Laccase mediated oxidation of industrial lignins: Is oxygen limiting?

Ortner, Andreas; Huber, Daniela; Haske-Cornelius, Oskar; Weber, Hedda K.; Hofer, Karin; Bauer, Wolfgang; Nyanhongo, Gibson S.; Guebitz, Georg M.

doi:10.1016/j.procbio.2015.05.003

Cited by 52 publications

(51 citation statements)

References 27 publications

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“…Commercial laccase from M. thermophila showed the ability to oxidize and polymerize Kraft lignin (KL). The extension of this polymerization depended on several parameters such as lignin origin, pH, temperature, phenolic mediators or reaction time [11,12,22,23]. The aim of this study was to test the capability of the enzymatic treatment of KL in the manufacturing of MDF with no synthetic resins.…”

Section: Resultsmentioning

confidence: 99%

Green Binder Based on Enzymatically Polymerized Eucalypt Kraft Lignin for Fiberboard Manufacturing: A Preliminary Study

Gouveia

Otero²,

Fernández‐Costas

et al. 2018

Polymers

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The capability of laccase from Myceliophthora thermophila to drive oxidative polymerization of Eucalyptus globulus Kraft lignin (KL) was studied as a previous step before applying this biotechnological approach for the manufacturing of medium-density fiberboards (MDF) at a pilot scale. This method, which improves the self-bonding capacity of wood fibers by lignin enzymatic cross-linking, mimics the natural process of lignification in living plants and trees. An interesting pathway to promote these interactions could be the addition of lignin to the system. The characterization of E. globulus KL after enzymatic treatment showed a decrease of phenolic groups as well as the aromatic protons without loss of aromaticity. There was also an extensive oxidative polymerization of the biomolecule. In the manufacture of self-bonded MDF, the synergy generated by the added lignin and laccase provided promising results. Thus, whenever laccase was present in the treatment, MDF showed an increase in mechanical and dimensional stability for increasing amounts of lignin. In a pilot scale, this method produced MDF that meets the requirements of the European standards for both thickness swell (TS) and internal bonding (IB) for indoor applications.

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Section: Resultsmentioning

confidence: 99%

Green Binder Based on Enzymatically Polymerized Eucalypt Kraft Lignin for Fiberboard Manufacturing: A Preliminary Study

Gouveia

Otero²,

Fernández‐Costas

et al. 2018

Polymers

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“…20−22 Fluorescence Intensity Measurements. Fluorescence intensity was measured as already described in Ortner et al 15 One hundred microliters of lignosulfonate taken at the times described above were incubated with 120 μL of a methoxyethanol:water (2:1 v/v) mixture, and the absorbance was measured at an excitation of 355 nm and an emission of 400 nm using a spectrophotometer (Infinite M200, Tecan, Switzerland).…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

Influence of Oxygen and Mediators on Laccase-Catalyzed Polymerization of Lignosulfonate

Huber

Ortner

Daxbacher

et al. 2016

ACS Sustainable Chem. Eng.

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Industrial utilization of lignin is of high interest since it represents around 30% of all nonfossil-based carbon sources worldwide. For various applications of lignosulfonates such as for dispersants or adhesives a larger molecular weight is essential. Here, we investigated laccase-catalyzed polymerization of lignosulfonate directly from the pulp and paper industry in the presence and absence of natural and synthetic mediators with and without oxygen supply. For example, laccase-mediated polymerization in the presence of a 2.5 mM TEMPO as mediator with a 10 cm 3 min −1 oxygen flow rate led to a 12-fold increase of the molecular weight, while without TEMPO a 13-fold increase was achieved. In contrast, without an external oxygen supply, only a 7-fold increase in molecular weight was achieved compared to a 4-fold increase for the TEMPO−laccase system. Fluorescence intensity, phenol content, and size exclusion chromatography measurements indicate that generally in the presence of high concentrations of mediators, such as TEMPO, vanillin, HBT, and 2,6-dimethoxyphenol, oxidation of other structural units in lignosulfonates may counteract desired polymerization reactions. In summary, for laccase-catalyzed polymerization of lignosulfonates, an external oxygen supply was found to be much more beneficial than the presence of laccase mediators.

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“…First, 5 mL of a 10% w·v −1 solution of Kraft lignin (KL) or lignosulfonate (LS) were prepared in double distilled water (ddH 2 O) and the pH was adjusted to 7, which is the optimal pH for the used laccase [ 8 ]. In addition, 50 or 100 mg of immobilized preparation were then added to the reaction solution and the polymerization process was conducted for 24 h at 21 °C and 400 rpm.…”

Section: Methodsmentioning

confidence: 99%

“…It is well-known that laccase-mediated polymerization may cause condensation reactions between the phenoxy radicals that are formed resulting in new C–C, aryl-aryl, ether, or aryl-alkyl cross-linkages [5]. Ortner et al studied the oxidation of various industrial lignins (Organosolv, Indulin and lignosulfonates) aqueous solutions and the potential of external oxygen supply was demonstrated, which was also strengthened by recent findings [8,9]. Additionally, polymerization of various lignins (Organosolv hardwood lignin, soda wheat straw lignin, alkali pretreated wheat straw lignin, kraft softwood, etc.)…”

Section: Introductionmentioning

confidence: 92%

Polymerization of Various Lignins via Immobilized Myceliophthora thermophila Laccase (MtL)

et al. 2016

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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.

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Laccase mediated oxidation of industrial lignins: Is oxygen limiting?

Cited by 52 publications

References 27 publications

Green Binder Based on Enzymatically Polymerized Eucalypt Kraft Lignin for Fiberboard Manufacturing: A Preliminary Study

Green Binder Based on Enzymatically Polymerized Eucalypt Kraft Lignin for Fiberboard Manufacturing: A Preliminary Study

Influence of Oxygen and Mediators on Laccase-Catalyzed Polymerization of Lignosulfonate

Polymerization of Various Lignins via Immobilized Myceliophthora thermophila Laccase (MtL)

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