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Muhammad Asgher - One of the best experts on this subject based on the ideXlab platform.

  • chitosan beads immobilized Manganese Peroxidase catalytic potential for detoxification and decolorization of textile effluent
    International Journal of Biological Macromolecules, 2016
    Co-Authors: Muhammad Bilal, Munawar Iqbal, Muhammad Asgher, Xuehong Zhang
    Abstract:

    Textile industry has led to severe environmental pollution and is posing a serious threat to the ecosystems. Immobilized biocatalysts have gained importance as potential bio-remediating agent. Manganese Peroxidase (MnP) was immobilized onto glutaraldehyde activated chitosan beads by crosslinking and employed for the degradation and detoxification of dyes in textile effluents. The efficiency of chitosan-immobilized MnP (CI-MnP) was evaluated on the basis of decolorization, water quality improvement and toxicity reduction. Maximum color removal of 97.31% was recorded and up to 82.40%, 78.30% and 91.7% reductions in COD, TOC, and BOD were achieved, respectively. The cytotoxicity of bio-treated effluents reduced significantly and 38.46%, 43.47% and 41.83% Allium cepa root length, root count and mitotic index were increased, respectively, whereas brine shrimp nauplii death reduced up to 63.64%. Mutagenicity (Ames test) reduced up to 73.44% and 75.43% for TA98 and TA100 strains, respectively. The CI-MnP retained 60% activity after 10 repeated decolorization batches. The CI-MnP showed excellent efficiency for the bioremediation of textile effluents and can be used for the remediation of toxic agents in wastewater. The monitoring of processed wastewater using bioassays is suggested to evaluate bio-efficiency of treatment method for safe disposal of effluents into water bodies.

  • enhanced catalytic potentiality of ganoderma lucidum ibl 05 Manganese Peroxidase immobilized on sol gel matrix
    Journal of Molecular Catalysis B-enzymatic, 2016
    Co-Authors: Muhammad Bilal, Muhammad Asgher
    Abstract:

    Abstract Sol-gel immobilization is an efficient approach to improve the catalytic and life-time properties of biocatalyst. A monomeric 43 kDa Manganese Peroxidase (MnP) from Ganoderma lucidum IBL-05 was immobilized using hydrophobic sol-gel matrix of tetramethoxysilane and propyltrimethoxysilane. The method led to very effective MnP immobilization (91.0%), and imparted remarkable stability to the enzyme (82.7 ± 0.9% after 2 months of storage at 4 °C). The optimum pH was 5.0 and 4.0 for soluble and sol-gel immobilized MnP, respectively. Sol-gel encapsulated MnP exhibited 43% residual activity at 50 °C, whereas the free enzyme lost its activity completely after 72 h. After 5 h reaction time, textile wastewater effluents were decolorized to different extents (with a maximum of 93.92%) by immobilized MnP. Operational stability of the entrapped MnP was significantly improved after immobilization, and it retained more than 70% of original activity after three repeated uses for the tested effluents. The chemical oxygen demand (COD) and total organic carbon (TOC) of maximally decolorized effluents were below the permissible limits. The cytotoxicity evaluated through Allium cepa and brine shrimp lethality tests was considerably reduced after treatment with immobilized MnP. The broader pH stability, better thermo-and storage stability, and high catalytic activity are the attractive features of immobilized MnP that make it a promising candidate for environmental biotechnology.

  • characteristic features and dye degrading capability of agar agar gel immobilized Manganese Peroxidase
    International Journal of Biological Macromolecules, 2016
    Co-Authors: Muhammad Bilal, Muhammad Asgher, Muhammad Shahid, Haq Nawaz Bhatti
    Abstract:

    Immobilization of enzymes has been regarded as an efficient approach to develop biocatalyst with improved activity and stability characteristics under reaction conditions. In the present study, purified Manganese Peroxidase (MnP) from Ganoderma lucidum IBL-05 was immobilized in agar-agar support using entrapment technique. Maximum immobilization yield was accomplished at 4.0% agar-agar gel. The immobilized MnP exhibited better resistance to changes in pH and temperature than the free enzyme, with optimal conditions being pH 6.0 and 50 °C. The kinetic parameters Km and Kcat/Km for free and entrapped MnP were calculated to be 65.6 mM and 6.99 M(-1) s(-1), and 82 mM and 8.15 M(-1) s(-1), respectively. Thermo-stability was significantly improved after immobilization. After 120 h, the insolubilized MnP retained its activity up to 71.9% and 60.3% at 30 °C and 40 °C, respectively. It showed activity until 10th cycle and retained 74.3% residual activity after 3th cycle. The effects of H2O2, ionic strength and potential inhibitors on activity of free and immobilized enzyme were investigated. Moreover, the decolorization of three structurally different dyes was monitored in order to assess the degrading capability of the entrapped MnP. The decolorization efficiencies for all the tested dyes were 78.6-84.7% after 12h. The studies concluded that the toxicity of dyes aqueous solutions was significantly reduced after treatment. The remarkable catalytic, thermo-stability and re-cycling features of the agar-agar immobilized MnP display a high potential for biotechnological applications.

  • dye decolorization and detoxification potential of ca alginate beads immobilized Manganese Peroxidase
    BMC Biotechnology, 2015
    Co-Authors: Muhammad Bilal, Muhammad Asgher
    Abstract:

    In view of compliance with increasingly stringent environmental legislation, an eco-friendly treatment technology of industrial dyes and effluents is a major environmental challenge in the color industry. In present study, a promising and eco‐friendly entrapment approach was adopted to immobilize purified Manganese Peroxidase (MnP) produced from an indigenous strain of Ganoderma lucidum IBL-05 on Ca-alginate beads. The immobilized MnP was subsequently used for enhanced decolorization and detoxification of textile reactive dyes). MnP isolated from solid-state culture of G. lucidum IBL-05, presented highest immobilization yield (83.9 %) using alginate beads prepared at optimized conditions of 4 % (w/v) sodium alginate, 2 % (w/v) Calcium chloride (CaCl2) and 0.5 mg/ml enzyme concentration. Immobilization of MnP enhanced optimum temperature but caused acidic shift in optimum pH of the enzyme. The immobilized MnP showed optimum activity at pH 4.0 and 60 °C as compared to pH 5.0 and 35 °C for free enzyme. The kinetic parameters K m and V max of MnP were significantly improved by immobilization. The enhanced catalytic potential of immobilized MnP led to 87.5 %, 82.1 %, 89.4 %, 95.7 % and 83 % decolorization of Sandal-fix Red C4BLN, Sandal-fix Turq Blue GWF, Sandal-fix Foron Blue E2BLN, Sandal-fix Black CKF and Sandal-fix Golden Yellow CRL dyes, respectively. The insolubilized MnP was reusable for 7 repeated cycles in dye color removal. Furthermore, immobilized MnP also caused a significant reduction in biochemical oxygen demand (BOD) (94.61-95.47 %), chemical oxygen demand (COD) (91.18-94.85 %), and total organic carbon (TOC) (89.58-95 %) of aqueous dye solutions. G. lucidum MnP was immobilized in Ca-alginate beads by entrapment method to improve its practical effectiveness. Ca-alginate bound MnP was catalytically more vigorous, thermo-stable, reusable and worked over wider ranges of pH and temperature as compared to its free counterpart. Results of cytotoxicity like hemolytic and brine shrimp lethality tests suggested that Ca-alginate immobilized MnP may effectively be used for detoxification of dyes and industrial effluents.

  • purification and biochemical characterization of extracellular Manganese Peroxidase from ganoderma lucidum ibl 05 and its application
    Scientific Research and Essays, 2015
    Co-Authors: Muhammad Bilal, Muhammad Asgher, Muhammad Ramzan
    Abstract:

    In this study an extracellular Manganese Peroxidase (MnP) was isolated from culture filtrate of an indigenous fungal strain Ganoderma lucidum IBL-05 under static conditions using wheat bran as substrate. The enzyme was purified by applying successively ammonium sulphate precipitation, dialysis, ion exchange and gel filtration chromatographic techniques. Purification procedure resulted in 3.43-fold purification with corresponding specific activity of 539.59 Umg-1. The purified MnP elucidated single band in 43 kDa region on sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The purified MnP showed optimum activity at pH 5 and 40°C temperature. The Km and Vmax for MnP toward MnSO4 as a substrate were found to be 65.5 mM and 640 UmL-1, respectively. It was observed that MnP activity enhanced by Mn2+ and Cu2+ and inhibited in the presence of Zn2+, Fe2+, EDTA and Cysteine to various extents with Hg2+ (most inhibitory). The purified MnP efficiently catalyzed the transformation of different synthetic textile dyes (Sandal-reactive dyes). Characterization revealed that MnP isolated from G. lucidum have potential to be used for myriad industrial and biotechnological applications.   Key words: Manganese Peroxidase, Ganoderma lucidum IBL-05, purification, characterization, kinetics, dye decolorization

Muhammad Bilal - One of the best experts on this subject based on the ideXlab platform.

  • chitosan beads immobilized Manganese Peroxidase catalytic potential for detoxification and decolorization of textile effluent
    International Journal of Biological Macromolecules, 2016
    Co-Authors: Muhammad Bilal, Munawar Iqbal, Muhammad Asgher, Xuehong Zhang
    Abstract:

    Textile industry has led to severe environmental pollution and is posing a serious threat to the ecosystems. Immobilized biocatalysts have gained importance as potential bio-remediating agent. Manganese Peroxidase (MnP) was immobilized onto glutaraldehyde activated chitosan beads by crosslinking and employed for the degradation and detoxification of dyes in textile effluents. The efficiency of chitosan-immobilized MnP (CI-MnP) was evaluated on the basis of decolorization, water quality improvement and toxicity reduction. Maximum color removal of 97.31% was recorded and up to 82.40%, 78.30% and 91.7% reductions in COD, TOC, and BOD were achieved, respectively. The cytotoxicity of bio-treated effluents reduced significantly and 38.46%, 43.47% and 41.83% Allium cepa root length, root count and mitotic index were increased, respectively, whereas brine shrimp nauplii death reduced up to 63.64%. Mutagenicity (Ames test) reduced up to 73.44% and 75.43% for TA98 and TA100 strains, respectively. The CI-MnP retained 60% activity after 10 repeated decolorization batches. The CI-MnP showed excellent efficiency for the bioremediation of textile effluents and can be used for the remediation of toxic agents in wastewater. The monitoring of processed wastewater using bioassays is suggested to evaluate bio-efficiency of treatment method for safe disposal of effluents into water bodies.

  • enhanced catalytic potentiality of ganoderma lucidum ibl 05 Manganese Peroxidase immobilized on sol gel matrix
    Journal of Molecular Catalysis B-enzymatic, 2016
    Co-Authors: Muhammad Bilal, Muhammad Asgher
    Abstract:

    Abstract Sol-gel immobilization is an efficient approach to improve the catalytic and life-time properties of biocatalyst. A monomeric 43 kDa Manganese Peroxidase (MnP) from Ganoderma lucidum IBL-05 was immobilized using hydrophobic sol-gel matrix of tetramethoxysilane and propyltrimethoxysilane. The method led to very effective MnP immobilization (91.0%), and imparted remarkable stability to the enzyme (82.7 ± 0.9% after 2 months of storage at 4 °C). The optimum pH was 5.0 and 4.0 for soluble and sol-gel immobilized MnP, respectively. Sol-gel encapsulated MnP exhibited 43% residual activity at 50 °C, whereas the free enzyme lost its activity completely after 72 h. After 5 h reaction time, textile wastewater effluents were decolorized to different extents (with a maximum of 93.92%) by immobilized MnP. Operational stability of the entrapped MnP was significantly improved after immobilization, and it retained more than 70% of original activity after three repeated uses for the tested effluents. The chemical oxygen demand (COD) and total organic carbon (TOC) of maximally decolorized effluents were below the permissible limits. The cytotoxicity evaluated through Allium cepa and brine shrimp lethality tests was considerably reduced after treatment with immobilized MnP. The broader pH stability, better thermo-and storage stability, and high catalytic activity are the attractive features of immobilized MnP that make it a promising candidate for environmental biotechnology.

  • mutagenicity and cytotoxicity assessment of biodegraded textile effluent by ca alginate encapsulated Manganese Peroxidase
    Biochemical Engineering Journal, 2016
    Co-Authors: Muhammad Bilal, Munawar Iqbal, Xuehong Zhang
    Abstract:

    Abstract Present study was aimed to appraise the potential of free and immobilized Manganese Peroxidase (MnP) for the decolorization and detoxification of textile effluent. MnP was immobilized in Ca-alginate beads at optimized conditions of sodium alginate, calcium chloride and enzyme concentrations. Maximum effluent decolorization of 87.4% was achieved in the presence of H2O2 (1 mmol l−1), 1-hydroxybenzotriazole (1 mmol l−1), pH (5.0) and temperature (40 °C) for 5 h of incubation time. The effluent treated at optimized conditions was subjected to toxicity evaluation. The cytotoxicity was evaluated using Allium cepa, brine shrimp and heamolytic bioassays; whereas mutagenicity was tested using Ames test of both treated and untreated effluent. The cytotoxicity of treated sample reduced significantly and A. cepa showed increase in root length, root count and mitotic index up to 38.46%, 43.47% and 41.83%, respectively, whereas red blood cells (RBCs) lysis reduced 69.84% and brine shrimp nauplii death reduced up to 63.64% in immobilized MnP treated effluent. The mutagenicity reduced up to 73.44% and 75.43% for TA98 and TA100 strains, respectively. The Ca-alginate beads encapsulated MnP revealed promising bio-catalytic efficiency and could be used for the decolorization and detoxification of textile effluents.

  • characteristic features and dye degrading capability of agar agar gel immobilized Manganese Peroxidase
    International Journal of Biological Macromolecules, 2016
    Co-Authors: Muhammad Bilal, Muhammad Asgher, Muhammad Shahid, Haq Nawaz Bhatti
    Abstract:

    Immobilization of enzymes has been regarded as an efficient approach to develop biocatalyst with improved activity and stability characteristics under reaction conditions. In the present study, purified Manganese Peroxidase (MnP) from Ganoderma lucidum IBL-05 was immobilized in agar-agar support using entrapment technique. Maximum immobilization yield was accomplished at 4.0% agar-agar gel. The immobilized MnP exhibited better resistance to changes in pH and temperature than the free enzyme, with optimal conditions being pH 6.0 and 50 °C. The kinetic parameters Km and Kcat/Km for free and entrapped MnP were calculated to be 65.6 mM and 6.99 M(-1) s(-1), and 82 mM and 8.15 M(-1) s(-1), respectively. Thermo-stability was significantly improved after immobilization. After 120 h, the insolubilized MnP retained its activity up to 71.9% and 60.3% at 30 °C and 40 °C, respectively. It showed activity until 10th cycle and retained 74.3% residual activity after 3th cycle. The effects of H2O2, ionic strength and potential inhibitors on activity of free and immobilized enzyme were investigated. Moreover, the decolorization of three structurally different dyes was monitored in order to assess the degrading capability of the entrapped MnP. The decolorization efficiencies for all the tested dyes were 78.6-84.7% after 12h. The studies concluded that the toxicity of dyes aqueous solutions was significantly reduced after treatment. The remarkable catalytic, thermo-stability and re-cycling features of the agar-agar immobilized MnP display a high potential for biotechnological applications.

  • dye decolorization and detoxification potential of ca alginate beads immobilized Manganese Peroxidase
    BMC Biotechnology, 2015
    Co-Authors: Muhammad Bilal, Muhammad Asgher
    Abstract:

    In view of compliance with increasingly stringent environmental legislation, an eco-friendly treatment technology of industrial dyes and effluents is a major environmental challenge in the color industry. In present study, a promising and eco‐friendly entrapment approach was adopted to immobilize purified Manganese Peroxidase (MnP) produced from an indigenous strain of Ganoderma lucidum IBL-05 on Ca-alginate beads. The immobilized MnP was subsequently used for enhanced decolorization and detoxification of textile reactive dyes). MnP isolated from solid-state culture of G. lucidum IBL-05, presented highest immobilization yield (83.9 %) using alginate beads prepared at optimized conditions of 4 % (w/v) sodium alginate, 2 % (w/v) Calcium chloride (CaCl2) and 0.5 mg/ml enzyme concentration. Immobilization of MnP enhanced optimum temperature but caused acidic shift in optimum pH of the enzyme. The immobilized MnP showed optimum activity at pH 4.0 and 60 °C as compared to pH 5.0 and 35 °C for free enzyme. The kinetic parameters K m and V max of MnP were significantly improved by immobilization. The enhanced catalytic potential of immobilized MnP led to 87.5 %, 82.1 %, 89.4 %, 95.7 % and 83 % decolorization of Sandal-fix Red C4BLN, Sandal-fix Turq Blue GWF, Sandal-fix Foron Blue E2BLN, Sandal-fix Black CKF and Sandal-fix Golden Yellow CRL dyes, respectively. The insolubilized MnP was reusable for 7 repeated cycles in dye color removal. Furthermore, immobilized MnP also caused a significant reduction in biochemical oxygen demand (BOD) (94.61-95.47 %), chemical oxygen demand (COD) (91.18-94.85 %), and total organic carbon (TOC) (89.58-95 %) of aqueous dye solutions. G. lucidum MnP was immobilized in Ca-alginate beads by entrapment method to improve its practical effectiveness. Ca-alginate bound MnP was catalytically more vigorous, thermo-stable, reusable and worked over wider ranges of pH and temperature as compared to its free counterpart. Results of cytotoxicity like hemolytic and brine shrimp lethality tests suggested that Ca-alginate immobilized MnP may effectively be used for detoxification of dyes and industrial effluents.

Michael H. Gold - One of the best experts on this subject based on the ideXlab platform.

  • high resolution crystal structure of Manganese Peroxidase substrate and inhibitor complexes
    Biochemistry, 2005
    Co-Authors: Munirathinam Sundaramoorthy, Michael H. Gold, Heather Youngs, Thomas L Poulos
    Abstract:

    Manganese Peroxidase (MnP) is an extracellular heme enzyme that catalyzes the peroxide-dependent oxidation of Mn(II) to Mn(III). The Mn(III) is released from the enzyme in complex with oxalate. One heme propionate and the side chains of Glu35, Glu39, and Asp179 were identified as Mn(II) ligands in the 2.0 A resolution crystal structure. The new 1.45 A crystal structure of MnP complexed with Mn(II) provides a more accurate view of the Mn-binding site. New features include possible partial protonation of Glu39 in the Mn-binding site and glycosylation at Ser336. This is also the first report of MnP-inhibitor complex structures. At the Mn-binding site, divalent Cd(II) exhibits octahedral, hexacoordinate ligation geometry similar to that of Mn(II). Cd(II) also binds to a putative second weak metal-binding site with tetrahedral geometry at the C-terminus of the protein. Unlike that for Mn(II) and Cd(II), coordination of trivalent Sm(III) at the Mn-binding site is octacoordinate. Sm(III) was removed from a MnP-Sm(III) crystal by soaking the crystal in oxalate and then reintroduced into the binding site. Thus, direct comparisons of Sm(III)-bound and metal-free structures were made using the same crystal. No ternary complex was observed upon incubation with oxalate. The reversible binding of Sm(III) may be a useful model for the reversible binding of Mn(III) to the enzyme, which is too unstable to allow similar examination.

  • Homologous expression of Phanerochaete chrysosporium Manganese Peroxidase, using bialaphos resistance as a dominant selectable marker
    Current Genetics, 2003
    Co-Authors: Biao Ma, Mary B. Mayfield, Michael H. Gold
    Abstract:

    Manganese Peroxidase (MnP) is a major extracellular component of the lignin-degrading system of the white-rot fungus, Phanerochaete chrysosporium . Homologous expression of recombinant MnP isozyme 1 (rMnP1) in P. chrysosporium was achieved using a novel transformation system for this fungus, which utilizes the Streptomyces hygroscopicus bialaphos-resistant gene, bar , as the selectable marker. The transformation frequency for this system is approximately 100 bialaphos-resistant transformants per microgram of plasmid DNA. Transformed strains all contain plasmid DNA, ectopically integrated into the fungal genome. Using this transformation system, the promoter region of the P. chrysosporium translation elongation factor gene was used to drive expression of mnp1 , encoding MnP1, in primary metabolic cultures of P. chrysosporium , where endogenous MnP was not expressed. Approximately 2–3 mg of active recombinant MnP1 per liter of extracellular medium was produced in agitated cultures of transformants.

  • the crystal structure of Manganese Peroxidase from phanerochaete chrysosporium at 2 06 a resolution
    Journal of Biological Chemistry, 1994
    Co-Authors: Munirathinam Sundaramoorthy, Michael H. Gold, Katsuyuki Kishi, Thomas L Poulos
    Abstract:

    The crystal structure of Manganese Peroxidase (MnP) from the lignin-degrading basidiomycetous fungus Phanerochaete chrysosporium has been solved using molecular replacement techniques and refined to R = 0.20 at 2.0 A. The overall structure is similar to that of two other fungal Peroxidases, lignin Peroxidase from P. chrysosporium and Arthromyces ramosus Peroxidase. Like the other fungal Peroxidases, MnP has two structural calcium ions. MnP also has two N-acetylglucosamine residues N-linked to Asn131 that are readily visible in the electron density map. The active site, consisting of a proximal His ligand H-bonded to an Asp residue and a distal side peroxide binding pocket consisting of a catalytic His and Arg, is the same as in the aforementioned fungal Peroxidases as well as yeast cytochrome c Peroxidase. MnP differs in having five rather than four disulfide bonds. The additional disulfide bond, Cys341-Cys348, is located near the C terminus of the polypeptide chain. Importantly, a new cation binding site, which we propose is the Manganese-binding site of MnP, was located in the crystal structure. The ligands constituting the Mn(2+)-binding site include Asp179, Glu35, Glu39, a heme propionate, and two water molecules. Electron transfer from Mn2+ to the heme edge or iron center is envisioned to occur through a sigma-bonded pathway along a heme propionate.

  • Manganese ii oxidation by Manganese Peroxidase from the basidiomycete phanerochaete chrysosporium kinetic mechanism and role of chelators
    Journal of Biological Chemistry, 1992
    Co-Authors: Hiroyuki Wariishi, K Valli, Michael H. Gold
    Abstract:

    Manganese oxidation by Manganese Peroxidase (MnP) was investigated. Stoichiometric, kinetic, and MnII binding studies demonstrated that MnP has a single Manganese binding site near the heme, and two MnIII equivalents are formed at the expense of one H2O2 equivalent. Since each catalytic cycle step is irreversible, the data fit a Peroxidase ping-pong mechanism rather than an ordered bi-bi ping-pong mechanism. MnIII-organic acid complexes oxidize terminal phenolic substrates in a second-order reaction. MnIII-lactate and -tartrate also react slowly with H2O2, with third-order kinetics. The latter slow reaction does not interfere with the rapid MnP oxidation of phenols. Oxalate and malonate are the only organic acid chelators secreted by the fungus in significant amounts. No relationship between stimulation of enzyme activity and chelator size was found, suggesting that the substrate is free MnII rather than a MnII-chelator complex. The enzyme competes with chelators for free MnII. Optimal chelators, such as malonate, facilitate MnIII dissociation from the enzyme, stabilize MnIII in aqueous solution, and have a relatively low MnII binding constant.

  • oxidation of phenolic arylglycerol beta aryl ether lignin model compounds by Manganese Peroxidase from phanerochaete chrysosporium oxidative cleavage of an alpha carbonyl model compound
    Biochemistry, 1992
    Co-Authors: Urs Tuor, Hiroyuki Wariishi, Hans E Schoemaker, Michael H. Gold
    Abstract:

    Manganese Peroxidase (MnP) oxidized 1-(3,5-dimethoxy-4-hydroxyphenyl)-2-(4-(hydroxy methyl)-2-methoxyphenoxy)-1,3-dihydroxypropane (I) in the presence of Mn II and H 2 O 2 to yield 1-(3,5- dimethoxy-4-hydroxyphenyl)-2-(4-(hydroxymethyl)-2-methoxyphenoxy)- 1-oxo-3-hydroxypropane (II), 2,6-dimethoxy-1,4-benzoquinone (III), 2,6-dimethoxy-1,4-dihydroxybenzene (IV), 2-(4-(hydroxy methyl)-2-methoxyphenoxy)-3-hydroxypropanal (V), syringaldehyde (VI), vanillyl alcohol (VII), and vanillin (VIII)

J M Lema - One of the best experts on this subject based on the ideXlab platform.

  • dye decolorization by Manganese Peroxidase in an enzymatic membrane bioreactor
    Biotechnology Progress, 2008
    Co-Authors: Carmen Lopez, Gumersindo Feijoo, Maria Teresa Moreira, J M Lema
    Abstract:

    In the present work an enzymatic membrane reactor (EMR) for the oxidation of azo dyes by Manganese Peroxidase (MnP) has been developed. The configuration consisted of a stirred tank reactor coupled with an ultrafiltration membrane. The membrane allowed for most of the enzymatic activity to be recovered while both the parent dye and the degradation products could pass through. Different operational strategies (batch, fed-batch, and continuous) and parameters such as enzyme activity, H 2 O 2 feeding rate, hydraulic retention time (in continuous operation), and dye loading rate were studied. At best conditions, a continuous operation with a dye decolorization higher than 85% and minimal enzymatic deactivation was feasible for 18 days, attaining an efficiency of 42.5 mg Orange II oxidized/MnP unit consumed.

  • evaluation of the enzyme Manganese Peroxidase in an industrial sequence for the lignin oxidation and bleaching of eucalyptus kraft pulp
    Journal of Applied Polymer Science, 2008
    Co-Authors: Gumersindo Feijoo, Maria Teresa Moreira, Pablo Alvarez, Thelmo A Luchau, J M Lema
    Abstract:

    Manganese Peroxidase produced by the white-rot fungus Bjerkandera sp. strain BOS55 was used for lignin oxidation and bleaching of eucalyptus oxygen- delignified kraft pulp. The optimization of the enzymatic stage and its implementation into an industrial chemical bleaching sequence were performed for the purpose of defining a new bleaching sequence. Parameters related to the selection and concentration of a chelating organic acid, Mn 21 , and hydrogen peroxide concentrations were opti- mized and applied to evaluate the implementation of an enzymatic stage into a chemical sequence composed of chelator and hydrogen peroxide or hydrogen peroxide with oxygen pressure stages. The brightness, reduction of the j number, and remaining Manganese Peroxidase activ- ity were assessed in conventional and enzyme-based bleaching sequences. High International Organization for Standardization (ISO) brightness (83%) and parallel j number reduction (5.5 points) were obtained with an enzy- matic stage/chelator stage/hydrogen peroxide with oxy- gen pressure stage sequence under the best operational conditions: 33 lM Mn 21 , oxalic acid, and 41.7 lM H2O2 added in pulses every 5 min for the enzymatic stage and a 2-h hydrogen peroxide with oxygen pressure stage at 588.4

  • operation of a two phase partitioning bioreactor for the oxidation of anthracene by the enzyme Manganese Peroxidase
    Chemosphere, 2007
    Co-Authors: Gemma Eibes, Gumersindo Feijoo, Maria Teresa Moreira, Andrew J Daugulis, J M Lema
    Abstract:

    Abstract A study was conducted to determine the potential of a two-phase partitioning bioreactor (TPPB) for the treatment of a poorly soluble compound, anthracene, by the enzyme Manganese Peroxidase (MnP) from the fungus Bjerkandera sp. BOS55. Silicone oil was used as the immiscible solvent, which contained anthracene at high concentrations. The optimization of the oxidation process was conducted taking into account the factors which may directly affect the MnP catalytic cycle (the concentration of H2O2 and malonic acid) and those that affect the mass transfer of anthracene between the organic and the aqueous phase (solvent and agitation speed). The main objective was carried out in terms of improved efficiency, i.e., maximizing the anthracene oxidized per unit of enzyme used. The TPPB reached nearly complete oxidation of anthracene at a conversion rate of 1.8 mg l−1 h−1 in 56 h, which suggests the application of enzymatic TPPBs for the removal of poorly soluble compounds.

  • oxidative degradation of azo dyes by Manganese Peroxidase under optimized conditions
    Biotechnology Progress, 2003
    Co-Authors: I Mielgo, Gumersindo Feijoo, Maria Teresa Moreira, Carmen Lopez, J M Lema
    Abstract:

    The application of enzyme-based systems in waste treatment is unusual, given that many drawbacks are derived from their use, including low efficiency, high costs and easy deactivation of the enzyme. The goal of this study is the development of a degradation system based on the use of the ligninolytic enzyme Manganese Peroxidase (MnP) for the degradation of azo dyes. The experimental work also includes the optimization of the process, with the objective of determining the influence of specific physicochemical factors, such as organic acids, H(2)O(2) addition, Mn(2+) concentration, pH, temperature, enzyme activity and dye concentration. A nearly total decolorization was possible at very low reaction times (10 min) and at high dye concentration (up to 1500 mg L(-)(1)). A specific oxidation capacity as high as 10 mg dye degraded per unit of MnP consumed was attained for a decolorization higher than 90%. Among all, the main factor affecting process efficiency was the strategy of H(2)O(2) addition. The continuous addition at a controlled flow permitted the progressive participation of H(2)O(2) in the catalytic cycle through a suitable regeneration of the oxidized form of the enzyme, which enhanced both the extent and the rate of decolorization. It was also found that, in this particular case, the presence of a chelating organic acid (e.g., malonic) was not required for an effective operation. Probably, Mn(3+) was chelated by the dye itself. The simplicity and high efficiency of the process open an interesting possibility of using of MnP for solving other environmental problems.

  • in vitro degradation of a polymeric dye poly r 478 by Manganese Peroxidase
    Biotechnology and Bioengineering, 2001
    Co-Authors: Maria Teresa Moreira, Gumersindo Feijoo, I Mielgo, C Palma, J M Lema
    Abstract:

    The aim of this study is the evaluation of the enzymatic action of the ligninolytic enzyme Manganese Peroxidase (MnP), through a suitable addition of H2O2, as a feasible system for the in vitro degradation of com- plex structures. For this purpose, a highly recalcitrant polymeric dye (Poly R-478) was selected as a model com- pound. An amperometric technique was used to deter- mine the H2O2 requirement in the decolorization by non- purified MnP. Two H2O2 supply strategies—fed-batch (every hour) or semicontinuous (every 5 min)—were ap- plied. The addition of H2O2 in pulses led to a limited decolorization after the pulses and the instantaneous consumption or decomposition of H2O2. Therefore, this way of addition may limit the actual H2O2 concentration in the reaction mixture. In contrast, the semicontinuous strategy maintained lower and prolonged concentrations of H2O2, which allowed a clearly greater decolorization (48% after 2 h). In addition, the effect of Mn +2 concentra- tion on the decolorization efficiency was investigated to establish the optimal application of the MnP-oxidative system. The enzymatic treatment provoked not only the destruction of the chromophoric groups but also a no- ticeable breakdown of the chemical structure of the dye. In experiments with pure enzyme, MnP proved to be the main factor responsible for the dye decolorization. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 75: 362-368, 2001.

Martin Hofrichter - One of the best experts on this subject based on the ideXlab platform.

  • review lignin conversion by Manganese Peroxidase mnp
    Enzyme and Microbial Technology, 2002
    Co-Authors: Martin Hofrichter
    Abstract:

    Manganese Peroxidase (MnP) is the most common lignin-modifying Peroxidase produced by almost all wood-colonizing basidiomycetes causing white-rot and various soil-colonizing litter-decomposing fungi. Multiple forms of this glycosylated heme protein with molecular weights normally at 40 to 50 kDa are secreted by ligninolytic fungi into their microenvironment. There, MnP preferentially oxidizes Manganese(II) ions (Mn2+), always present in wood and soils, into highly reactive Mn3+, which is stabilized by fungal chelators such as oxalic acid. Chelated Mn3+ in turn acts as low-molecular weight, diffusible redox-mediator that attacks phenolic lignin structures resulting in the formation of instable free radicals that tend to disintegrate spontaneously. MnP is capable of oxidizing and depolymerizing natural and synthetic lignins as well as entire lignocelluloses (milled straw or wood, pulp) in cell-free systems (in vitro). In vitro depolymerization is enhanced in the presence of co-oxidants such as thiols (e.g. glutathione) or unsaturated fatty acids and their derivatives (e.g. Tween 80). The review summarizes and discusses different approaches to prove lignin decomposition in vitro and lists, in addition, other recalcitrant substances oxidizible by MnP.

  • conversion of milled pine wood by Manganese Peroxidase from phlebia radiata
    Applied and Environmental Microbiology, 2001
    Co-Authors: Martin Hofrichter, Taina Lundell, Annele Hatakka
    Abstract:

    Purified Manganese Peroxidase (MnP) from the white-rot basidiomycete Phlebia radiata was found to convert in vitro milled pine wood (MPW) suspended in an aqueous reaction solution containing Tween 20, Mn2+, Mn-chelating organic acid (malonate), and a hydrogen peroxide-generating system (glucose-glucose oxidase). The enzymatic attack resulted in the polymerization of lower-molecular-mass, soluble wood components and in the partial depolymerization of the insoluble bulk of pine wood, as demonstrated by high-performance size exclusion chromatography (HPSEC). The surfactant Tween 80 containing unsaturated fatty acid redsidues promoted the disintegration of bulk MPW. HPSEC showed that the depolymerization yielded preferentially lignocellulose fragments with a predominant molecular mass of ca. 0.5 kDa. MnP from P. radiata (MnP3) turned out to be a stable enzyme remaining active for 2 days even at 37°C with vigorous stirring, and 65 and 35% of the activity applied was retained in Tween 20 and Tween 80 reaction mixtures, respectively. In the course of reactions, major part of the Mn-chelator malonate was decomposed (85 to 87%), resulting in an increase of pH from 4.4 to >6.5. An aromatic nonphenolic lignin structure (β-O-4 dimer), which is normally not attacked by MnP, was oxidizible in the presence of pine wood meal. This finding indicates that certain wood components may promote the degradative activities of MnP in a way similar to that promoted by Tween 80, unsaturated fatty acids, or thiols.

  • degradation of lignite low rank coal by ligninolytic basidiomycetes and their Manganese Peroxidase system
    Applied Microbiology and Biotechnology, 1999
    Co-Authors: Martin Hofrichter, D Ziegenhagen, S Sorge, R Ullrich, Friedemann Bublitz, Wolfgang Fritsche
    Abstract:

    Ligninolytic basidiomycetes (wood and leaf-litter-decaying fungi) have the ability to degrade low-rank coal (lignite). Extracellular Manganese Peroxidase is the crucial enzyme in the depolymerization process of both coal-derived humic substances and native coal. The depolymerization of coal by Mn Peroxidase is catalysed via chelated Mn(III) acting as a diffusible mediator with a high redox potential and can be enhanced in the presence of additional mediating agents (e.g. glutathione). The depolymerization process results in the formation of a complex mixture of lower-molecular-mass fulvic-acid-like compounds. Experiments using a synthetic 14C-labeled humic acid demonstrated that the Mn Peroxidase-catalyzed depolymerization of humic substances was accompanied by a substantial release of carbon dioxide (17%–50% of the initially added radioactivity was released as 14CO2). Mn Peroxidase was found to be a highly stable enzyme that remained active for several weeks under reaction conditions in a liquid reaction mixture and even persisted in sterile and native soil from an opencast mining area for some days.

  • coupling of Manganese Peroxidase mediated lipid peroxidation with destruction of nonphenolic lignin model compounds and 14c labeled lignins
    Biochemical and Biophysical Research Communications, 1999
    Co-Authors: Alexander N Kapich, Martin Hofrichter, Tamara Vares, Annele Hatakka
    Abstract:

    Abstract Linoleic acid, the predominant unsaturated fatty acid (UFA) in the lipids of wood-rotting fungi, was oxidized by Manganese Peroxidase (MnP) from the white-rot fungus Phlebia radiata through a peroxidation mechanism. The peroxidation was markedly stimulated by hydrogen peroxide. UFAs that are substrates for lipid peroxidation and surfactants that emulsify water-insoluble components were essential for the MnP-catalyzed destruction of a nonphenolic β-O-4-linked lignin model compound (LMC). Moreover, both components stimulated the MnP-catalyzed mineralization of 14 C-labeled synthetic lignin and 14 C-labeled wheat straw. A high level of destruction was obtained in reaction systems with Tween 80 acting both as surfactant and source of UFAs. The presence of the linoleic acid in reaction systems with MnP and Tween 80 additionally enhanced rate and level of LMC destruction and lignin mineralization. The results indicate that lipid peroxidation may play an important role in lignin biodegradation by wood-rotting basidiomycetes and support the hypothesis of coupling between the processes.

  • oxidative decomposition of malonic acid as basis for the action of Manganese Peroxidase in the absence of hydrogen peroxide
    FEBS Letters, 1998
    Co-Authors: Martin Hofrichter, Wolfgang Fritsche, D Ziegenhagen, Tamara Vares, M Friedrich, Marcus Jager, Annele Hatakka
    Abstract:

    Manganese Peroxidase (MnP) from the ligninolytic basidiomycetes Phlebia radiata and Nematoloma frowardii was found to decompose malonate oxidatively in the absence of H2O2 in a reaction system consisting of the enzyme, sodium malonate and MnCl2. The enzymatic oxidation resulted in a substantial decrease in malonate concentration and the formation of CO2, oxalate, glyoxylate and formate. Simultaneously with the decomposition of malonate, Mn(II) was oxidized to Mn(III) leading to high transient concentrations of the latter. MnP action in the absence of H2O2 started slowly after a lag period of 3 h. The lag period was considerably shortened after a single addition of Mn(III). Superoxide dismutase and catalase inhibited the enzymatic reaction partly, ascorbate completely. ESR studies demonstrated the formation of a carbon-centered radical during the course of the reaction. We propose that the latter generates peroxides that can be used by MnP to oxidize Mn(II) to Mn(III).