallate

Directory of Open Access Journals (Sweden)

Päivi Saastamoinen

2012-11-01

Full Text Available Nanofibrillated cellulose, NFC, is an interesting wood fibre-based material that could be utilized in coatings, foams, composites, packages, dispersions, and emulsions, due to its high tensile strength and barrier properties, light weight, and stabilizing features. To improve applicability and properties of NFC, modification of its surface properties is often needed. In this study, the applicability of laccase-aided surface modification with hydrophobic dodecyl gallate (DOGA on unbleached NFC was investigated. Also, laccase-catalyzed polymerization of DOGA and other phenolic compounds with lignin moieties was investigated by matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF MS. NFC modified with T. hirsuta-based laccase and DOGA showed decreased hydrophilicity, as compared with the native NFC, when coated on a paper surface. When dried as free-standing films, the surface properties of chemo-enzymatically modified NFC resembled those of the native NFC. The effect of modification was thus greatly influenced by different surface formation in differently prepared samples. Also, changing of the dispersion properties of DOGA by enzymatic polymerization affected the surface properties of the dried NFC samples. Covalent bonding between DOGA and NFC was not the main factor affecting the surface properties of the NFC in free-standing films or coatings.

Oxidation of lignin in hemp fibres by laccase: effects on mechanical properties of hemp fibres and unidirectional fibre/epoxy composites

DEFF Research Database (Denmark)

Liu, Ming; Baum, Andreas; Odermatt, Jürgen

2017-01-01

Laccase activity catalyzes oxidation and polymerization of phenols. The effect of laccase treatment on the mechanical properties of hemp fibres and hemp fibre/epoxy composites was examined. Laccase treatment on top of 0.5% EDTA + 0.2% endo-polygalacturonase (EPG) treatments increased the mechanical...... properties of hemp fibres and fibre/epoxy composites. Comparing all fibre treatments, composites with 0.5% EDTA + 0.2% EPG + 0.5% laccase treated fibres had highest stiffness of 42 GPa and highest ultimate tensile strength (UTS) of 326 MPa at a fibre volume content of 50%. The thermal resistance of hemp...... hemp fibres and their composites were due to laccase catalyzed polymerization of lignin moieties in hemp fibres....

A min cut-set-wise truncation procedure for importance measures computation in probabilistic safety assessment

Energy Technology Data Exchange (ETDEWEB)

Duflot, Nicolas [Universite de technologie de Troyes, Institut Charles Delaunay/LM2S, FRE CNRS 2848, 12, rue Marie Curie, BP2060, F-10010 Troyes cedex (France)], E-mail: nicolas.duflot@areva.com; Berenguer, Christophe [Universite de technologie de Troyes, Institut Charles Delaunay/LM2S, FRE CNRS 2848, 12, rue Marie Curie, BP2060, F-10010 Troyes cedex (France)], E-mail: christophe.berenguer@utt.fr; Dieulle, Laurence [Universite de technologie de Troyes, Institut Charles Delaunay/LM2S, FRE CNRS 2848, 12, rue Marie Curie, BP2060, F-10010 Troyes cedex (France)], E-mail: laurence.dieulle@utt.fr; Vasseur, Dominique [EPSNA Group (Nuclear PSA and Application), EDF Research and Development, 1, avenue du Gal de Gaulle, 92141 Clamart cedex (France)], E-mail: dominique.vasseur@edf.fr

2009-11-15

A truncation process aims to determine among the set of minimal cut-sets (MCS) produced by a probabilistic safety assessment (PSA) model which of them are significant. Several truncation processes have been proposed for the evaluation of the probability of core damage ensuring a fixed accuracy level. However, the evaluation of new risk indicators as importance measures requires to re-examine the truncation process in order to ensure that the produced estimates will be accurate enough. In this paper a new truncation process is developed permitting to estimate from a single set of MCS the importance measure of any basic event with the desired accuracy level. The main contribution of this new method is to propose an MCS-wise truncation criterion involving two thresholds: an absolute threshold in addition to a new relative threshold concerning the potential probability of the MCS of interest. The method has been tested on a complete level 1 PSA model of a 900 MWe NPP developed by 'Electricite de France' (EDF) and the results presented in this paper indicate that to reach the same accuracy level the proposed method produces a set of MCS whose size is significantly reduced.

A min cut-set-wise truncation procedure for importance measures computation in probabilistic safety assessment

International Nuclear Information System (INIS)

Duflot, Nicolas; Berenguer, Christophe; Dieulle, Laurence; Vasseur, Dominique

2009-01-01

A truncation process aims to determine among the set of minimal cut-sets (MCS) produced by a probabilistic safety assessment (PSA) model which of them are significant. Several truncation processes have been proposed for the evaluation of the probability of core damage ensuring a fixed accuracy level. However, the evaluation of new risk indicators as importance measures requires to re-examine the truncation process in order to ensure that the produced estimates will be accurate enough. In this paper a new truncation process is developed permitting to estimate from a single set of MCS the importance measure of any basic event with the desired accuracy level. The main contribution of this new method is to propose an MCS-wise truncation criterion involving two thresholds: an absolute threshold in addition to a new relative threshold concerning the potential probability of the MCS of interest. The method has been tested on a complete level 1 PSA model of a 900 MWe NPP developed by 'Electricite de France' (EDF) and the results presented in this paper indicate that to reach the same accuracy level the proposed method produces a set of MCS whose size is significantly reduced.

Diamination by n-coupling using a commercial laccase

CSIR Research Space (South Africa)

Wellington, Kevin W

2010-02-01

Full Text Available Nuclear diamination of p-hydrobenzoquinones with aromatic and aliphatic primary amines was catalyzed by a immobilised commercial laccase, Denilite II Base, from Novozymes. The amine and the p-hydrobenzoquinone was reacted under mild conditions (at...

Enzyme-Catalyzed Oxidation of 17β-Estradiol Using Immobilized Laccase from Trametes versicolor

Science.gov (United States)

Cardinal-Watkins, Chantale; Nicell, Jim A.

2011-01-01

Many natural and synthetic estrogens are amenable to oxidation through the catalytic action of oxidative enzymes such as the fungal laccase Trametes versicolor. This study focused on characterizing the conversion of estradiol (E2) using laccase that had been immobilized by covalent bonding onto silica beads contained in a bench-scale continuous-flow packed bed reactor. Conversion of E2 accomplished in the reactor declined when the temperature of the system was changed from room temperature to just above freezing at pH 5 as a result of a reduced rate of reaction rather than inactivation of the enzyme. Similarly, conversion increased when the system was brought to warmer temperatures. E2 conversion increased when the pH of the influent to the immobilized laccase reactor was changed from pH 7 to pH 5, but longer-term experiments showed that the enzyme is more stable at pH 7. Results also showed that the immobilized laccase maintained its activity when treating a constant supply of aqueous E2 at a low mean residence time over a 12-hour period and when treating a constant supply of aqueous E2 at a high mean residence time over a period of 9 days. PMID:21869925

Optimization of laccase production from Marasmiellus palmivorus LA1 by Taguchi method of Design of experiments.

Science.gov (United States)

Chenthamarakshan, Aiswarya; Parambayil, Nayana; Miziriya, Nafeesathul; Soumya, P S; Lakshmi, M S Kiran; Ramgopal, Anala; Dileep, Anuja; Nambisan, Padma

2017-02-13

Fungal laccase has profound applications in different fields of biotechnology due to its broad specificity and high redox potential. Any successful application of the enzyme requires large scale production. As laccase production is highly dependent on medium components and cultural conditions, optimization of the same is essential for efficient product production. Production of laccase by fungal strain Marasmiellus palmivorus LA1 under solid state fermentation was optimized by the Taguchi design of experiments (DOE) methodology. An orthogonal array (L8) was designed using Qualitek-4 software to study the interactions and relative influence of the seven selected factors by one factor at a time approach. The optimum condition formulated was temperature (28 °C), pH (5), galactose (0.8%w/v), cupric sulphate (3 mM), inoculum concentration (number of mycelial agar pieces) (6Nos.) and substrate length (0.05 m). Overall yield increase of 17.6 fold was obtained after optimization. Statistical optimization leads to the elimination of an insignificant medium component ammonium dihydrogen phosphate from the process and contributes to a 1.06 fold increase in enzyme production. A final production of 667.4 ± 13 IU/mL laccase activity paves way for the application of this strain for industrial applications. Study optimized lignin degrading laccases from Marasmiellus palmivorus LA1. This laccases can thus be used for further applications in different scales of production after analyzing the properties of the enzyme. Study also confirmed the use of taguchi method for optimizations of product production.

Development and mapping of gene-tagged SNP markers in laccases of maize (Zea mays L.)

DEFF Research Database (Denmark)

Andersen, J R; Asp, T; Lu, Y C

2009-01-01

Laccases, EC 1.10.3.2 or p-diphenol : dioxygen oxidoreductases, have been proposed to be involved in the oxidative polymerization of monolignols into lignins in plants. While 17 laccases have been identified in Arabidopsis, only five (ZmLac1-5) have so far been identified in maize. By a bioinform...

EVALUATION OF ENDOGLUCANASE, EXOGLUCANASE, LACCASE, AND LIGNIN PEROXIDASE ACTIVITIES ON TEN WHITE-ROT FUNGI

Directory of Open Access Journals (Sweden)

Sandra Montoya B

2014-12-01

Full Text Available This paper presents a way of tracking the production of lignocellulolytic enzymes in ten species of white rot fungi: Lentinula edodes, Schizophyllum commune, Trametes trogii, Coriolus versicolor, Pycnoporus sanguineus, Ganoderma applanatum, Ganoderma lucidum, Grifola frondosa, Pleurotus ostreatus and Auricularia delicata. These species were first screened on solid culture media containing carboxymethyl cellulose, crystalline cellulose, ABTS (2,2´-azino-bis(3-ethylbenzothiazoline-6-sulphonate and azure B, which showed the production of endoglucanase, exoglucanase, laccase and lignin peroxidase (LiP enzymes. Cellulolytic activities were detected after five days of incubation with congo red indicator, forming a clear-white halo in areas where cellulose was degraded. For ligninases, the tracking consisted of the monitoring in the formation of green halos due to ABTS oxidation for laccase, and decolorization halos on azure B for LiP during 14 days of incubation. From this qualitative screening, four strains were selected (G. lucidum, L. edodes, C. versicolor and T. trogii as the best producers of cellulolytic and ligninolytic enzymes. These four species were inoculated on a substrate of sawdust oak, yielding 51,8% of lignin degraded by L. edodes and 22% of cellulose degraded by C. versicolor.

Application of Bacterial Laccases for Sustainable Energy Production

DEFF Research Database (Denmark)

Lörcher, Samuel; Koschorreck, Katja; Shipovskov, Stepan

for a number of special applications, such as disposable implantable power suppliers for medical sensor-transmitters and drug delivery/activator systems and self-powered enzyme-based biosensors; and they do offer practical advantages of using abundant organic raw materials for clean and sustainable energy...... in vivo glucose monitoring in diabetes patients). However, the most attractive are oxygen-reducing enzymes such as blue-copper-containing laccases coupled to electrodes, which provide the 4e- bioelectroreduction of O2 to H2O (1.23 V vs. NHE) at potentials approaching the thermodynamic ones. Exploitation...... of laccase-based biocathodes in the biofuel cells and in the hybrid biobattery-type or photovoltaic power sources could essentially broaden their application, enabling extraction of energy from the sea water/water dissolved oxygen. Here we demonstrate up to 0.8 mW cm-2 extracted power densities and 1.5 month...

Zero-truncated negative binomial - Erlang distribution

Science.gov (United States)

Bodhisuwan, Winai; Pudprommarat, Chookait; Bodhisuwan, Rujira; Saothayanun, Luckhana

2017-11-01

The zero-truncated negative binomial-Erlang distribution is introduced. It is developed from negative binomial-Erlang distribution. In this work, the probability mass function is derived and some properties are included. The parameters of the zero-truncated negative binomial-Erlang distribution are estimated by using the maximum likelihood estimation. Finally, the proposed distribution is applied to real data, the number of methamphetamine in the Bangkok, Thailand. Based on the results, it shows that the zero-truncated negative binomial-Erlang distribution provided a better fit than the zero-truncated Poisson, zero-truncated negative binomial, zero-truncated generalized negative-binomial and zero-truncated Poisson-Lindley distributions for this data.

Angular truncation errors in integrating nephelometry

International Nuclear Information System (INIS)

Moosmueller, Hans; Arnott, W. Patrick

2003-01-01

Ideal integrating nephelometers integrate light scattered by particles over all directions. However, real nephelometers truncate light scattered in near-forward and near-backward directions below a certain truncation angle (typically 7 deg. ). This results in truncation errors, with the forward truncation error becoming important for large particles. Truncation errors are commonly calculated using Mie theory, which offers little physical insight and no generalization to nonspherical particles. We show that large particle forward truncation errors can be calculated and understood using geometric optics and diffraction theory. For small truncation angles (i.e., <10 deg. ) as typical for modern nephelometers, diffraction theory by itself is sufficient. Forward truncation errors are, by nearly a factor of 2, larger for absorbing particles than for nonabsorbing particles because for large absorbing particles most of the scattered light is due to diffraction as transmission is suppressed. Nephelometers calibration procedures are also discussed as they influence the effective truncation error

Performance of an alkalophilic and halotolerant laccase from gamma-proteobacterium JB in the presence of industrial pollutants.

Science.gov (United States)

Singh, Gursharan; Sharma, Prince; Capalash, Neena

2009-08-01

An alkalophilic and halotolerant laccase from gamma-proteobacterium JB catalyzed in high concentrations of organic solvents and various salts. The enzyme retained 80-100% activity in 10% concentration of dimethylsulfoxide (DMSO), ethanol, acetone or methanol; 100, 85 and 50% activity in 20 mM MgCl(2), 5.0 mM MnCl(2) and 0.1 mM CuCl(2); 140, 120 and 110% activity in 5.0 mM MnSO(4), 10 mM MgSO(4) and 1mM CaSO(4), respectively. Sodium halides inhibited the enzyme in the order: F(-)> Br(-)> I(-)> Cl(-). In 0.5 M NaCl, pH 6.0, laccase was approximately 60% active. Decolorization of indigo carmine by laccase at pH 9.0 was not inhibited even in the presence of 0.5 M NaCl. Release of chromophoric, reducing and hydrophobic compounds during biobleaching of straw rich-soda pulp by laccase was not inhibited when the enzyme was applied in the presence of 1 M NaCl at pH 8.0. Laccase retained 50% residual activity even when incubated with 5% calcium hypochlorite for 30 min.

The structure of the small laccase from Streptomyces coelicolor reveals a link between laccases and nitrite reductases

Czech Academy of Sciences Publication Activity Database

Skálová, Tereza; Dohnálek, Jan; Ostergaard, L. H.; Ostergaard, P. R.; Kolenko, Petr; Dušková, Jarmila; Štěpánková, Andrea; Hašek, Jindřich

2009-01-01

Roč. 385, č. 4 (2009), s. 1165-1178 ISSN 0022-2836 R&D Projects: GA MŠk 1K05008; GA ČR GA305/07/1073; GA AV ČR 1ET400500402 Institutional research plan: CEZ:AV0Z40500505 Keywords : laccase * oxidoreductase * multicopper blue protein * Streptomyces coelicolor * crystal structure Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.871, year: 2009

Electrochemical and AFM characterization on gold and carbon electrodes of a high redox potential laccase from Fusarium proliferatum.

Science.gov (United States)

González Arzola, K; Gimeno, Y; Arévalo, M C; Falcón, M A; Hernández Creus, A

2010-08-01

The redox potential of the T1 copper site of laccase from Fusarium proliferatum was determined by titration to be about 510 mV vs. SCE (750 mV vs. NHE), which makes it a high redox potential enzyme. Anaerobic electron transfer reactions between laccase and carbon and gold electrodes were detected, both in solution and when the enzyme was adsorbed on these surfaces. In solution, a single high-potential signal (660 mV vs. SCE) was recorded at the carbon surfaces, attributable to the T1 copper site of the enzyme. However, a well-defined oxidative process at about 660 mV and an anodic wave at 350 mV vs. SCE were recorded at the gold electrode, respectively associated with the T1 and T2 copper sites. Laccase-modified carbon electrodes behaved analogously when the enzyme was in solution, unlike laccase adsorbed on gold, which showed only a low-potential signal. Laccase molecules were successfully imaged by AFM; obtaining a thick compact stable film on Au(111), and large aggregates forming a complex network of small branches leaving voids on the HOPG surface. Laccase-modified carbon electrodes retained significant enzymatic activity, efficiently oxidising violuric acid and reducing molecular oxygen. Explanations are proposed for how protein-film organisation affects the electrode function. Copyright (c) 2009 Elsevier B.V. All rights reserved.

Green Synthesis and Antibacterial Activities of Silver Nanoparticles Using Extracellular Laccase of Lentinus edodes

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Agbaje LATEEF

2015-12-01

Full Text Available This study reports the multi-step mutagenesis of Lentinus edodes towards optimization of the production of laccase and novel application of laccase in the biosynthesis of silver nanoparticles (AgNPs which could be used to develop an eco-friendly method for the rapid biosynthesis of AgNPs. The wild strain of L. edodes was subjected to UV irradiation at 254 nm and the resultant viable mutant was further treated with acridine orange, a chemical mutagen. The strains were evaluated for the production of laccase and the crude laccase of the UV mutant (UV10 was used for the green synthesis of AgNPs. The particles were characterized by UV-Visible spectroscopy, Fourier transform infrared (FTIR spectroscopy and scanning electron microscopy (SEM. Laccase activities of wild, UV10 and UV10ACR8 strains of L. edodes were obtained as 2.6, 10.6 and 2.8 U/ml/min respectively after 7 days of fermentation, showing laccase yield improvement of 4.08-fold for UV10 mutant. UV-Visible spectroscopy indicated the formation of AgNPs at absorption band of 430 nm. FTIR result indicated that proteins were responsible for AgNP synthesis, while SEM analysis confirmed the formation of walnut-shaped nanoparticles with size range of 50-100 nm. The biosynthesized nanoparticles revealed effective inhibition against clinical isolates of Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae. To the best of the authors’ knowledge, this result represents the first report on the biosynthesis of AgNPs using L. edodes metabolite. The report adds to the growing relevance of L. edodes as potential industrially viable organism, used for diverse biotechnological applications.

Laccase-Catalyzed Decolorization of Malachite Green: Performance Optimization and Degradation Mechanism

Science.gov (United States)

Yang, Jie; Yang, Xiaodan; Lin, Yonghui; Ng, Tzi Bun; Lin, Juan; Ye, Xiuyun

2015-01-01

Malachite green (MG) was decolorized by laccase (LacA) of white-rot fungus Cerrena sp. with strong decolorizing ability. Decolorization conditions were optimized with response surface methodology. A highly significant quadratic model was developed to investigate MG decolorization with LacA, and the maximum MG decolorization ratio of 91.6% was predicted under the conditions of 2.8 U mL-1 LacA, 109.9 mg L-1 MG and decolorization for 172.4 min. Kinetic studies revealed the Km and kcat values of LacA toward MG were 781.9 mM and 9.5 s-1, respectively. UV–visible spectra confirmed degradation of MG, and the degradation mechanism was explored with liquid chromatography–mass spectrometry (LC-MS) analysis. Based on the LC-MS spectra of degradation products, LacA catalyzed MG degradation via two simultaneous pathways. In addition, the phytotoxicity of MG, in terms of inhibition on seed germination and seedling root elongation of Nicotiana tabacum and Lactuca sativa, was reduced after laccase treatment. These results suggest that laccase of Cerrena was effective in decolorizing MG and promising in bioremediation of wastewater in food and aquaculture industries. PMID:26020270

Laccase-catalyzed decolorization of malachite green: performance optimization and degradation mechanism.

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Jie Yang

Full Text Available Malachite green (MG was decolorized by laccase (LacA of white-rot fungus Cerrena sp. with strong decolorizing ability. Decolorization conditions were optimized with response surface methodology. A highly significant quadratic model was developed to investigate MG decolorization with LacA, and the maximum MG decolorization ratio of 91.6% was predicted under the conditions of 2.8 U mL(-1 LacA, 109.9 mg L(-1 MG and decolorization for 172.4 min. Kinetic studies revealed the Km and kcat values of LacA toward MG were 781.9 mM and 9.5 s(-1, respectively. UV-visible spectra confirmed degradation of MG, and the degradation mechanism was explored with liquid chromatography-mass spectrometry (LC-MS analysis. Based on the LC-MS spectra of degradation products, LacA catalyzed MG degradation via two simultaneous pathways. In addition, the phytotoxicity of MG, in terms of inhibition on seed germination and seedling root elongation of Nicotiana tabacum and Lactuca sativa, was reduced after laccase treatment. These results suggest that laccase of Cerrena was effective in decolorizing MG and promising in bioremediation of wastewater in food and aquaculture industries.

Purification of a new isoform of laccase from a Marasmius quercophilus strain isolated from a cork oak litter (Quercus suber L).

Science.gov (United States)

Farnet, A M; Criquet, S; Pocachard, E; Gil, G; Ferre, E

2002-01-01

A new isoform of laccase from Marasmius quercophilus is described in this study. The strain of this white-rot fungus was isolated for the first time on a cork oak litter. This isoform exhibited certain common properties of laccases (a molecular weight of 65 Kda, an optimum pH of 6.2 with syringaldazine). But this laccase has also particularly novel features: the best activity measured was observed at high temperatures (80 C) and this isoform was not inhibited with EDTA. Furthermore, this induced laccase was able to transform most of the aromatic compounds tested without the addition of mediators to the reaction mixture, and the transformation of certain chlorophenols (2-chlorophenol and 2,4-dichlorophenol) by a laccase isoform from M. quercophilus is reported here for the first time. We also demonstrate the importance of 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) as a mediator since it allowed veratryl alcohol and p-hydroxybenzoic acid transformation. Moreover, new products of transformation were observed using the combination of ABTS with this isoform of laccase.

Development of biosensors containing laccase and imidazolium bis(trifluoromethylsulfonyl)imide ionic liquid for the determination of rutin

International Nuclear Information System (INIS)

Franzoi, Ana Cristina; Migowski, Pedro; Dupont, Jairton; Cruz Vieira, Iolanda

2009-01-01

Biosensors based on hydrophobic ionic liquids (ILs) derived from the bis(trifluoromethylsulfonyl)imide [(CF 3 SO 2 ) 2 N - = Tf 2 N - ] anion associated with three different imidazolium cations: 1-butyl-3-methylimidazolium (BMI.Tf 2 N), 1-decyl-3-methylimidazolium (DMI.Tf 2 N) and 1-tetradecyl-3-methylimidazolium (TDMI.Tf 2 N), along with laccase from Aspergillus oryzae, were constructed and optimized for determination of rutin. The laccase catalyzes the oxidation of rutin to the corresponding o-quinone, which is electrochemically reduced back to rutin. The best performance was obtained with 50:20:15:15% (w/w/w/w) as the graphite powder:laccase:Nujol:ILs composition in 0.1 mol L -1 acetate buffer solution (pH 5.0). The parameters for the square-wave voltammetry experiments and scanning electron microscopy images of the biosensors were studied. Under the selected conditions, the cathodic peak current increased linearly in the rutin concentration ranges of 4.77 x 10 -6 to 4.62 x 10 -5 mol L -1 , 5.84 x 10 -6 to 5.36 x 10 -5 mol L -1 and 5.84 x 10 -6 to 5.36 x 10 -5 mol L -1 using the (I) BMI.Tf 2 N-laccase, (II) DMI.Tf 2 N-laccase and (III) TDMI.Tf 2 N-laccase, respectively. The rutin contents of commercial samples of pharmaceuticals were successfully determined by the biosensors and the results compared well with those obtained using the official method. The studies on rutin recovery from these samples gave values of 96.9-104.6%.

Molecular characterization of a novel thermostable laccase PPLCC2 from the brown rot fungus Postia placenta MAD-698-R

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Hongde An

2015-11-01

Conclusions: This is the first identified thermo activated and thermostable laccase in brown rot fungi. This investigation will contribute to understanding the roles played by laccases in brown rot fungi.

Comparative analyses of laccase-catalyzed amination reactions for production of novel β-lactam antibiotics.

Science.gov (United States)

Mikolasch, Annett; Manda, Katrin; Schlüter, Rabea; Lalk, Michael; Witt, Sabine; Seefeldt, Simone; Hammer, Elke; Schauer, Frieder; Jülich, Wolf-Dieter; Lindequist, Ulrike

2012-01-01

Seven novel β-lactam antibiotics with activities against Gram-positive bacterial strains, among them methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci, were synthesized by amination of 2,5-dihydroxyphenylacetic acid in usable yields (30-60%). These products protected mice against an infection with S. aureus lethal to the control animals. The results show the usefulness of laccase for the synthesis of potential new antibiotics, in addition to the interdependence of the laccase substrates, the amino coupling partners, and the product formation, yield, and activity. The syntheses of β-lactam antibiotics with 2,5-dihydroxyaromatic acid substructures (para-substituted) are then compared with those of 3,4-dihydroxyaromatic acid substructures (ortho-substituted). Para-substituted laccase substrates were better reaction partners in these syntheses than ortho-substituted compounds. Copyright © 2012 International Union of Biochemistry and Molecular Biology, Inc.

Exploring the Oxidation of Lignin-Derived Phenols by a Library of Laccase Mutants

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Isabel Pardo

2015-09-01

Full Text Available Saturation mutagenesis was performed over six residues delimiting the substrate binding pocket of a fungal laccase previously engineered in the lab. Mutant libraries were screened using sinapic acid as a model substrate, and those mutants presenting increased activity were selected for exploring the oxidation of lignin-derived phenols. The latter comprised a battery of phenolic compounds of interest due to their use as redox mediators or precursors of added-value products and their biological activity. The new laccase variants were investigated in a multi-screening assay and the structural determinants, at both the substrate and the protein level, for the oxidation of the different phenols are discussed. Laccase activity greatly varied only by changing one or two residues of the enzyme pocket. Our results suggest that once the redox potential threshold is surpassed, the contribution of the residues of the enzymatic pocket for substrate recognition and binding strongly influence the overall rate of the catalytic reaction.

Laccase-Catalyzed Surface Modification of Thermo-Mechanical Pulp (TMP) for the Production of Wood Fiber Insulation Boards Using Industrial Process Water

Science.gov (United States)

Schubert, Mark; Ruedin, Pascal; Civardi, Chiara; Richter, Michael; Hach, André; Christen, Herbert

2015-01-01

Low-density wood fiber insulation boards are traditionally manufactured in a wet process using a closed water circuit (process water). The water of these industrial processes contains natural phenolic extractives, aside from small amounts of admixtures (e.g., binders and paraffin). The suitability of two fungal laccases and one bacterial laccase was determined by biochemical characterization considering stability and substrate spectra. In a series of laboratory scale experiments, the selected commercial laccase from Myceliophtora thermophila was used to catalyze the surface modification of thermo-mechanical pulp (TMP) using process water. The laccase catalyzed the covalent binding of the phenolic compounds of the process water onto the wood fiber surface and led to change of the surface chemistry directly via crosslinking of lignin moieties. Although a complete substitution of the binder was not accomplished by laccase, the combined use of laccase and latex significantly improved the mechanical strength properties of wood fiber boards. The enzymatically-treated TMP showed better interactions with the synthetic binder, as shown by FTIR-analysis. Moreover, the enzyme is extensively stable in the process water and the approach requires no fresh water as well as no cost-intensive mediator. By applying a second-order polynomial model in combination with the genetic algorithm (GA), the required amount of laccase and synthetic latex could be optimized enabling the reduction of the binder by 40%. PMID:26046652

Laccase production by Coriolopsis caperata RCK2011: Optimization under solid state fermentation by Taguchi DOE methodology

Science.gov (United States)

Nandal, Preeti; Ravella, Sreenivas Rao; Kuhad, Ramesh Chander

2013-01-01

Laccase production by Coriolopsis caperata RCK2011 under solid state fermentation was optimized following Taguchi design of experiment. An orthogonal array layout of L18 (21 × 37) was constructed using Qualitek-4 software with eight most influensive factors on laccase production. At individual level pH contributed higher influence, whereas, corn steep liquor (CSL) accounted for more than 50% of the severity index with biotin and KH2PO4 at the interactive level. The optimum conditions derived were; temperature 30°C, pH 5.0, wheat bran 5.0 g, inoculum size 0.5 ml (fungal cell mass = 0.015 g dry wt.), biotin 0.5% w/v, KH2PO4 0.013% w/v, CSL 0.1% v/v and 0.5 mM xylidine as an inducer. The validation experiments using optimized conditions confirmed an improvement in enzyme production by 58.01%. The laccase production to the level of 1623.55 Ugds−1 indicates that the fungus C. caperata RCK2011 has the commercial potential for laccase. PMID:23463372

Biobleaching of wheat straw-rich soda pulp with alkalophilic laccase from gamma-proteobacterium JB: optimization of process parameters using response surface methodology.

Science.gov (United States)

Singh, Gursharan; Ahuja, Naveen; Batish, Mona; Capalash, Neena; Sharma, Prince

2008-11-01

An alkalophilic laccase from gamma-proteobacterium JB was applied to wheat straw-rich soda pulp to check its bleaching potential by using response surface methodology based on central composite design. The design was employed by selecting laccase units, ABTS (2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) concentration and pH as model factors. The results of second order factorial design experiments showed that all three independent variables had significant effect on brightness and kappa number of laccase-treated pulp. Optimum conditions for biobleaching of pulp with laccase preparation (specific activity, 65 nkat mg(-1) protein) were 20 nkat g(-1) of pulp, 2mM ABTS and pH 8.0 which enhanced brightness by 5.89% and reduced kappa number by 21.1% within 4h of incubation at 55 degrees C, without further alkaline extraction of pulp. Tear index (8%) and burst index (18%) also improved for laccase-treated pulp as compared to control raw pulp. Treatment of chemically (CEH1H2) bleached pulp with laccase showed significant effect on release of chromophores, hydrophobic and reducing compounds. Laccase-prebleaching of raw pulp reduced the use of hypochlorite by 10% to achieve brightness of resultant hand sheets similar to the fully chemically bleached pulp.

Laccase production by Pleurotus ostreatus and its application in synthesis of gold nanoparticles

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Ahmed I. El-Batal

2015-03-01

Optimization of production conditions yielded an enzyme with activity over 32,450 IU/g of fermented substrate. Factorial design was capable of establishing the conditions that multiplied the activity of the enzyme several folds, consequently, reducing the cost of production. The enzyme was capable of decolorizing several dyes with over 80% reduction in color confirming the aromatic degrading capability of laccase. The enzyme was also used in the synthesis of gold nanoparticles, proving that laccase from Pleurotus ostreatus has a strong potential in several industrial applications.

Characterization of the alkaline laccase Ssl1 from Streptomyces sviceus with unusual properties discovered by genome mining.

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Matthias Gunne

Full Text Available Fungal laccases are well investigated enzymes with high potential in diverse applications like bleaching of waste waters and textiles, cellulose delignification, and organic synthesis. However, they are limited to acidic reaction conditions and require eukaryotic expression systems. This raises a demand for novel laccases without these constraints. We have taken advantage of the laccase engineering database LccED derived from genome mining to identify and clone the laccase Ssl1 from Streptomyces sviceus which can circumvent the limitations of fungal laccases. Ssl1 belongs to the family of small laccases that contains only few characterized enzymes. After removal of the twin-arginine signal peptide Ssl1 was readily expressed in E. coli. Ssl1 is a small laccase with 32.5 kDa, consists of only two cupredoxin-like domains, and forms trimers in solution. Ssl1 oxidizes 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid (ABTS and phenolic substrates like 2,6-dimethoxy phenol, guaiacol, and syringaldazine. The k(cat value for ABTS oxidation was at least 20 times higher than for other substrates. The optimal pH for oxidation reactions is substrate dependent: for phenolic substrates the highest activities were detected at alkaline conditions (pH 9.0 for 2,6-dimethoxy phenol and guaiacol and pH 8.0 for syringaldazine, while the highest reaction rates with ABTS were observed at pH 4.0. Though originating from a mesophilic organism, Ssl demonstrates remarkable stability at elevated temperatures (T(1/2,60°C = 88 min and in a wide pH range (pH 5.0 to 11.0. Notably, the enzyme retained 80% residual activity after 5 days of incubation at pH 11. Detergents and organic co-solvents do not affect Ssl1 stability. The described robustness makes Ssl1 a potential candidate for industrial applications, preferably in processes that require alkaline reaction conditions.

Heterologous expression of a tannic acid-inducible laccase3 of Cryphonectria parasitica in Saccharomyces cerevisiae

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Kim Dae-Hyuk

2010-02-01

Full Text Available Abstract Background A tannic acid-inducible and mycoviral-regulated laccase3 (lac3 from the chestnut blight fungus Cryphonectria parasitica has recently been identified, but further characterization was hampered because of the precipitation of protein products by tannic acid supplementation. The present study investigated the heterologous expression of the functional laccase3 using a yeast Saccharomyces cerevisiae. Results Laccase activity in the culture broth of transformants measured using a laccase-specific substrate suggested that the lac3 gene was successfully expressed and the corresponding protein product secreted into the culture media. In addition, activity staining and Western blot analysis of a native gel revealed that the enzyme activity co-existed with the protein product specific to anti-laccase3 antibody, confirming that the cloned lac3 gene is responsible for the laccase activity. When transformants were grown on plates containing tannic acid-supplemented media, brown coloration was observed around transformed cells, indicating the oxidation of tannic acid. However, the enzymatic activity was measurable only in the selective ura- media and was negligible in nonselective nutrient-rich culture conditions. This was in part because of the increased plasmid instability in the nonselective media. Moreover, the protein product of lac3 appears to be sensitive to the cultured nonselective nutrient-rich broth, because a rapid decline in enzymatic activity was observed when the cultured broth of ura- media was mixed with that of nonselective nutrient-rich broth. In addition, constitutive expression of the lac3 gene resulted in a reduced cell number of the lac3 transformants compared to that of vector-only transformed control. However, the presence of recombinant vector without lac3 induction did not affect the growth of transformants. Conclusions The results suggest that expression of the lac3 gene has an inhibitory effect on the growth of

Cleavage and synthesis function of high and low redox potential laccases towards 4-morpholinoaniline and aminated as well as chlorinated phenols.

Science.gov (United States)

Hahn, Veronika; Mikolasch, Annett; Schauer, Frieder

2014-02-01

Laccases are able to mediate both cleavage and synthesis processes. The basis for this dual reaction capability lies in the property of the enzyme laccase to oxidize phenolic, and to some extent non-phenolic substances, to reactive radicals which can undergo on the one hand separations of small substitutents or large molecule parts from the parent compound and on the other hand coupling reactions with other radicals or molecules which are not themselves oxidizable by laccase. The cleavage of the non-phenolic compound 4-morpholinoaniline as well as the deamination of 4-aminophenol and the dechlorination of 4-chlorophenol resulted in the formation of 1,4-hydroquinone which is immediately oxidized by laccase to 1,4-benzoquinone. The formation of the 1,4-hydroquinone/1,4-benzoquinone is the rate limiting step for the synthesis of the heteromolecular dimers and trimers composed of 1,4-benzoquinone and one or two molecules of morpholine. In addition to the synthesis of new compounds from the cleavage products, 4-morpholinoaniline polymerized probably via azo groups and C-N bonds to a homomolecular dimer and trimer. Similarities and differences in cleavage and synthesis reactions catalyzed by the low redox potential laccase of Myceliophthora thermophila (0.46 V) and the high redox potential laccase of Pycnoporus cinnabarinus (0.79 V) were determined. In addition, the dependency of the cleavage and synthesis efficiencies on the (a) structure and redox potential of the laccase, (b) structure and redox potential of the substrate, (c) pH value of the buffer used, (d) incubation temperature, (e) solvent concentration, and (f) laccase activity is discussed in general.

Enzymatic removal of estrogenic activity of nonylphenol and octylphenol aqueous solutions by immobilized laccase from Trametes versicolor

Energy Technology Data Exchange (ETDEWEB)

Catapane, Maria [Institute of Genetics and Biophysics “ABT”, Via P. Castellino, 111, 80131 Naples (Italy); National Institute of Biostructures and Biosystems (INBB), Viale Medaglie d’Oro, 305, 00136 Rome (Italy); Nicolucci, Carla; Menale, Ciro; Mita, Luigi [National Institute of Biostructures and Biosystems (INBB), Viale Medaglie d’Oro, 305, 00136 Rome (Italy); Department of Experimental Medicine, Second University of Naples, Via S. M. di Costantinopoli, 16, 80138 Naples (Italy); Rossi, Sergio [Institute of Genetics and Biophysics “ABT”, Via P. Castellino, 111, 80131 Naples (Italy); Mita, Damiano G., E-mail: mita@igb.cnr.it [Institute of Genetics and Biophysics “ABT”, Via P. Castellino, 111, 80131 Naples (Italy); National Institute of Biostructures and Biosystems (INBB), Viale Medaglie d’Oro, 305, 00136 Rome (Italy); Department of Experimental Medicine, Second University of Naples, Via S. M. di Costantinopoli, 16, 80138 Naples (Italy); Diano, Nadia [Institute of Genetics and Biophysics “ABT”, Via P. Castellino, 111, 80131 Naples (Italy); National Institute of Biostructures and Biosystems (INBB), Viale Medaglie d’Oro, 305, 00136 Rome (Italy); Department of Experimental Medicine, Second University of Naples, Via S. M. di Costantinopoli, 16, 80138 Naples (Italy)

2013-03-15

Highlights: ► Endocrine disruptors cause adverse effects in living organisms. ► Nonylphenol and Octylphenol are alkylphenols recognized as endocrine disruptors. ► It is necessary to remove or reduce their presence in the environment. ► Waters polluted by these pollutants have been bioremediated by immobilized laccase from Trametes versicolor. ► Laccase treated solutions were found to have lost any estrogenic activity. -- Abstract: A fluidized bed reactor, filled with laccase-based beads, has been employed to bioremediate aqueous solutions polluted by endocrine disruptors belonging to the alkylphenols (APs) class. In particular Octylphenol and Nonylphenol have been studied. The catalytic activity of free and immobilized laccase from Trametes versicolor has been characterized as a function of pH, temperature and substrate concentration in the reaction medium. In view of practical applications for each substrate concentration the removal efficiency (RE), the time to halve the initial concentration (τ{sub 50}), and the t{sub c=0}, i.e. the time to reach complete pollutant removal, have been calculated. The immobilized laccase exhibited a lower affinity for octylphenol (K{sub m} = 1.11 mM) than for Nonylphenol (K{sub m} = 0.72 mM), but all the other parameters of applicative interest resulted more significant for octylphenol. For example, the times to reach the complete removal of octylphenol compared to those for nonylphenol at the same concentration is shorter of about 15% (at low concentrations) up to 40% (at high concentrations). The study of cell proliferation with MPP89 cells, a human mesothelioma cell line, and the assay with the YES test indicated the loss of estrogenic activity of the APs solutions after laccase treatment.

Laccases as a Potential Tool for the Efficient Conversion of Lignocellulosic Biomass: A Review

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Úrsula Fillat

2017-05-01

Full Text Available The continuous increase in the world energy and chemicals demand requires the development of sustainable alternatives to non-renewable sources of energy. Biomass facilities and biorefineries represent interesting options to gradually replace the present industry based on fossil fuels. Lignocellulose is the most promising feedstock to be used in biorefineries. From a sugar platform perspective, a wide range of fuels and chemicals can be obtained via microbial fermentation processes, being ethanol the most significant lignocellulose-derived fuel. Before fermentation, lignocellulose must be pretreated to overcome its inherent recalcitrant structure and obtain the fermentable sugars. Usually, harsh conditions are required for pretreatment of lignocellulose, producing biomass degradation and releasing different compounds that are inhibitors of the hydrolytic enzymes and fermenting microorganisms. Moreover, the lignin polymer that remains in pretreated materials also affects biomass conversion by limiting the enzymatic hydrolysis. The use of laccases has been considered as a very powerful tool for delignification and detoxification of pretreated lignocellulosic materials, boosting subsequent saccharification and fermentation processes. This review compiles the latest studies about the application of laccases as useful and environmentally friendly delignification and detoxification technology, highlighting the main challenges and possible ways to make possible the integration of these enzymes in future lignocellulose-based industries.

Laccase gene expression as a possible key adaptation for herbivorous niche expansion in the attine fungus-growing ants

DEFF Research Database (Denmark)

de Fine Licht, Henrik Hjarvard; Schiøtt, Morten; Boomsma, Jacobus Jan

generalist functional herbivores. Laccases are polyphenol oxidase enzymes (PPOs) that are best known for their ability to degrade lignin in saprophytic and wood-pathogenic fungi. We found that laccase activity was primarily expressed in newly constructed garden sections where secondary leaf compounds...

Comparison of two laccases from Trametes versicolor for application in the decolorization of dyes.

Science.gov (United States)

Li, Qi; Ge, Lin; Cai, Junli; Pei, Jianjun; Xie, Jingcong; Zhao, Linguo

2014-04-01

It has been previously demonstrated that laccases exhibit great potential for use in several industrial and environmental applications. In this paper, two laccase isoenzyme genes, lccB and lccC, were cloned and expressed in Pichia pastoris GS115. The sequence analysis indicated that the lccB and lccC genes consisted of 1,563 and 1,584 bp, and their open reading frames encoded 520 and 527 amino acids, respectively. They had 72.7% degree of identity in nucleotides and 86.7% in amino acids. The expression levels of LccB and LccC were up to 32,479 and 34,231 U/l, respectively. The recombinant laccases were purified by ultrafiltration and (NH4)2SO4 precipitation, showing a single band on SDS-PAGE, which had a molecular mass of 58 kDa. The optimal pH and temperature for LccB were 2.0 and 55°C with 2,2'-azino-bis-[3-ethylbenzthiazolinesulfonic acid (ABTS) as a substrate, whereas LccC exhibited optimal pH and temperature at 3.0 and 60°C. The apparent kinetic parameters of LccB were 0.43 mM for ABTS with a Vmax value of 51.28 U/mg, and the Km and Vmax values for LccC were 0.29 mM and 62.89 U/mg. The recombinant laccases were able to decolorize five types of dyes. Acid Violet 43 (100 g/ml) was completely decolorized by LccB or LccC (2 U/ml), and the decolorization of Reactive Blue KN-R (100 g/ml) was 91.6% by LccC (2 U/ml). Thus, the study characterizes useful laccase isoenzymes from T. versicolor that have the capability of being incorporated into the treatment of similar azo and anthraquinone dyes from dyeing industries.

STUDIES ON XYLANASE AND LACCASE ENZYMATIC PREBLEACHING TO REDUCE CHLORINE-BASED CHEMICALS DURING CEH AND ECF BLEACHING

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Vasanta V. Thakur,

2012-02-01

Full Text Available The biobleaching efficiency of xylanase and laccase enzymes was studied on kraft pulps from wood and nonwood based raw materials employed in the Indian paper industry. Treatment of these pulps with xylanase enzyme could result in improved properties, showing 2.0% ISO gain in pulp brightness and/or reducing the demand of chlorine-based bleach chemicals by up to 15% with simultaneous reduction of 20 to 25% in AOX generation in bleach effluents. Further, mill-scale trial results revealed that enzymatic prebleaching can be successfully employed with xylanases to reach the same bleach boosting efficacy. Laccase bleaching was also studied on hardwood pulp at a pH around 8.0, where most of the pulp mills in India are operating, in contrast to earlier studies on laccase enzyme bleaching, which were conducted at acidic pHs, i.e. 4.0 to 5.0. In case of laccase bleaching, interesting results were found wherein a bleach-boosting effect was observed even at pH 8.0. Further studies carried out with HOBT as mediator in comparison to the commonly used and expensive ABTS laccase mediator system (LMS resulted in improvement of the bleaching efficiency with reduction in demand of chlorine dioxide by more than 35%. Potential for further reduction was indicated by the brightness gain, when compared with a control using the DE(pD bleach sequence.

Mediator-assisted decolorization and detoxification of textile dyes/dye mixture by Cyathus bulleri laccase.

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Chhabra, Meenu; Mishra, Saroj; Sreekrishnan, T R

2008-12-01

Laccase from basidiomycete fungus Cyathus bulleri was evaluated for its ability to decolorize a number of reactive and acidic dyes in the presence of natural and synthetic mediators. The extent of decolorization was monitored at different mediator/dye concentrations and incubation time. Among the synthetic mediators, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) was effective at low mediator/dye ratios and resulted in 80-95% decolorization at rates that varied from 226 +/- 4 nmol min(-1) mg(-1) for Reactive Orange 1 to 1,333 +/- 15 nmol min(-1) mg(-1) for Reactive Red 198. Other synthetic mediators like 1-hydroxybenzotriazole and violuric acid showed both concentration- and time-dependent increases in percent decolorization. Natural mediators like vanillin, on the other hand, were found to be less effective on all the dyes except Reactive Orange 1. Computed rates of decolorization were about twofold lower than that with ABTS. The laccase-ABTS system also led to nearly 80% decolorization for the simulated dye mixture. No clear correlation between laccase activity on the mediator and its ability to decolorize dyes was found, but pH had a significant effect: Optimum pH for decolorization coincided with the optimum pH for mediator oxidation. The treated samples were also evaluated for toxicity in model microbial systems. The laccase-mediator system appears promising for treatment of textile wastewaters.

Purification, crystallization and preliminary X-ray structure analysis of the laccase from Ganoderma lucidum

International Nuclear Information System (INIS)

Lyashenko, Andrey V.; Belova, Oksana; Gabdulkhakov, Azat G.; Lashkov, Alexander A.; Lisov, Alexandr V.; Leontievsky, Alexey A.; Mikhailov, Al’bert M.

2011-01-01

The purification, crystallization and preliminary X-ray structure analysis of the laccase from G. lucidum are reported. The ligninolytic enzymes of the basidiomycetes play a key role in the global carbon cycle. A characteristic property of these enzymes is their broad substrate specificity, which has led to their use in various biotechnologies, thus stimulating research into the three-dimensional structures of ligninolytic enzymes. This paper presents the purification, crystallization and preliminary X-ray analysis of the laccase from the ligninolytic basidiomycete Ganoderma lucidum

Prediction and optimization of the laccase-mediated synthesis of the antimicrobial compound iodine (I2).

Science.gov (United States)

Schubert, M; Fey, A; Ihssen, J; Civardi, C; Schwarze, F W M R; Mourad, S

2015-01-10

An artificial neural network (ANN) and genetic algorithm (GA) were applied to improve the laccase-mediated oxidation of iodide (I(-)) to elemental iodine (I2). Biosynthesis of iodine (I2) was studied with a 5-level-4-factor central composite design (CCD). The generated ANN network was mathematically evaluated by several statistical indices and revealed better results than a classical quadratic response surface (RS) model. Determination of the relative significance of model input parameters, ranking the process parameters in order of importance (pH>laccase>mediator>iodide), was performed by sensitivity analysis. ANN-GA methodology was used to optimize the input space of the neural network model to find optimal settings for the laccase-mediated synthesis of iodine. ANN-GA optimized parameters resulted in a 9.9% increase in the conversion rate. Copyright © 2014 Elsevier B.V. All rights reserved.

Development of biosensors containing laccase and imidazolium bis(trifluoromethylsulfonyl)imide ionic liquid for the determination of rutin

Energy Technology Data Exchange (ETDEWEB)

Franzoi, Ana Cristina [Departamento de Quimica, Laboratorio de Biossensores, Universidade Federal de Santa Catarina, 88040-970 Florianopolis, SC (Brazil); Migowski, Pedro; Dupont, Jairton [Departamento de Quimica Organica, Laboratorio de Catalise Molecular, Universidade Federal do Rio Grande do Sul, 91501-970 Porto Alegre, RS (Brazil); Cruz Vieira, Iolanda, E-mail: iolanda@qmc.ufsc.br [Departamento de Quimica, Laboratorio de Biossensores, Universidade Federal de Santa Catarina, 88040-970 Florianopolis, SC (Brazil)

2009-04-20

Biosensors based on hydrophobic ionic liquids (ILs) derived from the bis(trifluoromethylsulfonyl)imide [(CF{sub 3}SO{sub 2}){sub 2}N{sup -} = Tf{sub 2}N{sup -}] anion associated with three different imidazolium cations: 1-butyl-3-methylimidazolium (BMI.Tf{sub 2}N), 1-decyl-3-methylimidazolium (DMI.Tf{sub 2}N) and 1-tetradecyl-3-methylimidazolium (TDMI.Tf{sub 2}N), along with laccase from Aspergillus oryzae, were constructed and optimized for determination of rutin. The laccase catalyzes the oxidation of rutin to the corresponding o-quinone, which is electrochemically reduced back to rutin. The best performance was obtained with 50:20:15:15% (w/w/w/w) as the graphite powder:laccase:Nujol:ILs composition in 0.1 mol L{sup -1} acetate buffer solution (pH 5.0). The parameters for the square-wave voltammetry experiments and scanning electron microscopy images of the biosensors were studied. Under the selected conditions, the cathodic peak current increased linearly in the rutin concentration ranges of 4.77 x 10{sup -6} to 4.62 x 10{sup -5} mol L{sup -1}, 5.84 x 10{sup -6} to 5.36 x 10{sup -5} mol L{sup -1} and 5.84 x 10{sup -6} to 5.36 x 10{sup -5} mol L{sup -1} using the (I) BMI.Tf{sub 2}N-laccase, (II) DMI.Tf{sub 2}N-laccase and (III) TDMI.Tf{sub 2}N-laccase, respectively. The rutin contents of commercial samples of pharmaceuticals were successfully determined by the biosensors and the results compared well with those obtained using the official method. The studies on rutin recovery from these samples gave values of 96.9-104.6%.

Truncated Groebner fans and lattice ideals

OpenAIRE

Lauritzen, Niels

2005-01-01

We outline a generalization of the Groebner fan of a homogeneous ideal with maximal cells parametrizing truncated Groebner bases. This "truncated" Groebner fan is usually much smaller than the full Groebner fan and offers the natural framework for conversion between truncated Groebner bases. The generic Groebner walk generalizes naturally to this setting by using the Buchberger algorithm with truncation on facets. We specialize to the setting of lattice ideals. Here facets along the generic w...

Effects of Soil Oxygen Conditions and Soil pH on Remediation of DDT-contaminated Soil by Laccase from White Rot Fungi

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Yuechun Zhao

2010-04-01

Full Text Available High residues of DDT in agricultural soils are of concern because they present serious threats to food security and human health. This article focuses on remediation of DDT-contaminated soil using laccase under different soil oxygen and soil pH conditions. The laboratory experiment results showed significant effects of soil oxygen conditions and soil pH on remediation of DDT-contaminated soil by laccase at the end of a 25-d incubation period. This study found the positive correlation between the concentration of oxygen in soil and the degradation of DDT by laccase. The residue of DDTs in soil under the atmosphere of oxygen decreased by 28.1% compared with the atmosphere of nitrogen at the end of the incubation with laccase. A similar pattern was observed in the remediation of DDT-contaminated soil by laccase under different flooding conditions, the higher the concentrations of oxygen in soil, the lower the residues of four DDT components and DDTs in soils. The residue of DDTs in the nonflooding soil declined by 16.7% compared to the flooded soil at the end of the incubation. The residues of DDTs in soils treated with laccase were lower in the pH range 2.5–4.5.

Reductant-dependent electron distribution among redox sites of laccase

DEFF Research Database (Denmark)

Farver, O; Goldberg, M; Wherland, S

1978-01-01

Rhus laccase (monophenol monooxygenase, monophenol,dihydroxyphenylalanine:oxygen oxidoreductase, EC 1.14.18.1) an O2/H2O oxidoreductase containing four copper ions bound to three redox sites (type 1, type 2, and type 3 Cu pair), was titrated anaerobically with several reductants having various ch...

Laccase from Aspergillus niger: A novel tool to graft multifunctional materials of interests and their characterization

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Hafiz M.N. Iqbal

2018-03-01

Full Text Available In the present study, we propose a green route to prepare poly(3-hydroxybutyrate [(P(3HB] grafted ethyl cellulose (EC based green composites with novel characteristics through laccase-assisted grafting. P(3HB was used as a side chain whereas, EC as a backbone material under ambient processing conditions. A novel laccase obtained from Aspergillus niger through its heterologous expression in Saccharomyces cerevisiae was used as a green catalyst for grafting purposes without the use of additional initiator and/or cross-linking agents. Subsequently, the resulting P(3HB-g-EC composites were characterized using a range of analytical and imagining techniques. Fourier transform infrared spectroscopy (FT-IR spectra showed an increase in the hydrogen-bonding type interactions between the side chains of P(3HB and backbone material of EC. Evidently, X-ray diffraction (XRD analysis revealed a decrease in the crystallinity of the P(3HB-g-EC composites as compared to the pristine individual polymers. A homogeneous P(3HB distribution was also achieved in case of the graft composite prepared in the presence of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS as a mediator along with laccase as compared to the composite prepared using pure laccase alone. A substantial improvement in the thermal and mechanical characteristics was observed for grafted composites up to the different extent as compared to the pristine counterparts. The hydrophobic/hydrophilic properties of the grafted composites were better than those of the pristine counterparts. Keywords: Biological polymers, Composite materials, Laccase, Aspergillus niger

Biocatalytic potential of laccase-like multicopper oxidases from Aspergillus niger

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Tamayo-Ramos Juan Antonio

2012-12-01

Full Text Available Abstract Background Laccase-like multicopper oxidases have been reported in several Aspergillus species but they remain uncharacterized. The biocatalytic potential of the Aspergillus niger fungal pigment multicopper oxidases McoA and McoB and ascomycete laccase McoG was investigated. Results The laccase-like multicopper oxidases McoA, McoB and McoG from the commonly used cell factory Aspergillus niger were homologously expressed, purified and analyzed for their biocatalytic potential. All three recombinant enzymes were monomers with apparent molecular masses ranging from 80 to 110 kDa. McoA and McoG resulted to be blue, whereas McoB was yellow. The newly obtained oxidases displayed strongly different activities towards aromatic compounds and synthetic dyes. McoB exhibited high catalytic efficiency with N,N-dimethyl-p-phenylenediamine (DMPPDA and 2,2-azino-di(3-ethylbenzthiazoline sulfonic acid (ABTS, and appeared to be a promising biocatalyst. Besides oxidizing a variety of phenolic compounds, McoB catalyzed successfully the decolorization and detoxification of the widely used textile dye malachite green. Conclusions The A. niger McoA, McoB, and McoG enzymes showed clearly different catalytic properties. Yellow McoB showed broad substrate specificity, catalyzing the oxidation of several phenolic compounds commonly present in different industrial effluents. It also harbored high decolorization and detoxification activity with the synthetic dye malachite green, showing to have an interesting potential as a new industrial biocatalyst.

Polymerization of Various Lignins via Immobilized Myceliophthora thermophila Laccase (MtL

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Daniela Huber

2016-08-01

Full Text Available Enzymatic polymerization of lignin is an environmentally-friendly and sustainable method that is investigated for its potential in opening-up new applications of one of the most abundant biopolymers on our planet. In this work, the laccase from Myceliophthora thermophila was successfully immobilized onto Accurel MP1000 beads (67% of protein bound to the polymeric carrier and the biocatalyzed oxidation of Kraft lignin (KL and lignosulfonate (LS were carried out. Fluorescence intensity determination, phenol content analysis and size exclusion chromatography were performed in order to elucidate the extent of the polymerization reaction. The collected results show an 8.5-fold decrease of the LS samples’ fluorescence intensity after laccase-mediated oxidation and a 12-fold increase of the weight average molecular weight was obtained.

Transiently truncated and differentially regulated expression of midkine during mouse embryogenesis

International Nuclear Information System (INIS)

Chen Qin; Yuan Yuanyang; Lin Shuibin; Chang Youde; Zhuo Xinming; Wei Wei; Tao Ping; Ruan Lingjuan; Li Qifu; Li Zhixing

2005-01-01

Midkine (MK) is a retinoic acid response cytokine, mostly expressed in embryonic tissues. Aberrant expression of MK was found in numerous cancers. In human, a truncated MK was expressed specifically in tumor/cancer tissues. Here we report the discovery of a novel truncated form of MK transiently expressed during normal mouse embryonic development. In addition, MK is concentrated at the interface between developing epithelium and mesenchyme as well as highly proliferating cells. Its expression, which is closely coordinated with angiogenesis and vasculogenesis, is spatiotemporally regulated with peaks in extensive organogenesis period and undifferentiated cells tailing off in maturing cells, implying its role in nascent blood vessel (endothelial) signaling of tissue differentiation and stem cell renewal/differentiation.. Cloning and sequencing analysis revealed that the embryonic truncated MK, in which the conserved domain is in-frame deleted, presumably producing a novel secreted small peptide, is different from the truncated form in human cancer tissues, whose deletion results in a frame-shift mutation. Our data suggest that MK may play a role in epithelium-mesenchyme interactions, blood vessel signaling, and the decision of proliferation vs differentiation. Detection of the transiently expressed truncated MK reveals its novel function in development and sheds light on its role in carcinogenesis

Statistical estimation for truncated exponential families

CERN Document Server

Akahira, Masafumi

2017-01-01

This book presents new findings on nonregular statistical estimation. Unlike other books on this topic, its major emphasis is on helping readers understand the meaning and implications of both regularity and irregularity through a certain family of distributions. In particular, it focuses on a truncated exponential family of distributions with a natural parameter and truncation parameter as a typical nonregular family. This focus includes the (truncated) Pareto distribution, which is widely used in various fields such as finance, physics, hydrology, geology, astronomy, and other disciplines. The family is essential in that it links both regular and nonregular distributions, as it becomes a regular exponential family if the truncation parameter is known. The emphasis is on presenting new results on the maximum likelihood estimation of a natural parameter or truncation parameter if one of them is a nuisance parameter. In order to obtain more information on the truncation, the Bayesian approach is also considere...

NLO renormalization in the Hamiltonian truncation

Science.gov (United States)

Elias-Miró, Joan; Rychkov, Slava; Vitale, Lorenzo G.

2017-09-01

Hamiltonian truncation (also known as "truncated spectrum approach") is a numerical technique for solving strongly coupled quantum field theories, in which the full Hilbert space is truncated to a finite-dimensional low-energy subspace. The accuracy of the method is limited only by the available computational resources. The renormalization program improves the accuracy by carefully integrating out the high-energy states, instead of truncating them away. In this paper, we develop the most accurate ever variant of Hamiltonian Truncation, which implements renormalization at the cubic order in the interaction strength. The novel idea is to interpret the renormalization procedure as a result of integrating out exactly a certain class of high-energy "tail states." We demonstrate the power of the method with high-accuracy computations in the strongly coupled two-dimensional quartic scalar theory and benchmark it against other existing approaches. Our work will also be useful for the future goal of extending Hamiltonian truncation to higher spacetime dimensions.

Advanced Synthesis of Conductive Polyaniline Using Laccase as Biocatalyst.

Science.gov (United States)

de Salas, Felipe; Pardo, Isabel; Salavagione, Horacio J; Aza, Pablo; Amougi, Eleni; Vind, Jesper; Martínez, Angel T; Camarero, Susana

2016-01-01

Polyaniline is a conductive polymer with distinctive optical and electrical properties. Its enzymatic synthesis is an environmentally friendly alternative to the use of harsh oxidants and extremely acidic conditions. 7D5L, a high-redox potential laccase developed in our lab, is the biocatalyst of choice for the synthesis of green polyaniline (emeraldine salt) due to its superior ability to oxidize aniline and kinetic stability at the required polymerization conditions (pH 3 and presence of anionic surfactants) as compared with other fungal laccases. Doses as low as 7.6 nM of 7D5L catalyze the polymerization of 15 mM aniline (in 24 h, room temperature, 7% yield) in the presence of different anionic surfactants used as doping templates to provide linear and water-soluble polymers. Aniline polymerization was monitored by the increase of the polaron absorption band at 800 nm (typical for emeraldine salt). Best polymerization results were obtained with 5 mM sodium dodecylbenzenesulfonate (SDBS) as template. At fixed conditions (15 mM aniline and 5mM SDBS), polymerization rates obtained with 7D5L were 2.5-fold the rates obtained with commercial Trametes villosa laccase. Moreover, polyaniline yield was notably boosted to 75% by rising 7D5L amount to 0.15 μM, obtaining 1g of green polyaniline in 1L-reaction volume. The green polymer obtained with the selected system (7D5L/SDBS) holds excellent electrochemical and electro-conductive properties displayed in water-dispersible nanofibers, which is advantageous for the nanomaterial to be readily cast into uniform films for different applications.

Formation and composition of adsorbates on hydrophobic carbon surfaces from aqueous laccase-maltodextrin mixture suspension

Energy Technology Data Exchange (ETDEWEB)

Corrales Ureña, Yendry Regina, E-mail: yendry386@hotmail.com [UNESP São Paulo State University, Av. Eng. Luiz Edmundo Carrijo Coube, 14-01, Bauru, São Paulo (Brazil); Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM, Wiener Strasse 12, 28359 Bremen (Germany); Lisboa-Filho, Paulo Noronha [UNESP São Paulo State University, Av. Eng. Luiz Edmundo Carrijo Coube, 14-01, Bauru, São Paulo (Brazil); Szardenings, Michael [Fraunhofer Institute for Cell Therapy and Immunology IZI, Perlickstrasse 1, 04103 Leipzig (Germany); Gätjen, Linda; Noeske, Paul-Ludwig Michael; Rischka, Klaus [Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM, Wiener Strasse 12, 28359 Bremen (Germany)

2016-11-01

Highlights: • Less than 10 nm layer formed on carbon based materials composed by laccase and maltodextrin. • Improvement of the wettability of carbon based materials. • A protein-polysaccharide biofilm layer formation at solid liquid interface. • Stable layers formed under buffer and water rinsing. - Abstract: A robust procedure for the surface bio-functionalization of carbon surfaces was developed. It consists on the modification of carbon materials in contact with an aqueous suspension of the enzyme laccase from Trametes versicolor and the lyophilization agent maltodextrin, with the pH value adjusted close to the isoelectric point of the enzyme. We report in-situ investigations applying Quartz Crystal Microbalance with Dissipation (QCM-D) for carbon-coated sensor surfaces and, moreover, ex-situ measurements with static contact angle measurements, X-ray Photoelectron Spectroscopy (XPS) and Scanning Force Microscopy (SFM) for smooth Highly Oriented Pyrolytic Graphite (HOPG) substrates, for contact times between the enzyme formulation and the carbon material surface ranging from 20 s to 24 h. QCM-D studies reveals the formation of rigid layer of biomaterial, a few nanometers thin, which shows a strongly improved wettability of the substrate surface upon contact angle measurements. Following spectroscopic characterization, these layers are composed of mixtures of laccase and maltodextrin. The formation of these adsorbates is attributed to attractive interactions between laccase, the maltodextrin-based lyophilization agent and the hydrophobic carbon surfaces; a short-term contact between the aqueous laccase mixture suspension and HOPG surfaces is shown to merely result in de-wetting patterns influencing the results of contact angle measurements. The new enzyme-based surface modification of carbon-based materials is suggested to be applicable for the improvement of not only the wettability of low energy substrate surfaces with fluid formulations like coatings

The novel role of fungal intracellular laccase: used to screen hybrids between Hypsizigus marmoreus and Clitocybe maxima by protoplasmic fusion.

Science.gov (United States)

Xu, Jianzhong; Zhang, Junlan; Zhang, Weiguo; Hu, Kaihui

2012-08-01

Laccase has been proved important in decolorization of Remazol Brilliant Blue R (RBBR), oxidation of 2, 2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, lignin degradation and fruiting-body formation. The decolorization of RBBR by laccase was firstly used to screen protoplast fusants. Fusants were obtained by protoplast fusion between the strains of Hypsizigus marmoreus and Clitocybe maxima, and two fusants (IM1 and IIIM5) were screened on PDA medium containing RBBR. These fusants were significant higher in laccase activity than H. marmoreus, nearly 413 and 395 times, respectively. Their hyphal growth rates were also remarkable higher than H. marmoreus, nearly 1.5 and 1.4 times, respectively. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis showed these fusants contained the laccase, and the molecular mass of the laccase was consistent with the laccase of C. maxima, nearly 62 kDa. The pileus color of the IM1 and IIIM5 also showed partial recombined characteristics comparing to the parental strains, while biological efficiency ratios were prominent higher than that of H. marmoreus, up to 14.58 and 10.87 %, respectively. Randomly amplified polymorphic DNA bands of fusants not only were similar to parental bands, but presented new non-parental bands. Using the Unweighted pair-group method together with mathematic averages method to gain a dendrogram, in which the fusants showed intra-cluster variations. Significantly, H. marmoreus was the dominant parent, while C. maxima were distant from the fusants. The differences among IM1, IIIM5 and H. marmoreus, and the similarities among IM1, IIIM5 and C. maxima indicated IM1 and IIIM5 were somatic hybrids of H. marmoreus and C. maxima. Accordingly, it is feasible to use laccase to screen fusants of H. marmoreus and C. maxima.

Screening of inducers for laccase production by Lentinula edodes in liquid medium Seleção de indutores para produção de lacase por Lentinula edodes

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José Renato P. Cavallazzi

2005-12-01

Full Text Available 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, suggesting that no isozyme was produced.Lacases são enzimas envolvidas na degradação da lignina e produzidas por diversos organismos. Devido à sua baixa especificidade por substratos, seu potencial para utilização em aplicações biotecnológicas tem sido objeto de investigação. A adição de indutores de lacases ao meio de cultivo de microrganismos aumenta a produção dessas enzimas, facilitando sua purificação e utilização. Este trabalho teve como objetivo investigar o efeito de alguns compostos utilizados como indutores de lacases em fungos na produção destas enzimas por Lentinula edodes (shiitake. Previamente a utilização de indutores, foi selecionado um meio de cultura para a produção de

Stability of Slopes Reinforced with Truncated Piles

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Shu-Wei Sun

2016-01-01

Full Text Available Piles are extensively used as a means of slope stabilization. A novel engineering technique of truncated piles that are unlike traditional piles is introduced in this paper. A simplified numerical method is proposed to analyze the stability of slopes stabilized with truncated piles based on the shear strength reduction method. The influential factors, which include pile diameter, pile spacing, depth of truncation, and existence of a weak layer, are systematically investigated from a practical point of view. The results show that an optimum ratio exists between the depth of truncation and the pile length above a slip surface, below which truncating behavior has no influence on the piled slope stability. This optimum ratio is bigger for slopes stabilized with more flexible piles and piles with larger spacing. Besides, truncated piles are more suitable for slopes with a thin weak layer than homogenous slopes. In practical engineering, the piles could be truncated reasonably while ensuring the reinforcement effect. The truncated part of piles can be filled with the surrounding soil and compacted to reduce costs by using fewer materials.

Characterization of an Alkali- and Halide-Resistant Laccase Expressed in E. coli: CotA from Bacillus clausii

DEFF Research Database (Denmark)

Brander, Søren; Mikkelsen, Jørn Dalgaard; Kepp, Kasper Planeta

2014-01-01

The limitations of fungal laccases at higher pH and salt concentrations have intensified the search for new extremophilic bacterial laccases. We report the cloning, expression, and characterization of the bacterial cotA from Bacillus clausii, a supposed alkalophilic ortholog of cotA from B. subti...

Combination of Superheated Steam with Laccase Pretreatment Together with Size Reduction to Enhance Enzymatic Hydrolysis of Oil Palm Biomass

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Nur Fatin Athirah Ahmad Rizal

2018-04-01

Full Text Available The combination of superheated steam (SHS with ligninolytic enzyme laccase pretreatment together with size reduction was conducted in order to enhance the enzymatic hydrolysis of oil palm biomass into glucose. The oil palm empty fruit bunch (OPEFB and oil palm mesocarp fiber (OPMF were pretreated with SHS and ground using a hammer mill to sizes of 2, 1, 0.5 and 0.25 mm before pretreatment using laccase to remove lignin. This study showed that reduction of size from raw to 0.25 mm plays important role in lignin degradation by laccase that removed 38.7% and 39.6% of the lignin from OPEFB and OPMF, respectively. The subsequent saccharification process of these pretreated OPEFB and OPMF generates glucose yields of 71.5% and 63.0%, which represent a 4.6 and 4.8-fold increase, respectively, as compared to untreated samples. This study showed that the combination of SHS with laccase pretreatment together with size reduction could enhance the glucose yield.

Laccase Gene Expression and Vinasse Biodegradation by Trametes hirsuta Strain Bm-2

Directory of Open Access Journals (Sweden)

Raúl Tapia-Tussell

2015-08-01

Full Text Available Vinasse is the dark-colored wastewater that is generated by bioethanol distilleries from feedstock molasses. The vinasse that is generated from molasses contains high amounts of pollutants, including phenolic compounds and melanoindin. The goal of this work was to study the expression of laccase genes in the Trametes hirsuta strain Bm-2, isolated in Yucatan, Mexico, in the presence of phenolic compounds, as well as its effectiveness in removing colorants from vinasse. In the presence of all phenolic compounds tested (guaiacol, ferulic acid, and vanillic acid, increased levels of laccase-encoding mRNA were observed. Transcript levels in the presence of guaiacol were 40 times higher than those in the control. The lcc1 and lcc2 genes of T. hirsuta were differentially expressed; guaiacol and vanillin induced the expression of both genes, whereas ferulic acid only induced the expression of lcc2. The discoloration of vinasse was concomitant with the increase in laccase activity. The highest value of enzyme activity (2543.7 U/mL was obtained in 10% (v/v vinasse, which corresponded to a 69.2% increase in discoloration. This study demonstrates the potential of the Bm-2 strain of T. hirsuta for the biodegradation of vinasse.

Long term repeated prescribed burning increases evenness in the basidiomycete laccase gene pool in forest soils.

Science.gov (United States)

Artz, Rebekka R E; Reid, Eileen; Anderson, Ian C; Campbell, Colin D; Cairney, John W G

2009-03-01

Repeated prescribed burning alters the biologically labile fraction of nutrients and carbon of soil organic matter (SOM). Using a long-term (30 years) repeated burning experiment where burning has been carried out at a 2- or 4-year frequency, we analysed the effect of prescribed burning on gross potential C turnover rates and phenol oxidase activity in relation to shifts in SOM composition as observed using Fourier-transform infrared spectroscopy. In tandem, we assessed the genetic diversity of basidiomycete laccases. While the overall effect of burning was a decline in phenol oxidase activity, Shannon diversity and evenness of laccases was significantly higher in burned sites. Co-correspondence analysis of SOM composition and laccase operational taxonomic unit frequency data also suggested a strong correlation. While this correlation could indicate that the observed increase in laccase genetic diversity due to burning is due to increased resource diversity, a temporal replacement of the most abundant members of the assembly by an otherwise dormant pool of fungi cannot be excluded. As such, our results fit the intermediate disturbance hypothesis. Effects were stronger in plots burned in 2-year rotations, suggesting that the 4-year burn frequency may be a more sustainable practice to ensure the long-term stability of C cycling in such ecosystems.

Role of ethanol on growth, laccase production and protease activity in Pycnoporus cinnabarinus ss3

OpenAIRE

Meza, Juan Carlos; Auria, Richard; Lomascolo, A.; Sigoillot, J. C.; Casalot, Laurence

2007-01-01

Laccase production by the strain Pycnoporus cinnabarinus ss3 was studied in a solid-state culture on sugar-cane bagasse using chemical compounds as inducers (ethanol, methanol, veratryl alcohol and ferulic acid). Laccase productions were about 5- to 8.5-fold higher than non-induced cultures. Liquid-culture experiments with "Glabeled ethanol were conducted. Ninety-eight percent of the initial amount of C-14 from ethanol was recovered as (CO2)-C-14, C-14-biomass and soluble C-14-compounds (main...

On the Truncated Pareto Distribution with applications

OpenAIRE

Zaninetti, Lorenzo; Ferraro, Mario

2008-01-01

The Pareto probability distribution is widely applied in different fields such us finance, physics, hydrology, geology and astronomy. This note deals with an application of the Pareto distribution to astrophysics and more precisely to the statistical analysis of mass of stars and of diameters of asteroids. In particular a comparison between the usual Pareto distribution and its truncated version is presented. Finally a possible physical mechanism that produces Pareto tails for the distributio...

Adaptation of the delta-m and δ-fit truncation methods to vector radiative transfer: Effect of truncation on radiative transfer accuracy

International Nuclear Information System (INIS)

Sanghavi, Suniti; Stephens, Graeme

2015-01-01

In the presence of aerosol and/or clouds, the use of appropriate truncation methods becomes indispensable for accurate but cost-efficient radiative transfer computations. Truncation methods allow the reduction of the large number (usually several hundreds) of Fourier components associated with particulate scattering functions to a more manageable number, thereby making it possible to carry out radiative transfer computations with a modest number of streams. While several truncation methods have been discussed for scalar radiative transfer, few rigorous studies have been made of truncation methods for the vector case. Here, we formally derive the vector form of Wiscombe's delta-m truncation method. Two main sources of error associated with delta-m truncation are identified as the delta-separation error (DSE) and the phase-truncation error (PTE). The view angles most affected by truncation error occur in the vicinity of the direction of exact backscatter. This view geometry occurs commonly in satellite based remote sensing applications, and is hence of considerable importance. In order to deal with these errors, we adapt the δ-fit approach of Hu et al. (2000) [17] to vector radiative transfer. The resulting δBGE-fit is compared with the vectorized delta-m method. For truncation at l=25 of an original phase matrix consisting of over 300 Fourier components, the use of the δBGE-fit minimizes the error due to truncation at these view angles, while practically eliminating error at other angles. We also show how truncation errors have a distorting effect on hyperspectral absorption line shapes. The choice of the δBGE-fit method over delta-m truncation minimizes errors in absorption line depths, thus affording greater accuracy for sensitive retrievals such as those of XCO 2 from OCO-2 or GOSAT measurements. - Highlights: • Derives vector form for delta-m truncation method. • Adapts δ-fit truncation approach to vector RTE as δBGE-fit. • Compares truncation

In silico analysis of Pycnoporus cinnabarinus laccase active site with toxic industrial dyes.

Science.gov (United States)

Prasad, Nirmal K; Vindal, Vaibhav; Narayana, Siva Lakshmi; Ramakrishna, V; Kunal, Swaraj Priyaranjan; Srinivas, M

2012-05-01

Laccases belong to multicopper oxidases, a widespread class of enzymes implicated in many oxidative functions in various industrial oxidative processes like production of fine chemicals to bioremediation of contaminated soil and water. In order to understand the mechanisms of substrate binding and interaction between substrates and Pycnoporus cinnabarinus laccase, a homology model was generated. The resulted model was further validated and used for docking studies with toxic industrial dyes- acid blue 74, reactive black 5 and reactive blue 19. Interactions of chemical mediators with the laccase was also examined. The docking analysis showed that the active site always cannot accommodate the dye molecules, due to constricted nature of the active site pocket and steric hindrance of the residues whereas mediators are relatively small and can easily be accommodated into the active site pocket, which, thereafter leads to the productive binding. The binding properties of these compounds along with identification of critical active site residues can be used for further site-directed mutagenesis experiments in order to identify their role in activity and substrate specificity, ultimately leading to improved mutants for degradation of these toxic compounds.

ABTS-Modified Silica Nanoparticles as Laccase Mediators for Decolorization of Indigo Carmine Dye

Directory of Open Access Journals (Sweden)

Youxun Liu

2015-01-01

Full Text Available Efficient reuse and regeneration of spent mediators are highly desired for many of the laccases’ biotechnology applications. This investigation demonstrates that a redox mediator 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS covalently attached to silica nanoparticles (SNPs effectively mediated dye decolorization catalyzed by laccase. Characteristics of ABTS-modified silica nanoparticles (ABTS-SNPs were researched by scanning electron microscopy and Fourier-transformed infrared spectroscopy. When ABTS and ABTS-SNPs were used as laccase mediators, the decolorization yields of 96 and 95% were, respectively, obtained for indigo carmine dye. The results suggest that ABTS immobilized on SNPs can be used as laccase mediators as they retain almost the same efficiency as the free ABTS. The oxidized ABTS-SNPs were regenerated by their reduction reaction with ascorbic acid. Decolorization efficiency of regenerated ABTS-SNPs and their initial forms were found to be almost equivalent. Six reuse cycles for spent ABTS-SNPs were run for the treatment of indigo carmine, providing decolorization yields of 96–77%. Compared with free mediator, the immobilized mediators have the advantage of being easily recovered, regenerated, and reused making the whole process environmentally friendly.

Bio-Prospecting Laccases in the Bacterial Diversity of Activated Sludge From Pulp and Paper Industry.

Science.gov (United States)

Gupta, Vijaya; Capalash, Neena; Gupta, Naveen; Sharma, Prince

2017-03-01

Activated sludge is an artificial ecosystem known to harbor complex microbial communities. Bacterial diversity in activated sludge from pulp and paper industry was studied to bioprospect for laccase, the multicopper oxidase applicable in a large number of industries due to its ability to utilize a wide range of substrates. Bacterial diversity using 454 pyrosequencing and laccase diversity using degenerate primers specific to conserved copper binding domain of laccase like multicopper oxidase (LMCO) genes were investigated. 1231 OTUs out of 11,425 sequence reads for bacterial diversity and 11 OTUs out of 15 reads for LMCO diversity were formed. Phylum Proteobacteria (64.95 %) with genus Thauera (13.65 %) was most abundant followed by phylum Bacteriodetes (11.46 %) that included the dominant genera Paludibacter (1.93 %) and Lacibacter (1.32 %). In case of LMCOs, 40 % sequences showed affiliation with Proteobacteria and 46.6 % with unculturable bacteria, indicating considerable novelty, and 13.3 % with Bacteroidetes. LMCOs belonged to H and J families.

Characterization of the laccase-mediated oligomerization of 4-hydroxybenzoic acid

NARCIS (Netherlands)

Slagman, S.; Escorihuela Fuentes, J.; Zuilhof, H.; Franssen, M.C.R.

2016-01-01

Modifying inert poly(ethersulfone) membranes using laccase has proven to be an environmentally benign and easily applicable process to alter the membrane's surface properties. By this method phenolic acid monomers such as 4-hydroxybenzoic acid are grafted from the membrane surface to make it

Yeast Hosts for the Production of Recombinant Laccases: A Review

Czech Academy of Sciences Publication Activity Database

Antošová, Zuzana; Sychrová, Hana

2016-01-01

Roč. 58, č. 2 (2016), s. 93-116 ISSN 1073-6085 R&D Projects: GA TA ČR(CZ) TA01011461 Institutional support: RVO:67985823 Keywords : laccase * yeasts * heterologous expression * recombinant * expression optimization Subject RIV: EE - Microbiology, Virology Impact factor: 1.634, year: 2016

Computing correct truncated excited state wavefunctions

Science.gov (United States)

Bacalis, N. C.; Xiong, Z.; Zang, J.; Karaoulanis, D.

2016-12-01

We demonstrate that, if a wave function's truncated expansion is small, then the standard excited states computational method, of optimizing one "root" of a secular equation, may lead to an incorrect wave function - despite the correct energy according to the theorem of Hylleraas, Undheim and McDonald - whereas our proposed method [J. Comput. Meth. Sci. Eng. 8, 277 (2008)] (independent of orthogonality to lower lying approximants) leads to correct reliable small truncated wave functions. The demonstration is done in He excited states, using truncated series expansions in Hylleraas coordinates, as well as standard configuration-interaction truncated expansions.

Molecular modeling and simulation studies of recombinant laccase from Yersinia enterocolitica suggests significant role in the biotransformation of non-steroidal anti-inflammatory drugs

International Nuclear Information System (INIS)

Singh, Deepti; Rawat, Surender; Waseem, Mohd; Gupta, Sunita; Lynn, Andrew; Nitin, Mukesh; Ramchiary, Nirala; Sharma, Krishna Kant

2016-01-01

The YacK gene from Yersinia enterocolitica strain 7, cloned in pET28a vector and expressed in Escherichia coli BL21 (DE3), showed laccase activity when oxidized with 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) and guaiacol. The recombinant laccase protein was purified and characterized biochemically with a molecular mass of ≈58 KDa on SDS-PAGE and showed positive zymogram with ABTS. The protein was highly robust with optimum pH 9.0 and stable at 70 °C upto 12 h with residual activity of 70%. Kinetic constants, K m values, for ABTS and guaiacol were 675 μM and 2070 μM, respectively, with corresponding Vmax values of 0.125 μmol/ml/min and 6500 μmol/ml/min. It also possess antioxidative property against BSA and Cu 2+ /H 2 O 2 model system. Constant pH MD simulation studies at different protonation states of the system showed ABTS to be most stable at acidic pH, whereas, diclofenac at neutral pH. Interestingly, aspirin drifted out of the binding pocket at acidic and neutral pH, but showed stable binding at alkaline pH. The biotransformation of diclofenac and aspirin by laccase also corroborated the in silico results. This is the first report on biotransformation of non-steroidal anti-inflammatory drugs (NSAIDs) using recombinant laccase from gut bacteria, supported by in silico simulation studies. - Highlights: • Laccase from Yersinia enterocolitica strain 7 was expressed in Escherichia coli BL21 (DE3). • Recombinant laccase was found to be thermostable and alkali tolerant. • The in silico and experimental studied proves the biotransformation of NSAIDs. • Laccase binds to ligands differentially under different protonation state. • Laccase also possesses free radical scavenging property.

Molecular modeling and simulation studies of recombinant laccase from Yersinia enterocolitica suggests significant role in the biotransformation of non-steroidal anti-inflammatory drugs

Energy Technology Data Exchange (ETDEWEB)

Singh, Deepti; Rawat, Surender [Laboratory of Enzymology and Recombinant DNA Technology, Department of Microbiology, Maharshi Dayanand University, Rohtak 124001, Haryana (India); Waseem, Mohd; Gupta, Sunita; Lynn, Andrew [School of Computational & Integrative Sciences, Jawaharlal Nehru University, New Delhi 110067 (India); Nitin, Mukesh; Ramchiary, Nirala [School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067 (India); Sharma, Krishna Kant, E-mail: kekulsharma@gmail.com [Laboratory of Enzymology and Recombinant DNA Technology, Department of Microbiology, Maharshi Dayanand University, Rohtak 124001, Haryana (India)

2016-01-08

The YacK gene from Yersinia enterocolitica strain 7, cloned in pET28a vector and expressed in Escherichia coli BL21 (DE3), showed laccase activity when oxidized with 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) and guaiacol. The recombinant laccase protein was purified and characterized biochemically with a molecular mass of ≈58 KDa on SDS-PAGE and showed positive zymogram with ABTS. The protein was highly robust with optimum pH 9.0 and stable at 70 °C upto 12 h with residual activity of 70%. Kinetic constants, K{sub m} values, for ABTS and guaiacol were 675 μM and 2070 μM, respectively, with corresponding Vmax values of 0.125 μmol/ml/min and 6500 μmol/ml/min. It also possess antioxidative property against BSA and Cu{sup 2+}/H{sub 2}O{sub 2} model system. Constant pH MD simulation studies at different protonation states of the system showed ABTS to be most stable at acidic pH, whereas, diclofenac at neutral pH. Interestingly, aspirin drifted out of the binding pocket at acidic and neutral pH, but showed stable binding at alkaline pH. The biotransformation of diclofenac and aspirin by laccase also corroborated the in silico results. This is the first report on biotransformation of non-steroidal anti-inflammatory drugs (NSAIDs) using recombinant laccase from gut bacteria, supported by in silico simulation studies. - Highlights: • Laccase from Yersinia enterocolitica strain 7 was expressed in Escherichia coli BL21 (DE3). • Recombinant laccase was found to be thermostable and alkali tolerant. • The in silico and experimental studied proves the biotransformation of NSAIDs. • Laccase binds to ligands differentially under different protonation state. • Laccase also possesses free radical scavenging property.

Expression of a new laccase from Moniliophthora roreri at high levels in Pichia pastoris and its potential application in micropollutant degradation

NARCIS (Netherlands)

Bronikowski, Agathe; Hagedoorn, P.L.; Koschorreck, Katja; Urlacher, Vlada B.

2017-01-01

Laccases have gained significant attention due to their emerging applications including bioremediation, biomass degradation and biofuel cells. One of the prerequisites for the industrial application of laccases is their sufficient availability. However, expression levels of recombinantly

Fitting Social Network Models Using Varying Truncation Stochastic Approximation MCMC Algorithm

KAUST Repository

Jin, Ick Hoon

2013-10-01

The exponential random graph model (ERGM) plays a major role in social network analysis. However, parameter estimation for the ERGM is a hard problem due to the intractability of its normalizing constant and the model degeneracy. The existing algorithms, such as Monte Carlo maximum likelihood estimation (MCMLE) and stochastic approximation, often fail for this problem in the presence of model degeneracy. In this article, we introduce the varying truncation stochastic approximation Markov chain Monte Carlo (SAMCMC) algorithm to tackle this problem. The varying truncation mechanism enables the algorithm to choose an appropriate starting point and an appropriate gain factor sequence, and thus to produce a reasonable parameter estimate for the ERGM even in the presence of model degeneracy. The numerical results indicate that the varying truncation SAMCMC algorithm can significantly outperform the MCMLE and stochastic approximation algorithms: for degenerate ERGMs, MCMLE and stochastic approximation often fail to produce any reasonable parameter estimates, while SAMCMC can do; for nondegenerate ERGMs, SAMCMC can work as well as or better than MCMLE and stochastic approximation. The data and source codes used for this article are available online as supplementary materials. © 2013 American Statistical Association, Institute of Mathematical Statistics, and Interface Foundation of North America.

Crystal structure of CotA laccase complexed with 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonate) at a novel binding site

International Nuclear Information System (INIS)

Liu, Zhongchuan; Xie, Tian; Zhong, Qiuping; Wang, Ganggang

2016-01-01

The crystal structure of CotA complexed with 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonate) in a hole motif has been solved; this novel binding site could be a potential structure-based target for protein engineering of CotA laccase. The CotA laccase from Bacillus subtilis is an abundant component of the spore outer coat and has been characterized as a typical laccase. The crystal structure of CotA complexed with 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS) in a hole motif has been solved. The novel binding site was about 26 Å away from the T1 binding pocket. Comparison with known structures of other laccases revealed that the hole is a specific feature of CotA. The key residues Arg476 and Ser360 were directly bound to ABTS. Site-directed mutagenesis studies revealed that the residues Arg146, Arg429 and Arg476, which are located at the bottom of the novel binding site, are essential for the oxidation of ABTS and syringaldazine. Specially, a Thr480Phe variant was identified to be almost 3.5 times more specific for ABTS than for syringaldazine compared with the wild type. These results suggest this novel binding site for ABTS could be a potential target for protein engineering of CotA laccases

Crystal structure of CotA laccase complexed with 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonate) at a novel binding site

Energy Technology Data Exchange (ETDEWEB)

Liu, Zhongchuan; Xie, Tian [Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, People’s Republic of (China); Key Laboratory of Environmental Microbiology of Sichuan Province, Chengdu 610041, People’s Republic of (China); Zhong, Qiuping [Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, People’s Republic of (China); Key Laboratory of Environmental Microbiology of Sichuan Province, Chengdu 610041, People’s Republic of (China); University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of (China); Wang, Ganggang, E-mail: wanggg@cib.ac.cn [Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, People’s Republic of (China); Key Laboratory of Environmental Microbiology of Sichuan Province, Chengdu 610041, People’s Republic of (China)

2016-03-24

The crystal structure of CotA complexed with 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonate) in a hole motif has been solved; this novel binding site could be a potential structure-based target for protein engineering of CotA laccase. The CotA laccase from Bacillus subtilis is an abundant component of the spore outer coat and has been characterized as a typical laccase. The crystal structure of CotA complexed with 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS) in a hole motif has been solved. The novel binding site was about 26 Å away from the T1 binding pocket. Comparison with known structures of other laccases revealed that the hole is a specific feature of CotA. The key residues Arg476 and Ser360 were directly bound to ABTS. Site-directed mutagenesis studies revealed that the residues Arg146, Arg429 and Arg476, which are located at the bottom of the novel binding site, are essential for the oxidation of ABTS and syringaldazine. Specially, a Thr480Phe variant was identified to be almost 3.5 times more specific for ABTS than for syringaldazine compared with the wild type. These results suggest this novel binding site for ABTS could be a potential target for protein engineering of CotA laccases.

Biochemical Characteristics of Three Laccase Isoforms from the Basidiomycete Pleurotus nebrodensis

Directory of Open Access Journals (Sweden)

Xianghe Yuan

2016-02-01

Full Text Available The characterization of three laccase isoforms from Pleurotus nebrodensis is described. Isoenzymes Lac1, Lac2 and Lac3 were purified to homogeneity using ion exchange chromatography on DEAE-cellulose, CM-cellulose and Q-Sepharose and a gel filtration step on Superdex 75. The molecular weights of the purified laccases were estimated to be 68, 64 and 51 kDa, respectively. The isoenzymes demonstrated the same optimum pH at 3.0 but slightly different temperature optima: 50–60 °C for Lac1 and Lac3 and 60 °C for Lac2. Lac2 was always more stable than the other two isoforms and exposure to 50 °C for 120 min caused 30% loss in activity. Lac2 was relatively less stable than the other two isoforms when exposed to the pH range of 3.0–8.0 for 24 h, but inactivation only occurred initially, with around 70% residual activity being maintained during the whole process. Oxidative ability towards aromatic compounds varied substantially among the isoforms and each of them displayed preference toward some substrates. Kinetic constants (Km, Kcat were determined by using a 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid diammonium salt (ABTS assay, with Lac3 showing the best affinity and Lac2 displaying the highest catalytic efficiency. Amino acid sequences from peptides derived from digestion of isoenzymes showed great consistency with laccases in the databases.

Mixtures of truncated basis functions

DEFF Research Database (Denmark)

Langseth, Helge; Nielsen, Thomas Dyhre; Rumí, Rafael

2012-01-01

In this paper we propose a framework, called mixtures of truncated basis functions (MoTBFs), for representing general hybrid Bayesian networks. The proposed framework generalizes both the mixture of truncated exponentials (MTEs) framework and the mixture of polynomials (MoPs) framework. Similar t...

Applications of Fast Truncated Multiplication in Cryptography

Directory of Open Access Journals (Sweden)

Laszlo Hars

2006-12-01

Full Text Available Truncated multiplications compute truncated products, contiguous subsequences of the digits of integer products. For an n-digit multiplication algorithm of time complexity O(nα, with 1<α≤2, there is a truncated multiplication algorithm, which is constant times faster when computing a short enough truncated product. Applying these fast truncated multiplications, several cryptographic long integer arithmetic algorithms are improved, including integer reciprocals, divisions, Barrett and Montgomery multiplications, 2n-digit modular multiplication on hardware for n-digit half products. For example, Montgomery multiplication is performed in 2.6 Karatsuba multiplication time.

Properties of truncated multiplicity distributions

International Nuclear Information System (INIS)

Lupia, S.

1995-01-01

Truncation effects on multiplicity distributions are discussed. Observables sensitive to the tail, like factorial moments, factorial cumulants and their ratio, are shown to be strongly affected by truncation. A possible way to overcome this problem by looking at the head of the distribution is suggested. (author)

Properties of truncated multiplicity distributions

Energy Technology Data Exchange (ETDEWEB)

Lupia, S. [Turin Univ. (Italy). Dipt. di Fisica

1995-12-31

Truncation effects on multiplicity distributions are discussed. Observables sensitive to the tail, like factorial moments, factorial cumulants and their ratio, are shown to be strongly affected by truncation. A possible way to overcome this problem by looking at the head of the distribution is suggested. (author)

Autoindicating optical properties of laccase as the base of an optical biosensor film for phenol determination

Energy Technology Data Exchange (ETDEWEB)

Sanz, J.; Marcos, S. de; Galban, J. [University of Zaragoza, Analytical Biosensors Group (GBA), Analytical Chemistry Department, Faculty of Sciences, Zaragoza (Spain)

2012-08-15

In the context of sustainable analytical chemistry, phenol has been determined through its enzymatic reaction with laccase. The method has been studied and optimized through the autoindicating optical properties of laccase both by intrinsic molecular absorption and fluorescence. The method shows a linear range from 9.79.10{sup -6} to 7.50.10{sup -4} M with a relative standard deviation of 1.07 %. The molecular absorption methodology has been implemented in a polyacrylamide film for the design of an autoindicating optical sensor. In order to increase the lifetime of the sensor, the reversibility study of the enzymatic reaction has proposed, as a novelty, the regeneration of laccase with an oxidase-type enzyme (glucose oxidase). The lifetime of the sensor film has improved from 15 to 30 measurements. The reaction mechanism has also been studied and confirmed by fluorescence and molecular absorption. The method leads to the determination of phenol in environmental samples. (orig.)

Truncated Calogero-Sutherland models

Science.gov (United States)

Pittman, S. M.; Beau, M.; Olshanii, M.; del Campo, A.

2017-05-01

A one-dimensional quantum many-body system consisting of particles confined in a harmonic potential and subject to finite-range two-body and three-body inverse-square interactions is introduced. The range of the interactions is set by truncation beyond a number of neighbors and can be tuned to interpolate between the Calogero-Sutherland model and a system with nearest and next-nearest neighbors interactions discussed by Jain and Khare. The model also includes the Tonks-Girardeau gas describing impenetrable bosons as well as an extension with truncated interactions. While the ground state wave function takes a truncated Bijl-Jastrow form, collective modes of the system are found in terms of multivariable symmetric polynomials. We numerically compute the density profile, one-body reduced density matrix, and momentum distribution of the ground state as a function of the range r and the interaction strength.

Stable ABTS Immobilized in the MIL-100(Fe) Metal-Organic Framework as an Efficient Mediator for Laccase-Catalyzed Decolorization.

Science.gov (United States)

Liu, Youxun; Geng, Yuanyuan; Yan, Mingyang; Huang, Juan

2017-06-02

The successful encapsulation of 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), a well-known laccase mediator, within a mesoporous metal-organic framework sample (i.e., MIL-100(Fe)) was achieved using a one-pot hydrothermal synthetic method. The as-prepared ABTS@MIL-100(Fe) was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, nitrogen sorption, and cyclic voltammetry (CV). Our ABTS@MIL-100(Fe)-based electrode exhibited an excellent electrochemical response, indicating that MIL-100(Fe) provides an appropriate microenvironment for the immobilization and electroactivity of ABTS molecules. ABTS@MIL-100(Fe) was then evaluated as an immobilized laccase mediator for dye removal using indigo carmine (IC) as a model dye. Through the application of laccase in combination with a free (ABTS) or immobilized (ABTS@MIL-100(Fe)) mediator, decolorization yields of 95% and 94%, respectively, were obtained for IC after 50 min. In addition, following seven reuse cycles of ABTS@MIL-100(Fe) for dye treatment, a decolorization yield of 74% was obtained. Dye decolorization occurred through the breakdown of the chromophoric group by the Laccase/ABTS@MIL-100(Fe) system, and a catalytic mechanism was proposed. We therefore expect that the stability, reusability, and validity of ABTS@MIL-100(Fe) as a laccase mediator potentially render it a promising tool for dye removal, in addition to reducing the high running costs and potential toxicity associated with synthetic mediators.

Lamp with a truncated reflector cup

Science.gov (United States)

Li, Ming; Allen, Steven C.; Bazydola, Sarah; Ghiu, Camil-Daniel

2013-10-15

A lamp assembly, and method for making same. The lamp assembly includes first and second truncated reflector cups. The lamp assembly also includes at least one base plate disposed between the first and second truncated reflector cups, and a light engine disposed on a top surface of the at least one base plate. The light engine is configured to emit light to be reflected by one of the first and second truncated reflector cups.

Generation of truncated recombinant form of tumor necrosis factor ...

African Journals Online (AJOL)

Purpose: To produce truncated recombinant form of tumor necrosis factor receptor 1 (TNFR1), cysteine-rich domain 2 (CRD2) and CRD3 regions of the receptor were generated using pET28a and E. coli/BL21. Methods: DNA coding sequence of CRD2 and CRD3 was cloned into pET28a vector and the corresponding ...

Decoration of the Truncated Tetrahedron—An Archimedean Polyhedron—To Produce a New Class of Convex Equilateral Polyhedra with Tetrahedral Symmetry

Directory of Open Access Journals (Sweden)

Stan Schein

2016-08-01

Full Text Available The Goldberg construction of symmetric cages involves pasting a patch cut out of a regular tiling onto the faces of a Platonic host polyhedron, resulting in a cage with the same symmetry as the host. For example, cutting equilateral triangular patches from a 6.6.6 tiling of hexagons and pasting them onto the full triangular faces of an icosahedron produces icosahedral fullerene cages. Here we show that pasting cutouts from a 6.6.6 tiling onto the full hexagonal and triangular faces of an Archimedean host polyhedron, the truncated tetrahedron, produces two series of tetrahedral (Td fullerene cages. Cages in the first series have 28n2 vertices (n ≥ 1. Cages in the second (leapfrog series have 3 × 28n2. We can transform all of the cages of the first series and the smallest cage of the second series into geometrically convex equilateral polyhedra. With tetrahedral (Td symmetry, these new polyhedra constitute a new class of “convex equilateral polyhedra with polyhedral symmetry”. We also show that none of the other Archimedean polyhedra, six with octahedral symmetry and six with icosahedral, can host full-face cutouts from regular tilings to produce cages with the host’s polyhedral symmetry.

Direct analysis by time-of-flight secondary ion mass spectrometry reveals action of bacterial laccase-mediator systems on both hardwood and softwood samples.

Science.gov (United States)

Goacher, Robyn E; Braham, Erick J; Michienzi, Courtney L; Flick, Robert M; Yakunin, Alexander F; Master, Emma R

2017-12-29

The modification and degradation of lignin play a vital role in carbon cycling as well as production of biofuels and bioproducts. The possibility of using bacterial laccases for the oxidation of lignin offers a route to utilize existing industrial protein expression techniques. However, bacterial laccases are most frequently studied on small model compounds that do not capture the complexity of lignocellulosic materials. This work studied the action of laccases from Bacillus subtilis and Salmonella typhimurium (EC 1.10.3.2) on ground wood samples from yellow birch (Betula alleghaniensis) and red spruce (Picea rubens). The ability of bacterial laccases to modify wood can be facilitated by small molecule mediators. Herein, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), gallic acid and sinapic acid mediators were tested. Direct analysis of the wood samples was achieved by time-of-flight secondary ion mass spectrometry (ToF-SIMS), a surface sensitive mass spectrometry technique that has characteristic peaks for H, G and S lignin. The action of the bacterial laccases on both wood samples was demonstrated and revealed a strong mediator influence. The ABTS mediator led to delignification, evident in an overall increase of polysaccharide peaks in the residual solid, along with equal loss of G and S-lignin peaks. The gallic acid mediator demonstrated minimal laccase activity. Meanwhile, the sinapic acid mediator altered the S/G peak ratio consistent with mediator attaching to the wood solids. The current investigation demonstrates the action of bacterial laccase-mediator systems directly on woody materials, and the potential of using ToF-SIMS to uncover the fundamental and applied role of bacterial enzymes in lignocellulose conversion. © 2017 Scandinavian Plant Physiology Society.

Formal truncations of connected kernel equations

International Nuclear Information System (INIS)

Dixon, R.M.

1977-01-01

The Connected Kernel Equations (CKE) of Alt, Grassberger and Sandhas (AGS); Kouri, Levin and Tobocman (KLT); and Bencze, Redish and Sloan (BRS) are compared against reaction theory criteria after formal channel space and/or operator truncations have been introduced. The Channel Coupling Class concept is used to study the structure of these CKE's. The related wave function formalism of Sandhas, of L'Huillier, Redish and Tandy and of Kouri, Krueger and Levin are also presented. New N-body connected kernel equations which are generalizations of the Lovelace three-body equations are derived. A method for systematically constructing fewer body models from the N-body BRS and generalized Lovelace (GL) equations is developed. The formally truncated AGS, BRS, KLT and GL equations are analyzed by employing the criteria of reciprocity and two-cluster unitarity. Reciprocity considerations suggest that formal truncations of BRS, KLT and GL equations can lead to reciprocity-violating results. This study suggests that atomic problems should employ three-cluster connected truncations and that the two-cluster connected truncations should be a useful starting point for nuclear systems

Biodegradation of brominated aromatics by cultures and laccase of Trametes versicolor

Czech Academy of Sciences Publication Activity Database

Uhnáková, Bronislava; Petříčková, Alena; Biedermann, David; Homolka, Ladislav; Vejvoda, Vojtěch; Bednář, P.; Papoušková, B.; Šulc, Miroslav; Martínková, Ludmila

2009-01-01

Roč. 76, č. 6 (2009), s. 826-832 ISSN 0045-6535 R&D Projects: GA MŠk 2B06151 Institutional research plan: CEZ:AV0Z50200510 Keywords : Brominated phenols * Tetrabromobisphenol A * Laccase Subject RIV: CE - Biochemistry Impact factor: 3.253, year: 2009

Laccase from Aspergillus niger: A novel tool to graft multifunctional materials of interests and their characterization.

Science.gov (United States)

Iqbal, Hafiz M N; Kyazze, Godfrey; Tron, Thierry; Keshavarz, Tajalli

2018-03-01

In the present study, we propose a green route to prepare poly(3-hydroxybutyrate) [(P(3HB)] grafted ethyl cellulose (EC) based green composites with novel characteristics through laccase-assisted grafting. P(3HB) was used as a side chain whereas, EC as a backbone material under ambient processing conditions. A novel laccase obtained from Aspergillus niger through its heterologous expression in Saccharomyces cerevisiae was used as a green catalyst for grafting purposes without the use of additional initiator and/or cross-linking agents. Subsequently, the resulting P(3HB)- g -EC composites were characterized using a range of analytical and imagining techniques. Fourier transform infrared spectroscopy (FT-IR) spectra showed an increase in the hydrogen-bonding type interactions between the side chains of P(3HB) and backbone material of EC. Evidently, X-ray diffraction (XRD) analysis revealed a decrease in the crystallinity of the P(3HB)- g -EC composites as compared to the pristine individual polymers. A homogeneous P(3HB) distribution was also achieved in case of the graft composite prepared in the presence of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) as a mediator along with laccase as compared to the composite prepared using pure laccase alone. A substantial improvement in the thermal and mechanical characteristics was observed for grafted composites up to the different extent as compared to the pristine counterparts. The hydrophobic/hydrophilic properties of the grafted composites were better than those of the pristine counterparts.

Perspective on rainbow-ladder truncation

International Nuclear Information System (INIS)

Eichmann, G.; Alkofer, R.; Krassnigg, A.; Cloeet, I. C.; Roberts, C. D.

2008-01-01

Prima facie the systematic implementation of corrections to the rainbow-ladder truncation of QCD's Dyson-Schwinger equations will uniformly reduce in magnitude those calculated mass-dimensioned results for pseudoscalar and vector meson properties that are not tightly constrained by symmetries. The aim and interpretation of studies employing rainbow-ladder truncation are reconsidered in this light

Modulating indium doped tin oxide electrode properties for laccase electron transfer enhancement

Energy Technology Data Exchange (ETDEWEB)

Diaconu, Mirela [National Institute for Biological Sciences, Centre of Bioanalysis, 296 Spl. Independentei, Bucharest 060031 (Romania); Chira, Ana [National Institute for Biological Sciences, Centre of Bioanalysis, 296 Spl. Independentei, Bucharest 060031 (Romania); Politehnica University of Bucharest, Faculty of Applied Chemistry and Materials Science, 1-7 Polizu Str., 011061 (Romania); Radu, Lucian, E-mail: gl_radu@chim.upb.ro [Politehnica University of Bucharest, Faculty of Applied Chemistry and Materials Science, 1-7 Polizu Str., 011061 (Romania)

2014-08-28

Indium doped tin oxide (ITO) electrodes were functionalized with gold nanoparticles (GNPs) and cysteamine monolayer to enhance the heterogeneous electron transfer process of laccase from Trametes versicolor. The assembly of GNP on ITO support was performed through generation of H{sup +} species at the electrode surface by hydroquinone electrooxidation at 0.9 V vs Ag/AgCl. Uniform distribution of gold nanoparticle aggregates on electrode surfaces was confirmed by atomic force microscopy. The size of GNP aggregates was in the range of 200–500 nm. The enhanced charge transfer at the GNP functionalized ITO electrodes was observed by cyclic voltammetry (CV) and electrochemical impedance spectroscopy. Electrocatalytic behavior of laccase immobilized on ITO modified electrode toward oxygen reduction reaction was evaluated using CV in the presence of 2,2′-azino-bis 3-ethylbenzothiazoline-6-sulfuric acid (ABTS). The obtained sigmoidal-shaped voltammograms for ABTS reduction in oxygen saturated buffer solution are characteristic for a catalytic process. The intensity of catalytic current increased linearly with mediator concentration up to 6.2 × 10{sup −4} M. The registered voltammogram in the absence of ABTS mediator clearly showed a significant faradaic current which is the evidence of the interfacial oxygen reduction. - Highlights: • Assembly of gold nanoparticles on indium tin oxide support at positive potentials • Electrochemical and morphological evaluation of the gold nanoparticle layer assembly • Bioelectrocatalytic oxygen reduction on laccase modified electrode.

Enhanced removal of aqueous acetaminophen by a laccase-catalyzed oxidative coupling reaction under a dual-pH optimization strategy.

Science.gov (United States)

Wang, Kaidong; Huang, Ke; Jiang, Guoqiang

2018-03-01

Acetaminophen is one kind of pharmaceutical contaminant that has been detected in municipal water and is hard to digest. A laccase-catalyzed oxidative coupling reaction is a potential method of removing acetaminophen from water. In the present study, the kinetics of radical polymerization combined with precipitation was studied, and the dual-pH optimization strategy (the enzyme solution at pH7.4 being added to the substrate solution at pH4.2) was proposed to enhance the removal efficiency of acetaminophen. The reaction kinetics that consisted of the laccase-catalyzed oxidation, radical polymerization and precipitation were studied by UV in situ, LC-MS and DLS (dynamic light scattering) in situ. The results showed that the laccase-catalyzed oxidation is the rate-limiting step in the whole process. The higher rate of enzyme-catalyzed oxidation under a dual-pH optimization strategy led to much faster formation of the dimer, trimer and tetramer. Similarly, the formation of polymerized products that could precipitate naturally from water was faster. Under the dual-pH optimization strategy, the initial laccase activity was increased approximately 2.9-fold, and the activity remained higher for >250s, during which approximately 63.7% of the total acetaminophen was transformed into biologically inactive polymerized products, and part of these polymerized products precipitated from the water. Laccase belongs to the family of multi-copper oxidases, and the present study provides a universal method to improve the activity of multi-copper oxidases for the high-performance removal of phenol and its derivatives. Copyright © 2017 Elsevier B.V. All rights reserved.

DECOLORIZATION OF DENIM DYESTUFF BY LACCASE ENZYME

Directory of Open Access Journals (Sweden)

Serap GEDİKLİ

2011-02-01

Full Text Available Large quantities of dyes used in the textile industry are discharged to recipient environment during manufacture. This situation is beginning of a process which is difficult to recovery and relevant toenvironment and human health. Therefore, pollution of dyestuff produced textile industry will be reduced by cleaning of polluted area and integrating biological approaches with technologies havingpolluting potential. In scope of this study, commercial denim dye was decolorized by using high laccase activity culture supernatant of Trametes versicolor ATCC 200801 pellets grown in potato dextrose broth including wheat bran and determined optimum conditions. In the result of experiments done, pH, initial dye concentration, temperature and incubation time were selected 4.0, 75 mg/l, 55 oCand 120 minutes, respectively. 68.02 % of decolorization was obtained at the determined optimum conditions. Furthermore, adding different metal ions to find in textile wastewater and supplementarychemical materials used fabric dyeing process to reaction medium, potential of decolorization copied with improvement was investigated effects of these. When the obtained data were examined, pollutantswhich tested at optimum conditions were observed not affected negatively decolorization. Even in the presence of Tween 80 detected the maximum inhibitor effect, 54.68 % of decolorization was obtained.

Laccase-Functionalized Graphene Oxide Assemblies as Efficient Nanobiocatalysts for Oxidation Reactions

NARCIS (Netherlands)

Patila, Michaela; Kouloumpis, Antonios; Gournis, Dimitrios; Rudolf, Petra; Stamatis, Haralambos

Multi-layer graphene oxide-enzyme nanoassemblies were prepared through the multi-point covalent immobilization of laccase from Trametes versicolor (TvL) on functionalized graphene oxide (fGO). The catalytic properties of the fGO-TvL nanoassemblies were found to depend on the number of the graphene

Variability of Laccase Activity in the White-Rot Basidiomycete Pleurotus ostreatus

Czech Academy of Sciences Publication Activity Database

Baldrian, Petr; Gabriel, Jiří

2002-01-01

Roč. 47, č. 4 (2002), s. 385-390 ISSN 0015-5632 R&D Projects: GA ČR GP204/02/P100 Institutional research plan: CEZ:AV0Z5020903 Keywords : laccase * pleurotus ostreatus Subject RIV: EE - Microbiology, Virology Impact factor: 0.979, year: 2002

Clustered survival data with left-truncation

DEFF Research Database (Denmark)

Eriksson, Frank; Martinussen, Torben; Scheike, Thomas H.

2015-01-01

Left-truncation occurs frequently in survival studies, and it is well known how to deal with this for univariate survival times. However, there are few results on how to estimate dependence parameters and regression effects in semiparametric models for clustered survival data with delayed entry....... Surprisingly, existing methods only deal with special cases. In this paper, we clarify different kinds of left-truncation and suggest estimators for semiparametric survival models under specific truncation schemes. The large-sample properties of the estimators are established. Small-sample properties...

High-yield water-based synthesis of truncated silver nanocubes

International Nuclear Information System (INIS)

Chang, Yun-Min; Lu, I-Te; Chen, Chih-Yuan; Hsieh, Yu-Chi; Wu, Pu-Wei

2014-01-01

Highlights: • Development of a water-based formula to fabricate truncated Ag nanocubes. • The sample exhibits (1 0 0), (1 1 0), and (1 1 1) on the facets, edges, and corners. • The sample shows three characteristic absorption peaks due to plasma resonance. -- Abstract: A high-yield water-based hydrothermal synthesis was developed using silver nitrate, ammonia, glucose, and cetyltrimethylammonium bromide (CTAB) as precursors to synthesize truncated silver nanocubes with uniform sizes and in large quantities. With a fixed CTAB concentration, truncated silver nanocubes with sizes of 49.3 ± 4.1 nm were produced when the molar ratio of glucose/silver cation was maintained at 0.1. The sample exhibited (1 0 0), (1 1 0), and (1 1 1) planes on the facets, edges, and corners, respectively. In contrast, with a slightly larger glucose/silver cation ratio of 0.35, well-defined nanocubes with sizes of 70.9 ± 3.8 nm sizes were observed with the (1 0 0) plane on six facets. When the ratio was further increased to 1.5, excess reduction of silver cations facilitated the simultaneous formation of nanoparticles with cubic, spherical, and irregular shapes. Consistent results were obtained from transmission electron microscopy, scanning electron microscopy, X-ray diffraction, and UV–visible absorption measurements

High-yield water-based synthesis of truncated silver nanocubes

Energy Technology Data Exchange (ETDEWEB)

Chang, Yun-Min; Lu, I-Te; Chen, Chih-Yuan; Hsieh, Yu-Chi; Wu, Pu-Wei, E-mail: ppwu@mail.nctu.edu.tw

2014-02-15

Highlights: • Development of a water-based formula to fabricate truncated Ag nanocubes. • The sample exhibits (1 0 0), (1 1 0), and (1 1 1) on the facets, edges, and corners. • The sample shows three characteristic absorption peaks due to plasma resonance. -- Abstract: A high-yield water-based hydrothermal synthesis was developed using silver nitrate, ammonia, glucose, and cetyltrimethylammonium bromide (CTAB) as precursors to synthesize truncated silver nanocubes with uniform sizes and in large quantities. With a fixed CTAB concentration, truncated silver nanocubes with sizes of 49.3 ± 4.1 nm were produced when the molar ratio of glucose/silver cation was maintained at 0.1. The sample exhibited (1 0 0), (1 1 0), and (1 1 1) planes on the facets, edges, and corners, respectively. In contrast, with a slightly larger glucose/silver cation ratio of 0.35, well-defined nanocubes with sizes of 70.9 ± 3.8 nm sizes were observed with the (1 0 0) plane on six facets. When the ratio was further increased to 1.5, excess reduction of silver cations facilitated the simultaneous formation of nanoparticles with cubic, spherical, and irregular shapes. Consistent results were obtained from transmission electron microscopy, scanning electron microscopy, X-ray diffraction, and UV–visible absorption measurements.

The Dynamics of Truncated Black Hole Accretion Disks. I. Viscous Hydrodynamic Case

Energy Technology Data Exchange (ETDEWEB)

Hogg, J. Drew; Reynolds, Christopher S. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)

2017-07-10

Truncated accretion disks are commonly invoked to explain the spectro-temporal variability in accreting black holes in both small systems, i.e., state transitions in galactic black hole binaries (GBHBs), and large systems, i.e., low-luminosity active galactic nuclei (LLAGNs). In the canonical truncated disk model of moderately low accretion rate systems, gas in the inner region of the accretion disk occupies a hot, radiatively inefficient phase, which leads to a geometrically thick disk, while the gas in the outer region occupies a cooler, radiatively efficient phase that resides in the standard geometrically thin disk. Observationally, there is strong empirical evidence to support this phenomenological model, but a detailed understanding of the dynamics of truncated disks is lacking. We present a well-resolved viscous, hydrodynamic simulation that uses an ad hoc cooling prescription to drive a thermal instability and, hence, produce the first sustained truncated accretion disk. With this simulation, we perform a study of the dynamics, angular momentum transport, and energetics of a truncated disk. We find that the time variability introduced by the quasi-periodic transition of gas from efficient cooling to inefficient cooling impacts the evolution of the simulated disk. A consequence of the thermal instability is that an outflow is launched from the hot/cold gas interface, which drives large, sub-Keplerian convective cells into the disk atmosphere. The convective cells introduce a viscous θ − ϕ stress that is less than the generic r − ϕ viscous stress component, but greatly influences the evolution of the disk. In the truncated disk, we find that the bulk of the accreted gas is in the hot phase.

Laccase 1 gene from Plutella xylostella (PxLac1) and its functions in humoral immune response.

Science.gov (United States)

Wang, Ze-Hua; Hu, Rong-Min; Ye, Xi-Qian; Huang, Jian-Hua; Chen, Xue-Xin; Shi, Min

Laccase (EC 1.10.3.2) is a phenoloxidase found in many insect species. The Laccase 1 gene from Plutella xylostella (PxLac1) was cloned, and its expression patterns and functions were determined using qPCR and RNAi methods. The results showed that the expression levels of PxLac1 were consistently high in all larval stages, and the most abundant was in the midgut during the 4th instar stage. Moreover, the expression of PxLac1 was up-regulated in response to bacterial infection, and decreased 24 h after being parasitized by Cotesia vestalis. Further analyses indicated that the effect of parasitization on PxLac1 was induced by active C. vestalis Bracovirus (CvBV). Haemocyte-free hemolymph phenoloxidase (PO) activity was suppressed when PxLac1 was treated with RNAi. Our results provide evidence for a connection between the Laccase 1 gene and insect immunity, and revealed that parasitoid polydnavirus suppresses host PO activity via PxLac1 regulation. Copyright © 2018. Published by Elsevier Ltd.

Synthesis and effect of modification on methacylate - acrylate microspheres for Trametes versicolor laccase enzyme immobilization

Science.gov (United States)

Mazlan, Siti Zulaikha; Hanifah, Sharina Abu

2014-09-01

Immobilization of laccase on the modified copolymer methacrylate-acrylate microspheres was studied. A poly (glycidyl methacrylate-co-n-butyl acrylate) microsphere consists of epoxy groups were synthesized using suspension photocuring technique. The epoxy group in poly (GMA-nBA) microspheres were converted into amino groups with aldehyde group. Laccase immobilization is based on having the amino groups on the enzyme surface and aldehyde group on the microspheres via covalent binding. Fourier transform infrared spectroscopy (FT-IR) analysis proved the successful surface modification on microspheres. The FTIR spectrum shows the characteristic peaks at 1646 cm-1 assigned to the conformation of the polymerization that took place between monomer GMA and nBA respectively. In addition, after modification, FTIR peaks that assigned to the epoxy ring (844 cm-1 and 904 cm-1) were decreased. The results obtained from FTIR method signify good agreement with the epoxy content method. Hence, the activity of the laccase-immobilized microspheres increased upon increasing the epoxy content. Furthermore, poly (GMA-nBA) exhibited uniform microspheres with below 2 μm surface. Immobilized enzyme showed a broader pH profile and higher temperature compared native enzyme.

Effects of Temperature and pH on Immobilized Laccase Activity in Conjugated Methacrylate-Acrylate Microspheres

Directory of Open Access Journals (Sweden)

Siti Zulaikha Mazlan

2017-01-01

Full Text Available Immobilization of laccase on the functionalized methacrylate-acrylate copolymer microspheres was studied. Poly(glycidyl methacrylate-co-n-butyl acrylate microspheres consisting of epoxy groups were synthesized using facile emulsion photocuring technique. The epoxy groups in poly(GMA-co-nBA microspheres were then converted to amino groups. Laccase immobilization is based on covalent binding via amino groups on the enzyme surface and aldehyde group on the microspheres. The FTIR spectra showed peak at 1646 cm−1 assigned to the conformation of the polymerization that referred to GMA and nBA monomers, respectively. After modification of the polymer, intensity of FTIR peaks assigned to the epoxy ring at 844 cm−1 and 904 cm−1 was decreased. The results obtained from FTIR exhibit a good agreement with the epoxy content method. The activity of laccase-immobilized microspheres increased upon increasing the epoxy content. Furthermore, poly(GMA-co-nBA microspheres revealed uniform size below 2 µm that contributes to large surface area of the microspheres to be used as a matrix, thus increasing the enzyme capacity and enzymatic reaction. Immobilized enzyme also shifted to higher pH and temperature compared to free enzyme.

Characterisation of manganese peroxidase and laccase producing bacteria capable for degradation of sucrose glutamic acid-Maillard reaction products at different nutritional and environmental conditions.

Science.gov (United States)

Kumar, Vineet; Chandra, Ram

2018-02-02

Maillard reactions products (MRPs) are a major colorant of distillery effluent. It is major source of environmental pollution due to its complex structure and recalcitrant nature. This study has revealed that sucrose glutamic acid-Maillard reaction products (SGA-MRPs) showed many absorption peaks between 200 and 450 nm. The absorption maximum peak was noted at 250 nm in spectrophotometric detection. This indicated the formation of variable molecular weight Maillard products during the SGA-MRPs formation at high temperature. The identified aerobic bacterial consortium consisting Klebsiella pneumoniae (KU726953), Salmonella enterica (KU726954), Enterobacter aerogenes (KU726955), Enterobacter cloaceae (KU726957) showed optimum production of MnP and laccase at 120 and 144 h of growth, respectively. The potential bacterial consortium showed decolourisation of Maillard product up to 70% in presence of glucose (1%), peptone (0.1%) at optimum pH (8.1), temperature (37 °C) and shaking speed (180 rpm) within 192 h of incubation. The reduction of colour of Maillard product correlated with shifting of absorption peaks in UV-Vis spectrophotometry analysis. Further, the changing of functional group in FT-IR data showed appearance of new peaks and GC-MS analysis of degraded sample revealed the depolymerisation of complex MRPs. The toxicity evaluation using seed of Phaseolus mungo L. showed reduction of toxicity of MRPs after bacterial treatment. Hence, this study concluded that developed bacterial consortium have capability for decolourisation of MRPs due to high content of MnP and laccase.

Banana peel: a potential substrate for laccase production by Aspergillus fumigatus VkJ2.4.5 in solid-state fermentation.

Science.gov (United States)

Vivekanand, V; Dwivedi, Pallavi; Pareek, Nidhi; Singh, Rajesh P

2011-09-01

In solid-state fermentation, among various solid supports evaluated, banana peel was found to be an ideal support and resulted into higher levels of laccase (6281.4 ± 63.60 U l(-1)) along with notable levels of manganese peroxidase production (1339.0 ± 131.23 U l(-1)) by Aspergillus fumigatus VkJ2.4.5. Maximum levels of laccase was achieved under derived conditions consisting of 80% of moisture level, 6 days of incubation period, 6% inoculum level, and an aeration level of 2.5 l min(-1). A column-tray bioreactor was designed to scale up and economize the enzyme production in three successive cycles of fermentation using the same fungal biomass. Thermal and pH stability profiles revealed that enzyme was stable up to 50°C and at varying pH range from 5-9 for up to 2 h. The apparent molecular weight of laccase was found to be 34 ± 1 kDa. MALDI-TOF/TOF analysis of the protein showed significant homology with maximum identity of 67% to other laccases reported in database.

Laccase activity in soils: Considerations for the measurement of enzyme activity

Czech Academy of Sciences Publication Activity Database

Eichlerová, Ivana; Šnajdr, Jaroslav; Baldrian, Petr

2012-01-01

Roč. 88, č. 10 (2012), s. 1154-1160 ISSN 0045-6535 R&D Projects: GA MŠk(CZ) OC10064; GA MŠk(CZ) ME10152; GA MZe QH72216 Institutional support: RVO:61388971 Keywords : Laccase * Soil * Michaelis constant Subject RIV: EE - Microbiology, Virology Impact factor: 3.137, year: 2012

Purification and characterization of an extracellular, thermo-alkali-stable, metal tolerant laccase from Bacillus tequilensis SN4.

Directory of Open Access Journals (Sweden)

Sonica Sondhi

Full Text Available A novel extracellular thermo-alkali-stable laccase from Bacillus tequilensis SN4 (SN4LAC was purified to homogeneity. The laccase was a monomeric protein of molecular weight 32 KDa. UV-visible spectrum and peptide mass fingerprinting results showed that SN4LAC is a multicopper oxidase. Laccase was active in broad range of phenolic and non-phenolic substrates. Catalytic efficiency (kcat/Km showed that 2, 6-dimethoxyphenol was most efficiently oxidized by the enzyme. The enzyme was inhibited by conventional inhibitors of laccase like sodium azide, cysteine, dithiothreitol and β-mercaptoethanol. SN4LAC was found to be highly thermostable, having temperature optimum at 85°C and could retain more than 80% activity at 70°C for 24 h. The optimum pH of activity for 2, 6-dimethoxyphenol, 2, 2'-azino bis[3-ethylbenzthiazoline-6-sulfonate], syringaldazine and guaiacol was 8.0, 5.5, 6.5 and 8.0 respectively. Enzyme was alkali-stable as it retained more than 75% activity at pH 9.0 for 24 h. Activity of the enzyme was significantly enhanced by Cu2+, Co2+, SDS and CTAB, while it was stable in the presence of halides, most of the other metal ions and surfactants. The extracellular nature and stability of SN4LAC in extreme conditions such as high temperature, pH, heavy metals, halides and detergents makes it a highly suitable candidate for biotechnological and industrial applications.

Decolorization of textile dye RB19 using volcanic rock matrix immobilized Bacillus thuringiensis cells with surface displayed laccase.

Science.gov (United States)

Wan, Juan; Sun, Xiaowen; Liu, Cheng; Tang, Mengjun; Li, Lin; Ni, Hong

2017-06-01

A triplicate volcanic rock matrix-Bacillus thuringiensis-laccase WlacD (VRMs-Bt-WlacD) dye decolorization system was developed. WlacD was displayed on the B. thuringiensis MB174 cell surface to prepare a whole-cell laccase biocatalyst by using two repeat N-terminal domains of autolysin Mbg (Mbgn) 2 as the anchoring motif. Immunofluorescence microscopic assays confirmed that the fusion protein (Mbgn) 2 -WlacD was anchored on the surface of the recombinant B. thuringiensis MB174. After optimization by a single factor test, L 9 (3 4 )-orthogonal test, Plackett-Burman test, steepest ascent method, and Box-Behnken response surface methodology, the whole-cell specific laccase activity of B. thuringiensis MB174 was improved to 555.2 U L -1 , which was 2.25 times than that of the primary culture condition. Optimized B. thuringiensis MB174 cells were further adsorbed by VRMs to prepare VRMs-Bt-WlacD, an immobilized whole-cell laccase biocatalyst. Decolorization capacity of as-prepared VRMs-Bt-WlacD toward an initial concentration of 500 mg L -1 of an textile dye reactive blue 19 (RB19) aqueous solution reached 72.36% at a solid-to-liquid ratio of 10 g-100 mL. Repeated decolorization-activation operations showed the high decolorization capacity of VRMs-Bt-WlacD and have the potential for large-scale or continuous operations.

Truncation correction for oblique filtering lines

International Nuclear Information System (INIS)

Hoppe, Stefan; Hornegger, Joachim; Lauritsch, Guenter; Dennerlein, Frank; Noo, Frederic

2008-01-01

State-of-the-art filtered backprojection (FBP) algorithms often define the filtering operation to be performed along oblique filtering lines in the detector. A limited scan field of view leads to the truncation of those filtering lines, which causes artifacts in the final reconstructed volume. In contrast to the case where filtering is performed solely along the detector rows, no methods are available for the case of oblique filtering lines. In this work, the authors present two novel truncation correction methods which effectively handle data truncation in this case. Method 1 (basic approach) handles data truncation in two successive preprocessing steps by applying a hybrid data extrapolation method, which is a combination of a water cylinder extrapolation and a Gaussian extrapolation. It is independent of any specific reconstruction algorithm. Method 2 (kink approach) uses similar concepts for data extrapolation as the basic approach but needs to be integrated into the reconstruction algorithm. Experiments are presented from simulated data of the FORBILD head phantom, acquired along a partial-circle-plus-arc trajectory. The theoretically exact M-line algorithm is used for reconstruction. Although the discussion is focused on theoretically exact algorithms, the proposed truncation correction methods can be applied to any FBP algorithm that exposes oblique filtering lines.

Immobilization of laccase by encapsulation in a sol-gel matrix and its characterization and use for the removal of estrogens.

Science.gov (United States)

Lloret, L; Eibes, G; Feijoo, G; Moreira, M T; Lema, J M; Hollmann, F

2011-01-01

Laccase from Myceliophthora thermophila was immobilized by encapsulation in a sol-gel matrix based on methyltrimethoxysilane and tetramethoxysilane. The amount of laccase used for the preparation of the hydrogel was in the range 2.2-22 mg of protein/mL sol and the corresponding enzymatic activities were in the range 5.5-17.0 U/g biocatalyst. The kinetic parameters of the encapsulated laccase showed that the immobilized enzyme presented lower affinity for the substrate 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS). However, the stability of laccase was significantly enhanced after immobilization; thus, both pH and thermal stability improved about 10-30% and tolerance to different inactivating agents (NaN(3) , ZnCl(2) , CoCl(2) , CaCl(2) , methanol, and acetone) was 20-40% higher. The reusability of the immobilized laccase was demonstrated in the oxidation of ABTS for several consecutive cycles, preserving 80% of the initial laccase activity after 10 cycles. The feasibility of the immobilized biocatalyst was tested for the continuous elimination of Acid Green 27 dye as a model compound in a packed-bed reactor (PBR). Removals of 70, 58, 57, and 55% were achieved after four consecutive cycles with limited adsorption on the support: only 10-15%. Finally, both batch stirred tank reactor (BSTR) operated in several cycles and PBR, containing the solid biocatalyst were applied for the treatment of a solution containing the endocrine disrupting chemicals (EDCs): estrone (E1), 17β-estradiol (E2), and 17α-ethinylestradiol (EE2). Eliminations of EDCs in the BSTR were higher than 85% and the reusability of the biocatalyst for the degradation of those estrogens was demonstrated. In the continuous operation of the PBR, E1 was degraded by 55% and E2 and EE2 were removed up to 75 and 60%, at steady-state conditions. In addition, a 63% decrease in estrogenic activity was detected. Copyright © 2011 American Institute of Chemical Engineers (AIChE).

The effect of laccase on cellulase-treated lignin in 1-n-butyl-3 ...

African Journals Online (AJOL)

treated lignin (CEL) in two different solution systems was further investigated. Results obtained were as follows: After laccase treatment of CEL in the heterogeneous water solution, CEL was then compared with control sample A. Ultraviolet (UV) ...

Laccase-catalyzed removal of the antimicrobials chlorophene and dichlorophen from water: Reaction kinetics, pathway and toxicity evaluation.

Science.gov (United States)

Shi, Huanhuan; Peng, Jianbiao; Li, Jianhua; Mao, Liang; Wang, Zunyao; Gao, Shixiang

2016-11-05

As active agents in cleaning and disinfecting products, antimicrobials have been widely spread in the environment and have drawn extensive attention as potential threats to the ecological system and human health. In this study, the laccase-catalyzed removal of two emerging antimicrobials, chlorophene (CP) and dichlorophen (DCP), was investigated under simulated environmental conditions. Intrinsic reaction kinetics showed that the removal of CP and DCP followed second-order reaction kinetics, first-order with respect to both the enzyme and the substrate concentration. It was also found that fulvic acid could suppress the transformation of CP and DCP by reversing the oxidation reactions through its action as a scavenger of the free radical intermediates produced from reactions between laccase and the substrates. Several reaction products were identified by a quadrupole time-of-flight mass spectrometer, and detailed reaction pathways were proposed. For both CP and DCP, direct polymerization was the principal pathway, and the coupling patterns were further corroborated based on molecular modeling. The nucleophilic substitution of chlorine by the hydroxyl group was observed, and further oxidation products capable of coupling with each other were also found. Additionally, toxicity evaluation tests using Scenedesmus obliquus confirmed that the toxicity of CP and DCP was effectively eliminated during the reaction processes. Copyright © 2016 Elsevier B.V. All rights reserved.

A High Redox Potential Laccase from Pycnoporus sanguineus RP15: Potential Application for Dye Decolorization

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Ana L. R. L. Zimbardi

2016-05-01

Full Text Available Laccase production by Pycnoporus sanguineus RP15 grown in wheat bran and corncob under solid-state fermentation was optimized by response surface methodology using a Central Composite Rotational Design. A laccase (Lacps1 was purified and characterized and the potential of the pure Lacps1 and the crude culture extract for synthetic dye decolorization was evaluated. At optimal conditions (eight days, 26 °C, 18% (w/w milled corncob, 0.8% (w/w NH4Cl and 50 mmol·L−1 CuSO4, initial moisture 4.1 mL·g−1, the laccase activity reached 138.6 ± 13.2 U·g−1. Lacps1 was a monomeric glycoprotein (67 kDa, 24% carbohydrate. Optimum pH and temperature for the oxidation of 2,2’-azino-bis(3-ethylbenzthiazoline-6-sulfonate (ABTS were 4.4 and 74.4 °C, respectively. Lacps1 was stable at pH 3.0–8.0, and after two hours at 55–60 °C, presenting high redox potential (0.747 V vs. NHE. ABTS was oxidized with an apparent affinity constant of 147.0 ± 6.4 μmol·L−1, maximum velocity of 413.4 ± 21.2 U·mg−1 and catalytic efficiency of 3140.1 ± 149.6 L·mmol−1·s−1. The maximum decolorization percentages of bromophenol blue (BPB, remazol brilliant blue R and reactive blue 4 (RB4, at 25 or 40 °C without redox mediators, reached 90%, 80% and 60%, respectively, using either pure Lacps1 or the crude extract. This is the first study of the decolorization of BPB and RB4 by a P. sanguineus laccase. The data suggested good potential for treatment of industrial dye-containing effluents.

Laccase applications in biofuels production: current status and future prospects.

Science.gov (United States)

Kudanga, Tukayi; Le Roes-Hill, Marilize

2014-08-01

The desire to reduce dependence on the ever diminishing fossil fuel reserves coupled with the impetus towards green energy has seen increased research in biofuels as alternative sources of energy. Lignocellulose materials are one of the most promising feedstocks for advanced biofuels production. However, their utilisation is dependent on the efficient hydrolysis of polysaccharides, which in part is dependent on cost-effective and benign pretreatment of biomass to remove or modify lignin and release or expose sugars to hydrolytic enzymes. Laccase is one of the enzymes that are being investigated not only for potential use as pretreatment agents in biofuel production, mainly as a delignifying enzyme, but also as a biotechnological tool for removal of inhibitors (mainly phenolic) of subsequent enzymatic processes. The current review discusses the major advances in the application of laccase as a potential pretreatment strategy, the underlying principles as well as directions for future research in the search for better enzyme-based technologies for biofuel production. Future perspectives could include synergy between enzymes that may be required for optimal results and the adoption of the biorefinery concept in line with the move towards the global implementation of the bioeconomy strategy.

Degradation of anthracene by laccase of Trametes versicolor in the presence of different mediator compounds.

Science.gov (United States)

Johannes, C; Majcherczyk, A; Hüttermann, A

1996-10-01

Laccase of Trametes versicolor was generally able to oxidize anthracene in vitro. After 72 h incubation about 35% of the anthracene was transformed stoichiometrically to 9,10-anthraquinone. Transformation of anthracene increased rapidly in the presence of different mediators that readily generate stable radicals: 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) and 1-hydroxybenzotriazole. For the reaction, the presence of both the laccase and the mediator was necessary. In the presence of 0.005 mM 1-hydroxybenzotriazole this conversion had removed 47% of the anthracene after 72 h; 75% of the substrate was oxidized during this period when ABTS (1 mM) was used as mediator. In contrast to reactions without or with only low concentrations of a mediator, there was a discrepancy between the disappearance of anthracene and the formation of 9,10-anthraquinone in mediator-forced reactions. Coupling-products of mediators with anthracene degradation products were found. Anthracene disappeared nearly completely after incubation for 72 h with laccase in a 0.1 mM solution of 1-hydroxybenzotriazole and was transformed to 9,10-anthraquinone in about 80% yield; 90% of the substrate was transformed in the presence of ABTS (2.0 mM) resulting again in 80% quinone. Phenothiazine was not effective in this system.

Laccase-Catalyzed Dimerization of Piceid, a Resveratrol Glucoside, and its Further Enzymatic Elaboration

Czech Academy of Sciences Publication Activity Database

Gavezzotti, P.; Bertacchi, F.; Fronza, G.; Křen, Vladimír; Monti, D.; Riva, S.

2015-01-01

Roč. 357, č. 8 (2015), s. 1831-1839 ISSN 1615-4150 R&D Projects: GA MŠk(CZ) LD13041 Institutional support: RVO:61388971 Keywords : glycosidase * laccase * piceid Subject RIV: CC - Organic Chemistry Impact factor: 6.453, year: 2015

Decolorization of industrial synthetic dyes using engineered Pseudomonas putida cells with surface-immobilized bacterial laccase

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Wang Wei

2012-06-01

Full Text Available Abstract Background Microbial laccases are highly useful in textile effluent dye biodegradation. However, the bioavailability of cellularly expressed or purified laccases in continuous operations is usually limited by mass transfer impediment or enzyme regeneration difficulty. Therefore, this study develops a regenerable bacterial surface-displaying system for industrial synthetic dye decolorization, and evaluates its effects on independent and continuous operations. Results A bacterial laccase (WlacD was engineered onto the cell surface of the solvent-tolerant bacterium Pseudomonas putida to construct a whole-cell biocatalyst. Ice nucleation protein (InaQ anchor was employed, and the ability of 1 to 3 tandemly aligned N-terminal repeats to direct WlacD display were compared. Immobilized WlacD was determined to be surface-displayed in functional form using Western blot analysis, immunofluorescence microscopy, flow cytometry, and whole-cell enzymatic activity assay. Engineered P. putida cells were then applied to decolorize the anthraquinone dye Acid Green (AG 25 and diazo-dye Acid Red (AR 18. The results showed that decolorization of both dyes is Cu2+- and mediator-independent, with an optimum temperature of 35°C and pH of 3.0, and can be stably performed across a temperature range of 15°C to 45°C. A high activity toward AG25 (1 g/l with relative decolorization values of 91.2% (3 h and 97.1% (18 h, as well as high activity to AR18 (1 g/l by 80.5% (3 h and 89.0% (18 h, was recorded. The engineered system exhibited a comparably high activity compared with those of separate dyes in a continuous three-round shake-flask decolorization of AG25/AR18 mixed dye (each 1 g/l. No significant decline in decolorization efficacy was noted during first two-rounds but reaction equilibriums were elongated, and the residual laccase activity eventually decreased to low levels. However, the decolorizing capacity of the system was easily retrieved

Systematic gene deletions evidences that laccases are involved in several stages of wood degradation in the filamentous fungus Podospora anserina.

Science.gov (United States)

Xie, Ning; Chapeland-Leclerc, Florence; Silar, Philippe; Ruprich-Robert, Gwenaël

2014-01-01

Transformation of plant biomass into biofuels may supply environmentally friendly alternative biological sources of energy. Laccases are supposed to be involved in the lysis of lignin, a prerequisite step for efficient breakdown of cellulose into fermentable sugars. The role in development and plant biomass degradation of the nine canonical laccases belonging to three different subfamilies and one related multicopper oxidase of the Ascomycota fungus Podospora anserina was investigated by targeted gene deletion. The 10 genes were inactivated singly, and multiple mutants were constructed by genetic crosses. lac6(Δ), lac8(Δ) and mco(Δ) mutants were significantly reduced in their ability to grow on lignin-containing materials, but also on cellulose and plastic. Furthermore, lac8(Δ), lac7(Δ), mco(Δ) and lac6(Δ) mutants were defective towards resistance to phenolic substrates and H2 O2 , which may also impact lignocellulose breakdown. Double and multiple mutants were generally more affected than single mutants, evidencing redundancy of function among laccases. Our study provides the first genetic evidences that laccases are major actors of wood utilization in a fungus and that they have multiple roles during this process apart from participation in lignin lysis. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

Enhanced performance of immobilized laccase in electrospun fibrous membranes by carbon nanotubes modification and its application for bisphenol A removal from water

Energy Technology Data Exchange (ETDEWEB)

Dai, Yunrong, E-mail: daiyr@cugb.edu.cn [School of Water Resources and Environment, School of Scientific Research, China University of Geosciences (Beijing), 100083, Beijing (China); Department of Urban Water Environmental Research, Chinese Research Academy of Environmental Sciences, 100012, Beijing (China); Yao, Jun, E-mail: yaojun@cugb.edu.cn [School of Water Resources and Environment, School of Scientific Research, China University of Geosciences (Beijing), 100083, Beijing (China); Song, Yonghui, E-mail: songyhcraes@gmail.com [Department of Urban Water Environmental Research, Chinese Research Academy of Environmental Sciences, 100012, Beijing (China); Liu, Xiaoling, E-mail: liuxl@craes.org.cn [Department of Urban Water Environmental Research, Chinese Research Academy of Environmental Sciences, 100012, Beijing (China); Wang, Siyu, E-mail: wangsy@craes.org.cn [Department of Urban Water Environmental Research, Chinese Research Academy of Environmental Sciences, 100012, Beijing (China); Yuan, Yu, E-mail: yhzmlyy90311@126.com [Department of Urban Water Environmental Research, Chinese Research Academy of Environmental Sciences, 100012, Beijing (China)

2016-11-05

Highlights: • Both MWCNTs and laccase could be successfully encapsulated into electrospun fibers. • MWCNTs-LCEFMs showed higher activity recovery and better stability than LCEFMs. • Specific surface area and tensile strength of MWCNTs-LCEFMs were also improved. • Addition of MWCNTs enhanced adsorption and removal efficiency of LCEFMs for BPA. • MWCNTs-LCEFMs exhibited better endurance to the change of pH and temperature. - Abstract: Multi-walled carbon nanotubes (MWCNTs) were used as modified materials to improve the performance of laccase-carrying electrospun fibrous membranes (LCEFMs). The MWCNTs modified LCEFMs (MWCNTs-LCEFMs) were successfully fabricated via emulsion electrospinning, with active laccase and MWCNTs encapsulated inside the fibers. After modified by an optimal amount (1.5 wt%, vs. polymer) of MWCNTs, the obtained MWCNTs-LCEFMs showed not only higher activity recovery (85.3%, vs. free laccase) than LCEFMs (71.2%), but also better storage and operational stability, which were mainly attributed to the promoted electron transfer in laccase-catalytic reaction. Furthermore, the specific surface area and tensile strength of MWCNTs-LCEFMs have also been enhanced nearly 2 and 3 times than those of LCEFMs, respectively. The MWCNTs-LCEFMs were applied to remove the widespread bisphenol A from water, where their removal efficiency reached above 90%, with the degradation efficiency accounting for over 80%, and their adsorption efficiency increased about 45% than that of LCEFMs. In addition, the endurances of MWCNTs-LCEFMs to environmental factors such as pH and temperature were also improved.

Enhanced performance of immobilized laccase in electrospun fibrous membranes by carbon nanotubes modification and its application for bisphenol A removal from water

International Nuclear Information System (INIS)

Dai, Yunrong; Yao, Jun; Song, Yonghui; Liu, Xiaoling; Wang, Siyu; Yuan, Yu

2016-01-01

Highlights: • Both MWCNTs and laccase could be successfully encapsulated into electrospun fibers. • MWCNTs-LCEFMs showed higher activity recovery and better stability than LCEFMs. • Specific surface area and tensile strength of MWCNTs-LCEFMs were also improved. • Addition of MWCNTs enhanced adsorption and removal efficiency of LCEFMs for BPA. • MWCNTs-LCEFMs exhibited better endurance to the change of pH and temperature. - Abstract: Multi-walled carbon nanotubes (MWCNTs) were used as modified materials to improve the performance of laccase-carrying electrospun fibrous membranes (LCEFMs). The MWCNTs modified LCEFMs (MWCNTs-LCEFMs) were successfully fabricated via emulsion electrospinning, with active laccase and MWCNTs encapsulated inside the fibers. After modified by an optimal amount (1.5 wt%, vs. polymer) of MWCNTs, the obtained MWCNTs-LCEFMs showed not only higher activity recovery (85.3%, vs. free laccase) than LCEFMs (71.2%), but also better storage and operational stability, which were mainly attributed to the promoted electron transfer in laccase-catalytic reaction. Furthermore, the specific surface area and tensile strength of MWCNTs-LCEFMs have also been enhanced nearly 2 and 3 times than those of LCEFMs, respectively. The MWCNTs-LCEFMs were applied to remove the widespread bisphenol A from water, where their removal efficiency reached above 90%, with the degradation efficiency accounting for over 80%, and their adsorption efficiency increased about 45% than that of LCEFMs. In addition, the endurances of MWCNTs-LCEFMs to environmental factors such as pH and temperature were also improved.

Screening of Colletotrichum (Ascomycota isolates, causal agents of Soybean Anthracnose, for Laccase production Relevamiento de la producción de lacasa en aislamientos de Colletotrichum (Ascomycota, agente causal de antracnosis de la Soja

Directory of Open Access Journals (Sweden)

L. Levin

2007-07-01

Full Text Available 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.Colletotrichum truncatum es el hongo patógeno más comúnmente asociado con la antracnosis de soja. Aunque la enzima ligninolítica lacasa se relaciona con la patogenicidad de un amplio rango de hongos fitopatógenos, su rol biológico en la interacción Colletotrichum -soja aún se desconoce. La extensión de la infección en la Argentina , nos ha llevado a examinar la producción de lacasa en cepas aisladas de plantas enfermas de soja de diferentes regiones de nuestro país. Se evaluó la producción in vitro de lacasa en diez cepas (ocho de ellas identificadas como C. truncatum . Sólo seis, todas correspondientes a C. truncatum , produjeron

Halide Binding and Inhibition of Laccase Copper Clusters: The Role of Reorganization Energy

DEFF Research Database (Denmark)

Kepp, Kasper Planeta

2015-01-01

Laccase-like proteins are multicopper oxidases involved in several biological and industrial processes. Their application is commonly limited due to inhibition by fluoride and chloride, and as-isolated proteins are often substantially activated by heat, suggesting that multiple redox states can c...

Removal of antibiotics in wastewater by enzymatic treatment with fungal laccase - Degradation of compounds does not always eliminate toxicity.

Science.gov (United States)

Becker, Dennis; Varela Della Giustina, Saulo; Rodriguez-Mozaz, Sara; Schoevaart, Rob; Barceló, Damià; de Cazes, Matthias; Belleville, Marie-Pierre; Sanchez-Marcano, José; de Gunzburg, Jean; Couillerot, Olivier; Völker, Johannes; Oehlmann, Jörg; Wagner, Martin

2016-11-01

In this study, the performance of immobilised laccase (Trametes versicolor) was investigated in combination with the mediator syringaldehyde (SYR) in removing a mixture of 38 antibiotics in an enzymatic membrane reactor (EMR). Antibiotics were spiked in osmosed water at concentrations of 10μg·L(-1) each. Laccase without mediator did not reduce the load of antibiotics significantly. The addition of SYR enhanced the removal: out of the 38 antibiotics, 32 were degraded by >50% after 24h. In addition to chemical analysis, the samples' toxicity was evaluated in two bioassays (a growth inhibition assay and the Microtox assay). Here, the addition of SYR resulted in a time-dependent increase of toxicity in both bioassays. In cooperation with SYR, laccase effectively removes a broad range of antibiotics. However, this enhanced degradation induces unspecific toxicity. If this issue is resolved, enzymatic treatment may be a valuable addition to existing water treatment technologies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Co-cultivation of mutant Penicillium oxalicum SAU(E)-3.510 and Pleurotus ostreatus for simultaneous biosynthesis of xylanase and laccase under solid-state fermentation.

Science.gov (United States)

Dwivedi, Pallavi; Vivekanand, V; Pareek, Nidhi; Sharma, Amit; Singh, Rajesh P

2011-10-01

Co-cultivation of mutant Penicillium oxalicum SAU(E)-3.510 and Pleurotus ostreatus MTCC 1804 was evaluated for the production of xylanase-laccase mixture under solid-state fermentation (SSF) condition. Growth compatibility between mutant P. oxalicum SAU(E)-3.510 and white rot fungi (P. ostreatus MTCC 1804, Trametes hirsuta MTCC 136 and Pycnoporus sp. MTCC 137) was analyzed by growing them on potato dextrose agar plate. Extracellular enzyme activities were determined spectrophotometrically. Under derived conditions, paired culturing of mutant P. oxalicum SAU(E)-3.510 and P. ostreatus MTCC 1804 resulted in 58% and 33% higher levels of xylanase and laccase production, respectively. A combination of sugarcane bagasse and black gram husk in a ratio of 3:1 was found to be the most ideal solid substrate and support for fungal colonization and enzyme production during co-cultivation. Maximum levels of xylanase (8205.31 ± 168.31 IU g(-1)) and laccase (375.53 ± 34.17 IU g(-1)) during SSF were obtained by using 4 g of solid support with 80% of moisture content. Furthermore, expressions of both xylanase and laccase were characterized during mixed culture by zymogram analysis. Improved levels of xylanase and laccase biosynthesis were achieved by co-culturing the mutant P. oxalicum SAU(E)-3.510 and P. ostreatus MTCC 1804. This may be because of efficient substrate utilization as compared to their respective monocultures in the presence of lignin degradation compounds because of synergistic action of xylanase and laccase. Understanding and developing the process of co-cultivation appears productive for the development of mixed enzyme preparation with tremendous potential for biobleaching. Copyright © 2011 Elsevier B.V. All rights reserved.

Analysis of the upper-truncated Weibull distribution for wind speed

International Nuclear Information System (INIS)

Kantar, Yeliz Mert; Usta, Ilhan

2015-01-01

Highlights: • Upper-truncated Weibull distribution is proposed to model wind speed. • Upper-truncated Weibull distribution nests Weibull distribution as special case. • Maximum likelihood is the best method for upper-truncated Weibull distribution. • Fitting accuracy of upper-truncated Weibull is analyzed on wind speed data. - Abstract: Accurately modeling wind speed is critical in estimating the wind energy potential of a certain region. In order to model wind speed data smoothly, several statistical distributions have been studied. Truncated distributions are defined as a conditional distribution that results from restricting the domain of statistical distribution and they also cover base distribution. This paper proposes, for the first time, the use of upper-truncated Weibull distribution, in modeling wind speed data and also in estimating wind power density. In addition, a comparison is made between upper-truncated Weibull distribution and well known Weibull distribution using wind speed data measured in various regions of Turkey. The obtained results indicate that upper-truncated Weibull distribution shows better performance than Weibull distribution in estimating wind speed distribution and wind power. Therefore, upper-truncated Weibull distribution can be an alternative for use in the assessment of wind energy potential

Voltammetry and single-molecule in situ scanning tunneling microscopy of laccases and bilirubin oxidase in electrocatalytic dioxygen reduction on Au(111) single-crystal electrodes

DEFF Research Database (Denmark)

Climent, Victor; Zhang, Jingdong; Friis, Esben Peter

2012-01-01

Laccases (E.C. 1.10.3.2) are multicopper oxidases catalytically active in the oxidation of diphenolics and related compounds by molecular dioxygen. The laccases contain a single-copper type I center and a trinuclear cluster of a single-copper type II and a dinuclear type III center. The oxidation...

Laccase-catalyzed modification of PES membranes with 4-hydroxybenzoic acid and gallic acid

NARCIS (Netherlands)

Nady, N.; Schroën, C.G.P.H.; Franssen, M.C.R.; Mohy Eldin, M.S.; Zuilhof, H.; Boom, R.M.

2012-01-01

We here report on the performance of poly(ethersulfone) membranes modified with 4-hydroxybenzoic acid and gallic acid as substrates, and using laccase as biocatalyst under several modification conditions. The average flux of the base membrane was never reduced more than 20% (mostly below 10%

Truncated forms of viral VP2 proteins fused to EGFP assemble into fluorescent parvovirus-like particles

Directory of Open Access Journals (Sweden)

Vuento Matti

2006-12-01

Full Text Available Abstract Fluorescence correlation spectroscopy (FCS monitors random movements of fluorescent molecules in solution, giving information about the number and the size of for example nano-particles. The canine parvovirus VP2 structural protein as well as N-terminal deletion mutants of VP2 (-14, -23, and -40 amino acids were fused to the C-terminus of the enhanced green fluorescent protein (EGFP. The proteins were produced in insect cells, purified, and analyzed by western blotting, confocal and electron microscopy as well as FCS. The non-truncated form, EGFP-VP2, diffused with a hydrodynamic radius of 17 nm, whereas the fluorescent mutants truncated by 14, 23 and 40 amino acids showed hydrodynamic radii of 7, 20 and 14 nm, respectively. These results show that the non-truncated EGFP-VP2 fusion protein and the EGFP-VP2 constructs truncated by 23 and by as much as 40 amino acids were able to form virus-like particles (VLPs. The fluorescent VLP, harbouring VP2 truncated by 23 amino acids, showed a somewhat larger hydrodynamic radius compared to the non-truncated EGFP-VP2. In contrast, the construct containing EGFP-VP2 truncated by 14 amino acids was not able to assemble into VLP-resembling structures. Formation of capsid structures was confirmed by confocal and electron microscopy. The number of fluorescent fusion protein molecules present within the different VLPs was determined by FCS. In conclusion, FCS provides a novel strategy to analyze virus assembly and gives valuable structural information for strategic development of parvovirus-like particles.

Degradation of sulfadimethoxine catalyzed by laccase with soybean meal extract as natural mediator: Mechanism and reaction pathway.

Science.gov (United States)

Liang, Shangtao; Luo, Qi; Huang, Qingguo

2017-08-01

Natural laccase-mediator systems have been well recognized as an eco-friendly and energy-saving approach in environmental remediation, whose further application is however limited by the high cost of natural mediators and relatively long treatment time span. This study evaluated the water extract of soybean meal, a low-cost compound system, in mediating the laccase catalyzed degradation of a model contaminant of emerging concern, sulfadimethoxine (SDM), and demonstrated it as a promising alternative mediator for soil and water remediation. Removal of 73.3% and 65.6% was achieved in 9 h using soybean meal extract (SBE) as the mediating system for laccase-catalyzed degradation of sulfadimethoxine at the concentration of 1 ppm and 10 ppm, respectively. Further degradation of sulfadimethoxine was observed with multiple SBE additions. Using SBE as mediator increased the 9-h removal of SDM at 1 ppm initial concentration by 52.9%, 49.4%, and 36.3% in comparison to the system mediated by 1-Hydroxybenzotriazole (HBT), p-Coumaric acid (COU) and 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonate) (ABTS), respectively. With the detection of stable coupling products formed with radical scavenger (5,5-Dimethyl-1-pyrroline N-oxide, DMPO), three phenolic compounds (vanillin, apocynin, and daidzein) in SBE were confirmed to serve as mediators for Trametes versicolor laccase. Reaction pathways were proposed based on the results of High Resolution Mass Spectrometry. SO 2 excursion happened during SDM transformation, leading to elimination of antimicrobial activity. Therefore, as a natural, phenol rich, and affordable compound system, the future application of SBE in wastewater and soil remediation is worth exploring. Copyright © 2017 Elsevier Ltd. All rights reserved.

Amperometric catechol biosensor based on laccase immobilized on nitrogen-doped ordered mesoporous carbon (N-OMC)/PVA matrix

International Nuclear Information System (INIS)

Guo, Meiqing; Wang, Hefeng; Huang, Di; Han, Zhijun; Wang, Xiaojun; Li, Qiang; Chen, Jing

2014-01-01

A functionalized nitrogen-containing ordered mesoporous carbon (N-OMC), which shows good electrical properties, was synthesized by the carbonization of polyaniline inside a SBA-15 mesoporous silica template. Based on this, through entrapping laccase onto the N-OMC/polyvinyl alcohol (PVA) film a facilely fabricated amperometric biosensor was developed. Laccase from Trametes versicolor was assembled on a composite film of a N-OMC/PVA modified Au electrode and the electrochemical behavior was investigated. The results indicated that the N-OMC modified electrode exhibits electrical properties towards catechol. The optimum experimental conditions of a biosensor for the detection of catechol were studied in detail. Under the optimal conditions, the sensitivity of the biosensor was 0.29 A*M −1 with a detection limit of 0.31 μM and a linear detection range from 0.39 μM to 8.98 μM for catechol. The calibration curve followed the Michaelis–Menten kinetics and the apparent Michaelis–Menten (K M app ) was 6.28 μM. This work demonstrated that the N-OMC/PVA composite provides a suitable support for laccase immobilization and the construction of a biosensor. (papers)

Purification, partial characterization, and reactivity with aromatic compounds of two laccases from Marasmius quercophilus strain 17.

Science.gov (United States)

Farnet, A M; Criquet, S; Tagger, S; Gil, G; Le Petit, J

2000-03-01

Two isozymes of laccase were obtained from an induced liquid culture of Marasmius quercophilus with p-hydroxybenzoic acid as the inducer. Both the constitutive and the induced isozyme have a molecular mass of 60 kDa as determined by polyacrylamide gel electrophoresis. Using isoelectric focusing, we found three isozymes with the constitutive enzyme (pI 4, 4.2, 4.4) and four of the induced form (pI 4.75, 4.85, 4.95, 5.1). We observed certain differences between these two isozymes; the specific activity of the induced isozyme was twice as high, and two optimum pH levels (5 and 6) were observed with the induced isozyme (only one, pH 5, for the constitutive isozyme). However, both of these enzymes have the same thermal stability and the same temperature for their highest activity (80 degrees C). Furthermore, the reactivity of both these enzymes with aromatic compounds was similar. The use of mediators extended the oxidized substrate range of the laccases studied. Various products of degradation were observed, depending on the mediator used. When laccase was used alone, the decrease of the signal corresponding to the aromatic cycle, without any formations of other peaks at different wavelengths, suggested polymerisation of aromatic compounds.

Valorization of spent oyster mushroom substrate and laccase recovery through successive solid state cultivation of Pleurotus, Ganoderma, and Lentinula strains.

Science.gov (United States)

Economou, Christina N; Diamantopoulou, Panagiota A; Philippoussis, Antonios N

2017-06-01

Spent mushroom substrate (SMS) of Pleurotus ostreatus was supplemented with wheat bran and soybean flour in various proportions to obtain C/N ratios of 10, 20, and 30, and their effect was evaluated in successive cultivation of Pleurotus ostreatus, Pleurotus pulmonarius, Ganoderma adspersum, Ganoderma resinaceum, and Lentinula edodes strains with respect to mycelium growth rate, biomass concentration, recovery of the enzyme laccase and crude exopolysaccharides, and also with additional fruiting body production. All fungi showed the highest growth rate on unamended SMS (C/N 30), with G. resinaceum being the fastest colonizer (Kr = 9.84 mm day -1 ), while biomass concentration maximized at C/N 10. Moreover, supplementation affected positively laccase activity, with P. pulmonarius furnishing the highest value (44,363.22 U g -1 ) at C/N 20. On the contrary, L. edodes growth, fruiting, and laccase secretion were not favored by SMS supplementation. Fruiting body formation was promoted at C/N 30 for Ganoderma and at C/N 20 for Pleurotus species. Exopolysaccharide production of further studied Pleurotus strains was favored at a C/N 20 ratio, at the initial stage of SMS colonization. The obtained results support the potential effective utilization of supplemented SMS for laccase production from Ganoderma spp. and for new fruiting body production of Pleurotus spp.

Learning Mixtures of Truncated Basis Functions from Data

DEFF Research Database (Denmark)

Langseth, Helge; Nielsen, Thomas Dyhre; Pérez-Bernabé, Inmaculada

2014-01-01

In this paper we investigate methods for learning hybrid Bayesian networks from data. First we utilize a kernel density estimate of the data in order to translate the data into a mixture of truncated basis functions (MoTBF) representation using a convex optimization technique. When utilizing a ke...... propose an alternative learning method that relies on the cumulative distribution function of the data. Empirical results demonstrate the usefulness of the approaches: Even though the methods produce estimators that are slightly poorer than the state of the art (in terms of log......In this paper we investigate methods for learning hybrid Bayesian networks from data. First we utilize a kernel density estimate of the data in order to translate the data into a mixture of truncated basis functions (MoTBF) representation using a convex optimization technique. When utilizing......-likelihood), they are significantly faster, and therefore indicate that the MoTBF framework can be used for inference and learning in reasonably sized domains. Furthermore, we show how a particular sub- class of MoTBF potentials (learnable by the proposed methods) can be exploited to significantly reduce complexity during inference....

Electrochemical estimation of the polyphenol index in wines using a laccase biosensor.

Science.gov (United States)

Gamella, M; Campuzano, S; Reviejo, A J; Pingarrón, J M

2006-10-18

The use of a laccase biosensor, under both batch and flow injection (FI) conditions, for a rapid and reliable amperometric estimation of the total content of polyphenolic compounds in wines is reported. The enzyme was immobilized by cross-linking with glutaraldehyde onto a glassy carbon electrode. Caffeic acid and gallic acid were selected as standard compounds to carry out such estimation. Experimental variables such as the enzyme loading, the applied potential, and the pH value were optimized, and different aspects regarding the operational stability of the laccase biosensor were evaluated. Using batch amperometry at -200 mV, the detection limits obtained were 2.6 x 10(-3) and 7.2 x 10(-4) mg L(-1) gallic acid and caffeic acid, respectively, which compares advantageously with previous biosensor designs. An extremely simple sample treatment consisting only of an appropriate dilution of wine sample with the supporting electrolyte solution (0.1 mol L(-1) citrate buffer of pH 5.0) was needed for the amperometric analysis of red, rosé, and white wines. Good correlations were found when the polyphenol indices obtained with the biosensor (in both the batch and FI modes) for different wine samples were plotted versus the results achieved with the classic Folin-Ciocalteu method. Application of the calibration transfer chemometric model (multiplicative fitting) allowed that the confidence intervals (for a significance level of 0.05) for the slope and intercept values of the amperometric index versus Folin-Ciocalteu index plots (r = 0.997) included the unit and zero values, respectively. This indicates that the laccase biosensor can be successfully used for the estimation of the polyphenol index in wines when compared with the Folin-Ciocalteu reference method.

Resveratrol acts as a natural profungicide and induces self-intoxication by a specific laccase

NARCIS (Netherlands)

Schouten, A.; Wagemakers, L.; Stefanato, F.L.; Kaaij, van der R.M.; Kan, van J.A.L.

2002-01-01

The grapevine (Vitis) secondary metabolite resveratrol is considered a phytoalexin, which protects the plant from Botrytis cinerea infection. Laccase activity displayed by the fungus is assumed to detoxify resveratrol and to facilitate colonization of grape. We initiated a functional molecular

Extracellular laccase production and phenolic degradation by an olive mill wastewater isolate

Directory of Open Access Journals (Sweden)

R. Kumar

2018-03-01

Full Text Available Olive mill wastewater (OMWW presents a challenge to the control of effluents due to the presence of a high organic load, antimicrobial agents (monomeric-polymeric phenols, volatile acids, polyalcohols, and tannins, salinity and acidity. In this study, the production of extracellular laccase, monomeric or polymeric phenol, from an OMWW isolate based on its ability to biodegrade phenols and gallic acid as a model of phenolic compounds in OMWW was investigated. Phylogenetic analysis of the 16S RNA gene sequences identified the bacterial isolate (Acinetobacter REY as being closest to Acinetobacter pittii. This isolate exhibited a constitutive production of extracellular laccase with an activity of 1.5 and 1.3 U ml/L when supplemented with the inducers CuSO4 and CuSO4+phenols, respectively. Batch experiments containing minimal media supplemented with phenols or gallic acid as the sole carbon and energy source were performed in order to characterize their phenolic biodegradability. Acinetobacter REY was capable of biodegrading up to 200 mg/L of phenols and gallic acid both after 10 h and 72 h, respectively.

Molecular and biochemical characterization of a highly stable bacterial laccase that occurs as a structural component of the Bacillus subtilis endospore coat.

Science.gov (United States)

Martins, Ligia O; Soares, Claudio M; Pereira, Manuela M; Teixeira, Miguel; Costa, Teresa; Jones, George H; Henriques, Adriano O

2002-05-24

The Bacillus subtilis endospore coat protein CotA shows laccase activity. By using comparative modeling techniques, we were able to derive a model for CotA based on the known x-ray structures of zucchini ascorbate oxidase and Cuprinus cereneus laccase. This model of CotA contains all the structural features of a laccase, including the reactive surface-exposed copper center (T1) and two buried copper centers (T2 and T3). Single amino acid substitutions in the CotA T1 copper center (H497A, or M502L) did not prevent assembly of the mutant proteins into the coat and did not alter the pattern of extractable coat polypeptides. However, in contrast to a wild type strain, both mutants produced unpigmented colonies and spores unable to oxidize syringaldazine (SGZ) and 2'2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). The CotA protein was purified to homogeneity from an overproducing Escherichia coli strain. The purified CotA shows an absorbance and a EPR spectra typical of blue multicopper oxidases. Optimal enzymatic activity was found at < or =pH 3.0 and at pH 7.0 for ABTS or SGZ oxidation, respectively. The apparent K(m) values for ABTS and SGZ at 37 degrees C were of 106 +/- 11 and 26 +/- 2 microm, respectively, with corresponding k(cat) values of 16.8 +/- 0.8 and 3.7 +/- 0.1 s(-1). Maximal enzyme activity was observed at 75 degrees C with ABTS as substrate. Remarkably, the coat-associated or the purified enzyme showed a half-life of inactivation at 80 degrees C of about 4 and 2 h, respectively, indicating that CotA is intrinsically highly thermostable.

New Schemes for Positive Real Truncation

Directory of Open Access Journals (Sweden)

Kari Unneland

2007-07-01

Full Text Available Model reduction, based on balanced truncation, of stable and of positive real systems are considered. An overview over some of the already existing techniques are given: Lyapunov balancing and stochastic balancing, which includes Riccati balancing. A novel scheme for positive real balanced truncation is then proposed, which is a combination of the already existing Lyapunov balancing and Riccati balancing. Using Riccati balancing, the solution of two Riccati equations are needed to obtain positive real reduced order systems. For the suggested method, only one Lyapunov equation and one Riccati equation are solved in order to obtain positive real reduced order systems, which is less computationally demanding. Further it is shown, that in order to get positive real reduced order systems, only one Riccati equation needs to be solved. Finally, this is used to obtain positive real frequency weighted balanced truncation.

Measuring a Truncated Disk in Aquila X-1

Science.gov (United States)

King, Ashley L.; Tomsick, John A.; Miller, Jon M.; Chenevez, Jerome; Barret, Didier; Boggs, Steven E.; Chakrabarty, Deepto; Christensen, Finn E.; Craig, William W.; Feurst, Felix;

Evolution of truncated moments of singlet parton distributions

International Nuclear Information System (INIS)

Forte, S.; Magnea, L.; Piccione, A.; Ridolfi, G.

2001-01-01

We define truncated Mellin moments of parton distributions by restricting the integration range over the Bjorken variable to the experimentally accessible subset x 0 ≤x≤1 of the allowed kinematic range 0≤x≤1. We derive the evolution equations satisfied by truncated moments in the general (singlet) case in terms of an infinite triangular matrix of anomalous dimensions which couple each truncated moment to all higher moments with orders differing by integers. We show that the evolution of any moment can be determined to arbitrarily good accuracy by truncating the system of coupled moments to a sufficiently large but finite size, and show how the equations can be solved in a way suitable for numerical applications. We discuss in detail the accuracy of the method in view of applications to precision phenomenology

Distribution, diversity and abundance of bacterial laccase-like genes in different particle size fractions of sediments in a subtropical mangrove ecosystem.

Science.gov (United States)

Luo, Ling; Zhou, Zhi-Chao; Gu, Ji-Dong

2015-10-01

This study investigated the diversity and abundance of bacterial lacasse-like genes in different particle size fractions, namely sand, silt, and clay of sediments in a subtropical mangrove ecosystem. Moreover, the effects of nutrient conditions on bacterial laccase-like communities as well as the correlation between nutrients and, both the abundance and diversity indices of laccase-like bacteria in particle size fractions were also studied. Compared to bulk sediments, Bacteroidetes, Caldithrix, Cyanobacteria and Chloroflexi were dominated in all 3 particle-size fractions of intertidal sediment (IZ), but Actinobacteria and Firmicutes were lost after the fractionation procedures used. The diversity index of IZ fractions decreased in the order of bulk > clay > silt > sand. In fractions of mangrove forest sediment (MG), Verrucomicrobia was found in silt, and both Actinobacteria and Bacteroidetes appeared in clay, but no new species were found in sand. The declining order of diversity index in MG fractions was clay > silt > sand > bulk. Furthermore, the abundance of lacasse-like bacteria varied with different particle-size fractions significantly (p clay > silt in both IZ and MG fractions. Additionally, nutrient availability was found to significantly affect the diversity and community structure of laccase-like bacteria (p fractions (p < 0.05). Therefore, this study further provides evidence that bacterial laccase plays a vital role in turnover of sediment organic matter and cycling of nutrients.

Characterization of mTOR-Responsive Truncated mRNAs in Cell Proliferation

Science.gov (United States)

2017-07-01

These findings identify a previously uncharacterized role for mTOR in modulating 3’- UTR length of mRNAs by alternative polyadenylation ( APA ). Another...outcome of APA in the mTOR-activated transcriptome is an early termination of mRNA transcription to produce truncated mRNAs with polyadenylation in...for exhaustive analysis of Alternative cleavage and polyadenylation ( APA ) events (Figure 1). In IntMAP, first the position of multiple

Fabrication of an Amperometric Flow-Injection Microfluidic Biosensor Based on Laccase for In Situ Determination of Phenolic Compounds

Directory of Open Access Journals (Sweden)

Juan C. Gonzalez-Rivera

2015-01-01

Full Text Available We aim to develop an in situ microfluidic biosensor based on laccase from Trametes pubescens with flow-injection and amperometry as the transducer method. The enzyme was directly immobilized by potential step chronoamperometry, and the immobilization was studied using cyclic voltammetry and electrochemical impedance spectroscopy. The electrode response by amperometry was probed using ABTS and syringaldazine. A shift of interfacial electron transfer resistance and the electron transfer rate constant from 18.1 kΩ to 3.9 MΩ and 4.6 × 10−2 cm s−1 to 2.1 × 10−4 cm s−1, respectively, evidenced that laccase was immobilized on the electrode by the proposed method. We established the optimum operating conditions of temperature (55°C, pH (4.5, injection flow rate (200 µL min−1, and applied potential (0.4 V. Finally, the microfluidic biosensor showed better lower limit of detection (0.149 µM and sensitivity (0.2341 nA µM−1 for ABTS than previous laccase-based biosensors and the in situ operation capacity.

Growth and extracellular laccase production in liquid cultures of Minimidochium parvum LPSC # 548 Strain Crecimiento y producción de lacasa extracelular en cultivos líquidos de Minimidochium parvum cepa LPSC # 548

Directory of Open Access Journals (Sweden)

Mario C. N. Saparrat

2007-07-01

Full Text Available Minimidochium parvum LPSC # 548, a fungus isolated from litter floating on waters of Río Santiago (Provincia de Buenos Aires, Argentina polluted with industrial effluents and crude-oil, was grown as a shaking culture on a C-limited medium to evaluate its ability to produce extracellular laccase. The effect of anthracene, CuSO4 · 5H2O, ethanol, guaiacol, humic acids, Kraft lignin, MnSO4· H2O, Tween 20 and veratryl alcohol on its growth and extracellular laccase activity levels was also analyzed. The cultures grown on basal medium produced maximum biomass (over 420 mg/100 ml and maximum extracellular laccase activity (351.7 ±53.3 pkat/ml after 5 days of incubation. Among the different factors tested, only the humic acids at 0.1 % (w/v were found to stimulate the growth of M. parvum . However, Tween 20 (0.1 %, v/v was the only one that produced an increase of laccase activity levels up to 2.5-fold compared to the control.Minimidochium parvum LPSC # 548, un hongo aislado de materia orgánica colectada en aguas de Río Santiago (Provincia de Buenos Aires, Argentina contaminadas con efluentes industriales y crudo de petróleo, se cultivó en un medio líquido limitante en carbono bajo agitación para evaluar su habilidad para producir lacasa extracelular. Se analizó también el efecto de ácidos húmicos, alcohol veratrílico, antraceno, CuSO4 · 5H2O, etanol, guaiacol, lignina Kraft, MnSO4· H2O y Tween 20 sobre el crecimiento fúngico y los niveles de actividad lacasa extracelular. Los cultivos sobre medio basal produjeron máximos niveles de biomasa (superior a 420 mg/100 ml y actividad lacasa extracelular (351,7 ±53,3 pkat/ml después de 5 días de incubación. Entre los diferentes agentes químicos testeados, sólo los ácidos húmicos al 0,1 % (p/v estimularon el crecimiento de M. parvum . No obstante, sólo el Tween 20 (0,1 %, v/v produjo un incremento de los niveles de actividad lacasa (2,5 veces comparado a cultivos control.

Visible-Light-Driven Oxidation of Organic Substrates with Dioxygen Mediated by a [Ru(bpy)3 ](2+) /Laccase System.

Science.gov (United States)

Schneider, Ludovic; Mekmouche, Yasmina; Rousselot-Pailley, Pierre; Simaan, A Jalila; Robert, Viviane; Réglier, Marius; Aukauloo, Ally; Tron, Thierry

2015-09-21

Oxidation reactions are highly important chemical transformations that still require harsh reaction conditions and stoichiometric amounts of chemical oxidants that are often toxic. To circumvent these issues, olefins oxidation is achieved in mild conditions upon irradiation of an aqueous solution of the complex [Ru(bpy)3 ](2+) and the enzyme laccase. Epoxide formation is coupled to the light-driven reduction of O2 by [Ru(bpy)3 ](2+) /laccase system. The reactivity can be explained by dioxygen acting both as an oxidative agent and as renewable electron acceptor, avoiding the use of a sacrificial electron acceptor. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DETERMINATION OF ENZYMES PRODUCED BY CERIPORIOPSIS SUBVERMISPORA DURING PRETREATMENT OF DIFFERENT BIOMASS SOURCES

Directory of Open Access Journals (Sweden)

Miroslav Ondrejovič

2012-02-01

Full Text Available The aim of this paper was to study of lignocellulolytic enzymes producing by Ceriporiopsis subvermispora during its cultivation on three types of plant biomass differentiated by chemical composition and physical properties (wheat straw, pine and poplar wood. The activity of lignocellulolytic enzymes in cultivation medium was determined by catalytic transformation of their natural substrates to products which were detected by photometric methods. Cellulase activities were very low while xylanases predominated. Wheat straw was best substrate for production of cellulases (4.38 U/mL and xylanases (23.34 U/mL. The maximum activity of cellulase and xylanase was reached at 8th and 3rd day, respectively. Laccase activity reached the maximum after 16 days and then gradually decreased. The best substrate for production of laccases was poplar wood (1.67 U/mL.

Impact of agricultural management on bacterial laccase-encoding genes with possible implications for soil carbon storage in semi-arid Mediterranean olive farming

Directory of Open Access Journals (Sweden)

Beatriz Moreno

2016-07-01

Full Text Available Background: In this work, we aimed to gain insights into the contribution of soil bacteria to carbon sequestration in Mediterranean habitats. In particular, we aimed to use bacterial laccase-encoding genes as molecular markers for soil organic C cycling. Using rainfed olive farming as an experimental model, we determined the stability and accumulation levels of humic substances and applied these data to bacterial laccase-encoding gene expression and diversity in soils under four different agricultural management systems (bare soils under tillage/no tillage and vegetation cover under chemical/mechanical management. Materials and Methods: Humic C (> 104 Da was subjected to isoelectric focusing. The GC-MS method was used to analyze aromatic hydrocarbons. Real-Time PCR quantification and denaturing gradient gel electrophoresis (DGGE for functional bacterial laccase-like multicopper oxidase (LMCO-encoding genes and transcripts were also carried out. Results: Soils under spontaneous vegetation, eliminated in springtime using mechanical methods for more than 30 years, showed the highest humic acid levels as well as the largest bacterial population rich in laccase genes and transcripts. The structure of the bacterial community based on LMCO genes also pointed to phylogenetic differences between these soils due to the impact of different management systems. Soils where herbicides were used to eliminate spontaneous vegetation once a year and those where pre-emergence herbicides resulted in bare soils clustered together for DNA-based DGGE analysis, which indicated a certain amount of microbial selection due to the application of herbicides. When LMCO-encoding gene expression was studied, soils where cover vegetation was managed either with herbicides or with mechanical methods showed less than 10% similarity, suggesting that the type of weed management strategy used can impact weed community composition and consequently laccase substrates derived from

Laccase catalyzed grafting of-N-OH type mediators to lignin via radical-radical coupling

NARCIS (Netherlands)

Munk, L.; Punt, A.M.; Kabel, M.A.; Meyer, A.S.

2017-01-01

Lignin is an underexploited resource in biomass refining. Laccases (EC 1.10.3.2) catalyze oxidation of phenolic hydroxyls using O2 as electron acceptor and may facilitate lignin modification in the presence of mediators. This study assessed the reactivity of four different synthetic mediators by

Data and performance profiles applying an adaptive truncation criterion, within linesearch-based truncated Newton methods, in large scale nonconvex optimization

Directory of Open Access Journals (Sweden)

Andrea Caliciotti

2018-04-01

Full Text Available In this paper, we report data and experiments related to the research article entitled “An adaptive truncation criterion, for linesearch-based truncated Newton methods in large scale nonconvex optimization” by Caliciotti et al. [1]. In particular, in Caliciotti et al. [1], large scale unconstrained optimization problems are considered by applying linesearch-based truncated Newton methods. In this framework, a key point is the reduction of the number of inner iterations needed, at each outer iteration, to approximately solving the Newton equation. A novel adaptive truncation criterion is introduced in Caliciotti et al. [1] to this aim. Here, we report the details concerning numerical experiences over a commonly used test set, namely CUTEst (Gould et al., 2015 [2]. Moreover, comparisons are reported in terms of performance profiles (Dolan and Moré, 2002 [3], adopting different parameters settings. Finally, our linesearch-based scheme is compared with a renowned trust region method, namely TRON (Lin and Moré, 1999 [4].

Conditional truncated plurigaussian simulation; Simulacao plurigaussiana truncada com condicionamento

Energy Technology Data Exchange (ETDEWEB)

Simon, Vitor Hugo

1997-12-01

The goal of this work was a development of an algorithm for the Truncated Plurigaussian Stochastic Simulation and its validation in a complex geologic model. The reservoir data comes from Aux Vases Zone at Rural Hill Field in Illinois, USA, and from the 2D geological interpretation, described by WEIMER et al. (1982), three sets of samples, with different grid densities ware taken. These sets were used to condition the simulation and to refine the estimates of the non-stationary matrix of facies proportions, used to truncate the gaussian random functions (RF). The Truncated Plurigaussian Model is an extension of the Truncated Gaussian Model (TG). In this new model its possible to use several facies with different spatial structures, associated with the simplicity of TG. The geological interpretation, used as a validation model, was chosen because it shows a set of NW/SE elongated tidal channels cutting the NE/SW shoreline deposits interleaved by impermeable facies. These characteristics of spatial structures of sedimentary facies served to evaluate the simulation model. Two independent gaussian RF were used, as well as an 'erosive model' as the truncation strategy. Also, non-conditional simulations were proceeded, using linearly combined gaussian RF with varying correlation coefficients. It was analyzed the influence of some parameters like: number of gaussian RF,correlation coefficient, truncations strategy, in the outcome of simulation, and also the physical meaning of these parameters under a geological point of view. It was showed, step by step, using an example, the theoretical model, and how to construct an algorithm to simulate with the Truncated Plurigaussian Model. The conclusion of this work was that even with a plain algorithm of the Conditional Truncated Plurigaussian and a complex geological model it's possible to obtain a usefulness product. (author)

Laccase enzyme detoxifies hydrolysates and improves biogas production from hemp straw and miscanthus.

Science.gov (United States)

Schroyen, Michel; Van Hulle, Stijn W H; Holemans, Sander; Vervaeren, Han; Raes, Katleen

2017-11-01

The impact of various phenolic compounds, vanillic acid, ferulic acid, p-coumaric acid and 4-hydroxybenzoic acid on anaerobic digestion of lignocellulosic biomass (hemp straw and miscanthus) was studied. Such phenolic compounds have been known to inhibit biogas production during anaerobic digestion. The different phenolic compounds were added in various concentrations: 0, 100, 500, 1000 and 2000mg/L. A difference in inhibition of biomethane production between the phenolic compounds was noted. Hydrolysis rate, during anaerobic digestion of miscanthus was inhibited up to 50% by vanillic acid, while vanillic acid had no influence on the initial rate of biogas production during the anaerobic digestion of hemp straw. Miscanthus has a higher lignin concentration (12-30g/100gDM) making it less accessible for degradation, and in combination with phenolic compounds released after harsh pretreatments, it can cause severe inhibition levels during the anaerobic digestion, lowering biogas production. To counter the inhibition, lignin degrading enzymes can be used to remove or degrade the inhibitory phenolic compounds. The interaction of laccase and versatile peroxidase individually with the different phenolic compounds was studied to have insight in the polymerization of inhibitory compounds or breakdown of lignocellulose. Hemp straw and miscanthus were incubated with 0, 100 and 500mg/L of the different phenolic compounds for 0, 6 and 24h and pretreated with the lignin degrading enzymes. A laccase pretreatment successfully detoxified the substrate, while versatile peroxidase however was inhibited by 100mg/L of each of the individual phenolic compounds. Finally a combination of enzymatic detoxification and subsequent biogas production showed that a decrease in phenolic compounds by laccase treatment can considerably lower the inhibition levels of the biogas production. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enzymatic grafting of simple phenols on flax and sisal pulp fibres using laccases.

Science.gov (United States)

Aracri, Elisabetta; Fillat, Amanda; Colom, José F; Gutiérrez, Ana; Del Río, José C; Martínez, Angel T; Vidal, Teresa

2010-11-01

Flax and sisal pulps were treated with two laccases (from Pycnoporus cinnabarinus, PcL and Trametes villosa, TvL, respectively), in the presence of different phenolic compounds (syringaldehyde, acetosyringone and p-coumaric acid in the case of flax pulp, and coniferaldehyde, sinapaldehyde, ferulic acid and sinapic acid in the case of sisal pulp). In most cases the enzymatic treatments resulted in increased kappa number of pulps suggesting the incorporation of the phenols into fibres. The covalent binding of these compounds to fibres was evidenced by the analysis of the treated pulps, after acetone extraction, by pyrolysis coupled with gas chromatography/mass spectrometry in the absence and/or in the presence of tetramethylammonium hydroxide (TMAH) as methylating agent. The highest extents of phenol incorporation were observed with the p-hydroxycinnamic acids, p-coumaric and ferulic acids. The present work shows for the first time the use of analytical pyrolysis as an effective approach to study fibre functionalization by laccase-induced grafting of phenols. Copyright 2010 Elsevier Ltd. All rights reserved.

Truncation in diffraction pattern analysis. Pt. 1

International Nuclear Information System (INIS)

Delhez, R.; Keijser, T.H. de; Mittemeijer, E.J.; Langford, J.I.

1986-01-01

An evaluation of the concept of a line profile is provoked by truncation of the range of intensity measurement in practice. The measured truncated line profile can be considered either as part of the total intensity distribution which peaks at or near the reciprocal-lattice points (approach 1), or as part of a component line profile which is confined to a single reciprocal-lattice point (approach 2). Some false conceptions in line-profile analysis can then be avoided and recipes can be developed for the extrapolation of the tails of the truncated line profile. Fourier analysis of line profiles, according to the first approach, implies a Fourier series development of the total intensity distribution defined within [l - 1/2, l + 1/2] (l indicates the node considered in reciprocal space); the second approach implies a Fourier transformation of the component line profile defined within [ - ∞, + ∞]. Exact descriptions of size broadening are provided by both approaches, whereas combined size and strain broadening can only be evaluated adequately within the first approach. Straightforward methods are given for obtaining truncation-corrected values for the average crystallite size. (orig.)

Truncation Depth Rule-of-Thumb for Convolutional Codes

Science.gov (United States)

Moision, Bruce

2009-01-01

In this innovation, it is shown that a commonly used rule of thumb (that the truncation depth of a convolutional code should be five times the memory length, m, of the code) is accurate only for rate 1/2 codes. In fact, the truncation depth should be 2.5 m/(1 - r), where r is the code rate. The accuracy of this new rule is demonstrated by tabulating the distance properties of a large set of known codes. This new rule was derived by bounding the losses due to truncation as a function of the code rate. With regard to particular codes, a good indicator of the required truncation depth is the path length at which all paths that diverge from a particular path have accumulated the minimum distance of the code. It is shown that the new rule of thumb provides an accurate prediction of this depth for codes of varying rates.

Investigation of propagation dynamics of truncated vector vortex beams.

Science.gov (United States)

Srinivas, P; Perumangatt, C; Lal, Nijil; Singh, R P; Srinivasan, B

2018-06-01

In this Letter, we experimentally investigate the propagation dynamics of truncated vector vortex beams generated using a Sagnac interferometer. Upon focusing, the truncated vector vortex beam is found to regain its original intensity structure within the Rayleigh range. In order to explain such behavior, the propagation dynamics of a truncated vector vortex beam is simulated by decomposing it into the sum of integral charge beams with associated complex weights. We also show that the polarization of the truncated composite vector vortex beam is preserved all along the propagation axis. The experimental observations are consistent with theoretical predictions based on previous literature and are in good agreement with our simulation results. The results hold importance as vector vortex modes are eigenmodes of the optical fiber.

The implication of Dichomitus squalens laccase isoenzymes in dye decolorization by immobilized fungal cultures

Czech Academy of Sciences Publication Activity Database

Šušla, Martin; Novotný, Čeněk; Svobodová, Kateřina

2007-01-01

Roč. 98, - (2007), s. 2109-2115 ISSN 0960-8524 R&D Projects: GA ČR GP526/06/P102; GA AV ČR IAA6020411 Institutional research plan: CEZ:AV0Z5020903 Keywords : decolorization * dichotomitus squalens * laccase Subject RIV: EE - Microbiology, Virology Impact factor: 3.103, year: 2007

Wigner distribution function of circularly truncated light beams

NARCIS (Netherlands)

Bastiaans, M.J.; Nijhawan, O.P.; Gupta, A.K.; Musla, A.K.; Singh, Kehar

1998-01-01

Truncating a light beam is expressed as a convolution of its Wigner distribution function and the WDF of the truncating aperture. The WDF of a circular aperture is derived and an approximate expression - which is exact in the space and the spatial-frequency origin and whose integral over the spatial

The effect of truncation on very small cardiac SPECT camera systems

International Nuclear Information System (INIS)

Rohmer, Damien; Eisner, Robert L.; Gullberg, Grant T.

2006-01-01

Background: The limited transaxial field-of-view (FOV) of a very small cardiac SPECT camera system causes view-dependent truncation of the projection of structures exterior to, but near the heart. Basic tomographic principles suggest that the reconstruction of non-attenuated truncated data gives a distortion-free image in the interior of the truncated region, but the DC term of the Fourier spectrum of the reconstructed image is incorrect, meaning that the intensity scale of the reconstruction is inaccurate. The purpose of this study was to characterize the reconstructed image artifacts from truncated data, and to quantify their effects on the measurement of tracer uptake in the myocardial. Particular attention was given to instances where the heart wall is close to hot structures (structures of high activity uptake).Methods: The MCAT phantom was used to simulate a 2D slice of the heart region. Truncated and non-truncated projections were formed both with and without attenuation. The reconstructions were analyzed for artifacts in the myocardium caused by truncation, and for the effect that attenuation has relative to increasing those artifacts. Results: The inaccuracy due to truncation is primarily caused by an incorrect DC component. For visualizing the left ventricular wall, this error is not worse than the effect of attenuation. The addition of a small hot bowel-like structure near the left ventricle causes few changes in counts on the wall. Larger artifacts due to the truncation are located at the boundary of the truncation and can be eliminated by sinogram interpolation. Finally,algebraic reconstruction methods are shown to give better reconstruction results than an analytical filtered back-projection reconstruction algorithm. Conclusion: Small inaccuracies in reconstructed images from small FOV camera systems should have little effect on clinical interpretation. However, changes in the degree of inaccuracy in counts from slice to slice are due to changes in

Truncation of a mannanase from Trichoderma harzianum improves its enzymatic properties and expression efficiency in Trichoderma reesei.

Science.gov (United States)

Wang, Juan; Zeng, Desheng; Liu, Gang; Wang, Shaowen; Yu, Shaowen

2014-01-01

To obtain high expression efficiency of a mannanase gene, ThMan5A, cloned from Trichoderma harzianum MGQ2, both the full-length gene and a truncated gene (ThMan5AΔCBM) that contains only the catalytic domain, were expressed in Trichoderma reesei QM9414 using the strong constitutive promoter of the gene encoding pyruvate decarboxylase (pdc), and purified to homogeneity, respectively. We found that truncation of the gene improved its expression efficiency as well as the enzymatic properties of the encoded protein. The recombinant strain expressing ThMan5AΔCBM produced 2,460 ± 45.1 U/ml of mannanase activity in the culture supernatant; 2.3-fold higher than when expressing the full-length ThMan5A gene. In addition, the truncated mannanase had superior thermostability compared with the full-length enzyme and retained 100 % of its activity after incubation at 60 °C for 48 h. Our results clearly show that the truncated ThMan5A enzyme exhibited improved characteristics both in expression efficiency and in its thermal stability. These characteristics suggest that ThMan5AΔCBM has potential applications in the food, feed, paper, and pulp industries.

Xenobiotics enhance laccase activity in alkali-tolerant γ-proteobacterium JB.

Science.gov (United States)

Singh, Gursharan; Batish, Mona; Sharma, Prince; Capalash, Neena

2009-01-01

Various genotoxic textile dyes, xenobiotics, substrates (10 µM) and agrochemicals (100 µg/ml) were tested for enhancement of alkalophilic laccase activity in γ-proteobacterium JB. Neutral Red, Indigo Carmine, Naphthol Base Bordears and Sulphast Ruby dyes increased the activity by 3.7, 2.7, 2.6 and 2.3 fold respectively. Xenobiotics/substrates like p-toluidine, 8-hydroxyquinoline and anthracine increased it by 3.4, 2.8 and 2.3 fold respectively. Atrazine and trycyclozole pesticides enhanced the activity by 1.95 and 1.5 fold respectively.

Combined strategies for improving production of a thermo-alkali stable laccase in Pichia pastoris

Directory of Open Access Journals (Sweden)

Jiayi Wang

2017-07-01

Conclusions: The productivity of the thermo-alkali stable laccase from B. licheniformis expressed in P. pastoris was significantly improved through the combination of site-directed mutagenesis and optimization of the cultivation process. The mutant enzyme retains good stability under high temperature and alkaline conditions, and is a good candidate for industrial application in dye decolorization.

Flexible scheme to truncate the hierarchy of pure states.

Science.gov (United States)

Zhang, P-P; Bentley, C D B; Eisfeld, A

2018-04-07

The hierarchy of pure states (HOPS) is a wavefunction-based method that can be used for numerically modeling open quantum systems. Formally, HOPS recovers the exact system dynamics for an infinite depth of the hierarchy. However, truncation of the hierarchy is required to numerically implement HOPS. We want to choose a "good" truncation method, where by "good" we mean that it is numerically feasible to check convergence of the results. For the truncation approximation used in previous applications of HOPS, convergence checks are numerically challenging. In this work, we demonstrate the application of the "n-particle approximation" to HOPS. We also introduce a new approximation, which we call the "n-mode approximation." We then explore the convergence of these truncation approximations with respect to the number of equations required in the hierarchy in two exemplary problems: absorption and energy transfer of molecular aggregates.

Flexible scheme to truncate the hierarchy of pure states

Science.gov (United States)

Zhang, P.-P.; Bentley, C. D. B.; Eisfeld, A.

2018-04-01

The hierarchy of pure states (HOPS) is a wavefunction-based method that can be used for numerically modeling open quantum systems. Formally, HOPS recovers the exact system dynamics for an infinite depth of the hierarchy. However, truncation of the hierarchy is required to numerically implement HOPS. We want to choose a "good" truncation method, where by "good" we mean that it is numerically feasible to check convergence of the results. For the truncation approximation used in previous applications of HOPS, convergence checks are numerically challenging. In this work, we demonstrate the application of the "n-particle approximation" to HOPS. We also introduce a new approximation, which we call the "n-mode approximation." We then explore the convergence of these truncation approximations with respect to the number of equations required in the hierarchy in two exemplary problems: absorption and energy transfer of molecular aggregates.

Truncated predictor feedback for time-delay systems

CERN Document Server

Zhou, Bin

2014-01-01

This book provides a systematic approach to the design of predictor based controllers for (time-varying) linear systems with either (time-varying) input or state delays. Differently from those traditional predictor based controllers, which are infinite-dimensional static feedback laws and may cause difficulties in their practical implementation, this book develops a truncated predictor feedback (TPF) which involves only finite dimensional static state feedback. Features and topics: A novel approach referred to as truncated predictor feedback for the stabilization of (time-varying) time-delay systems in both the continuous-time setting and the discrete-time setting is built systematically Semi-global and global stabilization problems of linear time-delay systems subject to either magnitude saturation or energy constraints are solved in a systematic manner Both stabilization of a single system and consensus of a group of systems (multi-agent systems) are treated in a unified manner by applying the truncated pre...

Structure based modification of Bluetongue virus helicase protein VP6 to produce a viable VP6-truncated BTV

Energy Technology Data Exchange (ETDEWEB)

Matsuo, Eiko [Microbiology and Immunology, Division of Animal Science, Department of Bioresource Science, Graduate School of Agricultural Science, Kobe University, 1-1, Rokkodai, Nada-ku, Kobe-City 657-8501 (Japan); Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT (United Kingdom); Leon, Esther; Matthews, Steve J. [Division of Molecular Biosciences, Centre for Structural Biology, Imperial College London, South Kensington, London SW7 2AZ (United Kingdom); Roy, Polly, E-mail: polly.roy@lshtm.ac.uk [Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT (United Kingdom)

2014-09-05

Highlights: • NMR analysis on BTV VP6 reveals two large loop regions. • The loss of a loop (aa 34–130) does not affect the overall fold of the protein. • A region of VP6 (aa 34–92) is not required for BTV replication. • A region of VP6 (aa 93–130) plays an essential role in the virus replication. - Abstract: Bluetongue virus core protein VP6 is an ATP hydrolysis dependent RNA helicase. However, despite much study, the precise role of VP6 within the viral capsid and its structure remain unclear. To investigate the requirement of VP6 in BTV replication, we initiated a structural and biological study. Multinuclear nuclear magnetic resonance spectra were assigned on his-tagged full-length VP6 (329 amino acid residues) as well as several truncated VP6 variants. The analysis revealed a large structured domain with two large loop regions that exhibit significant conformational exchange. One of the loops (amino acid position 34–130) could be removed without affecting the overall fold of the protein. Moreover, using a BTV reverse genetics system, it was possible to demonstrate that the VP6-truncated BTV was viable in BHK cells in the absence of any helper VP6 protein, suggesting that a large portion of this loop region is not absolutely required for BTV replication.

Stability mechanisms of a thermophilic laccase probed by molecular dynamics.

Directory of Open Access Journals (Sweden)

Niels J Christensen

Full Text Available Laccases are highly stable, industrially important enzymes capable of oxidizing a large range of substrates. Causes for their stability are, as for other proteins, poorly understood. In this work, multiple-seed molecular dynamics (MD was applied to a Trametes versicolor laccase in response to variable ionic strengths, temperatures, and glycosylation status. Near-physiological conditions provided excellent agreement with the crystal structure (average RMSD ∼0.92 Å and residual agreement with experimental B-factors. The persistence of backbone hydrogen bonds was identified as a key descriptor of structural response to environment, whereas solvent-accessibility, radius of gyration, and fluctuations were only locally relevant. Backbone hydrogen bonds decreased systematically with temperature in all simulations (∼9 per 50 K, probing structural changes associated with enthalpy-entropy compensation. Approaching T opt (∼350 K from 300 K, this change correlated with a beginning "unzipping" of critical β-sheets. 0 M ionic strength triggered partial denucleation of the C-terminal (known experimentally to be sensitive at 400 K, suggesting a general salt stabilization effect. In contrast, F(- (but not Cl(- specifically impaired secondary structure by formation of strong hydrogen bonds with backbone NH, providing a mechanism for experimentally observed small anion destabilization, potentially remedied by site-directed mutagenesis at critical intrusion sites. N-glycosylation was found to support structural integrity by increasing persistent backbone hydrogen bonds by ∼4 across simulations, mainly via prevention of F(- intrusion. Hydrogen-bond loss in distinct loop regions and ends of critical β-sheets suggest potential strategies for laboratory optimization of these industrially important enzymes.

Potentialities of a Membrane Reactor with Laccase Grafted Membranes for the Enzymatic Degradation of Phenolic Compounds in Water

Directory of Open Access Journals (Sweden)

Vorleak Chea

2014-10-01

Full Text Available This paper describes the degradation of phenolic compounds by laccases from Trametes versicolor in an enzymatic membrane reactor (EMR. The enzymatic membranes were prepared by grafting laccase on a gelatine layer previously deposited onto α-alumina tubular membranes. The 2,6-dimethoxyphenol (DMP was selected  from among the three different phenolic compounds tested (guaiacol, 4-chlorophenol and DMP to study the performance of the EMR in dead end configuration. At the lowest feed substrate concentration tested (100 mg·L−1, consumption increased with flux (up to 7.9 × 103 mg·h−1·m−2 at 128 L·h−1·m−2, whereas at the highest substrate concentration (500 mg·L−1, it was shown that the reaction was limited by the oxygen content.

New results to BDD truncation method for efficient top event probability calculation

International Nuclear Information System (INIS)

Mo, Yuchang; Zhong, Farong; Zhao, Xiangfu; Yang, Quansheng; Cui, Gang

2012-01-01

A Binary Decision Diagram (BDD) is a graph-based data structure that calculates an exact top event probability (TEP). It has been a very difficult task to develop an efficient BDD algorithm that can solve a large problem since its memory consumption is very high. Recently, in order to solve a large reliability problem within limited computational resources, Jung presented an efficient method to maintain a small BDD size by a BDD truncation during a BDD calculation. In this paper, it is first identified that Jung's BDD truncation algorithm can be improved for a more practical use. Then, a more efficient truncation algorithm is proposed in this paper, which can generate truncated BDD with smaller size and approximate TEP with smaller truncation error. Empirical results showed this new algorithm uses slightly less running time and slightly more storage usage than Jung's algorithm. It was also found, that designing a truncation algorithm with ideal features for every possible fault tree is very difficult, if not impossible. The so-called ideal features of this paper would be that with the decrease of truncation limits, the size of truncated BDD converges to the size of exact BDD, but should never be larger than exact BDD.

Maximum nondiffracting propagation distance of aperture-truncated Airy beams

Science.gov (United States)

Chu, Xingchun; Zhao, Shanghong; Fang, Yingwu

2018-05-01

Airy beams have called attention of many researchers due to their non-diffracting, self-healing and transverse accelerating properties. A key issue in research of Airy beams and its applications is how to evaluate their nondiffracting propagation distance. In this paper, the critical transverse extent of physically realizable Airy beams is analyzed under the local spatial frequency methodology. The maximum nondiffracting propagation distance of aperture-truncated Airy beams is formulated and analyzed based on their local spatial frequency. The validity of the formula is verified by comparing the maximum nondiffracting propagation distance of an aperture-truncated ideal Airy beam, aperture-truncated exponentially decaying Airy beam and exponentially decaying Airy beam. Results show that the formula can be used to evaluate accurately the maximum nondiffracting propagation distance of an aperture-truncated ideal Airy beam. Therefore, it can guide us to select appropriate parameters to generate Airy beams with long nondiffracting propagation distance that have potential application in the fields of laser weapons or optical communications.

Laccase electrodes based on the combination of single-walled carbon nanotubes and redox layered double hydroxides: Towards the development of biocathode for biofuel cells

Science.gov (United States)

Ding, Shou-Nian; Holzinger, Michael; Mousty, Christine; Cosnier, Serge

Single-walled carbon nanotubes (SWCNT) were combined with layered double hydroxides (LDH) intercalated with 2,2‧-azino-bis(3-ethylbenzothiazoline-6-sulfonate) diammonium salt [ZnCr-ABTS] to entrap and electrically connect laccase enzyme. The resulting laccase electrodes exhibited an electro-enzymatic activity for O 2 reduction. To improve this electrocatalytic activity, varying SWCNT quantities and loading methods were tested to optimize the configuration of the laccase electrodes. Furthermore, the resulting bioelectrode was successfully used as a biocathode for the elaboration of a membrane-less glucose/air biofuel cell. In 0.1 M phosphate buffer (PBS) of pH 6.0, containing glucose (5 mM) under ambient conditions, the assembled biofuel cell yielded a maximum power density of 18 μW cm -2 at a cell voltage of 0.3 V whereas this power decreased to 8.3 μW cm -2 for a biofuel cell based on the identical biocathode setup without SWCNT.

Laccase electrodes based on the combination of single-walled carbon nanotubes and redox layered double hydroxides: Towards the development of biocathode for biofuel cells

Energy Technology Data Exchange (ETDEWEB)

Ding, Shou-Nian; Holzinger, Michael; Cosnier, Serge [Departement de Chimie Moleculaire UMR-5250, ICMG FR-2607, CNRS Universite Joseph Fourier, BP-53, 38041 Grenoble Cedex 9 (France); Mousty, Christine [Laboratoire des Materiaux Inorganiques, Universite Blaise Pascal, CNRS UMR-6002, 63177 Aubiere Cedex (France)

2010-08-01

Single-walled carbon nanotubes (SWCNT) were combined with layered double hydroxides (LDH) intercalated with 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) diammonium salt [ZnCr-ABTS] to entrap and electrically connect laccase enzyme. The resulting laccase electrodes exhibited an electro-enzymatic activity for O{sub 2} reduction. To improve this electrocatalytic activity, varying SWCNT quantities and loading methods were tested to optimize the configuration of the laccase electrodes. Furthermore, the resulting bioelectrode was successfully used as a biocathode for the elaboration of a membrane-less glucose/air biofuel cell. In 0.1 M phosphate buffer (PBS) of pH 6.0, containing glucose (5 mM) under ambient conditions, the assembled biofuel cell yielded a maximum power density of 18 {mu}W cm{sup -2} at a cell voltage of 0.3 V whereas this power decreased to 8.3 {mu}W cm{sup -2} for a biofuel cell based on the identical biocathode setup without SWCNT. (author)

An iterative reconstruction from truncated projection data

International Nuclear Information System (INIS)

Anon.

1985-01-01

Various methods have been proposed for tomographic reconstruction from truncated projection data. In this paper, a reconstructive method is discussed which consists of iterations of filtered back-projection, reprojection and some nonlinear processings. First, the method is so constructed that it converges to a fixed point. Then, to examine its effectiveness, comparisons are made by computer experiments with two existing reconstructive methods for truncated projection data, that is, the method of extrapolation based on the smooth assumption followed by filtered back-projection, and modified additive ART

Direct electrochemistry of dopamine on gold-Agaricus bisporus laccase enzyme electrode: characterization and quantitative detection.

Science.gov (United States)

Shervedani, Reza Karimi; Amini, Akbar

2012-04-01

Direct electrochemistry of a new laccase enzyme immobilized on gold and its application as a biosensor for dopamine (DA) are investigated by voltammetry and electrochemical impedance spectroscopy. The sensor demonstrated a redox adsorption behavior with E(0') = + 180 mV vs. Ag/AgCl for immobilized Agaricus bisporus laccase (LacAB) enzyme. The MPA platform was assembled on Au with and without utilization of ultrasounds. Excellent results were obtained by using the enzyme electrode fabricated based on MPA assembled with sonication. The LacAB immobilized in this condition showed a large electrocatalytic activity for oxidation of DA. Accordingly, a third-generation (mediator free) biosensor was constructed for DA. The DA concentration could be measured in the linear range of 0.5 to 13.0 and 47.0 to 430.0 μmol L(-1) with correlation coefficients of 0.999 and 0.989, respectively, and a detection limit of 29.0 nmol L(-1). The biosensor was successfully tested for determination of DA in human blood plasma and pharmaceutical samples. Copyright © 2011 Elsevier B.V. All rights reserved.

Truncated Wigner dynamics and conservation laws

Science.gov (United States)

Drummond, Peter D.; Opanchuk, Bogdan

2017-10-01

Ultracold Bose gases can be used to experimentally test many-body theory predictions. Here we point out that both exact conservation laws and dynamical invariants exist in the topical case of the one-dimensional Bose gas, and these provide an important validation of methods. We show that the first four quantum conservation laws are exactly conserved in the approximate truncated Wigner approach to many-body quantum dynamics. Center-of-mass position variance is also exactly calculable. This is nearly exact in the truncated Wigner approximation, apart from small terms that vanish as N-3 /2 as N →∞ with fixed momentum cutoff. Examples of this are calculated in experimentally relevant, mesoscopic cases.

Plackett-Burman Design for rGILCC1 Laccase Activity Enhancement in Pichia pastoris: Concentrated Enzyme Kinetic Characterization

Directory of Open Access Journals (Sweden)

Edwin D. Morales-Álvarez

2017-01-01

Full Text Available Laccases are multicopper oxidases that catalyze aromatic and nonaromatic compounds with concomitant reduction of molecular oxygen to water. They are of great interest due to their potential biotechnological applications. In this work we statistically improved culture media for recombinant GILCC1 (rGILCC1 laccase production at low scale from Ganoderma lucidum containing the construct pGAPZαA-GlucPost-Stop in Pichia pastoris. Temperature, pH stability, and kinetic parameter characterizations were determined by monitoring concentrate enzyme oxidation at different ABTS substrate concentrations. Plackett-Burman Design allowed improving enzyme activity from previous work 36.08-fold, with a laccase activity of 4.69 ± 0.39 UL−1 at 168 h of culture in a 500 mL shake-flask. Concentrated rGILCC1 remained stable between 10 and 50°C and retained a residual enzymatic activity greater than 70% at 60°C and 50% at 70°C. In regard to pH stability, concentrated enzyme was more stable at pH 4.0 ± 0.2 with a residual activity greater than 90%. The lowest residual activity greater than 55% was obtained at pH 10.0 ± 0.2. Furthermore, calculated apparent enzyme kinetic parameters were a Vmax of 6.87 × 10−5 mM s−1, with an apparent Km of 5.36 × 10−2 mM. Collectively, these important stability findings open possibilities for applications involving a wide pH and temperature ranges.

Effect of the L499M mutation of the ascomycetous Botrytis aclada laccase on redox potential and catalytic properties

International Nuclear Information System (INIS)

Osipov, Evgeny; Polyakov, Konstantin; Kittl, Roman; Shleev, Sergey; Dorovatovsky, Pavel; Tikhonova, Tamara; Hann, Stephan; Ludwig, Roland; Popov, Vladimir

2014-01-01

The structures of the ascomycetous B. aclada laccase and its L499M T1-site mutant have been solved at 1.7 Å resolution. The mutant enzyme shows a 140 mV lower redox potential of the type 1 copper and altered kinetic behaviour. The wild type and the mutant have very similar structures, which makes it possible to relate the changes in the redox potential to the L499M mutation Laccases are members of a large family of multicopper oxidases that catalyze the oxidation of a wide range of organic and inorganic substrates accompanied by the reduction of dioxygen to water. These enzymes contain four Cu atoms per molecule organized into three sites: T1, T2 and T3. In all laccases, the T1 copper ion is coordinated by two histidines and one cysteine in the equatorial plane and is covered by the side chains of hydrophobic residues in the axial positions. The redox potential of the T1 copper ion influences the enzymatic reaction and is determined by the nature of the axial ligands and the structure of the second coordination sphere. In this work, the laccase from the ascomycete Botrytis aclada was studied, which contains conserved Ile491 and nonconserved Leu499 residues in the axial positions. The three-dimensional structures of the wild-type enzyme and the L499M mutant were determined by X-ray crystallography at 1.7 Å resolution. Crystals suitable for X-ray analysis could only be grown after deglycosylation. Both structures did not contain the T2 copper ion. The catalytic properties of the enzyme were characterized and the redox potentials of both enzyme forms were determined: E 0 = 720 and 580 mV for the wild-type enzyme and the mutant, respectively. Since the structures of the wild-type and mutant forms are very similar, the change in the redox potential can be related to the L499M mutation in the T1 site of the enzyme

Inference for shared-frailty survival models with left-truncated data

NARCIS (Netherlands)

van den Berg, G.J.; Drepper, B.

2016-01-01

Shared-frailty survival models specify that systematic unobserved determinants of duration outcomes are identical within groups of individuals. We consider random-effects likelihood-based statistical inference if the duration data are subject to left-truncation. Such inference with left-truncated

Immature truncated O-glycophenotype of cancer directly induces oncogenic features

DEFF Research Database (Denmark)

Radhakrishnan, Prakash; Dabelsteen, Sally; Madsen, Frey Brus

2014-01-01

Aberrant expression of immature truncated O-glycans is a characteristic feature observed on virtually all epithelial cancer cells, and a very high frequency is observed in early epithelial premalignant lesions that precede the development of adenocarcinomas. Expression of the truncated O-glycan s...

Probability distributions with truncated, log and bivariate extensions

CERN Document Server

Thomopoulos, Nick T

2018-01-01

This volume presents a concise and practical overview of statistical methods and tables not readily available in other publications. It begins with a review of the commonly used continuous and discrete probability distributions. Several useful distributions that are not so common and less understood are described with examples and applications in full detail: discrete normal, left-partial, right-partial, left-truncated normal, right-truncated normal, lognormal, bivariate normal, and bivariate lognormal. Table values are provided with examples that enable researchers to easily apply the distributions to real applications and sample data. The left- and right-truncated normal distributions offer a wide variety of shapes in contrast to the symmetrically shaped normal distribution, and a newly developed spread ratio enables analysts to determine which of the three distributions best fits a particular set of sample data. The book will be highly useful to anyone who does statistical and probability analysis. This in...

Impact of degree truncation on the spread of a contagious process on networks.

Science.gov (United States)

Harling, Guy; Onnela, Jukka-Pekka

2018-03-01

Understanding how person-to-person contagious processes spread through a population requires accurate information on connections between population members. However, such connectivity data, when collected via interview, is often incomplete due to partial recall, respondent fatigue or study design, e.g., fixed choice designs (FCD) truncate out-degree by limiting the number of contacts each respondent can report. Past research has shown how FCD truncation affects network properties, but its implications for predicted speed and size of spreading processes remain largely unexplored. To study the impact of degree truncation on predictions of spreading process outcomes, we generated collections of synthetic networks containing specific properties (degree distribution, degree-assortativity, clustering), and also used empirical social network data from 75 villages in Karnataka, India. We simulated FCD using various truncation thresholds and ran a susceptible-infectious-recovered (SIR) process on each network. We found that spreading processes propagated on truncated networks resulted in slower and smaller epidemics, with a sudden decrease in prediction accuracy at a level of truncation that varied by network type. Our results have implications beyond FCD to truncation due to any limited sampling from a larger network. We conclude that knowledge of network structure is important for understanding the accuracy of predictions of process spread on degree truncated networks.

Application of a truncated normal failure distribution in reliability testing

Science.gov (United States)

Groves, C., Jr.

1968-01-01

Statistical truncated normal distribution function is applied as a time-to-failure distribution function in equipment reliability estimations. Age-dependent characteristics of the truncated function provide a basis for formulating a system of high-reliability testing that effectively merges statistical, engineering, and cost considerations.

Truncation scheme of time-dependent density-matrix approach II

Energy Technology Data Exchange (ETDEWEB)

Tohyama, Mitsuru [Kyorin University School of Medicine, Mitaka, Tokyo (Japan); Schuck, Peter [Institut de Physique Nucleaire, IN2P3-CNRS, Universite Paris-Sud, Orsay (France); Laboratoire de Physique et de Modelisation des Milieux Condenses, CNRS et Universite Joseph Fourier, Grenoble (France)

2017-09-15

A truncation scheme of the Bogoliubov-Born-Green-Kirkwood-Yvon hierarchy for reduced density matrices, where a three-body density matrix is approximated by two-body density matrices, is improved to take into account a normalization effect. The truncation scheme is tested for the Lipkin model. It is shown that the obtained results are in good agreement with the exact solutions. (orig.)

Multiple-scattering theory with a truncated basis set

International Nuclear Information System (INIS)

Zhang, X.; Butler, W.H.

1992-01-01

Multiple-scattering theory (MST) is an extremely efficient technique for calculating the electronic structure of an assembly of atoms. The wave function in MST is expanded in terms of spherical waves centered on each atom and indexed by their orbital and azimuthal quantum numbers, l and m. The secular equation which determines the characteristic energies can be truncated at a value of the orbital angular momentum l max , for which the higher angular momentum phase shifts, δ l (l>l max ), are sufficiently small. Generally, the wave-function coefficients which are calculated from the secular equation are also truncated at l max . Here we point out that this truncation of the wave function is not necessary and is in fact inconsistent with the truncation of the secular equation. A consistent procedure is described in which the states with higher orbital angular momenta are retained but with their phase shifts set to zero. We show that this treatment gives smooth, continuous, and correctly normalized wave functions and that the total charge density calculated from the corresponding Green function agrees with the Lloyd formula result. We also show that this augmented wave function can be written as a linear combination of Andersen's muffin-tin orbitals in the case of muffin-tin potentials, and can be used to generalize the muffin-tin orbital idea to full-cell potentals

Molecular and biochemical characterization of a new thermostable bacterial laccase from Meiothermus ruber DSM 1279

DEFF Research Database (Denmark)

Kalyani, D. C.; Munk, L.; Mikkelsen, J. D.

2016-01-01

. Spectroscopic analysis of the purified enzyme by UV/visible and electron paramagnetic resonance spectroscopy confirmed that the Mrlac was a multicopper oxidase. The Mrlac had a molecular weight of ∼ 50 kDa and exhibited activity towards the canonical laccase substrates 2,2'-azino-bis(3-ethylbenzothiazoline-6...

Importance-truncated shell model for multi-shell valence spaces

Energy Technology Data Exchange (ETDEWEB)

Stumpf, Christina; Vobig, Klaus; Roth, Robert [Institut fuer Kernphysik, TU Darmstadt (Germany)

2016-07-01

The valence-space shell model is one of the work horses in nuclear structure theory. In traditional applications, shell-model calculations are carried out using effective interactions constructed in a phenomenological framework for rather small valence spaces, typically spanned by one major shell. We improve on this traditional approach addressing two main aspects. First, we use new effective interactions derived in an ab initio approach and, thus, establish a connection to the underlying nuclear interaction providing access to single- and multi-shell valence spaces. Second, we extend the shell model to larger valence spaces by applying an importance-truncation scheme based on a perturbative importance measure. In this way, we reduce the model space to the relevant basis states for the description of a few target eigenstates and solve the eigenvalue problem in this physics-driven truncated model space. In particular multi-shell valence spaces are not tractable otherwise. We combine the importance-truncated shell model with refined extrapolation schemes to approximately recover the exact result. We present first results obtained in the importance-truncated shell model with the newly derived ab initio effective interactions for multi-shell valence spaces, e.g., the sdpf shell.

Flow equation of quantum Einstein gravity in a higher-derivative truncation

International Nuclear Information System (INIS)

Lauscher, O.; Reuter, M.

2002-01-01

Motivated by recent evidence indicating that quantum Einstein gravity (QEG) might be nonperturbatively renormalizable, the exact renormalization group equation of QEG is evaluated in a truncation of theory space which generalizes the Einstein-Hilbert truncation by the inclusion of a higher-derivative term (R 2 ). The beta functions describing the renormalization group flow of the cosmological constant, Newton's constant, and the R 2 coupling are computed explicitly. The fixed point properties of the 3-dimensional flow are investigated, and they are confronted with those of the 2-dimensional Einstein-Hilbert flow. The non-Gaussian fixed point predicted by the latter is found to generalize to a fixed point on the enlarged theory space. In order to test the reliability of the R 2 truncation near this fixed point we analyze the residual scheme dependence of various universal quantities; it turns out to be very weak. The two truncations are compared in detail, and their numerical predictions are found to agree with a surprisingly high precision. Because of the consistency of the results it appears increasingly unlikely that the non-Gaussian fixed point is an artifact of the truncation. If it is present in the exact theory QEG is probably nonperturbatively renormalizable and ''asymptotically safe.'' We discuss how the conformal factor problem of Euclidean gravity manifests itself in the exact renormalization group approach and show that, in the R 2 truncation, the investigation of the fixed point is not afflicted with this problem. Also the Gaussian fixed point of the Einstein-Hilbert truncation is analyzed; it turns out that it does not generalize to a corresponding fixed point on the enlarged theory space

Multicomponent kinetic analysis and theoretical studies on the phenolic intermediates in the oxidation of eugenol and isoeugenol catalyzed by laccase.

Science.gov (United States)

Qi, Yan-Bing; Wang, Xiao-Lei; Shi, Ting; Liu, Shuchang; Xu, Zhen-Hao; Li, Xiqing; Shi, Xuling; Xu, Ping; Zhao, Yi-Lei

2015-11-28

Laccase catalyzes the oxidation of natural phenols and thereby is believed to initialize reactions in lignification and delignification. Numerous phenolic mediators have also been applied in laccase-mediator systems. However, reaction details after the primary O-H rupture of phenols remain obscure. In this work two types of isomeric phenols, EUG (eugenol) and ISO (trans-/cis-isoeugenol), were used as chemical probes to explore the enzymatic reaction pathways, with the combined methods of time-resolved UV-Vis absorption spectra, MCR-ALS, HPLC-MS, and quantum mechanical (QM) calculations. It has been found that the EUG-consuming rate is linear to its concentration, while the ISO not. Besides, an o-methoxy quinone methide intermediate, (E/Z)-4-allylidene-2-methoxycyclohexa-2,5-dienone, was evidenced in the case of EUG with the UV-Vis measurement, mass spectra and TD-DFT calculations; in contrast, an ISO-generating phenoxyl radical, a (E/Z)-2-methoxy-4-(prop-1-en-1-yl) phenoxyl radical, was identified in the case of ISO. Furthermore, QM calculations indicated that the EUG-generating phenoxyl radical (an O-centered radical) can easily transform into an allylic radical (a C-centered radical) by hydrogen atom transfer (HAT) with a calculated activation enthalpy of 5.3 kcal mol(-1) and then be fast oxidized to the observed eugenol quinone methide, rather than an O-radical alkene addition with barriers above 12.8 kcal mol(-1). In contrast, the ISO-generating phenoxyl radical directly undergoes a radical coupling (RC) process, with a barrier of 4.8 kcal mol(-1), while the HAT isomerization between O- and C-centered radicals has a higher reaction barrier of 8.0 kcal mol(-1). The electronic conjugation of the benzyl-type radical and the aromatic allylic radical leads to differentiation of the two pathways. These results imply that competitive reaction pathways exist for the nascent reactive intermediates generated in the laccase-catalyzed oxidation of natural phenols, which is

Approximate truncation robust computed tomography—ATRACT

International Nuclear Information System (INIS)

Dennerlein, Frank; Maier, Andreas

2013-01-01

We present an approximate truncation robust algorithm to compute tomographic images (ATRACT). This algorithm targets at reconstructing volumetric images from cone-beam projections in scenarios where these projections are highly truncated in each dimension. It thus facilitates reconstructions of small subvolumes of interest, without involving prior knowledge about the object. Our method is readily applicable to medical C-arm imaging, where it may contribute to new clinical workflows together with a considerable reduction of x-ray dose. We give a detailed derivation of ATRACT that starts from the conventional Feldkamp filtered-backprojection algorithm and that involves, as one component, a novel original formula for the inversion of the two-dimensional Radon transform. Discretization and numerical implementation are discussed and reconstruction results from both, simulated projections and first clinical data sets are presented. (paper)

Enhancing propagation characteristics of truncated localized waves in silica

KAUST Repository

Salem, Mohamed

2011-07-01

The spectral characteristics of truncated Localized Waves propagating in dispersive silica are analyzed. Numerical experiments show that the immunity of the truncated Localized Waves propagating in dispersive silica to decay and distortion is enhanced as the non-linearity of the relation between the transverse spatial spectral components and the wave vector gets stronger, in contrast to free-space propagating waves, which suffer from early decay and distortion. © 2011 IEEE.

The pbrB gene encodes a laccase required for DHN-melanin synthesis in conidia of Talaromyces (Penicillium) marneffei.

Science.gov (United States)

Sapmak, Ariya; Boyce, Kylie J; Andrianopoulos, Alex; Vanittanakom, Nongnuch

2015-01-01

Talaromyces marneffei (Basionym: Penicillium marneffei) is a significant opportunistic fungal pathogen in patients infected with human immunodeficiency virus in Southeast Asia. T. marneffei cells have been shown to become melanized in vivo. Melanins are pigment biopolymers which act as a non-specific protectant against various stressors and which play an important role during virulence in fungi. The synthesis of the two most commonly found melanins in fungi, the eumelanin DOPA-melanin and the allomelanin DHN-melanin, requires the action of laccase enzymes. The T. marneffei genome encodes a number of laccases and this study describes the characterization of one of these, pbrB, during growth and development. A strain carrying a PbrB-GFP fusion shows that pbrB is expressed at high levels during asexual development (conidiation) but not in cells growing vegetatively. The pbrB gene is required for the synthesis of DHN-melanin in conidia and when deleted results in brown pigmented conidia, in contrast to the green conidia of the wild type.

Truncation of CPC solar collectors and its effect on energy collection

Science.gov (United States)

Carvalho, M. J.; Collares-Pereira, M.; Gordon, J. M.; Rabl, A.

1985-01-01

Analytic expressions are derived for the angular acceptance function of two-dimensional compound parabolic concentrator solar collectors (CPC's) of arbitrary degree of truncation. Taking into account the effect of truncation on both optical and thermal losses in real collectors, the increase in monthly and yearly collectible energy is also evaluated. Prior analyses that have ignored the correct behavior of the angular acceptance function at large angles for truncated collectors are shown to be in error by 0-2 percent in calculations of yearly collectible energy for stationary collectors.

Vortex breakdown in a truncated conical bioreactor

Energy Technology Data Exchange (ETDEWEB)

Balci, Adnan; Brøns, Morten [DTU Compute, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Herrada, Miguel A [E.S.I, Universidad de Sevilla, Camino de los Descubrimientos s/n, E-41092 (Spain); Shtern, Vladimir N, E-mail: mobr@dtu.dk [Shtern Research and Consulting, Houston, TX 77096 (United States)

2015-12-15

This numerical study explains the eddy formation and disappearance in a slow steady axisymmetric air–water flow in a vertical truncated conical container, driven by the rotating top disk. Numerous topological metamorphoses occur as the water height, H{sub w}, and the bottom-sidewall angle, α, vary. It is found that the sidewall convergence (divergence) from the top to the bottom stimulates (suppresses) the development of vortex breakdown (VB) in both water and air. At α = 60°, the flow topology changes eighteen times as H{sub w} varies. The changes are due to (a) competing effects of AMF (the air meridional flow) and swirl, which drive meridional motions of opposite directions in water, and (b) feedback of water flow on AMF. For small H{sub w}, the AMF effect dominates. As H{sub w} increases, the swirl effect dominates and causes VB. The water flow feedback produces and modifies air eddies. The results are of fundamental interest and can be relevant for aerial bioreactors. (paper)

Vortex breakdown in a truncated conical bioreactor

International Nuclear Information System (INIS)

Balci, Adnan; Brøns, Morten; Herrada, Miguel A; Shtern, Vladimir N

2015-01-01

This numerical study explains the eddy formation and disappearance in a slow steady axisymmetric air–water flow in a vertical truncated conical container, driven by the rotating top disk. Numerous topological metamorphoses occur as the water height, H w , and the bottom-sidewall angle, α, vary. It is found that the sidewall convergence (divergence) from the top to the bottom stimulates (suppresses) the development of vortex breakdown (VB) in both water and air. At α = 60°, the flow topology changes eighteen times as H w varies. The changes are due to (a) competing effects of AMF (the air meridional flow) and swirl, which drive meridional motions of opposite directions in water, and (b) feedback of water flow on AMF. For small H w , the AMF effect dominates. As H w increases, the swirl effect dominates and causes VB. The water flow feedback produces and modifies air eddies. The results are of fundamental interest and can be relevant for aerial bioreactors. (paper)

Ultrasound-assisted extraction and characterization of hydrolytic and oxidative enzymes produced by solid state fermentation.

Science.gov (United States)

Szabo, Orsolya Erzsebet; Csiszar, Emilia; Toth, Karolina; Szakacs, George; Koczka, Bela

2015-01-01

Ligninolytic and hydrolytic enzymes were produced with six selected fungi on flax substrate by solid state fermentation (SSF). The extracellular enzyme production of the organisms in two SSF media was evaluated by measuring the soluble protein concentration and the filter paper, endoxylanase, 1,4-β-d-glucosidase, 1,4-β-d-endoglucanase, polygalacturonase, lignin peroxidase, manganese peroxidase and laccase activities of the clear culture solutions produced by conventional extraction from the SSF materials. The SSF material of the best enzyme producer (Trichoderma virens TUB F-498) was further investigated to enhance the enzyme recovery by low frequency ultrasound treatment. Performance of both the original and ultrasound macerated crude enzyme mixtures was evaluated in degradation of the colored lignin-containing and waxy materials of raw linen fabric. Results proved that sonication (at 40%, 60% and 80% amplitudes, for 60min) did not result in reduction in the filter paper, lignin peroxidase and laccase activities of the crude enzyme solution, but has a significant positive effect on the efficiency of enzyme extraction from the SSF material. Depending on the parameters of sonication, the enzyme activities in the extracts obtained can be increased up to 129-413% of the original activities measured in the control extracts recovered by a common magnetic stirrer. Sonication also has an effect on both the enzymatic removal of the lignin-containing color materials and hydrophobic surface layer from the raw linen. Copyright © 2014 Elsevier B.V. All rights reserved.

Human truncated thioredoxin (Trx80) as a novel mitogenic cytokine for white blood cells

OpenAIRE

Pekkari, Klas

2001-01-01

Thioredoxin (Trx) is a 12 kDa protein present in all species with a well-conserved active site sequence comprising -Cys-Gly-Pro-Cys-, which catalyzes oxido-reductase reactions. Trx regulates the activity of transcription factors and intracellular signalling pathways, and secreted Trx is a co-cytokine with several interleukins. In addition to full-length Trx a 10 kDa C-terminally truncated form of the protein is produced mainly by monocytes. This protein has unique eosinophil...

Application of Polarization Modulated Infrared Reflection Absorption Spectroscopy for electrocatalytic activity studies of laccase adsorbed on modified gold electrodes

International Nuclear Information System (INIS)

Olejnik, Piotr; Pawłowska, Aleksandra; Pałys, Barbara

2013-01-01

Orientation of the enzyme macromolecule on the electrode surface is crucially important for the efficiency of the electron transport between the active site and electrode surface. The orientation can be controlled by affecting the surface charge and the pH of the buffer solution. In this contribution we study laccase physically adsorbed on gold surface modified by mercapto-ethanol, lipid and variously charged diazonium salts. Polarization Modulated Infrared Reflection Absorption Spectroscopy (PMIRRAS) enables the molecular orientation study of the protein molecule by comparison of the amide I to amide II band intensity ratios assuming that the protein secondary structure does not change. We observe significant differences in the intensity ratios depending on the kind of support and the enzyme deposition. The comparison of infrared spectra and cyclic voltammetry responses of variously prepared laccase layers reveals that the parallel orientation of beta-sheet moieties results in high enzyme activity

Implication of mycelium-associated laccase from Irpex lacteus in the decolorization of synthetic dyes

Czech Academy of Sciences Publication Activity Database

Svobodová, Kateřina; Majcherczyk, A.; Novotný, Čeněk; Kuees, U.

2007-01-01

Roč. 99, - (2007), s. 463-471 ISSN 0960-8524 R&D Projects: GA AV ČR IAA6020411 Grant - others:XE(XE) Marie Curie Fellowship HPMT-CT-2001-00259; DE(DE) Deutsche Bundesstiftung Umwelt Institutional research plan: CEZ:AV0Z50200510 Source of funding: R - rámcový projekt EK ; O - operačné programy Keywords : irpex lacteus * dye decolorization * laccase Subject RIV: EE - Microbiology, Virology Impact factor: 3.103, year: 2007

Modifications of Geometric Truncation of the Scattering Phase Function

Science.gov (United States)

Radkevich, A.

2017-12-01

Phase function (PF) of light scattering on large atmospheric particles has very strong peak in forward direction constituting a challenge for accurate numerical calculations of radiance. Such accurate (and fast) evaluations are important in the problems of remote sensing of the atmosphere. Scaling transformation replaces original PF with a sum of the delta function and a new regular smooth PF. A number of methods to construct such a PF were suggested. Delta-M and delta-fit methods require evaluation of the PF moments which imposes a numerical problem if strongly anisotropic PF is given as a function of angle. Geometric truncation keeps the original PF unchanged outside the forward peak cone replacing it with a constant within the cone. This approach is designed to preserve the asymmetry parameter. It has two disadvantages: 1) PF has discontinuity at the cone; 2) the choice of the cone is subjective, no recommendations were provided on the choice of the truncation angle. This choice affects both truncation fraction and the value of the phase function within the forward cone. Both issues are addressed in this study. A simple functional form of the replacement PF is suggested. This functional form allows for a number of modifications. This study consider 3 versions providing continuous PF. The considered modifications also bear either of three properties: preserve asymmetry parameter, provide continuity of the 1st derivative of the PF, and preserve mean scattering angle. The second problem mentioned above is addressed with a heuristic approach providing unambiguous criterion of selection of the truncation angle. The approach showed good performance on liquid water and ice clouds with different particle size distributions. Suggested modifications were tested on different cloud PFs using both discrete ordinates and Monte Carlo methods. It was showed that the modifications provide better accuracy of the radiance computation compare to the original geometric truncation.

Purificação de lacases PPO-I de Botryosphaeria rhodina - DOI: 10.4025/actascibiolsci.v27i3.1317 Purification of laccases PPO-I of fungus Botryosphaeria rhodina - DOI: 10.4025/actascibiolsci.v27i3.1317

Directory of Open Access Journals (Sweden)

Dalva Tomoe Miyagui

2005-03-01

Full Text Available Lacases são glicoproteínas polifenol oxidases envolvidas na patogenicidade de alguns fungos e úteis em processos biotecnológicos. O ascomiceto ligninolítico Botryosphaeria rhodina tem sido estudado como produtor de exopolissacarídeos e de lacases PPO-I e PPO-II induzidas pelo álcool veratrílico. Como as lacases produzidas ainda não foram isoladas, o objetivo deste trabalho foi purificar lacases PPO-I e identificar os carboidratos constituintes da porção glicosídica. O fungo foi cultivado em meio mínimo de Vogel contendo 1% de glicose e 30,4 mM de álcool veratrílico, a 28C e agitação de 180 rpm durante 4,5 dias. O extrato livre de células apresentou elevada concentração de carboidratos e de PPO-I estáveis a 4ºC e -18ºC durante 40 dias. Técnicas de ultrafiltração, cromatografia em gel Sephadex G-100 e em resina DEAE-Celulose purificaram lacases PPO-I com peso molecular de 113 kDa por eletroforese PAGE-SDS, contendo 40% de proteínas e 60% carboidratos identificados por HPAEC-PAD como fucose, galactose, manose, glucose e glucosaminaLaccases are glycoprotein polyphenol oxidases which are involved in fungal pathogenicity and they are also useful for biotechnological applications. The ligninolytic ascomycete, Botryosphaeria rhodina, has been studied as producer of exopolysaccharide and PPO-I and PPO-II laccases induced by veratryl alcohol. However, as the induced laccases have not been isolated, the aim of this study was to purify the enzyme and to identify the carbohydrates constituents of the glycosidic moiety. The fungus was cultivated on broth Vogel, 1% glucose and 30.4mM veratryl alcohol during 4.5 days at 28°C/180 rpm. The extracellular fluid showed high carbohydrate concentration and the stability of PPO-I laccase under conditions of refrigeration and freezing at 4ºC-18ºC over 40 days. The purification was developed by ultrafiltration using a NMWL 100 and 30 kDa membrane, gelfiltration on Sephadex G-100, and ion

Heterologous expression of laccase cDNA from Ceriporiopsis subvermispora yields copper-activated apoprotein and complex isoform patterns

Science.gov (United States)

Luis F. Larrondo; Marcela Avila; Loreto Salas; Dan Cullen; Rafael Vicuna

2003-01-01

Analysis of genomic clones encoding a putative laccase in homokaryon strains of Ceriporiopsis subvermispora led to the identification of an allelic variant of the previously described lcs-1 gene. A cDNA clone corresponding to this gene was expressed in Aspergillus nidulans and in Aspergillus niger. Enzyme assays and Western blots showed that both hosts secreted active...

A Support Vector Machine Approach for Truncated Fingerprint Image Detection from Sweeping Fingerprint Sensors

Science.gov (United States)

Chen, Chi-Jim; Pai, Tun-Wen; Cheng, Mox

2015-01-01

A sweeping fingerprint sensor converts fingerprints on a row by row basis through image reconstruction techniques. However, a built fingerprint image might appear to be truncated and distorted when the finger was swept across a fingerprint sensor at a non-linear speed. If the truncated fingerprint images were enrolled as reference targets and collected by any automated fingerprint identification system (AFIS), successful prediction rates for fingerprint matching applications would be decreased significantly. In this paper, a novel and effective methodology with low time computational complexity was developed for detecting truncated fingerprints in a real time manner. Several filtering rules were implemented to validate existences of truncated fingerprints. In addition, a machine learning method of supported vector machine (SVM), based on the principle of structural risk minimization, was applied to reject pseudo truncated fingerprints containing similar characteristics of truncated ones. The experimental result has shown that an accuracy rate of 90.7% was achieved by successfully identifying truncated fingerprint images from testing images before AFIS enrollment procedures. The proposed effective and efficient methodology can be extensively applied to all existing fingerprint matching systems as a preliminary quality control prior to construction of fingerprint templates. PMID:25835186

A Support Vector Machine Approach for Truncated Fingerprint Image Detection from Sweeping Fingerprint Sensors

Directory of Open Access Journals (Sweden)

Chi-Jim Chen

2015-03-01

Full Text Available A sweeping fingerprint sensor converts fingerprints on a row by row basis through image reconstruction techniques. However, a built fingerprint image might appear to be truncated and distorted when the finger was swept across a fingerprint sensor at a non-linear speed. If the truncated fingerprint images were enrolled as reference targets and collected by any automated fingerprint identification system (AFIS, successful prediction rates for fingerprint matching applications would be decreased significantly. In this paper, a novel and effective methodology with low time computational complexity was developed for detecting truncated fingerprints in a real time manner. Several filtering rules were implemented to validate existences of truncated fingerprints. In addition, a machine learning method of supported vector machine (SVM, based on the principle of structural risk minimization, was applied to reject pseudo truncated fingerprints containing similar characteristics of truncated ones. The experimental result has shown that an accuracy rate of 90.7% was achieved by successfully identifying truncated fingerprint images from testing images before AFIS enrollment procedures. The proposed effective and efficient methodology can be extensively applied to all existing fingerprint matching systems as a preliminary quality control prior to construction of fingerprint templates.

Propagation of truncated modified Laguerre-Gaussian beams

Science.gov (United States)

Deng, D.; Li, J.; Guo, Q.

2010-01-01

By expanding the circ function into a finite sum of complex Gaussian functions and applying the Collins formula, the propagation of hard-edge diffracted modified Laguerre-Gaussian beams (MLGBs) through a paraxial ABCD system is studied, and the approximate closed-form propagation expression of hard-edge diffracted MLGBs is obtained. The transverse intensity distribution of the MLGB carrying finite power can be characterized by a single bright and symmetric ring during propagation when the aperture radius is very large. Starting from the definition of the generalized truncated second-order moments, the beam quality factor of MLGBs through a hard-edged circular aperture is investigated in a cylindrical coordinate system, which turns out to be dependent on the truncated radius and the beam orders.

Computational analysis and low-scale constitutive expression of laccases synthetic genes GlLCC1 from Ganoderma lucidum and POXA 1B from Pleurotus ostreatus in Pichia pastoris.

Directory of Open Access Journals (Sweden)

Claudia M Rivera-Hoyos

Full Text Available Lacasses are multicopper oxidases that can catalyze aromatic and non-aromatic compounds concomitantly with reduction of molecular oxygen to water. Fungal laccases have generated a growing interest due to their biotechnological potential applications, such as lignocellulosic material delignification, biopulping and biobleaching, wastewater treatment, and transformation of toxic organic pollutants. In this work we selected fungal genes encoding for laccase enzymes GlLCC1 in Ganoderma lucidum and POXA 1B in Pleurotus ostreatus. These genes were optimized for codon use, GC content, and regions generating secondary structures. Laccase proposed computational models, and their interaction with ABTS [2, 2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid] substrate was evaluated by molecular docking. Synthetic genes were cloned under the control of Pichia pastoris glyceraldehyde-3-phosphate dehydrogenase (GAP constitutive promoter. P. pastoris X-33 was transformed with pGAPZαA-LaccGluc-Stop and pGAPZαA-LaccPost-Stop constructs. Optimization reduced GC content by 47 and 49% for LaccGluc-Stop and LaccPost-Stop genes, respectively. A codon adaptation index of 0.84 was obtained for both genes. 3D structure analysis using SuperPose revealed LaccGluc-Stop is similar to the laccase crystallographic structure 1GYC of Trametes versicolor. Interaction analysis of the 3D models validated through ABTS, demonstrated higher substrate affinity for LaccPost-Stop, in agreement with our experimental results with enzymatic activities of 451.08 ± 6.46 UL-1 compared to activities of 0.13 ± 0.028 UL-1 for LaccGluc-Stop. This study demonstrated that G. lucidum GlLCC1 and P. ostreatus POXA 1B gene optimization resulted in constitutive gene expression under GAP promoter and α-factor leader in P. pastoris. These are important findings in light of recombinant enzyme expression system utility for environmentally friendly designed expression systems, because of the wide range

Balanced truncation for linear switched systems

DEFF Research Database (Denmark)

Petreczky, Mihaly; Wisniewski, Rafal; Leth, John-Josef

2013-01-01

In this paper, we present a theoretical analysis of the model reduction algorithm for linear switched systems from Shaker and Wisniewski (2011, 2009) and . This algorithm is a reminiscence of the balanced truncation method for linear parameter varying systems (Wood et al., 1996) [3]. Specifically...

Truncated Newton-Raphson Methods for Quasicontinuum Simulations

National Research Council Canada - National Science Library

Liang, Yu; Kanapady, Ramdev; Chung, Peter W

2006-01-01

.... In this research, we report the effectiveness of the truncated Newton-Raphson method and quasi-Newton method with low-rank Hessian update strategy that are evaluated against the full Newton-Raphson...

The Stars and Gas in Outer Parts of Galaxy Disks : Extended or Truncated, Flat or Warped?

NARCIS (Netherlands)

van der Kruit, P. C.; Funes, JG; Corsini, EM

2008-01-01

I review observations of truncations of stellar disks and models for their origin, compare observations of truncations in moderately inclined galaxies to those in edge-on systems and discuss the relation between truncations and H I-warps and their systematics and origin. Truncations are a common

On truncated Taylor series and the position of their spurious zeros

DEFF Research Database (Denmark)

Christiansen, Søren; Madsen, Per A.

2006-01-01

A truncated Taylor series, or a Taylor polynomial, which may appear when treating the motion of gravity water waves, is obtained by truncating an infinite Taylor series for a complex, analytical function. For such a polynomial the position of the complex zeros is considered in case the Taylor...

Degradation of Aflatoxins by Means of Laccases from Trametes versicolor: An In Silico Insight

Directory of Open Access Journals (Sweden)

Luca Dellafiora

2017-01-01

Full Text Available Mycotoxins are secondary metabolites of fungi that contaminate food and feed, and are involved in a series of foodborne illnesses and disorders in humans and animals. The mitigation of mycotoxin content via enzymatic degradation is a strategy to ensure safer food and feed, and to address the forthcoming issues in view of the global trade and sustainability. Nevertheless, the search for active enzymes is still challenging and time-consuming. The in silico analysis may strongly support the research by providing the evidence-based hierarchization of enzymes for a rational design of more effective experimental trials. The present work dealt with the degradation of aflatoxin B1 and M1 by laccase enzymes from Trametes versicolor. The enzymes–substrate interaction for various enzyme isoforms was investigated through 3D molecular modeling techniques. Structural differences among the isoforms have been pinpointed, which may cause different patterns of interaction between aflatoxin B1 and M1. The possible formation of different products of degradation can be argued accordingly. Moreover, the laccase gamma isoform was identified as the most suitable for protein engineering aimed at ameliorating the substrate specificity. Overall, 3D modeling proved to be an effective analytical tool to assess the enzyme–substrate interaction and provided a solid foothold for supporting the search of degrading enzyme at the early stage.

Conductive cotton prepared by polyaniline in situ polymerization using laccase.

Science.gov (United States)

Zhang, Ya; Dong, Aixue; Wang, Qiang; Fan, Xuerong; Cavaco-Paulo, Artur; Zhang, Ying

2014-09-01

The high-redox-potential catalyst laccase, isolated from Aspergillus, was first used as a biocatalyst in the oxidative polymerization of water-soluble conductive polyaniline, and then conductive cotton was prepared by in situ polymerization under the same conditions. The polymerization of aniline was performed in a water dispersion of sodium dodecylbenzenesulfonate (SDBS) micellar solution with atmospheric oxygen serving as the oxidizing agent. This method is ecologically clean and permits a greater degree of control over the kinetics of the reaction. The conditions for polyaniline synthesis were optimized. Characterizations of the conducting polyaniline and cotton were carried out using Fourier transform infrared spectroscopy, UV-vis spectroscopy, cyclic voltammetry, the fabric induction electrostatic tester, and the far-field EMC shielding effectiveness test fixture.

Comparing cell viability and ethanol fermentation of the thermotolerant yeast Kluyveromyces marxianus and Saccharomyces cerevisiae on steam-exploded biomass treated with laccase.

Science.gov (United States)

Moreno, Antonio D; Ibarra, David; Ballesteros, Ignacio; González, Alberto; Ballesteros, Mercedes

2013-05-01

In this study, the thermotolerant yeast Kluyveromyces marxianus CECT 10875 was compared to the industrial strain Saccharomyces cerevisiae Ethanol Red for lignocellulosic ethanol production. For it, whole slurry from steam-exploded wheat straw was used as raw material, and two process configurations, simultaneous saccharification and fermentation (SSF) and presaccharification and simultaneous saccharification and fermentation (PSSF), were evaluated. Compared to S. cerevisiae, which was able to produce ethanol in both process configurations, K. marxianus was inhibited, and neither growth nor ethanol production occurred during the processes. However, laccase treatment of the whole slurry removed specifically lignin phenols from the overall inhibitory compounds present in the slurry and triggered the fermentation by K. marxianus, attaining final ethanol concentrations and yields comparable to those obtained by S. cerevisiae. Copyright © 2012 Elsevier Ltd. All rights reserved.

Laccase-based biocathodes: Comparison of chitosan and Nafion.

Science.gov (United States)

El Ichi-Ribault, S; Zebda, A; Laaroussi, A; Reverdy-Bruas, N; Chaussy, D; Belgacem, M N; Suherman, A L; Cinquin, P; Martin, D K

2016-09-21

Chitosan and Nafion(®) are both reported as interesting polymers to be integrated into the structure of 3D electrodes for biofuel cells. Their advantage is mainly related to their chemical properties, which have a positive impact on the stability of electrodes such as the laccase-based biocathode. For optimal function in implantable applications the biocathode requires coating with a biocompatible semi-permeable membrane that is designed to prevent the loss of enzyme activity and to protect the structure of the biocathode. Since such membranes are integrated into the electrodes ultimately implanted, they must be fully characterized to demonstrate that there is no interference with the performance of the electrode. In the present study, we demonstrate that chitosan provides superior stability compared with Nafion(®) and should be considered as an optimum solution to enhance the biocompatibility and the stability of 3D bioelectrodes. Copyright © 2016 Elsevier B.V. All rights reserved.

Isolation, one-step affinity purification, and characterization of a polyextremotolerant laccase from the halophilic bacterium Aquisalibacillus elongatus and its application in the delignification of sugar beet pulp.

Science.gov (United States)

Rezaei, Shahla; Shahverdi, Ahmad Reza; Faramarzi, Mohammad Ali

2017-04-01

The aim of the present work was to study the ability of a halophilic bacterial laccase to efficient delignification in extreme conditions. Here, a highly stable extracellular laccase showing ligninolytic activity from halophilic Aquisalibacillus elongatus is described. The laccase production was strongly influenced by NaCl and CuSO 4 and under optimal conditions reached 4.8UmL -1 . The monomeric enzyme of 75kDa was purified by a synthetic affinity column with 68.2% yield and 99.8-fold purification. The enzyme showed some valuable features viz. stability against a wide range of organic solvents, salts, metals, inhibitors, and surfactants and specificity to a wide spectrum of substrates diverse in structure and redox potential. It retained more than 50% of the original activity at 25-75°C and pH 5.0-10.0. Furthermore, the enzyme was found to be effective in the delignification of sugar beet pulp in an ionic liquid that makes it useful for industrial applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Production of biodiesel by transesterification of corn and soybean oils with ethanol or butanol using resin-bound truncated Candida antarctica lipase B

Science.gov (United States)

Enzymatic catalysts, such as lipases, have advantages over chemical catalysts for transesterification of triglycerides to produce biodiesel. A gene encoding a synthetic truncated Candida antarctica lipase B (CALB) was generated via automated PCR and expressed in Saccharomyces cerevisiae. Western b...

Closed-form kinetic parameter estimation solution to the truncated data problem

International Nuclear Information System (INIS)

Zeng, Gengsheng L; Kadrmas, Dan J; Gullberg, Grant T

2010-01-01

In a dedicated cardiac single photon emission computed tomography (SPECT) system, the detectors are focused on the heart and the background is truncated in the projections. Reconstruction using truncated data results in biased images, leading to inaccurate kinetic parameter estimates. This paper has developed a closed-form kinetic parameter estimation solution to the dynamic emission imaging problem. This solution is insensitive to the bias in the reconstructed images that is caused by the projection data truncation. This paper introduces two new ideas: (1) it includes background bias as an additional parameter to estimate, and (2) it presents a closed-form solution for compartment models. The method is based on the following two assumptions: (i) the amount of the bias is directly proportional to the truncated activities in the projection data, and (ii) the background concentration is directly proportional to the concentration in the myocardium. In other words, the method assumes that the image slice contains only the heart and the background, without other organs, that the heart is not truncated, and that the background radioactivity is directly proportional to the radioactivity in the blood pool. As long as the background activity can be modeled, the proposed method is applicable regardless of the number of compartments in the model. For simplicity, the proposed method is presented and verified using a single compartment model with computer simulations using both noiseless and noisy projections.

Analytic reconstruction algorithms for triple-source CT with horizontal data truncation

International Nuclear Information System (INIS)

Chen, Ming; Yu, Hengyong

2015-01-01

Purpose: This paper explores a triple-source imaging method with horizontal data truncation to enlarge the field of view (FOV) for big objects. Methods: The study is conducted by using theoretical analysis, mathematical deduction, and numerical simulations. The proposed algorithms are implemented in c + + and MATLAB. While the basic platform is constructed in MATLAB, the computationally intensive segments are coded in c + +, which are linked via a MEX interface. Results: A triple-source circular scanning configuration with horizontal data truncation is developed, where three pairs of x-ray sources and detectors are unevenly distributed on the same circle to cover the whole imaging object. For this triple-source configuration, a fan-beam filtered backprojection-type algorithm is derived for truncated full-scan projections without data rebinning. The algorithm is also extended for horizontally truncated half-scan projections and cone-beam projections in a Feldkamp-type framework. Using their method, the FOV is enlarged twofold to threefold to scan bigger objects with high speed and quality. The numerical simulation results confirm the correctness and effectiveness of the developed algorithms. Conclusions: The triple-source scanning configuration with horizontal data truncation cannot only keep most of the advantages of a traditional multisource system but also cover a larger FOV for big imaging objects. In addition, because the filtering is shift-invariant, the proposed algorithms are very fast and easily parallelized on graphic processing units

A Line Search Multilevel Truncated Newton Algorithm for Computing the Optical Flow

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Lluís Garrido

2015-06-01

Full Text Available We describe the implementation details and give the experimental results of three optimization algorithms for dense optical flow computation. In particular, using a line search strategy, we evaluate the performance of the unilevel truncated Newton method (LSTN, a multiresolution truncated Newton (MR/LSTN and a full multigrid truncated Newton (FMG/LSTN. We use three image sequences and four models of optical flow for performance evaluation. The FMG/LSTN algorithm is shown to lead to better optical flow estimation with less computational work than both the LSTN and MR/LSTN algorithms.

Low-mode truncation methods in the sine-Gordon equation

International Nuclear Information System (INIS)

Xiong Chuyu.

1991-01-01

In this dissertation, the author studies the chaotic and coherent motions (i.e., low-dimensional chaotic attractor) in some near integrable partial differential equations, particularly the sine-Gordon equation and the nonlinear Schroedinger equation. In order to study the motions, he uses low mode truncation methods to reduce these partial differential equations to some truncated models (low-dimensional ordinary differential equations). By applying many methods available to low-dimensional ordinary differential equations, he can understand the low-dimensional chaotic attractor of PDE's much better. However, there are two important questions one needs to answer: (1) How many modes is good enough for the low mode truncated models to capture the dynamics uniformly? (2) Is the chaotic attractor in a low mode truncated model close to the chaotic attractor in the original PDE? And how close is? He has developed two groups of powerful methods to help to answer these two questions. They are the computation methods of continuation and local bifurcation, and local Lyapunov exponents and Lyapunov exponents. Using these methods, he concludes that the 2N-nls ODE is a good model for the sine-Gordon equation and the nonlinear Schroedinger equation provided one chooses a 'good' basis and uses 'enough' modes (where 'enough' depends on the parameters of the system but is small for the parameter studied here). Therefore, one can use 2N-nls ODE to study the chaos of PDE's in more depth

N-terminally truncated POM121C inhibits HIV-1 replication.

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Hideki Saito

Full Text Available Recent studies have identified host cell factors that regulate early stages of HIV-1 infection including viral cDNA synthesis and orientation of the HIV-1 capsid (CA core toward the nuclear envelope, but it remains unclear how viral DNA is imported through the nuclear pore and guided to the host chromosomal DNA. Here, we demonstrate that N-terminally truncated POM121C, a component of the nuclear pore complex, blocks HIV-1 infection. This truncated protein is predominantly localized in the cytoplasm, does not bind to CA, does not affect viral cDNA synthesis, reduces the formation of 2-LTR and diminished the amount of integrated proviral DNA. Studies with an HIV-1-murine leukemia virus (MLV chimeric virus carrying the MLV-derived Gag revealed that Gag is a determinant of this inhibition. Intriguingly, mutational studies have revealed that the blockade by N-terminally-truncated POM121C is closely linked to its binding to importin-β/karyopherin subunit beta 1 (KPNB1. These results indicate that N-terminally-truncated POM121C inhibits HIV-1 infection after completion of reverse transcription and before integration, and suggest an important role for KPNB1 in HIV-1 replication.

Estimation of Panel Data Regression Models with Two-Sided Censoring or Truncation

DEFF Research Database (Denmark)

Alan, Sule; Honore, Bo E.; Hu, Luojia

2014-01-01

This paper constructs estimators for panel data regression models with individual speci…fic heterogeneity and two–sided censoring and truncation. Following Powell (1986) the estimation strategy is based on moment conditions constructed from re–censored or re–truncated residuals. While these moment...

A generalized right truncated bivariate Poisson regression model with applications to health data.

Science.gov (United States)

Islam, M Ataharul; Chowdhury, Rafiqul I

2017-01-01

A generalized right truncated bivariate Poisson regression model is proposed in this paper. Estimation and tests for goodness of fit and over or under dispersion are illustrated for both untruncated and right truncated bivariate Poisson regression models using marginal-conditional approach. Estimation and test procedures are illustrated for bivariate Poisson regression models with applications to Health and Retirement Study data on number of health conditions and the number of health care services utilized. The proposed test statistics are easy to compute and it is evident from the results that the models fit the data very well. A comparison between the right truncated and untruncated bivariate Poisson regression models using the test for nonnested models clearly shows that the truncated model performs significantly better than the untruncated model.

Bounded real and positive real balanced truncation using Σ-normalised coprime factors

NARCIS (Netherlands)

Trentelman, H.L.

2009-01-01

In this article, we will extend the method of balanced truncation using normalised right coprime factors of the system transfer matrix to balanced truncation with preservation of half line dissipativity. Special cases are preservation of positive realness and bounded realness. We consider a half

No chiral truncation of quantum log gravity?

Science.gov (United States)

Andrade, Tomás; Marolf, Donald

2010-03-01

At the classical level, chiral gravity may be constructed as a consistent truncation of a larger theory called log gravity by requiring that left-moving charges vanish. In turn, log gravity is the limit of topologically massive gravity (TMG) at a special value of the coupling (the chiral point). We study the situation at the level of linearized quantum fields, focussing on a unitary quantization. While the TMG Hilbert space is continuous at the chiral point, the left-moving Virasoro generators become ill-defined and cannot be used to define a chiral truncation. In a sense, the left-moving asymptotic symmetries are spontaneously broken at the chiral point. In contrast, in a non-unitary quantization of TMG, both the Hilbert space and charges are continuous at the chiral point and define a unitary theory of chiral gravity at the linearized level.

Reduction of variable-truncation artifacts from beam occlusion during in situ x-ray tomography

Science.gov (United States)

Borg, Leise; Jørgensen, Jakob S.; Frikel, Jürgen; Sporring, Jon

2017-12-01

Many in situ x-ray tomography studies require experimental rigs which may partially occlude the beam and cause parts of the projection data to be missing. In a study of fluid flow in porous chalk using a percolation cell with four metal bars drastic streak artifacts arise in the filtered backprojection (FBP) reconstruction at certain orientations. Projections with non-trivial variable truncation caused by the metal bars are the source of these variable-truncation artifacts. To understand the artifacts a mathematical model of variable-truncation data as a function of metal bar radius and distance to sample is derived and verified numerically and with experimental data. The model accurately describes the arising variable-truncation artifacts across simulated variations of the experimental setup. Three variable-truncation artifact-reduction methods are proposed, all aimed at addressing sinogram discontinuities that are shown to be the source of the streaks. The ‘reduction to limited angle’ (RLA) method simply keeps only non-truncated projections; the ‘detector-directed smoothing’ (DDS) method smooths the discontinuities; while the ‘reflexive boundary condition’ (RBC) method enforces a zero derivative at the discontinuities. Experimental results using both simulated and real data show that the proposed methods effectively reduce variable-truncation artifacts. The RBC method is found to provide the best artifact reduction and preservation of image features using both visual and quantitative assessment. The analysis and artifact-reduction methods are designed in context of FBP reconstruction motivated by computational efficiency practical for large, real synchrotron data. While a specific variable-truncation case is considered, the proposed methods can be applied to general data cut-offs arising in different in situ x-ray tomography experiments.

Amplitude reconstruction from complete photoproduction experiments and truncated partial-wave expansions

International Nuclear Information System (INIS)

Workman, R. L.; Tiator, L.; Wunderlich, Y.; Doring, M.; Haberzettl, H.

2017-01-01

Here, we compare the methods of amplitude reconstruction, for a complete experiment and a truncated partial-wave analysis, applied to the photoproduction of pseudoscalar mesons. The approach is pedagogical, showing in detail how the amplitude reconstruction (observables measured at a single energy and angle) is related to a truncated partial-wave analysis (observables measured at a single energy and a number of angles).

Modified Truncated Multiplicity Analysis to Improve Verification of Uranium Fuel Cycle Materials

International Nuclear Information System (INIS)

LaFleur, A.; Miller, K.; Swinhoe, M.; Belian, A.; Croft, S.

2015-01-01

Accurate verification of 235U enrichment and mass in UF6 storage cylinders and the UO2F2 holdup contained in the process equipment is needed to improve international safeguards and nuclear material accountancy at uranium enrichment plants. Small UF6 cylinders (1.5'' and 5'' diameter) are used to store the full range of enrichments from depleted to highly-enriched UF6. For independent verification of these materials, it is essential that the 235U mass and enrichment measurements do not rely on facility operator declarations. Furthermore, in order to be deployed by IAEA inspectors to detect undeclared activities (e.g., during complementary access), it is also imperative that the measurement technique is quick, portable, and sensitive to a broad range of 235U masses. Truncated multiplicity analysis is a technique that reduces the variance in the measured count rates by only considering moments 1, 2, and 3 of the multiplicity distribution. This is especially important for reducing the uncertainty in the measured doubles and triples rates in environments with a high cosmic ray background relative to the uranium signal strength. However, we believe that the existing truncated multiplicity analysis throws away too much useful data by truncating the distribution after the third moment. This paper describes a modified truncated multiplicity analysis method that determines the optimal moment to truncate the multiplicity distribution based on the measured data. Experimental measurements of small UF6 cylinders and UO2F2 working reference materials were performed at Los Alamos National Laboratory (LANL). The data were analyzed using traditional and modified truncated multiplicity analysis to determine the optimal moment to truncate the multiplicity distribution to minimize the uncertainty in the measured count rates. The results from this analysis directly support nuclear safeguards at enrichment plants and provide a more accurate verification method for UF6

Immobilisation of laccase on Eupergit supports and its application for the removal of endocrine disrupting chemicals in a packed-bed reactor.

Science.gov (United States)

Lloret, L; Hollmann, F; Eibes, G; Feijoo, G; Moreira, M T; Lema, J M

2012-06-01

Laccase from Myceliophthora thermophila was covalently immobilised on Eupergit C and Eupergit C 250L yielding specific activities of up to 17 and 80 U/g, respectively. Due to its superior activity, Eupergit C 250L was chosen for further research. The somewhat lower catalytic efficiency (based on the ratio between the turnover number and the Michaelis constant, k(cat)/K(M)) of the immobilised enzyme in comparison with that of the free enzyme was balanced by its increased stability and broader operational window related to temperature and pH. The feasibility of the immobilised laccase was tested by using a packed bed reactor (PBR) operating in consecutive cycles for the removal of Acid Green 27 dye as model substrate. High degrees of elimination were achieved (88, 79, 69 and 57% in 4 consecutive cycles), while the levels of adsorption on the support varied from 18 to 6%, proving that dye removal took place mainly due to the action of the enzyme. Finally, a continuous PBR with the solid biocatalyst was applied for the treatment of a solution containing the following endocrine disrupting chemicals: estrone (E1), 17β-estradiol (E2) and 17α-ethinylestradiol (EE2). At steady-state operation, E1 was degraded by 65% and E2 and EE2 were removed up to 80% and only limited adsorption of these compounds on the support, between 12 and 22%, was detected. In addition, a 79% decrease in estrogenic activity was detected in the effluent of the enzymatic reactor while only 14% was attained by inactivated laccase.

Modeling the Effect of APC Truncation on Destruction Complex Function in Colorectal Cancer Cells

Science.gov (United States)

Barua, Dipak; Hlavacek, William S.

2013-01-01

In colorectal cancer cells, APC, a tumor suppressor protein, is commonly expressed in truncated form. Truncation of APC is believed to disrupt degradation of β—catenin, which is regulated by a multiprotein complex called the destruction complex. The destruction complex comprises APC, Axin, β—catenin, serine/threonine kinases, and other proteins. The kinases and , which are recruited by Axin, mediate phosphorylation of β—catenin, which initiates its ubiquitination and proteosomal degradation. The mechanism of regulation of β—catenin degradation by the destruction complex and the role of truncation of APC in colorectal cancer are not entirely understood. Through formulation and analysis of a rule-based computational model, we investigated the regulation of β—catenin phosphorylation and degradation by APC and the effect of APC truncation on function of the destruction complex. The model integrates available mechanistic knowledge about site-specific interactions and phosphorylation of destruction complex components and is consistent with an array of published data. We find that the phosphorylated truncated form of APC can outcompete Axin for binding to β—catenin, provided that Axin is limiting, and thereby sequester β—catenin away from Axin and the Axin-recruited kinases and . Full-length APC also competes with Axin for binding to β—catenin; however, full-length APC is able, through its SAMP repeats, which bind Axin and which are missing in truncated oncogenic forms of APC, to bring β—catenin into indirect association with Axin and Axin-recruited kinases. Because our model indicates that the positive effects of truncated APC on β—catenin levels depend on phosphorylation of APC, at the first 20-amino acid repeat, and because phosphorylation of this site is mediated by , we suggest that is a potential target for therapeutic intervention in colorectal cancer. Specific inhibition of is predicted to limit binding of β—catenin to truncated

A Lynden-Bell integral estimator for the tail index of right-truncated ...

African Journals Online (AJOL)

By means of a Lynden-Bell integral with deterministic threshold, Worms and Worms [A Lynden-Bell integral estimator for extremes of randomly truncated data. Statist. Probab. Lett. 2016; 109: 106-117] recently introduced an asymptotically normal estimator of the tail index for randomly right-truncated Pareto-type data.

Truncated States Obtained by Iteration

International Nuclear Information System (INIS)

Cardoso, W. B.; Almeida, N. G. de

2008-01-01

We introduce the concept of truncated states obtained via iterative processes (TSI) and study its statistical features, making an analogy with dynamical systems theory (DST). As a specific example, we have studied TSI for the doubling and the logistic functions, which are standard functions in studying chaos. TSI for both the doubling and logistic functions exhibit certain similar patterns when their statistical features are compared from the point of view of DST

TtMCO: A highly thermostable laccase-like multicopper oxidase from the thermophilic Thermobaculum terrenum

DEFF Research Database (Denmark)

Brander, Søren; Mikkelsen, Jørn Dalgaard; Kepp, Kasper Planeta

2015-01-01

This paper reports the identification, heterologous expression in Escherichia coli and characterization of TtMCO from the thermophilic bacterium Thermobaculum terrenum, the first laccase-like multi-copper oxidase (LMCO) from the distinct Phylum Chloroflexi. TtMCO has only 39% identity to its...... closest characterized homologue, CotA from Bacillus subtilis, but sequence and spectrophotometry confirmed copper coordination similar to that of LMCOs. TtMCO is extremely thermophilic with a half-time of inactivation of 2.24 days at 70 degrees C and 350 min at 80°C and pH 7, consistent...

A Multistep Extending Truncation Method towards Model Construction of Infinite-State Markov Chains

Directory of Open Access Journals (Sweden)

Kemin Wang

2014-01-01

Full Text Available The model checking of Infinite-State Continuous Time Markov Chains will inevitably encounter the state explosion problem when constructing the CTMCs model; our method is to get a truncated model of the infinite one; to get a sufficient truncated model to meet the model checking of Continuous Stochastic Logic based system properties, we propose a multistep extending advanced truncation method towards model construction of CTMCs and implement it in the INFAMY model checker; the experiment results show that our method is effective.

Development of an enzymatic microreactor based on microencapsulated laccase with off-line capillary electrophoresis for measurement of oxidation reactions.

Science.gov (United States)

Roman-Gusetu, Georgiana; Waldron, Karen C; Rochefort, Dominic

2009-11-20

Microencapsulation is used here as a new technique to immobilize enzymes in a microreactor coupled off-line to capillary electrophoresis (CE), allowing the determination of enzymatic reaction products. The redox enzyme laccase was encapsulated using the method of interfacial cross-linking of poly(ethyleneimine) (PEI). The 50 microm diameter capsules were slurry packed from a suspension into a capillary-sized reactor made easily and quickly from a short length of 530 microm diameter fused-silica tubing. The volume of the bed of laccase microcapsules in the microreactor was in the order of 1.1 microL through which 50 microL of the substrate o-phenylenediamine (OPD) was flowed. The oxidation product 2,3-diaminophenazine (DAP) and the remaining OPD were quantified by CE in a pH 2.5 phosphate buffer. Peak migration time reproducibility was in the order of 0.4% RSD and peak area reproducibility was less than 1.7% RSD within the same day. Using the OPD peak area calibration curve, a conversion efficiency of 48% was achieved for a 2-min oxidation reaction in the microreactor.

Molecular dynamics simulations of lipid bilayers : major artifacts due to truncating electrostatic interactions

NARCIS (Netherlands)

Patra, M.; Karttunen, M.E.J.; Hyvönen, M.T.; Falck, E.; Lindqvist, P.; Vattulainen, I.

2003-01-01

We study the influence of truncating the electrostatic interactions in a fully hydrated pure dipalmitoylphosphatidylcholine (DPPC) bilayer through 20 ns molecular dynamics simulations. The computations in which the electrostatic interactions were truncated are compared to similar simulations using

On the viability of the truncated Israel–Stewart theory in cosmology

International Nuclear Information System (INIS)

Shogin, Dmitry; Amundsen, Per Amund; Hervik, Sigbjørn

2015-01-01

We apply the causal Israel–Stewart theory of irreversible thermodynamics to model the matter content of the Universe as a dissipative fluid with bulk and shear viscosity. Along with the full transport equations we consider their widely used truncated version. By implementing a dynamical systems approach to Bianchi type IV and V cosmological models with and without cosmological constant, we determine the future asymptotic states of such Universes and show that the truncated Israel–Stewart theory leads to solutions essentially different from the full theory. The solutions of the truncated theory may also manifest unphysical properties. Finally, we find that in the full theory shear viscosity can give a substantial rise to dissipative fluxes, driving the fluid extremely far from equilibrium, where the linear Israel–Stewart theory ceases to be valid. (paper)

Riesz Representation Theorem on Bilinear Spaces of Truncated Laurent Series

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Sabarinsyah

2017-06-01

Full Text Available In this study a generalization of the Riesz representation theorem on non-degenerate bilinear spaces, particularly on spaces of truncated Laurent series, was developed. It was shown that any linear functional on a non-degenerate bilinear space is representable by a unique element of the space if and only if its kernel is closed. Moreover an explicit equivalent condition can be identified for the closedness property of the kernel when the bilinear space is a space of truncated Laurent series.

Immobilized laccase-based biosensor for the detection of disubstituted methyl and methoxy phenols - application of Box-Behnken design with response surface methodology for modeling and optimization of performance parameters.

Science.gov (United States)

Sarika, C; Rekha, K; Narasimha Murthy, B

2016-11-01

An amperometric principle-based biosensor, employing immobilized laccase enzyme from Trametes versicolor, was developed for the detection of disubstituted methyl and methoxy phenols. Three immobilization methods such as entrapment, cross-linking, and co-cross-linking, with bovine serum albumin (BSA) on nylon membrane have been compared. Among tested methods of immobilization, co-cross-linking method with BSA was superior to the other methods in terms of; sensitivity, limit of detection, response time, and operating stability. The increased sensitivity of the probe optimization of concentrations of laccase, BSA and glutaraldehyde can be achieved by, employing the Box-Behnken design of experiment.

Pressure-sensitive paint on a truncated cone in hypersonic flow at incidences

International Nuclear Information System (INIS)

Yang, L.; Erdem, E.; Zare-Behtash, H.; Kontis, K.; Saravanan, S.

2012-01-01

Highlights: ► Global pressure map over the truncated cone is obtained at various incidence angles in Mach 5 flow. ► Successful application of AA-PSP in hypersonic flow expands operation area of this technique. ► AA-PSP reveals complex three-dimensional pattern which is difficult for transducer to obtain. ► Quantitative data provides strong correlation with colour Schlieren and oil flow results. ► High spatial resolution pressure mappings identify small scale vortices and flow separation. - Abstract: The flow over a truncated cone is a classical and fundamental problem for aerodynamic research due to its three-dimensional and complicated characteristics. The flow is made more complex when examining high angles of incidence. Recently these types of flows have drawn more attention for the purposes of drag reduction in supersonic/hypersonic flows. In the present study the flow over a truncated cone at various incidences was experimentally investigated in a Mach 5 flow with a unit Reynolds number of 13.5 × 10 6 m −1 . The cone semi-apex angle is 15° and the truncation ratio (truncated length/cone length) is 0.5. The incidence of the model varied from −12° to 12° with 3° intervals relative to the freestream direction. The external flow around the truncated cone was visualised by colour Schlieren photography, while the surface flow pattern was revealed using the oil flow method. The surface pressure distribution was measured using the anodized aluminium pressure-sensitive paint (AA-PSP) technique. Both top and sideviews of the pressure distribution on the model surface were acquired at various incidences. AA-PSP showed high pressure sensitivity and captured the complicated flow structures which correlated well with the colour Schlieren and oil flow visualisation results.

Overexpression of a novel thermostable and chloride-tolerant laccase from Thermus thermophilus SG0.5JP17-16 in Pichia pastoris and its application in synthetic dye decolorization.

Directory of Open Access Journals (Sweden)

Huiping Liu

Full Text Available Laccases have been used for the decolorization and detoxification of synthetic dyes due to their ability to oxidize a wide variety of dyes with water as the sole byproduct. A putative laccase gene (LacTT from Thermus thermophilus SG0.5JP17-16 was screened using the genome mining approach, and it was highly expressed in Pichia pastoris, yielding a high laccase activity of 6130 U/L in a 10-L fermentor. The LacTT open reading frame encoded a protein of 466 amino acid residues with four putative Cu-binding regions. The optimal pH of the recombinant LacTT was 4.5, 6.0, 7.5 and 8.0 with 2,2'-azino-bis(3-ethylbenzothazoline-6-sulfonic acid (ABTS, syringaldazine (SGZ, guaiacol, and 2,6-dimethoxyphenol (2,6-DMP as the substrate, respectively. The optimal temperature of LacTT was 90°C with guaiacol as the substrate. LacTT was highly stable at pH 4.0-11.0 and thermostable at 40°C-90°C, confirming that it is a pH-stable and thermostable laccase. Furthermore, LacTT also exhibited high tolerance to halides such as NaCl, NaBr and NaF, and decolorized 100%, 94%, 94% and 73% of Congo Red, Reactive Black B and Reactive Black WNN, and Remazol Brilliant Blue R, respectively. Interestingly, addition of high concentration of NaCl increased the RBBR decolorization efficiency of LacTT. These results suggest that LacTT is a good candidate for industrial applications such as dyestuff processing and degradation of dyes in textile wastewaters.

On truncations of the exact renormalization group

CERN Document Server

Morris, T R

1994-01-01

We investigate the Exact Renormalization Group (ERG) description of (Z_2 invariant) one-component scalar field theory, in the approximation in which all momentum dependence is discarded in the effective vertices. In this context we show how one can perform a systematic search for non-perturbative continuum limits without making any assumption about the form of the lagrangian. Concentrating on the non-perturbative three dimensional Wilson fixed point, we then show that the sequence of truncations n=2,3,\\dots, obtained by expanding about the field \\varphi=0 and discarding all powers \\varphi^{2n+2} and higher, yields solutions that at first converge to the answer obtained without truncation, but then cease to further converge beyond a certain point. No completely reliable method exists to reject the many spurious solutions that are also found. These properties are explained in terms of the analytic behaviour of the untruncated solutions -- which we describe in some detail.

Immobilisation of laccase on Eupergit supports and its application for the removal of endocrine disrupting chemicals in a packed-bed reactor

NARCIS (Netherlands)

Lloret, L.; Hollmann, F.; Eibes, G.; Feijoo, G.; Moreira, M.T.; Lema, J.M.

2011-01-01

Laccase from Myceliophthora thermophila was covalently immobilised on Eupergit C and Eupergit C 250L yielding specific activities of up to 17 and 80 U/g, respectively. Due to its superior activity, Eupergit C 250L was chosen for further research. The somewhat lower catalytic efficiency (based on the

Influence of Laccase and Tyrosinase on the Antioxidant Capacity of Selected Phenolic Compounds on Human Cell Lines

Directory of Open Access Journals (Sweden)

Matthias Riebel

2015-09-01

Full Text Available Polyphenolic compounds affect the color, odor and taste of numerous food products of plant origin. In addition to the visual and gustatory properties, they serve as radical scavengers and have antioxidant effects. Polyphenols, especially resveratrol in red wine, have gained increasing scientific and public interest due to their presumptive beneficial impact on human health. Enzymatic oxidation of phenolic compounds takes place under the influence of polyphenol oxidases (PPO, including tyrosinase and laccase. Several studies have demonstrated the radical scavenger effect of plants, food products and individual polyphenols in vitro, but, apart from resveratrol, such impact has not been proved in physiological test systems. Furthermore, only a few data exist on the antioxidant capacities of the enzymatic oxidation products of phenolic compounds generated by PPO. We report here first results about the antioxidant effects of phenolic substances, before and after oxidation by fungal model tyrosinase and laccase. In general, the common chemical 2,2-diphenyl-1-picrylhydrazyl assay and the biological tests using two different types of cell cultures (monocytes and endothelial cells delivered similar results. The phenols tested showed significant differences with respect to their antioxidant activity in all test systems. Their antioxidant capacities after enzymatic conversion decreased or increased depending on the individual PPO used.

Resonant Excitation of a Truncated Metamaterial Cylindrical Shell by a Thin Wire Monopole

DEFF Research Database (Denmark)

Kim, Oleksiy S.; Erentok, Aycan; Breinbjerg, Olav

2009-01-01

A truncated metamaterial cylindrical shell excited by a thin wire monopole is investigated using the integral equation technique as well as the finite element method. Simulations reveal a strong field singularity at the edge of the truncated cylindrical shell, which critically affects the matching...

Laccase on Black Pearl 2000 modified glassy carbon electrode: Characterization of direct electron transfer and biological sensing properties for pyrocatechol

International Nuclear Information System (INIS)

Wang Kunqi; Tang Juan; Zhang Zuoming; Gao Ying; Chen Gang

2012-01-01

Highlights: ► Laccase can complete direct electron transfer process on BP2000 matrices. ► Laccase immobilized on BP2000 matrices has catalytic oxidation effect to pyrocatechol. ► A pyrocatechol biosensor has constructed been using Nafion/Lac-BP2000/GC electrode. ► Detection limit and linear range of the biosensor are 0.003 mM and 0.003–5.555 mM. - Abstract: In this paper, it was found that Laccase (Lac) could be stably immobilized on the glassy carbon electrode modified with Black Pearl 2000 (BP2000) and Nafion by a simple technique. The adsorption behavior of Lac immobilized on BP2000 matrix was characterized by environment scanning electron microscope (ESEM), ultraviolet–visible (UV–vis) and Fourier transform infrared (FTIR), which demonstrated that BP2000 could facilitate the electron exchange between the active center of Lac and modified electrode. The direct electrochemistry and electrocatalysis behavior of Lac on the modified electrode were characterized by cyclic voltammogram (CV) which indicated that Lac immobilized on the modified electrode displayed a direct, nearly reversible and surface-controlled redox reaction with an enhanced electron-transfer rate constant of 1.940 s −1 at the scan rate of 100 mV s −1 in 0.1 M phosphate buffer solution (PBS) (pH 7.0). Furthermore, it was also discovered that, in the presence of O 2 , Lac immobilized on the modified electrode exhibited the electrocatalytic response to pyrocatechol, and the kinetic apparent Michaelis-constant (K M app ) obtained from the Lineweaver–Burk equation was 1.79 mM. The detection limit, linear range and sensitivity of the Lac biosensor were 0.003 mM, 0.003–5.555 mM and 99.84 μA mM −1 cm −2 , respectively.

Laccase-13 Regulates Seed Setting Rate by Affecting Hydrogen Peroxide Dynamics and Mitochondrial Integrity in Rice

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Yang Yu

2017-07-01

Full Text Available Seed setting rate is one of the most important components of rice grain yield. To date, only several genes regulating setting rate have been identified in plant. In this study, we showed that laccase-13 (OsLAC13, a member of laccase family genes which are known for their roles in modulating phenylpropanoid pathway and secondary lignification in cell wall, exerts a regulatory function in rice seed setting rate. OsLAC13 expressed in anthers and promotes hydrogen peroxide production both in vitro and in the filaments and anther connectives. Knock-out of OsLAC13 showed significantly increased seed setting rate, while overexpression of this gene exhibited induced mitochondrial damage and suppressed sugar transportation in anthers, which in turn affected seed setting rate. OsLAC13 also induced H2O2 production and mitochondrial damage in the root tip cells which caused the lethal phenotype. We also showed that high abundant of OsmiR397, the suppressor of OsLAC13 mRNA, increased the seed setting rate of rice plants, and restrains H2O2 accumulation in roots during oxidative stress. Our results suggested a novel regulatory role of OsLAC13 gene in regulating seed setting rate by affecting H2O2 dynamics and mitochondrial integrity in rice.

truncSP: An R Package for Estimation of Semi-Parametric Truncated Linear Regression Models

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Maria Karlsson

2014-05-01

Full Text Available Problems with truncated data occur in many areas, complicating estimation and inference. Regarding linear regression models, the ordinary least squares estimator is inconsistent and biased for these types of data and is therefore unsuitable for use. Alternative estimators, designed for the estimation of truncated regression models, have been developed. This paper presents the R package truncSP. The package contains functions for the estimation of semi-parametric truncated linear regression models using three different estimators: the symmetrically trimmed least squares, quadratic mode, and left truncated estimators, all of which have been shown to have good asymptotic and ?nite sample properties. The package also provides functions for the analysis of the estimated models. Data from the environmental sciences are used to illustrate the functions in the package.

Efficient secretion of three fungal laccases from Saccharomyces cerevisiae and their potential for decolorization of textile industry effluent - A comparative study

Czech Academy of Sciences Publication Activity Database

Antošová, Zuzana; Herkommerová, Klára; Pichová, I.; Sychrová, Hana

2018-01-01

Roč. 34, č. 1 (2018), s. 69-80 ISSN 8756-7938 R&D Projects: GA TA ČR(CZ) TA01011461 Institutional support: RVO:67985823 Keywords : laccase * decolorization * gene expression * expression optimization * Saccharomyces cerevisiae Subject RIV: EI - Biotechnology ; Bionics OBOR OECD: Industrial biotechnology Impact factor: 1.986, year: 2016

Motion of isolated open vortex filaments evolving under the truncated local induction approximation

Science.gov (United States)

Van Gorder, Robert A.

2017-11-01

The study of nonlinear waves along open vortex filaments continues to be an area of active research. While the local induction approximation (LIA) is attractive due to locality compared with the non-local Biot-Savart formulation, it has been argued that LIA appears too simple to model some relevant features of Kelvin wave dynamics, such as Kelvin wave energy transfer. Such transfer of energy is not feasible under the LIA due to integrability, so in order to obtain a non-integrable model, a truncated LIA, which breaks the integrability of the classical LIA, has been proposed as a candidate model with which to study such dynamics. Recently Laurie et al. ["Interaction of Kelvin waves and nonlocality of energy transfer in superfluids," Phys. Rev. B 81, 104526 (2010)] derived truncated LIA systematically from Biot-Savart dynamics. The focus of the present paper is to study the dynamics of a section of common open vortex filaments under the truncated LIA dynamics. We obtain the analog of helical, planar, and more general filaments which rotate without a change in form in the classical LIA, demonstrating that while quantitative differences do exist, qualitatively such solutions still exist under the truncated LIA. Conversely, solitons and breather solutions found under the LIA should not be expected under the truncated LIA, as the existence of such solutions relies on the existence of an infinite number of conservation laws which is violated due to loss of integrability. On the other hand, similarity solutions under the truncated LIA can be quite different to their counterparts found for the classical LIA, as they must obey a t1/3 type scaling rather than the t1/2 type scaling commonly found in the LIA and Biot-Savart dynamics. This change in similarity scaling means that Kelvin waves are radiated at a slower rate from vortex kinks formed after reconnection events. The loss of soliton solutions and the difference in similarity scaling indicate that dynamics emergent under

The combination of i-leader truncation and gemcitabine improves oncolytic adenovirus efficacy in an immunocompetent model.

Science.gov (United States)

Puig-Saus, C; Laborda, E; Rodríguez-García, A; Cascalló, M; Moreno, R; Alemany, R

2014-02-01

Adenovirus (Ad) i-leader protein is a small protein of unknown function. The C-terminus truncation of the i-leader protein increases Ad release from infected cells and cytotoxicity. In the current study, we use the i-leader truncation to enhance the potency of an oncolytic Ad. In vitro, an i-leader truncated oncolytic Ad is released faster to the supernatant of infected cells, generates larger plaques, and is more cytotoxic in both human and Syrian hamster cell lines. In mice bearing human tumor xenografts, the i-leader truncation enhances oncolytic efficacy. However, in a Syrian hamster pancreatic tumor model, which is immunocompetent and less permissive to human Ad, antitumor efficacy is only observed when the i-leader truncated oncolytic Ad, but not the non-truncated version, is combined with gemcitabine. This synergistic effect observed in the Syrian hamster model was not seen in vitro or in immunodeficient mice bearing the same pancreatic hamster tumors, suggesting a role of the immune system in this synergism. These results highlight the interest of the i-leader C-terminus truncation because it enhances the antitumor potency of an oncolytic Ad and provides synergistic effects with gemcitabine in the presence of an immune competent system.

Local and accumulated truncation errors in a class of perturbative numerical methods

International Nuclear Information System (INIS)

Adam, G.; Adam, S.; Corciovei, A.

1980-01-01

The approach to the solution of the radial Schroedinger equation using piecewise perturbative theory with a step function reference potential leads to a class of powerful numerical methods, conveniently abridged as SF-PNM(K), where K denotes the order at which the perturbation series was truncated. In the present paper rigorous results are given for the local truncation errors and bounds are derived for the accumulated truncated errors associated to SF-PNM(K), K = 0, 1, 2. They allow us to establish the smoothness conditions which have to be fulfilled by the potential in order to ensure a safe use of SF-PNM(K), and to understand the experimentally observed behaviour of the numerical results with the step size h. (author)

Enhanced production of laccase by a marine fungus during treatment of colored effluents and synthetic dyes

Digital Repository Service at National Institute of Oceanography (India)

DeSouza-Ticlo, D.; Tiwari, R.; Sah, A.K.; Raghukumar, C.

. Laccase (EC 1.10.3.2, benzenediol:oxygen oxidoreductase) is a multicopper blue oxidase capable of oxidizing ortho and para-diphenols and aromatic amines by removing an electron and proton from a hydroxyl group to form a free radical. These enzymes lack...) were collected in sterile plastic bags and processed within 3 hours. They were washed free of attached soil particles and other extraneous matter using sterile seawater. The wood pieces were then incubated in sterile bags lined with moist filter...

Frequency interval balanced truncation of discrete-time bilinear systems

DEFF Research Database (Denmark)

Jazlan, Ahmad; Sreeram, Victor; Shaker, Hamid Reza

2016-01-01

This paper presents the development of a new model reduction method for discrete-time bilinear systems based on the balanced truncation framework. In many model reduction applications, it is advantageous to analyze the characteristics of the system with emphasis on particular frequency intervals...... are the solution to a pair of new generalized Lyapunov equations. The conditions for solvability of these new generalized Lyapunov equations are derived and a numerical solution method for solving these generalized Lyapunov equations is presented. Numerical examples which illustrate the usage of the new...... generalized frequency interval controllability and observability gramians as part of the balanced truncation framework are provided to demonstrate the performance of the proposed method....

Adaptive bit plane quadtree-based block truncation coding for image compression

Science.gov (United States)

Li, Shenda; Wang, Jin; Zhu, Qing

2018-04-01

Block truncation coding (BTC) is a fast image compression technique applied in spatial domain. Traditional BTC and its variants mainly focus on reducing computational complexity for low bit rate compression, at the cost of lower quality of decoded images, especially for images with rich texture. To solve this problem, in this paper, a quadtree-based block truncation coding algorithm combined with adaptive bit plane transmission is proposed. First, the direction of edge in each block is detected using Sobel operator. For the block with minimal size, adaptive bit plane is utilized to optimize the BTC, which depends on its MSE loss encoded by absolute moment block truncation coding (AMBTC). Extensive experimental results show that our method gains 0.85 dB PSNR on average compare to some other state-of-the-art BTC variants. So it is desirable for real time image compression applications.

Caracterización de la lacasa obtenida por dos métodos de producción con Pleurotus ostreatus Characterising laccase obtained by two production methods using Pleurotus ostreatus

Directory of Open Access Journals (Sweden)

Martínez César

2003-12-01

Full Text Available El objetivo de este trabajo fue caracterizar y evaluar diferentes métodos de purificación y separación cromatográfica de un caldo rico en enzima lacasa, producida por una variedad del basidiomycete Pleurotus ostreatus. Se llevaron a cabo dos procesos de producción, a saber: a FES (Fermentación en Estado Sólido; b fermentación en sumergido. El proceso de FES se basó en la producción de un extracto de caldo crudo rico en enzima lacasa a partir del crecimiento micelial sobre salvado con vinaza en relación 1:1 w/v duran te 20 días. Se obtuvo un caldo crudo con una actividad promedio de 20 U/ml. En el caso del proceso de fermentación en sumergido, se trabajó con el medio reportado por Hublick y Schinner (2000 con algunas modificaciones, y se obtuvo un crecimiento del hongo en forma de pellets, en un período de 15 días, con actividad promedio de 10 U/ml en el caldo crudo. Las isoenzimas aisladas en los procesos cromatográficos se caracterizaron de acuerdo a sus propiedades moleculares y cinéticas, se determinó su peso molecular por electroforesis de placa vertical (SDS-PAGE y sus parámetros cinéticos, por ejemplo estabilidad, en un rango de temperatura y pH. Palabras clave: lacasa; Pleurotus ostreatus; fermentación en estado sólido (FES; fermentación en sumergido; isoenzimas; laccase; Pleurotus ostreatus; Solid State Fermentation (SSF; Submerged Fermentation; isoenzymesThis project was designed for characterising and evaluating different methods of chromatographic separation and purification regarding a laccase enzyme-rich broth produced by Pleurotus ostreatus, a variety of basidiomycetes. SSF (Solid State Fermentation and Submerged Fermentation production processes were employed. The SSF process was based on producing a raw broth rich in laccase enzyme from mycelium grown on bran with 1:1 vinasse w/v for 20 days. A raw broth was obtained having an average 20 U/ml activity. The medium reported by Hublick and Schinner (2000

Structure of laccase from Streptomyces coelicolor after soaking with potassium hexacyanoferrate and at an improved resolution of 2.3 Å

Czech Academy of Sciences Publication Activity Database

Skálová, Tereza; Dušková, Jarmila; Hašek, Jindřich; Štěpánková, Andrea; Kovaľ, Tomáš; Ostergaard, L. H.; Dohnálek, Jan

2011-01-01

Roč. 67, č. 1 (2011), s. 27-32 ISSN 1744-3091 R&D Projects: GA ČR GA305/07/1073; GA AV ČR IAA500500701 Institutional research plan: CEZ:AV0Z40500505; CEZ:AV0Z10100521 Keywords : laccase * potassium hexacyanoferrate * X-ray diffraction Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.506, year: 2011

Evidence for Truncated Exponential Probability Distribution of Earthquake Slip

KAUST Repository

Thingbaijam, Kiran Kumar; Mai, Paul Martin

2016-01-01

Earthquake ruptures comprise spatially varying slip on the fault surface, where slip represents the displacement discontinuity between the two sides of the rupture plane. In this study, we analyze the probability distribution of coseismic slip, which provides important information to better understand earthquake source physics. Although the probability distribution of slip is crucial for generating realistic rupture scenarios for simulation-based seismic and tsunami-hazard analysis, the statistical properties of earthquake slip have received limited attention so far. Here, we use the online database of earthquake source models (SRCMOD) to show that the probability distribution of slip follows the truncated exponential law. This law agrees with rupture-specific physical constraints limiting the maximum possible slip on the fault, similar to physical constraints on maximum earthquake magnitudes.We show the parameters of the best-fitting truncated exponential distribution scale with average coseismic slip. This scaling property reflects the control of the underlying stress distribution and fault strength on the rupture dimensions, which determines the average slip. Thus, the scale-dependent behavior of slip heterogeneity is captured by the probability distribution of slip. We conclude that the truncated exponential law accurately quantifies coseismic slip distribution and therefore allows for more realistic modeling of rupture scenarios. © 2016, Seismological Society of America. All rights reserverd.

Evidence for Truncated Exponential Probability Distribution of Earthquake Slip

KAUST Repository

Thingbaijam, Kiran K. S.

2016-07-13

Earthquake ruptures comprise spatially varying slip on the fault surface, where slip represents the displacement discontinuity between the two sides of the rupture plane. In this study, we analyze the probability distribution of coseismic slip, which provides important information to better understand earthquake source physics. Although the probability distribution of slip is crucial for generating realistic rupture scenarios for simulation-based seismic and tsunami-hazard analysis, the statistical properties of earthquake slip have received limited attention so far. Here, we use the online database of earthquake source models (SRCMOD) to show that the probability distribution of slip follows the truncated exponential law. This law agrees with rupture-specific physical constraints limiting the maximum possible slip on the fault, similar to physical constraints on maximum earthquake magnitudes.We show the parameters of the best-fitting truncated exponential distribution scale with average coseismic slip. This scaling property reflects the control of the underlying stress distribution and fault strength on the rupture dimensions, which determines the average slip. Thus, the scale-dependent behavior of slip heterogeneity is captured by the probability distribution of slip. We conclude that the truncated exponential law accurately quantifies coseismic slip distribution and therefore allows for more realistic modeling of rupture scenarios. © 2016, Seismological Society of America. All rights reserverd.

Intersection spaces, spatial homology truncation, and string theory

CERN Document Server

Banagl, Markus

2010-01-01

Intersection cohomology assigns groups which satisfy a generalized form of Poincaré duality over the rationals to a stratified singular space. The present monograph introduces a method that assigns to certain classes of stratified spaces cell complexes, called intersection spaces, whose ordinary rational homology satisfies generalized Poincaré duality. The cornerstone of the method is a process of spatial homology truncation, whose functoriality properties are analyzed in detail. The material on truncation is autonomous and may be of independent interest to homotopy theorists. The cohomology of intersection spaces is not isomorphic to intersection cohomology and possesses algebraic features such as perversity-internal cup-products and cohomology operations that are not generally available for intersection cohomology. A mirror-symmetric interpretation, as well as applications to string theory concerning massless D-branes arising in type IIB theory during a Calabi-Yau conifold transition, are discussed.

The Apparent Lack of Lorentz Invariance in Zero-Point Fields with Truncated Spectra

Directory of Open Access Journals (Sweden)

Daywitt W. C.

2009-01-01

Full Text Available The integrals that describe the expectation values of the zero-point quantum-field-theoretic vacuum state are semi-infinite, as are the integrals for the stochastic electrodynamic vacuum. The unbounded upper limit to these integrals leads in turn to infinite energy densities and renormalization masses. A number of models have been put forward to truncate the integrals so that these densities and masses are finite. Unfortunately the truncation apparently destroys the Lorentz invariance of the integrals. This note argues that the integrals are naturally truncated by the graininess of the negative-energy Planck vacuum state from which the zero-point vacuum arises, and are thus automatically Lorentz invariant.

Reduction of variable-truncation artifacts from beam occlusion during in situ x-ray tomography

DEFF Research Database (Denmark)

Borg, Leise; Jørgensen, Jakob Sauer; Frikel, Jürgen

2017-01-01

Many in situ x-ray tomography studies require experimental rigs which may partially occlude the beam and cause parts of the projection data to be missing. In a study of fluid flow in porous chalk using a percolation cell with four metal bars drastic streak artifacts arise in the filtered...... and artifact-reduction methods are designed in context of FBP reconstruction motivated by computational efficiency practical for large, real synchrotron data. While a specific variable-truncation case is considered, the proposed methods can be applied to general data cut-offs arising in different in situ x-ray...... backprojection (FBP) reconstruction at certain orientations. Projections with non-trivial variable truncation caused by the metal bars are the source of these variable-truncation artifacts. To understand the artifacts a mathematical model of variable-truncation data as a function of metal bar radius and distance...

Propagation of a general-type beam through a truncated fractional Fourier transform optical system.

Science.gov (United States)

Zhao, Chengliang; Cai, Yangjian

2010-03-01

Paraxial propagation of a general-type beam through a truncated fractional Fourier transform (FRT) optical system is investigated. Analytical formulas for the electric field and effective beam width of a general-type beam in the FRT plane are derived based on the Collins formula. Our formulas can be used to study the propagation of a variety of laser beams--such as Gaussian, cos-Gaussian, cosh-Gaussian, sine-Gaussian, sinh-Gaussian, flat-topped, Hermite-cosh-Gaussian, Hermite-sine-Gaussian, higher-order annular Gaussian, Hermite-sinh-Gaussian and Hermite-cos-Gaussian beams--through a FRT optical system with or without truncation. The propagation properties of a Hermite-cos-Gaussian beam passing through a rectangularly truncated FRT optical system are studied as a numerical example. Our results clearly show that the truncated FRT optical system provides a convenient way for laser beam shaping.

Functional analysis of Rift Valley fever virus NSs encoding a partial truncation.

Science.gov (United States)

Head, Jennifer A; Kalveram, Birte; Ikegami, Tetsuro

2012-01-01

Rift Valley fever virus (RVFV), belongs to genus Phlebovirus of the family Bunyaviridae, causes high rates of abortion and fetal malformation in infected ruminants as well as causing neurological disorders, blindness, or lethal hemorrhagic fever in humans. RVFV is classified as a category A priority pathogen and a select agent in the U.S., and currently there are no therapeutics available for RVF patients. NSs protein, a major virulence factor of RVFV, inhibits host transcription including interferon (IFN)-β mRNA synthesis and promotes degradation of dsRNA-dependent protein kinase (PKR). NSs self-associates at the C-terminus 17 aa., while NSs at aa.210-230 binds to Sin3A-associated protein (SAP30) to inhibit the activation of IFN-β promoter. Thus, we hypothesize that NSs function(s) can be abolished by truncation of specific domains, and co-expression of nonfunctional NSs with intact NSs will result in the attenuation of NSs function by dominant-negative effect. Unexpectedly, we found that RVFV NSs truncated at aa. 6-30, 31-55, 56-80, 81-105, 106-130, 131-155, 156-180, 181-205, 206-230, 231-248 or 249-265 lack functions of IFN-β mRNA synthesis inhibition and degradation of PKR. Truncated NSs were less stable in infected cells, while nuclear localization was inhibited in NSs lacking either of aa.81-105, 106-130, 131-155, 156-180, 181-205, 206-230 or 231-248. Furthermore, none of truncated NSs had exhibited significant dominant-negative functions for NSs-mediated IFN-β suppression or PKR degradation upon co-expression in cells infected with RVFV. We also found that any of truncated NSs except for intact NSs does not interact with RVFV NSs even in the presence of intact C-terminus self-association domain. Our results suggest that conformational integrity of NSs is important for the stability, cellular localization and biological functions of RVFV NSs, and the co-expression of truncated NSs does not exhibit dominant-negative phenotype.

Functional analysis of Rift Valley fever virus NSs encoding a partial truncation.

Directory of Open Access Journals (Sweden)

Jennifer A Head

Full Text Available Rift Valley fever virus (RVFV, belongs to genus Phlebovirus of the family Bunyaviridae, causes high rates of abortion and fetal malformation in infected ruminants as well as causing neurological disorders, blindness, or lethal hemorrhagic fever in humans. RVFV is classified as a category A priority pathogen and a select agent in the U.S., and currently there are no therapeutics available for RVF patients. NSs protein, a major virulence factor of RVFV, inhibits host transcription including interferon (IFN-β mRNA synthesis and promotes degradation of dsRNA-dependent protein kinase (PKR. NSs self-associates at the C-terminus 17 aa., while NSs at aa.210-230 binds to Sin3A-associated protein (SAP30 to inhibit the activation of IFN-β promoter. Thus, we hypothesize that NSs function(s can be abolished by truncation of specific domains, and co-expression of nonfunctional NSs with intact NSs will result in the attenuation of NSs function by dominant-negative effect. Unexpectedly, we found that RVFV NSs truncated at aa. 6-30, 31-55, 56-80, 81-105, 106-130, 131-155, 156-180, 181-205, 206-230, 231-248 or 249-265 lack functions of IFN-β mRNA synthesis inhibition and degradation of PKR. Truncated NSs were less stable in infected cells, while nuclear localization was inhibited in NSs lacking either of aa.81-105, 106-130, 131-155, 156-180, 181-205, 206-230 or 231-248. Furthermore, none of truncated NSs had exhibited significant dominant-negative functions for NSs-mediated IFN-β suppression or PKR degradation upon co-expression in cells infected with RVFV. We also found that any of truncated NSs except for intact NSs does not interact with RVFV NSs even in the presence of intact C-terminus self-association domain. Our results suggest that conformational integrity of NSs is important for the stability, cellular localization and biological functions of RVFV NSs, and the co-expression of truncated NSs does not exhibit dominant-negative phenotype.

Truncated Dual-Cap Nucleation Site Development

Science.gov (United States)

Matson, Douglas M.; Sander, Paul J.

2012-01-01

During heterogeneous nucleation within a metastable mushy-zone, several geometries for nucleation site development must be considered. Traditional spherical dual cap and crevice models are compared to a truncated dual cap to determine the activation energy and critical cluster growth kinetics in ternary Fe-Cr-Ni steel alloys. Results of activation energy results indicate that nucleation is more probable at grain boundaries within the solid than at the solid-liquid interface.

Substratum formulation for laccase and mycelial biomass production of Pleurotus ostreatusFormulação de substratos na produção de biomassa micelial e de lacase de Pleurotus ostreatus

Directory of Open Access Journals (Sweden)

Juliana Silveira do Valle

2012-10-01

Full Text Available Pleurotus ostreatus is a producer of biomass and laccase, an enzyme used in fermentation processes for the hydrolysis of lignocellulosic substrate, with potential use in biofuel production and animal feed. Thus, there is a need to seek more appropriate regional substrate for the production of mycelial biomass and laccase. Hence, the aim of this study was to evaluate the effect of physical and chemical characteristics of agro-industrial byproducts in a substratum formulation for the mycelial growth and laccase production by P. ostreatus. The experiment was conducted with the milled raw materials: soy fiber, wheat bran, rice bran, corn grain and corn cob that were separated according to size and analyzed for carbon/nitrogen (C/N ratio. Mycelial growth was evaluated on substratum in cylindrical tubes of borosilicate. Then laccase production was assessed using a 26-2 fractional factorial design with the variables: raw material granulometry and addition of minerals (copper, zinc, iron, cadmium and magnesium in the substrate. The production of laccase was determined by oxidation of ABTS (2,2’-bisazin-(3-ethylbenzothiazoline-6-sulfonic acid. The results indicate that the most important factor for mycelial growth is the holding capacity of oxygen in the substratum. For mycelial growth of P. ostreatus the corn cob and wheat bran are the best components for the substrate. The other raw materials reduced the mycelial growth. However the most important factor for the induction of laccase production is the reduction of particle size, increasing the contact area between the mycelium and the substratum. Pleurotus ostreatus é um produtor de biomassa e lacase, enzima utilizada em processos fermentativos para a hidrólise de substratos lignocelulósicos, com potencial de utilização na produção de biocombustíveis e na alimentação animal. Desta forma, há a necessidade de buscar substratos regionais mais apropriados para a produção de biomassa micelial

Varying coefficient subdistribution regression for left-truncated semi-competing risks data.

Science.gov (United States)

Li, Ruosha; Peng, Limin

2014-10-01

Semi-competing risks data frequently arise in biomedical studies when time to a disease landmark event is subject to dependent censoring by death, the observation of which however is not precluded by the occurrence of the landmark event. In observational studies, the analysis of such data can be further complicated by left truncation. In this work, we study a varying co-efficient subdistribution regression model for left-truncated semi-competing risks data. Our method appropriately accounts for the specifical truncation and censoring features of the data, and moreover has the flexibility to accommodate potentially varying covariate effects. The proposed method can be easily implemented and the resulting estimators are shown to have nice asymptotic properties. We also present inference, such as Kolmogorov-Smirnov type and Cramér Von-Mises type hypothesis testing procedures for the covariate effects. Simulation studies and an application to the Denmark diabetes registry demonstrate good finite-sample performance and practical utility of the proposed method.

Symmetric truncations of the shallow-water equations

International Nuclear Information System (INIS)

Rouhi, A.; Abarbanel, H.D.I.

1993-01-01

Conservation of potential vorticity in Eulerian fluids reflects particle interchange symmetry in the Lagrangian fluid version of the same theory. The algebra associated with this symmetry in the shallow-water equations is studied here, and we give a method for truncating the degrees of freedom of the theory which preserves a maximal number of invariants associated with this algebra. The finite-dimensional symmetry associated with keeping only N modes of the shallow-water flow is SU(N). In the limit where the number of modes goes to infinity (N→∞) all the conservation laws connected with potential vorticity conservation are recovered. We also present a Hamiltonian which is invariant under this truncated symmetry and which reduces to the familiar shallow-water Hamiltonian when N→∞. All this provides a finite-dimensional framework for numerical work with the shallow-water equations which preserves not only energy and enstrophy but all other known conserved quantities consistent with the finite number of degrees of freedom. The extension of these ideas to other nearly two-dimensional flows is discussed

Autocorrelation as a source of truncated Lévy flights in foreign exchange rates

Science.gov (United States)

Figueiredo, Annibal; Gleria, Iram; Matsushita, Raul; Da Silva, Sergio

2003-05-01

We suggest that the ultraslow speed of convergence associated with truncated Lévy flights (Phys. Rev. Lett. 73 (1994) 2946) may well be explained by autocorrelations in data. We show how a particular type of autocorrelation generates power laws consistent with a truncated Lévy flight. Stock exchanges have been suggested to be modeled by a truncated Lévy flight (Nature 376 (1995) 46; Physica A 297 (2001) 509; Econom. Bull. 7 (2002) 1). Here foreign exchange rate data are taken instead. Scaling power laws in the “probability of return to the origin” are shown to emerge for most currencies. A novel approach to measure how distant a process is from a Gaussian regime is presented.

Whey protein isolate with improved film properties through cross-linking catalyzed by small laccase from Streptomyces coelicolor.

Science.gov (United States)

Quan, Wei; Zhang, Chong; Zheng, Meixia; Lu, Zhaoxin; Lu, Fengxia

2018-08-01

The effects of small laccase (SLAC) from Streptomyces coelicolor on the properties of whey protein isolate (WPI) films were studied. WPI was catalyze by SLAC without phenolic acid assistance. Particle size distribution results showed that some complexes with higher relative molecular weight formed in WPI samples treated with SLAC. The content of α-helixes decreased while those of β-sheets and random coils increased following SLAC treatment according to circular dichroism results. Fourier transform infrared spectral analysis suggested that some conformational changes occurred in WPI following SLAC treatment. Analysis of WPI films prepared by casting after SLAC treatment indicated that their film properties were all improved, including mechanical properties, solubility, water vapor, oxygen and carbon dioxide barrier properties, film color, light transmission, transparency and thermal properties. Compared with that of the control film, some obvious differences in the morphology of the WPI films were observed following SLAC treatment. This report demonstrates that laccase can directly catalyze protein cross-linking, which may be useful to improve the performance of protein films. In this study, SLAC was applied to WPI edible film during the film-making process. The results showed that SLAC can catalyze WPI cross-linking without phenolic acid assistance, and WPI film properties were improved after SLAC treatment. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

Oxidation of Wine Polyphenols by Secretomes of Wild Botrytis cinerea Strains from White and Red Grape Varieties and Determination of Their Specific Laccase Activity.

Science.gov (United States)

Zimdars, Sabrina; Hitschler, Julia; Schieber, Andreas; Weber, Fabian

2017-12-06

Processing of Botrytis cinerea-infected grapes leads to enhanced enzymatic browning reactions mainly caused by the enzyme laccase which is able to oxidize a wide range of phenolic compounds. The extent of color deterioration depends on the activity of the enzymes secreted by the fungus. The present study revealed significant differences in the oxidative properties of secretomes of several B. cinerea strains isolated from five grape varieties. The presumed laccase-containing secretomes varied in their catalytic activity toward six phenolic compounds present in grapes. All strains led to identical product profiles for five of six substrates, but two strains showed deviating product profiles during gallic acid oxidation. Fast oxidation of caffeic acid, ferulic acid, and malvidin 3-O-glucoside was observed. Product formation rates and relative product concentrations were determined. The results reflect the wide range of enzyme activity and the corresponding different impact on color deterioration by B. cinerea.

Efficient secretion of three fungal laccases from Saccharomyces cerevisiae and their potential for decolorization of textile industry effluent - A comparative study

Czech Academy of Sciences Publication Activity Database

Antošová, Z.; Herkommerová, Klára; Pichová, Iva; Sychrová, H.

2018-01-01

Roč. 34, č. 1 (2018), s. 69-80 ISSN 8756-7938 R&D Projects: GA TA ČR(CZ) TA01011461; GA MŠk LO1302 Institutional support: RVO:61388963 Keywords : laccase * decolorization * gene expression * expression optimization * Saccharomyces cerevisiae Subject RIV: CE - Biochemistry OBOR OECD: Biochemistry and molecular biology Impact factor: 1.986, year: 2016

A Residual Approach for Balanced Truncation Model Reduction (BTMR of Compartmental Systems

Directory of Open Access Journals (Sweden)

William La Cruz

2014-05-01

Full Text Available This paper presents a residual approach of the square root balanced truncation algorithm for model order reduction of continuous, linear and time-invariante compartmental systems. Specifically, the new approach uses a residual method to approximate the controllability and observability gramians, whose resolution is an essential step of the square root balanced truncation algorithm, that requires a great computational cost. Numerical experiences are included to highlight the efficacy of the proposed approach.