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Xylan (Beechwood)

Xylan Beechwood P-XYLNBE
Product code: P-XYLNBE-10G



10 g

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Content: 10 g or 50 g
Shipping Temperature: Ambient
Storage Temperature: Ambient
Physical Form: Powder
Stability: > 10 years under recommended storage conditions
CAS Number: 9014-63-5
Source: Beechwood
Purity: > 95%
Monosaccharides (%): Xylose: Glucuronic Acid: Other sugars = 80.8: 11.4: 7.8
Main Chain Glycosidic Linkage: β-1,4 and α-1,2
Substrate For (Enzyme): endo-1,4-β-Xylanase

Highly purified xylan from beechwood for use in research, biochemical enzyme assays and in vitro diagnostic analysis.

Suitable as a replacement for birchwood xylan as a substrate for β-xylanase in DNSA reducing sugar assay.

Data booklets for each pack size are located in the Documents tab.

Megazyme publication
Novel substrates for the automated and manual assay of endo-1,4-β-xylanase.

Mangan, D., Cornaggia, C., Liadova, A., McCormack, N., Ivory, R., McKie, V. A., Ormerod, A. & McCleary, D. V. (2017). Carbohydrate Research, 445, 14-22.

endo-1,4-β-Xylanase (EC is employed across a broad range of industries including animal feed, brewing, baking, biofuels, detergents and pulp (paper). Despite its importance, a rapid, reliable, reproducible, automatable assay for this enzyme that is based on the use of a chemically defined substrate has not been described to date. Reported herein is a new enzyme coupled assay procedure, termed the XylX6 assay, that employs a novel substrate, namely 4,6-O-(3-ketobutylidene)-4-nitrophenyl-β-45-O-glucosyl-xylopentaoside. The development of the substrate and associated assay is discussed here and the relationship between the activity values obtained with the XylX6 assay versus traditional reducing sugar assays and its specificity and reproducibility were thoroughly investigated.

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Megazyme publication
A Comparison of Polysaccharide Substrates and Reducing Sugar Methods for the Measurement of endo-1,4-β-Xylanase.

McCleary, B. V. & McGeough, P. (2015). Appl. Biochem. Biotechnol., 177(5), 1152-1163.

The most commonly used method for the measurement of the level of endo-xylanase in commercial enzyme preparations is the 3,5-dinitrosalicylic acid (DNS) reducing sugar method with birchwood xylan as substrate. It is well known that with the DNS method, much higher enzyme activity values are obtained than with the Nelson-Somogyi (NS) reducing sugar method. In this paper, we have compared the DNS and NS reducing sugar assays using a range of xylan-type substrates and accurately compared the molar response factors for xylose and a range of xylo-oligosaccharides. Purified beechwood xylan or wheat arabinoxylan is shown to be a suitable replacement for birchwood xylan which is no longer commercially available, and it is clearly demonstrated that the DNS method grossly overestimates endo-xylanase activity. Unlike the DNS assay, the NS assay gave the equivalent colour response with equimolar amounts of xylose, xylobiose, xylotriose and xylotetraose demonstrating that it accurately measures the quantity of glycosidic bonds cleaved by the endo-xylanase. The authors strongly recommend cessation of the use of the DNS assay for measurement of endo-xylanase due to the fact that the values obtained are grossly overestimated due to secondary reactions in colour development.

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Xylanase impact beyond performance: a prebiotic approach in broiler chickens.

Van Hoeck, V., Wu, D., Somers, I., Wealleans, A., Vasanthakumari, B. L., Sanchez, A. G. & Morisset, D. (2021). Journal of Applied Poultry Research, 30(4), 100193.

Microbiome plasticity in chickens provides an attractive target for future potential therapeutic platforms. However, a better understanding of the chicken microbial ecology and how interventions such as xylanase addition can modulate this is needed. Interest in xylanase as an essential additive for livestock in manipulating growth performance has been reported as early as 1980s. In this paper, we describe how a new xylanase leads to an array of benefits in broilers, not only by improving broiler performance and nutrient digestibility, but also by clearly improving gut health. Gut health improvements are demonstrated by better intestinal morphology, different volatile fatty acid profile in the gut and even promotion of beneficial over pathogenic micro-organisms in the intestinal tract. Our study confirms that supplementation of xylanase at the lowest dose of 30,000 U/kg (10 g/t) and above significantly improves broiler performance and digestibility. Furthermore, the observation that xylanase can modulate broilers’ intestinal morphology and microbial content beneficially, by stimulating Lactobacilli growth and thus exerting a prebiotic effect, provides novel and useful insights for future applications.

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Primary interactions of biomass components during fast pyrolysis.

Usino, D. O., Ylitervo, P., Moreno, A., Sipponen, M. H. & Richards, T. (2021). Journal of Analytical and Applied Pyrolysis, 159, 105297.

Fast pyrolysis is an industrially attractive method to produce fuels and chemicals from biomass; however, to gain better control over the process, the reactions and interactions between the components and decomposition products need elucidation. This study investigated primary reactions during fast pyrolysis of biomass. Pyrolysis of the three main biomass components (cellulose, hemicellulose and lignin) and their blends was carried out with a micro-pyrolyser connected to a Gas Chromatograph-Mass Spectrometer/Flame Ionisation Detector (GC–MS/FID). The blends of the individual components were prepared in similar proportions to that of native biomass (birchwood) and were pyrolysed at 600 °C for 2 s. The results showed that the two-component blends decrease the production of saccharides to a large extent. This was especially noticeable for levoglucosan when cellulose was mixed with either hemicellulose or lignin. Similarly, in the presence of cellulose, the formation of phenolic compounds from lignin was inhibited by 62 %. However, no differences were found in yields of the main products for the xylan-lignin blend compared to those from the individual components. The yields of volatile products from the cellulose-xylan blend were promoted for a majority of the product categories and were most pronounced for the aldehydes. Furthermore, while the formation of the phenols and saccharides was slightly inhibited for the three-component blend, the aldehydes, ketones and furans showed an increased production compared to the weighed sum of products expected, based on the pyrolysis of the individual components. The native biomass showed a similar trend as the three-component blend in all product categories except for the saccharides, which were inhibited to a large extent. This study provides a better understanding of the interactions occurring between different components during fast pyrolysis of biomass.

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The Jo-In protein welding system is a relevant tool to create CBM-containing plant cell wall degrading enzymes.

Badruna, L., Burlat, V., Roblin, P., Enjalbert, T., Lippens, G., Venditto, I., Donohue, M. J. & Montanier, C. Y. (2021). New Biotechnology, 65, 31-41.

Irrespective of their biological origin, most proteins are composed of several elementary domains connected by linkers. These domains are either functionally independent units, or part of larger multidomain structures whose functions are defined by their spatial proximity. Carbohydrate-degrading enzymes provide examples of a range of multidomain structures, in which catalytic protein domains are frequently appended to one or more non-catalytic carbohydrate-binding modules which specifically bind to carbohydrate motifs. While the carbohydrate-binding specificity of these modules is clear, their function is not fully elucidated. Herein, an original approach to tackle the study of carbohydrate-binding modules using the Jo-In biomolecular welding protein pair is presented. To provide a proof of concept, recombinant xylanases appended to two different carbohydrate-binding modules have been created and produced. The data reveal the biochemical properties of four xylanase variants and provide the basis for correlating enzyme activity to structural properties and to the nature of the substrate and the ligand specificity of the appended carbohydrate-binding module. It reveals that specific spatial arrangements favour activity on soluble polymeric substrates and that activity on such substrates does not predict the behaviour of multimodular enzymes on insoluble plant cell wall samples. The results highlight that the Jo-In protein welding system is extremely useful to design multimodular enzyme systems, especially to create rigid conformations that decrease the risk of intermodular interference. Further work on Jo-In will target the introduction of varying degrees of flexibility, providing the means to study this property and the way it may influence multimodular enzyme functions.

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Hemicellulosic biomass conversion by Moroccan hot spring Bacillus paralicheniformis CCMM B940 evidenced by glycoside hydrolase activities and whole genome sequencing.

Maski, S., Ngom, S. I., Rached, B., Chouati, T., Benabdelkhalek, M., El Fahime, E., Amar, M. & Béra-Maillet, C. (2021). 3 Biotech, 11(8), 1-13.

Thermophilic bacteria, especially from the genus Bacillus, constitute a huge potential source of novel enzymes that could be relevant for biotechnological applications. In this work, we described the cellulose and hemicellulose-related enzymatic activities of the hot spring Bacillus aerius CCMM B940 from the Moroccan Coordinated Collections of Microorganisms (CCMM), and revealed its potential for hemicellulosic biomass utilization. Indeed, B940 was able to degrade complex polysaccharides such as xylan and lichenan and exhibited activity towards carboxymethylcellulose. The strain was also able to grow on agriculture waste such as orange and apple peels as the sole carbon source. Whole-genome sequencing allowed the reclassification of CCMM B940 previously known as B. aerius into Bacillus paralicheniformis since the former species name has been rejected. The draft genome reported here is composed of 38 contigs resulting in a genome of 4,315,004 bp and an average G + C content of 45.87%, and is an important resource for illuminating the molecular mechanisms of carbohydrate metabolism. The annotated genomic sequences evidenced more than 52 genes encoding glycoside hydrolases and pectate lyases belonging to 27 different families of CAZymes that are involved in the degradation of plant cell wall carbohydrates. Genomic predictions in addition to in vitro experiments have revealed broad hydrolytic capabilities of the strain, thus reinforcing its relevance for biotechnology applications.

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The mutation of Thr315 to Asn of GH10 xylanase XynR increases the alkaliphily but decreases the alkaline resistance.

Kuwata, K., Suzuki, M., Takita, T., Yatsunami, R., Nakamura, S., & Yasukawa, K. (2021). Bioscience, Biotechnology, and Biochemistry, In Press.

XynR is a thermophilic and alkaline GH10 xylanase, identified in the culture broth of alkaliphilic and thermophilic Bacillus sp. strain TAR-1. We previously selected S92E as a thermostable variant from a site saturation mutagenesis library. Here, we attempted to select the alkaliphilic XynR variant from the library and isolated T315N. In the hydrolysis of beechwood xylan, T315N and S92E/T315N exhibited a broader bell-shaped pH-dependent activity than the wild-type (WT) XynR and S92E. The optimal pH values of T315N and S92E/T315N were 6.5-9.5 while those of WT and S92E were 6.5-8.5. On the other hand, T315N and S92E/T315N exhibited a narrower bell-shaped pH dependence of stability: the pHs at which the activity was stable after the incubation at 37°C for 24 h were 6.0-8.5 for T315N and S92E/T315N, but 6.0-10.0 for WT and S92E. These results indicated that the mutation of Thr315 to Asn increased the alkaliphily but decreased the alkaline resistance.

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Improvement of cellulase and xylanase production in Penicillium oxalicum under solid-state fermentation by flippase recombination enzyme/recognition target-mediated genetic engineering of transcription repressors.

Lin, Y. Y., Zhao, S., Lin, X., Zhang, T., Li, C. X., Luo, X. M. & Feng, J. X. (2021). Bioresource Technology, 125366.

Penicillium oxalicum has received increasing attention as a potential cellulase-producer. In this study, a copper-controlled flippase recombination enzyme/recognition target (FLP/FRT)-mediated recombination system was constructed in P. oxalicum, to overcome limited availability of antibiotic resistance markers. Using this system, two crucial transcription repressor genes atf1 and cxrC for the production of cellulase and xylanase under solid-state fermentation (SSF) were simultaneously deleted, thereby leading to 2.4- to 29.1-fold higher cellulase and 78.9% to 130.8% higher xylanase production than the parental strain under SSF, respectively. Glucose and xylose released from hydrolysis of pretreated sugarcane bagasse achieved 10.6%-13.5% improvement by using the crude enzymes from the engineered strain ΔatfcxrC::flp under SSF in comparison with that of the parental strain. Consequently, these results provide a feasible strategy for improved cellulase and xylanase production by filamentous fungi.

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Development and characterization of whey protein isolate and xylan composite films with and without enzymatic crosslinking.

Seiwert, K., Kamdem, D. P., Kocabaş, D. S. & Ustunol, Z. (2021). Food Hydrocolloids, 120, 106847.

Biodegradable food packaging provides an environmentally-conscious alternative to plastic food packaging options. This study investigated whey protein edible films containing 10-40 g xylan/100 g whey protein isolate (WPI). Transglutaminase (TG) was used as a cross-linking agent in WPI-only and 40 g xylan/100 g WPI films. The food packaging properties investigated were water vapor permeability (WVP), oxygen permeability (OP), tensile stress, and % elongation at break. Thermal properties were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Crystallinity and microstructure were assessed using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Composite films containing 40 g xylan/100 g WPI that were also treated with TG showed the greatest improvement in properties important to food packaging. Compared to the WPI-only control films, WVP decreased from 6.41 to 3.89 g mm/m2 day kPa (p < 0.05), OP decreased from 21.85 to 7.32 cc μm/m2 day kPa (p < 0.05), and tensile stress increased from 6.73 MPa to 15.96 MPa (p < 0.05). The % elongation at break decreased significantly from 12.5% in WPI-only films to 5.8-1.4% in all xylan and TG treated films (p < 0.05). The temperature of melting increased from 121°C in control films to a maximum of 166°C in the 20 g xylan/100 g WPI films, indicating increased intermolecular strength. Film microstructure showed separate organization of xylan within films. Crystallinity was identified with increasing xylan content through XRD analysis, suggesting increased polymer packing.

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A biorefinery approach for enzymatic complex production for the synthesis of xylooligosaccharides from sugarcane bagasse.

Valladares-Diestra, K. K., de Souza Vandenberghe, L. P. & Soccol, C. R. (2021). Bioresource Technology, 333, 125174.

The use of low-cost feedstock for enzyme production is an environmental and economic solution. Sugarcane bagasse and soybean meal are employed in this study for optimised xylanase production with the concomitant synthesis of proteases. The enzymatic complex is produced by submerged fermentation by Aspergillus niger. Optimisation steps lead to a 2.16-fold increase in enzymatic activity. The fermentation kinetics are studied in Erlenmeyer flasks, a stirred tank reactor and a bubble column reactor, with the xylanase activities reaching 52.9; 33.7 and 60.5 U.mL−1, respectively. The protease production profile is also better in the bubble column reactor, exceeding 7 U.mL−1. The enzyme complex is then evaluated for the synthesis of xylooligosaccharides from sugarcane extracted xylan with a production of 3.1 g.L−1 where xylotriose is the main product. Excellent perspectives are observed for the developed process with potential applications in the animal feed, prebiotics and paper industries.

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Partial purification and characterization of endoxylanase from a fungus, Leohumicola incrustata.

Adeoyo, O. R., Pletschke, B. I. & Dames, J. F. (2021). Bio-Research, 19(1), 1192-1201.

Xylanases are glycoside hydrolases (GH) that degrade β-1,4-xylan, a linear polysaccharide found as hemicellulose in cell wall of plants. Endoxylanase (Endo-1,4-β-xylanase, EC randomly catalyses xylan to produce varying short xylooligosaccharides (XOS). This study aimed to determine the characteristics of a partially purified endoxylanase from Leohumicola incrustata. Enzyme production was carried out using beechwood (BW) xylan, after which the cell-free crude filtrate was concentrated using the ammonium sulphate precipitation method. The hydrolysed products were analysed by thin-layer chromatography (TLC) and zymography. The result showed that the enzyme produced varying smaller-sized linear xylooligosaccharides with Rf values corresponding to those of xylobiose, xylotriose, xylotetraose, xylopentaose, xylohexaose and other higher oligomers. The endoxylanase had a molecular mass of 72 kDa. The enzyme is stable in the presence of K+, Na+, Ca2+, Fe2+, Mg2+, Zn2+, Co2+, pH of 5.0 and temperature of 37oC. However, the activity gradually decreased after 60 min at 50oC and retained over 69% activity after 120 min, while at 60 and 70oC, the enzyme activity sharply decreased (pre-incubation periods). Endoxylanase from L. incrustata is comparable to those of other microorganisms and should be considered an attractive candidate for future industrial applications.

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Evaluation of spent mushroom substrate after cultivation of Pleurotus ostreatus as a new raw material for xylooligosaccharides production using crude xylanases from Aspergillus flavus KUB2.

Seekram, P., Thammasittirong, A. & Thammasittirong, S. N. R. (2021). 3 Biotech, 11(4), 1-9.

Xylooligosaccharides (XOS), a novel functional food and feed ingredient, can be produced from lignocellulosic biomass. In this study, spent mushroom substrate (SMS) gathered after Pleurotus ostreatus cultivation was investigated for its potential as a new raw material for XOS production using crude xylanases produced in-house from Aspergillus flavus KUB2. Xylan was extracted from SMS using the alkaline extraction method. The highest true recovery of xylan (20.76%) and the relative recovery of xylan (83.73%) were obtained from SMS extracted with 4 M NaOH. Enzymatic hydrolysis of SMS-extracted xylan using crude fungal xylanases from A. flavus KUB2 produced a maximum total XOS in the range 1.37-1.48 mg/ml, which was mainly composed of XOS with a low degree of polymerization (xylobiose and xylotriose). XOS derived from SMS-extracted xylan positively influenced the growth of probiotic bacteria, suggesting the prebiotic nature of XOS. The results indicated that XOS with prebiotic properties can be produced from SMS xylan using crude xylanases without any purification, which offers economic potential for food and feed applications.

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Feruloyl esterase (FAE-1) sourced from a termite hindgut and GH10 xylanases synergy improves degradation of arabinoxylan.

Mafa, M. S., Malgas, S. & Pletschke, B. I. (2021). AMB Express, 11(1), 1-9.

Cereal feedstocks have high arabinoxylan content as their main hemicellulose, which is linked to lignin by hydroxycinnamic acids such as ferulic acid. The ferulic acid is linked to arabinoxylan by ester bonds, and generally, the high substitution of ferulic acid leads to a loss of activity of xylanases targeting the arabinoxylan. In the current study, a feruloyl esterase (FAE-1) from a termite hindgut bacteria was functionally characterised and used in synergy with xylanases during xylan hydrolysis. The FAE-1 displayed temperature and pH optima of 60℃ and 7.0, respectively. FAE-1 did not release reducing sugars from beechwood xylan (BWX), wheat arabinoxylan (WAX) and oat spelt xylan (OX), however, displayed high activity of 164.74 U/mg protein on p-nitrophenyl-acetate (pNPA). In contrast, the GH10 xylanases; Xyn10 and XT6, and a GH11 xylanase, Xyn2A, showed more than two-fold increased activity on xylan substrates with low sidechain substitutions; BWX and OX, compared to the highly branched substrate, WAX. Interestingly, the FAE-1 and GH10 xylanases (Xyn10D and XT6) displayed a degree of synergy (DS) that was higher than 1 in all enzyme loading combinations during WAX hydrolysis. The 75%XT6:25%FAE-1 synergistic enzyme combination increased the release of reducing sugars by 1.34-fold from WAX compared to the control, while 25%Xyn10D:75%FAE-1 synergistic combination released about 2.1-fold of reducing sugars from WAX compared to controls. These findings suggest that FAE-1 can be used in concert with xylanases, particularly those from GH10, to efficiently degrade arabinoxylans contained in cereal feedstocks for various industrial settings such as in animal feeds and baking.

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Characterization of efficient xylanases from industrial-scale pulp and paper wastewater treatment microbiota.

Wang, J., Liang, J., Li, Y., Tian, L. & Wei, Y. (2021). AMB Express, 11(1), 1-11.

Xylanases are widely used enzymes in the food, textile, and paper industries. Most efficient xylanases have been identified from lignocellulose-degrading microbiota, such as the microbiota of the cow rumen and the termite hindgut. Xylanase genes from efficient pulp and paper wastewater treatment (PPWT) microbiota have been previously recovered by metagenomics, assigning most of the xylanase genes to the GH10 family. In this study, a total of 40 GH10 family xylanase genes derived from a certain PPWT microbiota were cloned and expressed in Escherichia coli BL21 (DE3). Among these xylanase genes, 14 showed xylanase activity on beechwood substrate. Two of these, PW-xyl9 and PW-xyl37, showed high activities, and were purified to evaluate their xylanase properties. Values of optimal pH and temperature for PW-xyl9 were pH 7 and 60℃, respectively, while those for PW-xyl37 were pH 7 and 55℃, respectively; their specific xylanase activities under optimal conditions were 470.1 U/mg protein and 113.7 U/mg protein, respectively. Furthermore, the Km values of PW-xyl9 and PW-xyl37 were determined as 8.02 and 18.8 g/L, respectively. The characterization of these two xylanases paves the way for potential application in future pulp and paper production and other industries, indicating that PPWT microbiota has been an undiscovered reservoir of efficient lignocellulase genes. This study demonstrates that a metagenomic approach has the potential to screen efficient xylanases of uncultured microorganisms from lignocellulose-degrading microbiota. In a similar way, other efficient lignocellulase genes might be identified from PPWT treatment microbiota in the future.

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Four cellulose-active lytic polysaccharide monooxygenases from Cellulomonas species.

Li, J., Solhi, L., Goddard-Borger, E. D., Mathieu, Y., Wakarchuk, W. W., Withers, S. G. & Brumer, H. (2021). Biotechnology for Biofuels, 14(1), 1-19.

Background: The discovery of lytic polysaccharide monooxygenases (LPMOs) has fundamentally changed our understanding of microbial lignocellulose degradation. Cellulomonas bacteria have a rich history of study due to their ability to degrade recalcitrant cellulose, yet little is known about the predicted LPMOs that they encode from Auxiliary Activity Family 10 (AA10). Results: Here, we present the comprehensive biochemical characterization of three AA10 LPMOs from Cellulomonas flavigena (CflaLPMO10A, CflaLPMO10B, and CflaLPMO10C) and one LPMO from Cellulomonas fimi (CfiLPMO10). We demonstrate that these four enzymes oxidize insoluble cellulose with C1 regioselectivity and show a preference for substrates with high surface area. In addition, CflaLPMO10B, CflaLPMO10C, and CfiLPMO10 exhibit limited capacity to perform mixed C1/C4 regioselective oxidative cleavage. Thermostability analysis indicates that these LPMOs can refold spontaneously following denaturation dependent on the presence of copper coordination. Scanning and transmission electron microscopy revealed substrate-specific surface and structural morphological changes following LPMO action on Avicel and phosphoric acid-swollen cellulose (PASC). Further, we demonstrate that the LPMOs encoded by Cellulomonas flavigena exhibit synergy in cellulose degradation, which is due in part to decreased autoinactivation. Conclusions: Together, these results advance understanding of the cellulose utilization machinery of historically important Cellulomonas species beyond hydrolytic enzymes to include lytic cleavage. This work also contributes to the broader mapping of enzyme activity in Auxiliary Activity Family 10 and provides new biocatalysts for potential applications in biomass modification.

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Location of uronic acid group in Japanese cedar and Japanese beech wood cell walls as evaluated by the influences of minerals on thermal reactivity.

Wang, J., Minami, E. & Kawamoto, H. (2021). Journal of Wood Science, 67(1), 1-8.

The thermal reactivities of cellulose and hemicellulose are significantly different in cell walls when compared with isolated components and differ in Japanese cedar (softwood) and Japanese beech (hardwood). Uronic acid bound to xylan promotes the thermal degradation of cellulose and hemicellulose, and its effect is different depending on the form of free acid (acting as an acid catalyst) or metal uronate (acting as a base catalyst). We evaluated the location of uronic acid in the cell wall by identifying the components affected by demineralization in pyrolysis of cedar and beech wood. The thermal reactivities of xylan and glucomannan in beech were changed by demineralization, but in cedar, glucomannan and cellulose reactivities were changed. Therefore, the location of uronic acid in the cell wall was established and differed between cedar and beech; close to glucomannan and xylan in beech, but close to glucomannan and cellulose in cedar. Such information is important for understanding the ultrastructure and pyrolysis behavior of softwood and hardwood cell walls.

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Functional analyses of xylanolytic enzymes involved in xylan degradation and utilization in Neurospora crassa.

Wang, R. & Arioka, M. (2020). International Journal of Biological Macromolecules, 169, 302-310.

Neurospora crassa possesses six putative xylanases and four putative xylosidases. qRT-PCR results showed that the expression of all these xylanolytic enzymes was induced by xylan. Except for two intracellular β-xylosidases, others were shown to be secreted enzymes based on the localization analysis of EGFP-fusion proteins. Among them, GH10-1, GH10-2, GH11-1, and GH11-2 were successfully expressed and characterized as typical endo-β-1,4-xylanases that hydrolyze the xylooligosaccharides with a polymeric degree not less than three or four. Strains deleted for either gh10-1, gh10-2, gh3-7, or gh3-8 displayed decreased growth in xylan and biomass media. Disruption of gh3-7 or gh43-1 resulted in enhanced-xylanolytic enzyme activity when cultivated in biomass medium. Collectively, these results suggest that xylooligosaccharides released by the actions of xylanases and xylosidases not only serve as the carbon sources to maintain the growth of N. crassa, but they also act as inducers to trigger the expression of hydrolytic enzymes in vivo.

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Saccharogenic refining of Ginkgo biloba leaf residues using a cost-effective enzyme cocktail prepared by the fungal strain A32 isolated from ancient ginkgo biloba tree.

Wang, J., Lei, Z., Zhang, Y., Lu, W., Li, S., Luo, W. & Song, P. (2020). Bioresource Technology, 317, 123980.

To reduce environmental pollution and waste of biomass from Ginkgo biloba leaf residues (GBLRs), we developed a cost-effective enzyme system to hydrolyze GBLRs into available reducing sugars (RS). Biomass characteristics of GBLRs were investigated, which indicated that the acid hydrolyzed fraction was 49.43% of the dry weight of GBLRs. The fraction could be effectively converted into RS by an enzyme cocktail with high polygalacturonase activity without traditionally intricate pretreatment. The strain A32 isolated from the ancient ginkgo soil was used for the production of the enzyme cocktail, and a response surface methodology was used to optimize the enzymatic production. The enzyme cocktail released 87.2% of RS from GBLRs at 35°C for 72 h with 1% (m/v) of loading, and the RS concentration arrived 8.95 ± 0.39 mg/ml with 9% of GBLRs loading. The cost-effective system of self-prepared enzyme cocktail is promising for facilitating GBLRs' bio-based industry.

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Improving the catalytic activity of thermostable xylanase from Thermotoga maritima via mutagenesis of non-catalytic residues at glycone subsites.

Yang, J., Ma, T., Shang-guan, F. & Han, Z. (2020). Enzyme and Microbial Technology, 139, 109579.

Endo-β-1,4-xylanase from Thermotoga maritima, TmxB, is an industrially attractive enzyme due to its extreme thermostability. To improve its application value, four variants were designed on the basis of multiple sequence and three-dimensional structure alignments. Wild-type TmxB (wt-TmxB) and its mutants were produced via a Pichia pastoris expression system. Among four single-site mutants, the tyrosine substitution of a threonine residue (T74Y) at putative -3/-4 subsite led to a 1.3-fold increase in specific activity at 40°C - 100°C and pH 5 for 5 min, with beechwood xylan as the substrate. T74Y had an improved catalytic efficiency (k>cat/K>m), being 1.6 times that of wt-TmxB. Variants DY (two amino acid insertions) and N68Q displayed a slight increase (1.2 fold) and dramatic decline (1.7 fold) in catalytic efficiency, respectively. Mutant E67Y was totally inactive under all test conditions. Structural modeling and docking simulation elucidated structural insights into the molecular mechanism of activity changes for these TmxB variants. This study helps in further understanding the roles of the non-catalytic amino acids at the glycone subsites of xylanases from glycoside hydrolase family 10.

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Biochemical Characterization of an Extracellular Xylanase from Aestuariibacter sp. PX-1 Newly Isolated from the Coastal Seawater of Jeju Island in Korea.

Kim, J. H. (2020). Microbiology and Biotechnology Letters, 48(2), 215-222.

The marine microorganism PX-1, which can hydrolyze xylan, was isolated from coastal sea water of Jeju Island, Korea. Based on the 16S rRNA gene sequence and chemotaxonomy analysis, PX-1 was identified as a species of the genus Aestuariibacter and named Aestuariibacter sp PX-1. From the culture broth of PX-1, an extracellular xylanase was purified to homogeneity through ammonium sulfate precipitation and subsequent adsorption chromatography using insoluble xylan. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration chromatography estimated the molecular weight of the purified putative xylanase (XylA) as approximately 64 kDa. XylA showed xylanase activity toward beechwood xylan, with a maximum enzymatic activity at pH 6.0 and 45°C. Through thin-layer chromatographic analysis of the xylan hydrolysate produced by XylA, it was confirmed that XylA is an endo-type xylanase that decomposes xylan into xylose and xyloligosaccharides of various lengths. The Km and Vmax values of XylA for beechwood xylan were 27.78 mM and 78.13 μM/min, respectively.

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