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Laccase

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https://www.readbyqxmd.com/read/27904924/sequential-lignin-depolymerization-by-combination-of-biocatalytic-and-formic-acid-formate-treatment-steps
#1
Christoph A Gasser, Monika Čvančarová, Erik M Ammann, Andreas Schäffer, Patrick Shahgaldian, Philippe F-X Corvini
Lignin, a complex three-dimensional amorphous polymer, is considered to be a potential natural renewable resource for the production of low-molecular-weight aromatic compounds. In the present study, a novel sequential lignin treatment method consisting of a biocatalytic oxidation step followed by a formic acid-induced lignin depolymerization step was developed and optimized using response surface methodology. The biocatalytic step employed a laccase mediator system using the redox mediator 1-hydroxybenzotriazole...
November 30, 2016: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/27890094/functional-expression-production-and-biochemical-characterization-of-a-laccase-using-yeast-surface-display-technology
#2
Brandt Bertrand, María R Trejo-Hernández, Daniel Morales-Guzmán, Luis Caspeta, Ramón Suárez Rodríguez, Fernando Martínez-Morales
A Trametes versicolor laccase was functionally expressed on the membrane surface of Saccharomyces cerevisiae EBY100. Laccase expression was increased 6.57-fold by medium optimization and surpassed production by the native strain. Maximal laccase and biomass production reached 19 735 ± 1719 Ug(-1) and 6.22 ± 0.53 gL(-1) respectively, after 2 d of culture. Optimum oxidization of all substrates by laccase was observed at pH 3. Laccase showed high affinity towards substrates used with Km (mM) and Vmax (μmol min(-1)) values of 0...
December 2016: Fungal Biology
https://www.readbyqxmd.com/read/27889212/study-of-the-effect-of-the-bacterial-and-fungal-communities-present-in-real-wastewater-effluents-on-the-performance-of-fungal-treatments
#3
Marina Badia-Fabregat, Daniel Lucas, Tero Tuomivirta, Hannu Fritze, Taina Pennanen, Sara Rodríguez-Mozaz, Damià Barceló, Glòria Caminal, Teresa Vicent
The use of the ligninolytic fungi Trametes versicolor for the degradation of micropollutants has been widely studied. However, few studies have addressed the treatment of real wastewater containing pharmaceutically active compounds (PhAC) under non-sterile conditions. The main drawback of performing such treatments is the difficulty for the inoculated fungus to successfully compete with the other microorganisms growing in the bioreactor. In the present study, several fungal treatments were performed under non-sterile conditions in continuous operational mode with two types of real wastewater effluent, namely, a reverse osmosis concentrate (ROC) from a wastewater treatment plant and a veterinary hospital wastewater (VHW)...
November 23, 2016: Science of the Total Environment
https://www.readbyqxmd.com/read/27885197/a-thermostable-bilirubin-oxidizing-enzyme-from-activated-sludge-isolated-by-a-metagenomic-approach
#4
Nobutada Kimura, Yoichi Kamagata
A gene coding for a multicopper oxidase (BopA) was identified through the screening of a metagenomic library constructed from wastewater treatment activated sludge. The recombinant BopA protein produced in Escherichia coli exhibited oxidation activity toward 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS) in the presence of copper, suggesting that BopA is laccase. A bioinformatic analysis of the bopA gene sequence indicated that it has a phylogenetically bacterial origin, possibly derived from a bacterium within the phylum Deinococcus-Thermus...
November 23, 2016: Microbes and Environments
https://www.readbyqxmd.com/read/27885193/biodegradation-of-polycyclic-aromatic-hydrocarbons-by-a-thermotolerant-white-rot-fungus-trametes-polyzona-rynf13
#5
Churapa Teerapatsakul, Chetsada Pothiratana, Lerluck Chitradon, Surachai Thachepan
The biodegradation of three polycyclic aromatic hydrocarbons (PAHs), phenanthrene, fluorene, and pyrene, by a newly isolated thermotolerant white rot fungal strain RYNF13 from Thailand, was investigated. The strain RYNF13 was identified as Trametes polyzona, based on an analysis of its internal transcribed spacer sequence. The strain RYNF13 was superior to most white rot fungi. The fungus showed excellent removal of PAHs at a high concentration of 100 mg·L(-1). Complete degradation of phenanthrene in a mineral salt glucose medium culture was observed within 18 days of incubation at 30°C, whereas 90% of fluorene and 52% of pyrene were degraded under the same conditions...
November 22, 2016: Journal of General and Applied Microbiology
https://www.readbyqxmd.com/read/27879337/interactions-between-melanin-enzymes-and-their-atypical-recruitment-to-the-secretory-pathway-by-palmitoylation
#6
Srijana Upadhyay, Xinping Xu, Xiaorong Lin
: Melanins are biopolymers that confer coloration and protection to the host organism against biotic or abiotic insults. The level of protection offered by melanin depends on its biosynthesis and its subcellular localization. Previously, we discovered that Aspergillus fumigatus compartmentalizes melanization in endosomes by recruiting all melanin enzymes to the secretory pathway. Surprisingly, although two laccases involved in the late steps of melanization are conventional secretory proteins, the four enzymes involved in the early steps of melanization lack a signal peptide or a transmembrane domain and are thus considered "atypical" secretory proteins...
November 22, 2016: MBio
https://www.readbyqxmd.com/read/27878568/bioremoval-of-humic-acid-from-water-by-white-rot-fungi-exploring-the-removal-mechanisms
#7
M Zahmatkesh, H Spanjers, M J Toran, P Blánquez, J B van Lier
Twelve white rot fungi (WRF) strains were screened on agar plates for their ability to bleach humic acid (HA). Four fungal strains were selected and tested in liquid media for removal of HA. Bioremediation was investigated by HA color removal and changes in the concentration and molecular size distribution of HA by size exclusion chromatography. Trametes versicolor and Phanerochaete chrysosporium showed the highest HA removal efficiency, reaching about 80%. Laccase and manganese peroxidase were measured as extracellular enzymes and their relation to the HA removal by WRF was investigated...
December 2016: AMB Express
https://www.readbyqxmd.com/read/27878336/co-culturing-effects-of-coexisting-bacteria-on-wood-degradation-by-trametes-versicolor
#8
Ichiro Kamei
White-rot fungi are the main decomposers of wood cell-wall polymer in forest ecosystems. Little is known, however, about the interactions between white-rot fungi and other coexisting microorganisms in decayed wood. A white-rot fungus, Trametes versicolor strain TN6F, was isolated from a fruit body, and 44 strains of coexisting cultivable bacteria were isolated from its substrate, natural white rot-decayed wood. The effects of these bacteria on fungal growth were examined by an in vitro confrontation growth assay...
November 22, 2016: Current Microbiology
https://www.readbyqxmd.com/read/27875965/stimulation-of-laccase-biocatalysis-in-ionic-liquids-a-review-on-recent-progress
#9
Hao Liu, Xing Wu, Jianliang Sun, Shicheng Chen
It has been well known that laccases can directly or indirectly catalyze oxidation of a broad species of phenols, amines and many other electron acceptors. However, laccases as biocatalyst in "green" ionic liquids (ILs) media instead of conventional solvents are less known and regarded as an innovative research direction. The presence of ILs can either inhibit or stimulate laccase activity, strongly depending on water-miscibility and kosmotropic natures of ILs. In addition, enzyme source, mediator, pH as well as water content are very important factors which influence laccase activity and stability...
November 22, 2016: Current Protein & Peptide Science
https://www.readbyqxmd.com/read/27872999/laccase-catalysis-for-the-synthesis-of-bioactive-compounds
#10
REVIEW
Tukayi Kudanga, Blessing Nemadziva, Marilize Le Roes-Hill
The demand for compounds of therapeutic value is increasing mainly because of new applications of bioactive compounds in medicine, pharmaceutical, agricultural, and food industries. This has necessitated the search for cost-effective methods for producing bioactive compounds and therefore the intensification of the search for enzymatic approaches in organic synthesis. Laccase is one of the enzymes that have shown encouraging potential as biocatalysts in the synthesis of bioactive compounds. Laccases are multicopper oxidases with a diverse range of catalytic activities revolving around synthesis and degradative reactions...
November 21, 2016: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/27871379/decolourisation-of-acid-orange-7-in-a-microbial-fuel-cell-with-a-laccase-based-biocathode-influence-of-mitigating-ph-changes-in-the-cathode-chamber
#11
Priyadharshini Mani, Taj Keshavarz, T S Chandra, Godfrey Kyazze
Biocathodes may be a suitable replacement of platinum in microbial fuel cells (MFCs) if the cost of MFCs is to be reduced. However, the use of enzymes as bio-cathodes is fraught with loss of activity as time progresses. A possible cause of this loss in activity might be pH increase in the cathode as pH gradients in MFCs are well known. This pH increase is however, accompanied by simultaneous increase in salinity; therefore salinity may be a confounding variable. This study investigated various ways of mitigating pH changes in the cathode of MFCs and their effect on laccase activity and decolourisation of a model azo dye Acid orange 7 in the anode chamber...
January 2017: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/27871375/a-novel-simple-screening-method-for-investigating-the-properties-of-lignin-oxidative-activity
#12
Fabio Tonin, Elisa Vignali, Loredano Pollegioni, Paola D'Arrigo, Elena Rosini
Enzymatic lignin degradation represents a key challenge for integrated biorefineries. Notwithstanding the rich content in aromatic compounds, lignin's complex structure has hampered identification of an effective and cost-efficient enzymatic procedure to transform it into less complex product families. Advancements in enzymatically modifying or degrading lignin require a simple and reliable analytical method to quickly screen diverse lignin samples by employing different enzymes and conditions. Here, we report on a novel, rapid, and economic colorimetric assay for lignin oxidation based on the reaction of 2,4-dinitrophenylhydrazine with the carbonyl groups generated by enzymatic oxidation...
January 2017: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/27871279/biodegradation-of-lignin-and-nicotine-with-white-rot-fungi-for-the-delignification-and-detoxification-of-tobacco-stalk
#13
Yulong Su, He Xian, Sujuan Shi, Chengsheng Zhang, S M Nuruzzaman Manik, Jingjing Mao, Ge Zhang, Weihong Liao, Qian Wang, Haobao Liu
BACKGROUND: Tobacco stalk is one kind of abundant crop residues in China. The high lignification of tobacco stalk increases its reusing cost and the existing of nicotine will cause serious pollution. The biodegradation of lignocellulosic biomass has been demonstrated to be an environmental and economical approach for the utilization of plant stalk. Meanwhile, many nicotine-degrading microorganisms were found in nature. However, microorganisms which could degraded both nicotine and lignin haven't been reported...
November 21, 2016: BMC Biotechnology
https://www.readbyqxmd.com/read/27870600/a-laccase-gene-sh-lac-is-involved-in-the-growth-and-melanin-biosynthesis-of-scleromitrula-shiraiana
#14
Zhiyuan Lǚ, Xin Kang, Zhonghuai Xiang, Ningjia He
Scleromitrula shiraiana causes the popcorn disease in mulberry trees resulting in severe economic losses. Previous studies have shown that melanin may play a vital role in establishing the pathogenicity of fungi. In the present study, we identified the melanin produced in S. shiraiana belongs to DHN melanin by GC-MS, and cloned the laccase Sh-lac, a potential DHN melanin biosynthesis gene from S. shiraiana. We obtained two stable Sh-lac silenced transformants using RNAi, ilac-4 and 8 to elucidate the DHN melanin biosynthetic pathway in S...
November 21, 2016: Phytopathology
https://www.readbyqxmd.com/read/27869681/induction-of-laccase-lignin-peroxidase-and-manganese-peroxidase-activities-in-white-rot-fungi-using-copper-complexes
#15
Martina Vrsanska, Stanislava Voberkova, Vratislav Langer, Dagmar Palovcikova, Amitava Moulick, Vojtech Adam, Pavel Kopel
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(im)₄(H₂O)₂](btc)·3H₂O, where im = imidazole, H₃btc = 1,3,5-benzenetricarboxylic acid, [Cu₃(pmdien)₃(btc)](ClO₄)₃·6H₂O) and [Cu₃(mdpta)₃(btc)](ClO₄)₃·4H₂O, where pmdien = N,N,N',N'',N''-pentamethyl-diethylenetriamine and mdpta = N,N-bis-(3-aminopropyl)methyl- amine), and their potential application for laccase and peroxidases induction have been tested...
November 17, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/27863181/impact-of-phosphate-and-other-medium-components-on-physiological-regulation-of-bacterial-laccase-production
#16
Kavleen Kaur, Gursharan Singh, Vijaya Gupta, Neena Capalash, Prince Sharma
Laccases are multicopper oxidases known to catalyze the transformation of a wide range of phenolic and non-phenolic substrates using oxygen as electron acceptor and forming water as the only by product. Their potential relevance in several industries requires the constant search for novel laccases. Positive outcome of the isolation of laccase producing bacteria depends on the nature and concentration of media constituents. Several attempts to isolate laccase producing bacteria failed when the phosphate-containing M9 minimal medium was used...
November 14, 2016: Biotechnology Progress
https://www.readbyqxmd.com/read/27858135/expression-in-pichia-pastoris-and-characterization-of-two-novel-dirigent-proteins-for-atropselective-formation-of-gossypol
#17
Isabelle Effenberger, Michael Harport, Jens Pfannstiel, Iris Klaiber, Andreas Schaller
We established an efficient fed-batch fermentation process for two novel dirigent proteins from cotton plants, GbDIR2 from Gossypium barbadense and GhDIR3 from G. hirsutum, using the engineered Pichia pastoris GlycoSwitch® SuperMan5 strain to prevent hyperglycosylation. The two (His)6-tagged proteins were purified by metal-chelate affinity chromatography and obtained in quantities of 12 and 15 mg L(-1) of culture volume, respectively. Glycosylation sites were identified for the native and for the enzymatically deglycosylated proteins by mass spectrometry, confirming five to six of the seven predicted glycosylation sites in the NxS/T sequence context...
November 17, 2016: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/27846985/array-of-biosensors-for-discrimination-of-grapes-according-to-grape-variety-vintage-and-ripeness
#18
C Medina-Plaza, J A de Saja, J A Fernández-Escudero, E Barajas, G Medrano, M L Rodriguez-Mendez
A bioelectronic tongue based on nanostructured biosensors specific for the simultaneous detection of sugars and phenols has been developed. The array combined oxidases and dehydrogenases immobilized on a lipidic layer prepared using the Langmuir-Blodgett technique where Glucose oxidase, d-Fructose dehydrogenase, Tyrosinase or Laccase were imbibed. A phthalocyanine was co-immobilized in the sensing layer and used as electron mediator. The array thus formed has been used to analyze grapes and provides global information about the samples while providing specific information about their phenolic and their sugar content...
December 1, 2016: Analytica Chimica Acta
https://www.readbyqxmd.com/read/27842719/laccase-and-electrochemically-mediated-conversion-of-triclosan-metabolite-formation-and-influence-on-antibacterial-activity
#19
Elham Jahangiri, Bettina Seiwert, Thorsten Reemtsma, Dietmar Schlosser
Metabolite formation from radical-based oxidation of the environmental pollutant triclosan (TCS) was compared using an ascomycete (Phoma sp. UHH 5-1-03) and a basidiomycete (Trametes versicolor) laccase, laccase-redox mediator systems, and electrochemical oxidation (EC). Laccase oxidation predominantly yielded TCS di- and trimers, but notably also caused TCS ether bond cleavage. The latter was more prominent during EC-catalysed TCS oxidation, which generally resulted in a broader and more divergent product spectrum...
November 11, 2016: Chemosphere
https://www.readbyqxmd.com/read/27834376/biocatalytic-trifluoromethylation-of-unprotected-phenols
#20
Robert C Simon, Eduardo Busto, Nina Richter, Verena Resch, Kendall N Houk, Wolfgang Kroutil
Organofluorine compounds have become important building blocks for a broad range of advanced materials, polymers, agrochemicals, and increasingly for pharmaceuticals. Despite tremendous progress within the area of fluorination chemistry, methods for the direct introduction of fluoroalkyl-groups into organic molecules without prefunctionalization are still highly desired. Here we present a concept for the introduction of the trifluoromethyl group into unprotected phenols by employing a biocatalyst (laccase), tBuOOH, and either the Langlois' reagent or Baran's zinc sulfinate...
November 11, 2016: Nature Communications
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