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The pulp and paper industry discharges massive amount of wastewater containing hazardous organochlorine compounds released during different processing stages. Therefore, some cost-effective and nonpolluting practices such as enzymatic treatments are required for the potential mitigation of effluents released in the environment. Various xylanolytic enzymes such as xylanases, laccases, cellulases and hemicellulases are used to hydrolyse raw materials in the paper manufacturing industry. These enzymes are used either individually or in combination, which has the efficient potential to be considered for bio-deinking and bio-bleaching components. They are highly dynamic, renewable, and high in specificity for enhancing paper quality. The xylanase act on the xylan and cellulases act on the cellulose fibers, and thus increase the bleaching efficacy of paper. Similarly, hemicellulase enzyme like endo-xylanases, arabinofuranosidase and β-D-xylosidases have been described as functional properties towards the biodegradation of biomass. In contrast, laccase enzymes act as multi-copper oxidoreductases, bleaching the paper by the oxidation and reduction process. Laccases possess low redox potential compared to other enzymes, which need some redox mediators to catalyze. The enzymatic process can be affected by various factors such as pH, temperature, metal ions, incubation periods, etc. These factors can either increase or decrease the efficiency of the enzymes. This review draws attention to the xylanolytic enzyme-based advanced technologies for pulp bleaching in the paper industry., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Hypothesis: Due to their highly retentive properties, innovative recently developed, semi-interpenetrated hydrogels made up of poly(vinyl pyrrolidone) (PVP) chains embedded in a poly(2-hydroxyethyl methacrylate) (p(HEMA)) network should be efficiently used as cleaning material for fragile and degraded paper artworks. In restoration practice, indeed the wet cleaning of these artworks is usually performed by immersion of paper in water, a procedure which may lead to several drawbacks, including paper fibers swelling and dissolution of water-soluble original components., Experiments: This class of gels were yet presented in literature, but their interactions with paper materials and ability to be spiked with active enzymes (as cleaning agents), have not been analyzed. To establish the suitability of these hydrogels as paper cleaning materials, first, a rheological and microstructural characterization of the gels was performed. Moreover, diffusion of macromolecules inside gels was studied using fluorescence microscopy, to check if these innovative hydrogels can be used as carriers for hydrolytic enzymes. Indeed, pastes and glues are usually found in old paper artworks, and their removal is a very delicate operation that requires a selective action, which is granted by specific hydrolytic enzymes. At the same time, spectroscopic analyses on paper samples under investigation before and after cleaning treatment has been performed, thus assessing the capabilty of these gels as cleaning materials., Findings: With the aim of demonstrating the versatility of these hydrogels, several case studies, i.e., the removal of grime and water-soluble cellulose degradation byproducts, the removal of animal glue and the removal of starch paste from real samples, are presented. Results obtained with these gels have been compared to those obtained by using another gel used for paper artworks cleaning, i.e., Gellan gel., (Copyright © 2017 Elsevier Inc. All rights reserved.)

A modified process consisting of an initial mechanical refining (R) followed by a low-alkali (5.5% NaOH) cold caustic extraction (CCE) and finally an endoglucanase (EG) treatment (R-5.5%CCE-EG) was investigated for upgrading paper-grade pulp to dissolving pulp. Results showed that compared to the conventional process (9%CCE-EG), the modified process can decrease the alkali concentration (from 9% to 5.5%) to achieve a similar hemicelluloses removal while simultaneously enhancing the Fock reactivity (from 62.2% to 81.0%). The improved results were due to the fact that the mechanical refining resulted in favorable fiber morphological changes, including increased pore volume/size, water retention value and specific surface area. Consequently, the hemicelluloses removal was enhanced even under the subsequent low-alkali CCE condition. A synergic effect of refining, low alkali concentration and enzymatic activation was responsible for the higher reactivity of resulting dissolving pulp., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Microfluidic biosensing systems with enzyme-based detection have been extensively studied in the last years owing to features such as high specificity, a broad range of analytes and a high degree of automation. This review gives an overview of the most important factors associated with these systems. In the first part, frequently used immobilization protocols such as physisorption and covalent bonding and detection techniques such as amperometry and fluorescence measurements are discussed with respect to effort, lifetime and measurement range. The Michaelis-Menten model describing the kinetics of enzymatic reactions, the role of redox mediators and the limitations of the linear measurement range of enzymatic sensors are introduced. Several possibilities of extending the linear measurement range in microfluidic systems such as diffusion-limiting membranes and the flow injection setup are presented. Regarding the integration of enzymes into microfluidic systems during the fabrication process, the constraints imposed by the biomolecules due to the limited usage of high temperatures and solvents are addressed. In the second part, the most common forms of enzyme integration into microfluidic systems, i.e. in channels and on electrodes, on microparticles, on paper and thread and as injected enzyme solutions, are reviewed, focusing on fabrication, applications and performance., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The use of enzymes has a high potential in the pulp and paper industry to improve the economics of the paper production process and to achieve, at the same time, a reduced environmental impact. Specific enzymes contribute to reduce the amount of chemicals and energy required for the modification of fibers and helps to prevent the formation or development of biofilms. This review is aimed at presenting the latest progresses made in the application of enzymes as refining aids and biofilm control agents.

Microbiological control programmes at industrial level should aim at reducing both the detrimental effects of microorganisms on the process and the environmental impact associated to the use of biocides as microbiological control products. To achieve this target, new efficient and environmentally friendly products are required. In this paper, 17 non-specific, commercial enzymatic mixtures were tested to assess their efficacy for biofilm prevention and control at laboratory and pilot plant scale. Pectin methylesterase, an enzyme found in the formulation of two of the mixtures tested, was identified as an active compound able to reduce biofilm formation by 71% compared to control tests.

The effect of polymer on the retention and the thermal stability of bioactive enzymatic papers was measured using a colorimetric technique quantifying the intensity of the enzyme-substrate product complex. Alkaline phosphatase (ALP) was used as model enzyme. Three water soluble polymers: a cationic polyacrylamide (CPAM), an anionic polyacrylic acid (PAA) and a neutral polyethylene oxide (PEO) were selected as retention aids. The model polymers increased the enzyme adsorption on paper by around 50% and prevented enzyme desorption upon rewetting of the papers. The thermal deactivation of ALP retained on paper with polymers follows two sequential first order reactions. This was also observed for ALP simply physisorbed on paper. The retention aid polymers instigated a rapid initial deactivation which significantly decreased the longevity of the enzymatic papers. This suggests some enzyme-polymer interaction probably affecting the enzyme tertiary structure. A deactivation mathematical model predicting the enzymatic paper half-life was developed., (Crown Copyright 2010. Published by Elsevier B.V. All rights reserved.)

Expansin is a plant protein family that induces plant cell wall-loosening and cellulose disruption without exerting cellulose-hydrolytic activity. Expansin-like proteins have also been found in other eukaryotes such as nematodes and fungi. While searching for an expansin produced by bacteria, we found that the BsEXLX1 protein from Bacillus subtilis had a structure that was similar to that of a beta-expansin produced by maize. Therefore, we cloned the BsEXLX1 gene and expressed it in Escherichia coli to evaluate its function. When incubated with filter paper as a cellulose substrate, the recombinant protein exhibited both cellulose-binding and cellulose-weakening activities, which are known functions of plant expansins. In addition, evaluation of the enzymatic hydrolysis of filter paper revealed that the recombinant protein also displayed a significant synergism when mixed with cellulase. By comparing the activity of a mixture of cellulase and the bacterial expansin to the additive activity of the individual proteins, the synergistic activity was found to be as high as 240% when filter paper was incubated with cellulase and BsEXLX1, which was 5.7-fold greater than the activity of cellulase alone. However, this synergistic effect was observed when only a low dosage of cellulase was used. This is the first study to characterize the function of an expansin produced by a non-eukaryotic source.

Enzymatic bonding methods, based on laccase or peroxidase enzymes, for lignocellulosic products such as medium-density fiberboard and particleboard are discussed with reference to the increasing costs of presently used petroleum-based adhesives and the health concerns associated with formaldehyde emissions from current composite products. One approach is to improve the self-bonding properties of the particles by oxidation of their surface lignin before they are fabricated into boards. Another method involves using enzymatically pre-treated lignins as adhesives for boards and laminates. The application of this technology to achieve wet strength characteristics in paper is also reviewed.

The protocol for the enzymatic deinking of laser printed waste papers on a laboratory scale using cellulase (C) and hemicellulase (H) of Aspergillus niger (Amano) was developed as an effective method for paper recycling. A maximum deinking efficiency of almost 73% by the enzyme combination of C:H was obtained using the deinking conditions of pulping consistency of 1.0% (w/v) with the pulping time of 1.0min, temperature of 50 degrees C, pH=3.5, agitation rate of 60rpm, pulp concentration of 4% (w/v), concentration of each enzyme of 2.5U/g air dried pulp and the enzyme ratio of 1:1. The deinking efficiency was further enhanced to 95% using the optimized flotation system consisting of pH=6.0, Tween 80 of concentration 0.5% (w/w), working air flow rate of 10.0L/min and temperature of 45 degrees C. The deinked papers were found to exhibit properties comparable to the commercial papers suggesting the effectiveness of the enzymatic process developed.

Zygorhynchus vuilleminii, a nonmelanin-containing fungus, was not lysed by mycolytic actinomycetes. Several enzymes and Streptomyces enzyme preparations digesting walls of other fungi were without appreciable activity on walls of Zygorhynchus species. A bacterium able to solubilize a portion of the Zygorhynchus wall released little or no reducing sugars from these structures. Fractions of Z. vuilleminii walls were resistant to glucanase hydrolysis, but certain fractions were digested by chitinase and microbial enzyme preparations. The walls and several wall fractions were not readily susceptible to degradation by a soil community. Walls of lysis-resistant Zygorhynchus species contained glucosamine, fucose, glucuronic acid, and galactose but little or no glucose. Resistant wall fractions were rich in uronic acid and fucose, whereas the readily degradable fractions contained abundant glucosamine. Cultural conditions affected the extent of digestion and composition of the walls. Possible reasons for the resistance of Zygorhynchus to lysis in nature are discussed.

The growth of oyster mushroom (Pleurotus ostreatus) on pulp and paper industry wastes was studied. Specifically, the question was investigated whether solid-state fermentation of P. ostreatus on paper-mill deinking sludge and primary sludge substrates is appropriate for production of enzymes, relevant to the pulp and paper industry. Following fermentation, extracellular protein was extracted and the specific activities of four enzymes were determined, namely, the cellulase, xylanase, lipase and peroxidase. Furthermore, the effects of the pH of the extraction buffer on these enzyme activities were determined, along with the effects of the incubation time. The data show that P. ostreatus can grow on solid wastes from the pulp and paper industry, which could help to minimize the waste volume and to decrease the ecological impact. Furthermore, the solid wastes in focus are good substrates for the production of commercially interesting enzymes. [ABSTRACT FROM AUTHOR]

In the past, the animal glues were used in paper manufacturing and in restoration of artworks preserved in museums, libraries and archives. By ageing they went through deterioration creating distortions, tensions, cockling and discolouration in paper materials. Consequently, the removal of glue residues becomes an essential step in the restoration of ancient and artwork paper material. Current mechanical and chemical methods display serious drawbacks mainly related to aggressiveness towards material or toxicity for restorers. Bio-based methods for paper cleaning rely on the use of enzymes that require skilled operators, optimal application conditions and high costs, creating difficulties in mastering enzyme use so far. This paper describes a first attempt of biocleaning ancient paper from organic deposits using living bacteria. The non-pathogenic, non-spore-forming and non-cellulolytic original strain Ochrobactrum sp. TNS15 E was successfully applied -immobilised in an agar gel-on original paper specimens dating back to the 17th. After 4 h of contact with the bacterial pack, the cellulose fibres underlying glue were disclosed, highlighting the bacterial capacity of removing the glue layer without damaging the paper or leaving undesirable residues. Both colorimetry and SEM analyses proved the results. The procedure is simple, low-cost and safe for the artefact, the restorers and the environment. [ABSTRACT FROM AUTHOR]

The synthesis of lignin and its deposition in secondary cell walls leads to the formation of sclerenchyma, a tissue having mechanical strength. This biochemical mechanism arose about 400-420 million years ago, in the Early Silurian period, in the first vascular plants (Tracheophyta order). The appearance of sclerenchyma is related to the emergence of plants on land and formation of the terrestrial flora. Lignified tissues of plants also perform conducting and protective functions, in addition to its mechanical (supporting) one. The polymorphic options of the enzymes involved into biosynthesis of lignin and its accompanying substances (PAL (phenylalanine ammonia-lyase), C4H (cinnamate 4-hydroxylase), C3H ( p-coumarate 3-hydroxylase), F5H (ferulate 5-hydroxylase), COMT (caffeic acid O-methyltransferase), CCoAOMT (caffeoyl-CoA Omethyltransferase), 4CL (4-coumarate:CoA ligase), CCR (cinnamoyl-CoA reductase), CAD (cinnamyl alcohol dehydrogenase), and SAD (sinapyl alcohol dehydrogenase) were considered with the use of a number of plants: corn, millet, sorghum, rice, wheat, fescue, elephant grass, brachypodium (purple false brome), tobacco, alfalfa, arabidopsis, poplar, eucalyptus, pine, spruce, and ginkgo. Mutant variants of enzymes can be found in natural or breeding populations; they may be also obtained with the use of mutagens. In recent decades, T-DNA-mutagenesis is widely used. Mutations can cause changes in the expression of the corresponding genes and (or) disturb the structure of protein molecules. As a result, numerous changes in the phenotype can occur. Among them are changes in the structure and chemical composition of tissues, as well as in growth processes and plant development. The appearance of colored (brown midrib, reddish brown, pink, red-brown, red-wine, etc.) forms of plants was described in many species. Some publications noted an interrelation between the biosynthesis of monolignols and that of flavonoid pigments. Mutant forms are widely used at present to produce forage cultivars and bioethanol, to improve pulp properties (production of paper and viscose fiber), and to sequester atmospheric carbon. The synthesis of mutants from this group of enzymes and their use are considered promising trends of modern plant biotechnology. [ABSTRACT FROM AUTHOR]

Use of recycled fiber material for the production of paper and paperboard has a significant share in solving problems related to environmental protection and conservation of energy resources. One of the most important processes for the paper recycling with printing press is a deinking. Perspective method for deinking of waste paper by the method of flotation is the enzyme treatment at neutral pH. The aim of this work is to study the deinking of recycled paper with offset printing press through flotation and use of enzymes. [ABSTRACT FROM AUTHOR]

In view of the worldwide economic and environmental issues associated with the extensive use of petro-chemicals, there has been increasing research interest during the past decade in the value of residual biomass. Because of its renewable nature and abundant availability, residual biomass has attracted considerable attention as an alternate feedstock and potential energy source. To expand the range of natural bio-resources, significant progress related to the lignocellulose bio-technology has been achieved, and researchers have been re-directing their interests to biomass-based fuels, ligninolytic enzymes, chemicals, and biocompatible materials, which can be obtained from a variety of lignocellulosic waste materials. This review article focuses on the potential applications of lignocellulosic materials in biotechnology, including the production of bio-fuels, enzymes, chemicals, the pulp and paper, animal feed, and composites. [ABSTRACT FROM AUTHOR]

Bioactive papers are advanced cellulose-based functional materials that incorporate biomolecules with specific recognition ability for analytes. Although there is a wide range of potential applications for these papers, only a few have reached the commercial stage. There are fundamental questions that have to be addressed before they can be developed in large scale. One of the central questions in bioactive paper development is the impact of the properties of the cellulosic support on both immobilization and functionality of biomolecules. This paper presents a literature review on inkjet printing of biomolecules for bioactive paper applications and reports recent progress made in understanding factors that affect the activity of enzymes physically immobilized on cellulosic supports. [ABSTRACT FROM AUTHOR]

The article presents a study on the use of cellulase and hemicellulas enzymes for the reduction of refining energy requirement of different types of pulp. The study involves hardwood kraft pulp, long fiber fraction of bamboo pulp, old corrugated containers and mixed pulp containing new double-lined kraft cuttings, and long fiber fraction of bamboo pulp. The study is expected to benefit those mills that are not limited by refining capacity or power, and further benefits by way of savings in the maintenance cost of the refiner, or the mill can produce more paper without augmenting the refining capacity.

The article discusses the results of a study characterizing the cellobiose dehydrogenase (CDH) enzyme from the white-rot basidiomycete Trametes hirsuta. The molecular weight of the enzyme was 92kDa. The potential of using CDH for the biological treatment of wood chips without negative effects on paper strength is explored.

Abstract: The endoglucanase Cel5A from Trichoderma reesei and an endoglucanase from Aspergillus sp. (Novozym 476™ from Novozyme A/S) were evaluated as probes for the surface properties of soft- and hardwood chemical pulp fibres. The hydrolysis time curves were in accordance with a two-phase degradation model described by a biexponential function. The kinetic parameters corresponding to the amount of fast and slow degraded parts of the substrate correlated to tensile index, relative bonded area and z-strength of the paper. All paper properties showing a correlation with enzyme kinetic parameters were related to fibre–fibre interactions. Fluorescence labelling of the reducing end groups in pulp fibres followed by enzyme treatment indicated that the fast substrate class corresponds to the population of “loose” cellulose chain ends not tightly associated with the bulk cellulose. The correlation between the parameters of enzyme kinetics and mechanical properties of the paper produced from the corresponding pulp found in this study should allow a rapid evaluation of the raw fibre material used in paper making process. [Copyright &y& Elsevier]

The enzymatic mode of action in paper fibre upgrading is still uncertain. In an attempt to clarify how enzymes modify pulp and paper properties, several parameters were analysed in the present work: (i) thermal analysis of the water-solid surface interactions; (ii) fibre cake permeability; (iii) particle size analysis. The results obtained suggest that enzymes modify the interfacial properties of fibres, increasing the water affinity, which in turn change the technical properties of pulp and paper, such as drainability and strength. The modification of paper and pulps following a treatment with cellulose-binding domains further supports this hypothesis. [ABSTRACT FROM AUTHOR]