Phenolics as Mediators to Accelerate the Enzymatically Initialized Oxidation of Laccase-Mediator-Systems for the Production of Medium Density Fiberboards

Kirsch, A.A; Ostendorf, Kolja; Kharazipour, Alireza; Euring, Markus

doi:10.15376/biores.11.3.7091-7101

Cited by 7 publications

(9 citation statements)

References 16 publications

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“…The best results were obtained using 4-hydroxybenzoic acid as mediator, leading to a TS of 19% and a simultaneous improvement in the mechanical properties. Other authors [35] used a laccase-mediator-system to introduce a water-based wax as hydrophobic agent in the manufacturing of a binderless MDF. Until then, the combined use of hydrophobic agents and enzymes were supposed to be incompatible because the hydrophobic agents coated the fibers hindering the enzymatic access to lignin [4].…”

Section: Resultsmentioning

confidence: 99%

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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%

“…Until then, the combined use of hydrophobic agents and enzymes were supposed to be incompatible because the hydrophobic agents coated the fibers hindering the enzymatic access to lignin [4]. However, [35] obtained an MDF with IB as high as 0.9 MPa and TS of 17% using 1% of hydrowax in a laccase treatment with vanillic alcohol as mediator.…”

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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“…Blends of conventional phenolformaldehyde (PF) resins with lignosulfonate (from 10:5 to 6: 5) added to 2:1 beech:cerris fibers from thermomechanical pulping (TMP), for instance, increased water absorption and thickness swelling (TS) and decreased bending strength of medium-density fiberboard (MDF) pressed at 190 °C. The hydrophilic lignosulfonate however acted in the system only as a filler because lignin does not hydrolyze at this pressing temperature (Yotov et al, 2015). Adding hydrophobizers could be a solution to improve moisture resistance, but this may hinder good gluing (Mathiasson and Kubát, 1995;Kües et al, 2007;Kirsch et al, 2016). Use of a novel hot-air/hot-steam curing to achieve higher temperatures for lignin repolymerization under reduction of press times (Euring et al, 2015;Euring et al, 2016) improved physical properties of panels produced with lignin admixture (Kirsch et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

“…Commercial fiberboards are obtained from hot-pressing wood fibers mainly from TMP with the addition of suitable petrochemical glues (Dunky and Niemz, 2002;Müller et al, 2007). There is considerable interest to replace conventional adhesives in MDF production by sustainable green alternatives, including enzymatic solutions (Kües et al, 2007;Kirsch et al, 2016;Perna et al, 2019;Ostendorf et al, 2020). TMP fibers have a plasticized glassy lignin layer on the surface, due to heating above the glass transition point of lignin during the TMP process (Mai et al, 2004;Kloeser et al, 2007;Kües et al, 2007;Widsten and Kandelbauer, 2008).…”

Section: Introductionmentioning

confidence: 99%

“…Novozym 51003 contains a thermostable laccase recombinantly produced from a gene of the ascomycete Myceliophthora thermophila (MtL) cloned in Aspergillus oryzae and is applicable for the oxidation of a broad range of lignocellulosic materials (Novozymes, 2007;Lund et al, 2016;Ernst et al, 2018). Earlier LMS studies required a 1 L incubation solution of 100 U/ml of this asco-laccase (Euring et al, 2011;Euring et al, 2013;Euring et al, 2016) or even 200 U/ ml (Kirsch et al, 2016), per 1 kg fiber mass (atro, for "absolut trocken," absolutely dry) for the production of MDF of good technical quality at the pilot plant scale. Due to its price [around 30€ per liter in year 2020 (Univar, 2020)], it could still be difficult to integrate the LMS into a cost-oriented MDF company.…”

Section: Introductionmentioning

confidence: 99%

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Enzymatic Oxidation of Ca-Lignosulfonate and Kraft Lignin in Different Lignin-Laccase-Mediator-Systems and MDF Production

Euring

Ostendorf

Rühl

et al. 2022

Front. Bioeng. Biotechnol.

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Laccase-mediator-oxidized lignin offers replacement for conventional chemical binders to produce fiberboards. Compared to the previously reported laccase–mediator system (LMS), a lignin-laccase-mediator-system (LLMS) has an advantage in that it requires much shorter fiber-enzyme incubation time due to significantly increased redox reactions. However, the cost of regularly applying laccase on an industrial scale is currently too high. We have employed CcLcc5 from cultures of the basidiomycete Coprinopsis cinerea as a novel basi-laccase (a CAZy subfamily AA1_1 laccase) in medium-density fiberboard (MDF) production, in comparison to the commercial formulation Novozym 51003 with recombinantly produced asco-laccase MtL (a CAZy subfamily AA1_3 laccase-like multicopper oxidase from the ascomycete Myceliophthora thermophila). With the best-performing natural mediator 2,6-dimethoxyphenol (DMP), unpurified CcLcc5 was almost as good as formulated Novozym 51003 in increasing the molecular weight (MW) of the technical lignins tested, the hydrophilic high-MW Ca-lignosulfonate and the hydrophobic low-MW kraft lignin (Indulin AT). Oxygen consumption rates of the two distantly related, poorly conserved enzymes (31% sequence identity) with different mediators and lignosulfonate were also comparable, but Indulin AT significantly reduced the oxidative activity of Novozym 51003 unlike CcLcc5, regardless of the mediator used, either DMP or guaiacol. Oxygen uptake by both laccases was much faster with both technical lignins with DMP than with guaiacol. In case of lignosulfonate and DMP, 20–30 min of incubation was sufficient for full oxygen consumption, which fits in well in time with the usual binder application steps in industrial MDF production processes. LLMS-bonded MDF was thus produced on a pilot-plant scale with either crude CcLcc5 or Novozym 51003 at reduced enzyme levels of 5 kU/kg absolutely dry wood fiber with lignosulfonate and mediator DMP. Boards produced with CcLcc5 were comparably good as those made with Novozym 51003. Boards reached nearly standard specifications in internal bond strength (IB) and modulus of rupture (MOR), while thickness swelling (TS) was less good based on the hydrophilic character of lignosulfonate. LLMS-bonded MDF with Indulin AT and DMP performed better in TS but showed reduced IB and MOR values.

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Wood Adhesives Based on Natural Resources: A Critical Review: Part III. Tannin‐ and Lignin‐Based Adhesives

Dunky

2021

Progress in Adhesion and Adhesives

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Phenolics as Mediators to Accelerate the Enzymatically Initialized Oxidation of Laccase-Mediator-Systems for the Production of Medium Density Fiberboards

Cited by 7 publications

References 16 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

Enzymatic Oxidation of Ca-Lignosulfonate and Kraft Lignin in Different Lignin-Laccase-Mediator-Systems and MDF Production

Wood Adhesives Based on Natural Resources: A Critical Review: Part III. Tannin‐ and Lignin‐Based Adhesives

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