Xylanase and laccase aided bio‐bleaching of wheat straw pulp

Dedhia, Bhavin S.; Vetal, Mangesh D.; Rathod, Virendra K.; Csóka, Levente

doi:10.1002/cjce.21798

Cited by 19 publications

(11 citation statements)

References 18 publications

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“…While this study has focused on xylanase inactivation, even laccase is susceptible to inactivation, and although the mechanism of inactivation has not been established, the phenomenon has been well documented (Paice et al ; Kurniawati and Nicell ; Fillat et al ; Khlifi et al ; Ashe et al ). For example, a commercial Myceliophthora thermophila laccase lost 75% activity after 12 h upon exposure to 1·5% (oven dry pulp basis) HBT (Dedhia et al ). In the case of Pleurotus ostreatus laccase, when used in the LMS to remove trace organic contaminants, HBT and VA were detrimental to laccase activity at all concentrations examined (Ashe et al ).…”

Section: Discussionmentioning

confidence: 99%

Establishing the oxidative tolerance of Thermomyces lanuginosus xylanase

Badon

Tekverk

Vishnosky

et al. 2019

J of Applied Microbiology

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Aims This work aims to determine the tolerance of xylanase towards enzyme‐generated oxidative conditions, such as those produced by the peroxidase or laccase mediator systems (LMS). Methods and Results The activity of Thermomyces lanuginosus xylanase was measured after incubation with lignin peroxidase, manganese peroxidase or laccase plus various mediators. The laccase system, using mediators such as 1‐hydroxybenzotriazole and violuric acid, resulted in complete loss of xylanase activity, accompanied by an increase in the solution potential. However, an increase in solution potential alone was not sufficient to inactivate xylanase, nor was loss of xylanase activity always accompanied by a significant increase in solution potential, as observed with N‐hydroxyphthalimide as the mediator. Neither lignin peroxidase nor manganese peroxidase impacted xylanase activity; only extended treatment with elevated hydrogen peroxide concentration promoted modest xylanase activity loss. The mechanism of inactivation as determined by the tryptophan‐modifying reagent N‐bromosuccinimide (NBS) indicated that oxidation of just one of the eight tryptophan residues of T. lanuginosus xylanase would be sufficient to result in complete loss of xylanase activity, since xylanase is completely inactivated at 1 : 1 molar ratio of NBS to xylanase. Conclusions While showing tolerance to peroxidase‐based enzyme systems, T. lanuginosus xylanase is readily inactivated in the presence of the LMS. Based upon treatment with NBS as the oxidant, inactivation can be attributed to modification of a single tryptophan residue. Significance and Impact of the Study The simultaneous application of mixed hydrolytic and oxidative enzyme systems is of importance to biomass processing industries. Understanding the tolerance of xylanase to oxidative conditions will facilitate the design of reaction conditions or enzyme variants to maximize the impact of mixed enzyme systems.

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Section: Discussionmentioning

confidence: 99%

Establishing the oxidative tolerance of Thermomyces lanuginosus xylanase

Badon

Tekverk

Vishnosky

et al. 2019

J of Applied Microbiology

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“…. But in studies of Dedhia et al (2014) with wheat straw, a commercial xylanase reduced only 7.25% the kappa number using 6 IU g -1 ; and A. fumigatus ABK9 reduced only 0.7, 1.2, 2.7, 3.3 and 4 points in kappa number, using 20, 40, 60, 80 and 100 U/g dry pulp/6 h, respectively (Das et al, 2013).…”

Section: Assays Of Cellulose Biobleaching Using Xylanase From a Flavusmentioning

confidence: 93%

“…In fact, treating cellulosic pulps with xylanases selectively removes residual xylan and hence reduces the usage of chlorine during the bleaching process (Woolridge, 2014;Bankeeree et al, 2014;Nawel et al, 2011;Abdel-Sater and El-Said, 2001). Chlorine is the base of bleaching process of pulp and paper industry and present serious environmental effects such as the production of toxic and mutagenic residues (Dedhia et al, 2014;Goluguri et al, 2012;Yeasmin et al, 2011); therefore, environmental demands have necessitated that the pulp and paper industry find various alternatives to chlorine-based chemical bleaching processes for the production of bleached kraft pulp. A xylanase pretreatment, always used as a mixture, can deink pulp of waste paper, lower bleaching chemical use by 10-20% and usually results in greater final brightness (Goluguri et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Production of cellulase-free xylanase by Aspergillus flavus: Effect of polyols on the thermostability and its application on cellulose pulp biobleaching

Silva¹,

Guimarães²,

Peixoto-Nogueira³

et al. 2015

Afr. J. Biotechnol.

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The production of xylanase without cellulase is required for prebleaching of pulp in pulp and paper industry. Aspergillus flavus produced high levels of xylanase on agricultural residues with wheat bran and sugarcane bagasse (4.17 U/mg), and wheat bran and corncob (2.97 U/mg). Xylanase was found to be stable at 45°C with 100% of its original activity remaining after 2 h incubation. At 50°C, xylanase was stable for the first twenty minutes, and had half-life of 50 min. The pH stability for the xylanase from A. flavus was most stable in the range of pH 3.0-8.0 retaining more that 100% activity after 1 h. The addition of 5% glycerol, mannitol or xylitol protected the xylanase from thermal inactivation at 50°C. The protective effect by glycerol, xylitol and mannitol resulted in increases of 162, 262.5 and 150% when compared with the control at 120 min, approximately. Increasing the polyols concentration up to 20% (w/v) further improved the thermostability of xylanase after 120 min at 50°C by 300% when compared with the control (no additive). The kappa number reduced 2.56 points, which corresponds to 18.34 kappa efficiency. This xylanase is an attractive enzyme for potential future application in the pulp and paper industries, since industrial application requires a cellulase-free activity, maintenance of high temperature and enzyme stability are desirable.

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“…In the presence of redox mediators, laccases can even catalyze the breakdown of non-phenolic lignin structures, including the cleavage of β-O-4 linkages [55,56]. Typical mediators in laccase-mediator systems include 2,2 0 -azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 1-hydroxybenzotriazole (1-HBT) and the natural mediator acetosyringone (4-hydroxy-3,5-dimethoxyacetophenone) [55][56][57][58].…”

Section: Enzymes Involved In Fungal Lignin Degradationmentioning

confidence: 99%

Lignin Degradation Processes and the Purification of Valuable Products

Schoenherr¹,

Ebrahimi²,

Czermak³

2018

Lignin - Trends and Applications

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Lignin is a heterogeneous, phenolic and polydisperse biopolymer which resists degradation due to its aromatic and highly branched structure. Lignin is the most abundant renewable source of aromatic molecules on earth. The valorization of lignin could therefore provide a sustainable alternative to petroleum refineries for the production of valuable aromatic compounds. Even so, paper mills and lignocellulose feedstock biorefineries treat lignin largely as a waste product. In paper mills, 98% of technical lignin is incinerated for internal energy recovery while only 2% is used commercially (e.g. for the production of aromatics such as vanillin). The reasons for the underutilization of lignin include its recalcitrance to degradation and the challenge of separating mixtures of numerous degradation products. The successful valorization of lignin in the future thus depends on a broad understanding of biological and technical degradation processes, and the implementation of efficient product purification strategies. This article describes enzymatic, photocatalytic and thermochemical lignin degradation processes and considers purification methods for valuable lignin-derived degradation products. We focus on the potential of membrane-based separation technology, including data from our own recent research.

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Xylanase and laccase aided bio‐bleaching of wheat straw pulp

Cited by 19 publications

References 18 publications

Establishing the oxidative tolerance of Thermomyces lanuginosus xylanase

Establishing the oxidative tolerance of Thermomyces lanuginosus xylanase

Production of cellulase-free xylanase by Aspergillus flavus: Effect of polyols on the thermostability and its application on cellulose pulp biobleaching

Lignin Degradation Processes and the Purification of Valuable Products

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