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This article is a Commentary on Yu et al. (2024), 244: 1024–1040.

The use of mineral-based fillers tends to reduce the mechanical properties of paper, which can limit their application. The filler surface modification is a significant treatment to overcome this limitation. This research aims to offer a novel modified mineral-based filler to provide its industrial application. The surface of precipitated calcium carbonate (PCC) was modified with xylan (XS), which is a type of hemicellulose, a polysaccharide consisting mainly of xylose residues. It is used as a filler at different filler dosage levels in paper pulp. Modified PCC(MPCC) was characterized with Fourier transform infrared spectroscopy, Thermogravimetric analysis, X-ray photoelectron spectroscopy, X-ray diffraction and Field-emission scanning electron microscopy analyses. The analysis demonstrated that the MPCC filler surface was coated with XS successfully. The effect of PCC and MPCC-filled hand-sheet paper physical, chemical and optical properties were studied. The experimental results showed that the mechanical (tensile, burst, tear strength) and optical (brightness, opacity) of hand-sheet paper filled with MPCC were significantly improved compared with unmodified PCC-filled paper at the same ash content. The filler retention of PCC and MPCC fillers in paper was investigated, and the MPCC filler showed better filler retention properties in paper stock than the PCC filler. [ABSTRACT FROM AUTHOR]

Corncob biomass (CCB), an agricultural residue having highest xylan content forms a potential source of platform chemicals such as xylooligosaccharides (XOS) and xylose. This study aims at evaluating the synergistic effect of Sonophotocatalysis (SP) for enhanced extraction of corncob xylan. The effect of different pretreatment methods namely Sonocatalysis (US + ZnO), Photocatalysis (PC), Ultrasonication at 20% amplitude (US 20) and Sonophotocatalysis at amplitude of 20% (SP 20) were studied. Amongst, SP 20 resulted in two folds and five folds enhanced xylan extraction compared to US 20 and PC, respectively. The temperature change from 30 ± 2 to > 90 ± 2 °C by varying sonication amplitude (20%, 50%, 70% and 90%) and extraction time (15, 30 and 60 min) were studied. The results indicated that 90.1 ± 1.8% of CCB xylan could be extracted within 15 min of extraction when pretreated with SP 90. This reaction condition resulted in 14.59 ± 1% of xylose and 84.5 ± 2.01% of total XOS relative to the initial xylan content. The CCB pretreated with SP 90 resulted in 36% and 83% increased xylan extraction compared to US and PC, respectively. The thin layer chromatography analysis substantiates the result obtained in quantitative analysis. The compositional analysis of pretreated CCB with SP 90 showed higher cellulose (52.5 ± 1.5%), lignin (15.1 ± 0.9%) content and reduced hemicellulose (3.5 ± 0.7%). FTIR studies revealed that variation in the peak band at 1730 cm−1 which is characteristic peak for hemicellulose proved breakage of ester linkage between lignin and hemicellulose when CCB pretreated by SP 90. The particle size distribution of US and SP 90 pretreated reduced from 417 ± 1.5 to 170 ± 1.2 µm. SEM analysis revealed distinguished difference in the structure of CCB between untreated and pretreated samples. From our study it was evident that combination of US and PC resulted in enhanced extraction of CCB xylan with reduced time and mild reaction condition without the use of additional chemicals. Further the extracted xylan was simultaneously hydrolyzed into xylose and XOS of DP (2–4) i.e. X2, X3 and X4. This shows that SP could be a promising process for one pot production of XOS and xylose from CCB xylan. Highlights: Preliminary results showed SP @ amplitude of 20% (SP 20) resulted enhanced xylan extraction compared to US and PC respectively. The temperature change from 30 ± 2 to 90 ± 2 °C by varying sonication amplitude (20%, 50%, 70% and 90%) and extraction time (15, 30 and 60 min) were studied. SP 90 resulted in 90.1 ± 1.8% of CCB xylan extraction within 15 min along with xylose and XOS's were obtained as hydrolyzed products. [ABSTRACT FROM AUTHOR]

Summary: Polysaccharide structural complexity not only influences cell wall strength and extensibility but also hinders pathogenic and biotechnological attempts to saccharify the wall. In certain species and tissues, glucuronic acid side groups on xylan exhibit arabinopyranose or galactose decorations whose genetic and evolutionary basis is completely unknown, impeding efforts to understand their function and engineer wall digestibility.Genetics and polysaccharide profiling were used to identify the responsible loci in Arabidopsis and Eucalyptus from proposed candidates, while phylogenies uncovered a shared evolutionary origin. GH30‐family endo‐glucuronoxylanase activities were analysed by electrophoresis, and their differing specificities were rationalised by phylogeny and structural analysis.The newly identified xylan arabinopyranosyltransferases comprise an overlooked subfamily in the GT47‐A family of Golgi glycosyltransferases, previously assumed to comprise mainly xyloglucan galactosyltransferases, highlighting an unanticipated adaptation of both donor and acceptor specificities. Further neofunctionalisation has produced a Myrtaceae‐specific xylan galactosyltransferase. Simultaneously, GH30 endo‐glucuronoxylanases have convergently adapted to overcome these decorations, suggesting a role for these structures in defence. The differential expression of glucuronoxylan‐modifying genes across Eucalyptus tissues, however, hints at further functions.Our results demonstrate the rapid adaptability of biosynthetic and degradative carbohydrate‐active enzyme activities, providing insight into plant–pathogen interactions and facilitating plant cell wall biotechnological utilisation. See also the Commentary on this article by Mortimer & Scheller, 244: 749–751. [ABSTRACT FROM AUTHOR]

Plant cell walls are complex, multifunctional structures, built up of polysaccharides and proteins. The configuration and abundance of cell wall constituents determine cellular elongation and plant growth. The emphasis of this review is on rice, a staple crop with economic importance, serving as model for grasses/cereals. Recent advancements have contributed to a better understanding of the grass/cereal cell wall. This review brings together current knowledge of the organization and metabolism of the rice cell wall, and addresses gaps in the information regarding the cell wall and enzymes involved. Several cell wall fractions, including cellulose, mixed-linkage glucans, and glucuronoarabinoxylans, are well understood in rice and other grasses/grains. Conversely, there are still open questions and missing links in relation to xyloglucans, glucomannans, pectin, lignin, and arabinogalactan proteins. There is still a large and untapped potential to identify carbohydrate-active enzymes (CAZymes), to characterize their activity, and to elucidate their involvement in the metabolism of the mentioned cell wall fractions. This review highlights the involvement of carbohydrate-active enzymes in rice cell wall metabolism, providing an update of current understanding with the aim of demarcating research areas with potential for further investigations. [ABSTRACT FROM AUTHOR]

SUMMARY Cotton fiber is the most valuable naturally available material for the textile industry and the fiber length and strength are key determinants of its quality. Dynamic changes in the pectin, xyloglucan, xylan, and cellulose polysaccharide epitope content during fiber growth contribute to complex remodeling of fiber cell wall (CW) and quality. Detailed knowledge about polysaccharide compositional and structural alteration in the fiber during fiber elongation and strengthening is important to understand the molecular dynamics of fiber development and improve its quality. Here, large‐scale glycome profiling coupled with fiber phenotype and transcriptome profiling was conducted on fiber collected daily covering the most critical window of fiber development. The profiling studies with high temporal resolution allowed us to identify specific polysaccharide epitopes associated with distinct fiber phenotypes that might contribute to fiber quality. This study revealed the critical role of highly branched RG‐I pectin epitopes such as β‐1,4‐linked‐galactans, β‐1,6‐linked‐galactans, and arabinogalactans, in addition to earlier reported homogalacturonans and xyloglucans in the formation of cotton fiber middle lamella and contributing to fiber plasticity and elongation. We also propose the essential role of heteroxylans (Xyl‐MeGlcA and Xyl‐3Ar), as a guiding factor for secondary CW cellulose microfibril arrangement, thus contributing to fiber strength. Correlation analysis of profiles of polysaccharide epitopes from glycome data and expression profiles of glycosyltransferase‐encoding genes from transcriptome data identified several key putative glycosyltransferases that are potentially involved in synthesizing the critical polysaccharide epitopes. The findings of this study provide a foundation to identify molecular factors that dictate important fiber traits. [ABSTRACT FROM AUTHOR]

BACKGROUND RESULTS CONCLUSION The conversion of biomass into high value‐added platform compounds is an important method of biomass utilization. The conversion of hemicellulose represented by xylan into furfural can not only reduce the consumption of fossil fuels, but also promotes the development and utilization of non‐edible biomass resources. In this study, a bifunctional solid‐acid catalyst prepared from agricultural and forestry waste Pueraria (P. eduli) Residues was used to convert xylan into furfural in a biphasic system.In this study, P. eduli Residues was used as raw material to prepare a P. eduli Residues‐based carbon solid‐acid catalyst (PR/C‐SO3H‐Fe) by one‐step sulfonation carbonization and impregnation. The catalyst catalyzes the conversion of xylan to furfural in a biphasic system (2‐methyltetrahydrofuran/water). The physicochemical properties of the catalysts were characterized by X‐ray powder diffraction, scanning electron microscopy, differential thermogravimetric analysis, Brunauer–Emmett–Teller surface area, Fourier transform infrared spectroscopy and ammonia temperature‐programmed desorption. Subsequently, the experimental conditions were studied and optimized, such as metal species, iron ion concentration, reaction time and temperature, volume ratio of organic phase to water phase and ratio of substrate to catalyst. The results showed that under conditions of 160 °C, 50 mg catalyst, 100 mg xylan and 7 mL reaction solvent, the yield of furfural could reach 78.94% after 3 h of reaction.This study provides an effective research method for the conversion of xylan into furfural, and provides a reference for the catalytic conversion and utilization of hemicellulose in agricultural and forestry biomass. It also provides a feasible method for the resource utilization of agricultural and forestry waste. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

SUMMARY: Xylan is one of the major hemicelluloses in plant cell walls and its xylosyl backbone is often decorated at O‐2 with glucuronic acid (GlcA) and/or methylglucuronic acid (MeGlcA) residues. The GlcA/MeGlcA side chains may be further substituted with 2‐O‐arabinopyranose (Arap) or 2‐O‐galactopyranose (Gal) residues in some plant species, but the enzymes responsible for these substitutions remain unknown. During our endeavor to investigate the enzymatic activities of Arabidopsis MUR3‐clade members of the GT47 glycosyltransferase family, we found that one of them was able to transfer Arap from UDP‐Arap onto O‐2 of GlcA side chains of xylan, and thus it was named xylan 2‐O‐arabinopyranosyltransferase 1 (AtXAPT1). The function of AtXAPT1 was verified in planta by its T‐DNA knockout mutation showing a loss of the Arap substitution on xylan GlcA side chains. Further biochemical characterization of XAPT close homologs from other plant species demonstrated that while the poplar ones had the same catalytic activity as AtXAPT1, those from Eucalyptus, lemon‐scented gum, sea apple, 'Ohi'a lehua, duckweed and purple yam were capable of catalyzing both 2‐O‐Arap and 2‐O‐Gal substitutions of xylan GlcA side chains albeit with differential activities. Sequential reactions with XAPTs and glucuronoxylan methyltransferase 3 (GXM3) showed that XAPTs acted poorly on MeGlcA side chains, whereas GXM3 could efficiently methylate arabinosylated or galactosylated GlcA side chains of xylan. Furthermore, molecular docking and site‐directed mutagenesis analyses of Eucalyptus XAPT1 revealed critical roles of several amino acid residues at the putative active site in its activity. Together, these findings establish that XAPTs residing in the MUR3 clade of family GT47 are responsible for 2‐O‐arabinopyranosylation and 2‐O‐galactosylation of GlcA side chains of xylan. Significance Statement: Xylan is one of the major hemicelluloses in plant cell walls and its GlcA side chains may be further substituted with 2‐O‐Arap or 2‐O‐Gal residues. We have uncovered the functions of a subgroup of MUR3‐clade GT47 members in catalyzing the transfer of 2‐O‐Arap and/or 2‐O‐Gal onto GlcA side chains of xylan, which expands our understanding of glycosyltransferases involved in xylan substitutions. [ABSTRACT FROM AUTHOR]

Abstract The present study deals with the production of cellulase-free endoxylanase by Aspergillus niger ISL-9 using wheat bran as a solid substrate. Endoxylanase was produced under a solid-state fermentation. Various growth parameters were optimized for the improved production of the enzyme. The Substrate level of 15 g was optimized as it provided the fungus with balanced aeration and nutrition. Among the six moisture contents investigated, Moisture Content 5 (MC5) was optimized (g/l: malt extract, 10; (NH4)2HPO4, 2.5; urea, 1.0) and 10 mL of MC5 was found to give the highest production of endoxylanase. The pH and time of incubation were optimized to 6.2 and 48 h respectively. The Inoculum size of 2 mL (1.4 × 106 spores/mL) gave the maximum enzyme production. After optimization of these growth parameters, a significantly high endoxylanase activity of 21.87 U/g was achieved. Very negligible Carboxymethylcellulase (CMCase) activity was observed indicating the production of cellulase-free endoxylanase. The notable finding is that the endoxylanase activity was increased by 1.4-fold under optimized conditions (p ≤ 0.05). The overall comparison of kinetic parameters for enhanced production of endoxylanase by A. niger ISL-9 under Solid State Fermentation (SSF) was also studied. Different kinetic variables which included specific growth rate, product yield coefficients, volumetric rates and specific rates were observed at 48, 72 and 96 h incubation time and were compared for MC1 and MC5. Among the kinetic parameters, the most significant result was obtained with volumetric rate constant for product formation (Qp) that was found to be optimum (1.89 U/h) at 72 h incubation period and a high value of Qp i.e.1.68 U/h was also observed at 48 h incubation period. Thus, the study demonstrates a cost-effective and environmentally sustainable process for xylanase production and exhibits scope towards successful industrial applications.

The present study deals with the production of cellulase-free endoxylanase by Aspergillus niger ISL-9 using wheat bran as a solid substrate. Endoxylanase was produced under a solid-state fermentation. Various growth parameters were optimized for the improved production of the enzyme. The Substrate level of 15 g was optimized as it provided the fungus with balanced aeration and nutrition. Among the six moisture contents investigated, Moisture Content 5 (MC5) was optimized (g/l: malt extract, 10; (NH4)2HPO4, 2.5; urea, 1.0) and 10 mL of MC5 was found to give the highest production of endoxylanase. The pH and time of incubation were optimized to 6.2 and 48 h respectively. The Inoculum size of 2 mL (1.4 × 106 spores/mL) gave the maximum enzyme production. After optimization of these growth parameters, a significantly high endoxylanase activity of 21.87 U/g was achieved. Very negligible Carboxymethylcellulase (CMCase) activity was observed indicating the production of cellulase-free endoxylanase. The notable finding is that the endoxylanase activity was increased by 1.4-fold under optimized conditions (p ≤ 0.05). The overall comparison of kinetic parameters for enhanced production of endoxylanase by A. niger ISL-9 under Solid State Fermentation (SSF) was also studied. Different kinetic variables which included specific growth rate, product yield coefficients, volumetric rates and specific rates were observed at 48, 72 and 96 h incubation time and were compared for MC1 and MC5. Among the kinetic parameters, the most significant result was obtained with volumetric rate constant for product formation (Qp) that was found to be optimum (1.89 U/h) at 72 h incubation period and a high value of Qp i.e.1.68 U/h was also observed at 48 h incubation period. Thus, the study demonstrates a cost-effective and environmentally sustainable process for xylanase production and exhibits scope towards successful industrial applications. [ABSTRACT FROM AUTHOR]

The valorization of lignocellulosic biomass, derived from various bio-waste materials, has received considerable attention as a sustainable approach to improve production chains while reducing environmental impact. Microbial enzymes have emerged as key players in the degradation of polysaccharides, offering versatile applications in biotechnology and industry. Among these enzymes, glycoside hydrolases (GHs) play a central role. Xylanases, in particular, are used in a wide range of applications and are essential for the production of xylose, which can be fermented into bioethanol or find use in many other industries. Currently, fungal secretomes dominate as the main reservoir of lignocellulolytic enzymes, but thermophilic microorganisms offer notable advantages in terms of enzyme stability and production efficiency. Here we present the genomic characterization of Geobacillus stearothermophilus GF16 to identify genes encoding putative enzymes involved in lignocellulose degradation. Thermostable GHs secreted by G. stearothermophilus GF16 were investigated and found to be active on different natural polysaccharides and synthetic substrates, revealing an array of inducible GH activities. In particular, the concentrated secretome possesses significant thermostable xylanase and β-xylosidase activities (5 ×103 U/L and 1.7 ×105 U/L, respectively), highlighting its potential for application in biomass valorization. We assessed the hemicellulose hydrolysis capabilities of various agri-food wastes using the concentrated secretome of the strain cultivated on xylan. An impressive 300-fold increase in xylose release compared to a commercially available cocktail was obtained with the secretome, underscoring the remarkable efficacy of this approach. [Display omitted] • Genome characterization of G. stearothermophilus GF16 reveals genes potentially involved in hemicellulose degradation. • The secretome of GF16 grown on a minimal medium enriched with 0.1 % xylan shows inducible xylanolytic properties. • G. stearothermophilus GF16 CAZymes are pivotal in converting agri-food wastes into value-added products, such as xylose. [ABSTRACT FROM AUTHOR]

A fast, reliable, low‐cost, and efficient method for the recovery of xylan from agro‐residue materials is needed to improve the use of xylan in industrial processes. Xylan was extracted from two agrowastes (corncobs and wheat bran) using a cost‐effective alkali extraction method. The characteristic band patterns and bending vibrations associated with hemicellulose and beta glycoside linkage could be seen in the corncob‐extracted xylan (CCEx) and wheatbran‐extracted xylan (WBEx). Scanning electron microscopy (SEM) analysis showed that the extracted xylans consisted of aggregated and nonaggregated particles with irregular morphology and rough surfaces. Particle‐size analysis displayed average sizes of 205.6, 210.8, and 794.2 nm for commercial beechwood xylan (Bx), CCEx, and WBEx, respectively. Alkali extraction was performed with different concentrations of NaOH, from 5% to 20%, with a solid–liquid ratio of 1:20. It was found that 82.90 and 76.77% of xylan were extracted from corncob and wheat bran, respectively, which represents a higher yield obtained in a shorter duration in comparison with studies in the literature. The enzymatic hydrolysis of wheat bran and corncob that used 250 IU/mL of Enterobacter hormaechie KS1 xylanase yielded 334.38 and 162.35 mg/g of xylooligosaccharides. Their properties were studied and were found to be very similar to those of commercial xylan. They could reduce costs if applied in industry. [ABSTRACT FROM AUTHOR]

Eucalyptus branches and bark represent highly abundant and available feedstocks with great potential for obtaining bio-based products. Distinct and integrated pretreatment fractionation strategies for eucalyptus branches and bark were performed for the efficient production of xylooligosaccharides (XOS). By combining pretreatments, a high yield of XOS was obtained from eucalyptus branches and bark. The branches and bark were presoaked in 8% (w/w) sodium hydroxide at 60 °C for 30 min to provide a deacetylation effect. The residues were then hydrothermally treated. The findings revealed that 4.64% of XOS originated from the bark and 6.19% from eucalyptus branches. It has been demonstrated that xylan may be selectively depolymerized during pretreatment by preventing excessive hydrolysis through the use of deacetylation in the first phase of the process. More XOS was produced using hydrothermal treatment, yielding 8.00% (w/w) in the branches and 5.12% in the bark. A significant amount of XOS with DP 2–5 might be obtained in certain experiments, up to 60%, but the most abundant XOS are usually those with DP > 5 (approximately 80% of all XOS). This work provides new insights into the effective generation of XOS under relatively mild conditions by overcoming the recalcitrant structure of eucalyptus branches and bark, representing a noteworthy advancement towards forestry leftover valorization. [ABSTRACT FROM AUTHOR]

Plant cell walls are largely composed of polysaccharide polymers, including cellulose, hemicelluloses (xyloglucan, xylan, mannan, and mixed-linkage β-1,3/1,4-glucan), and pectins. Among these cell wall polysaccharides, xyloglucan, xylan, mannan, and pectins are often O-acetylated, and polysaccharide O-acetylation plays important roles in cell wall assembly and disease resistance. Genetic and biochemical analyses have implicated the involvement of three groups of proteins in plant cell wall polysaccharide O-acetylation: trichome birefringence-like (TBL)/domain of unknown function 231 (DUF231), reduced wall acetylation (RWA), and altered xyloglucan 9 (AXY9). Although the exact roles of RWAs and AXY9 are yet to be identified, members of the TBL/DUF231 family have been found to be O-acetyltransferases responsible for the O-acetylation of xyloglucan, xylan, mannan, and pectins. Here, we provide a comprehensive overview of the occurrence of O-acetylated cell wall polysaccharides, the biochemical properties, structural features, and evolution of cell wall polysaccharide O-acetyltransferases, and the potential biotechnological applications of manipulations of cell wall polysaccharide acetylation. Further in-depth studies of the biochemical mechanisms of cell wall polysaccharide O-acetylation will not only enrich our understanding of cell wall biology, but also have important implications in engineering plants with increased disease resistance and reduced recalcitrance for biofuel production. [ABSTRACT FROM AUTHOR]

Local evolution of delignification and xylan removal inside wood chips was investigated throughout the initial stages of kraft cooking. Model chips of birch sapwood were pulped at 145, 155 and 165 °C, utilizing white liquors with hydroxide content ranging from 0.25 to 0.55 mol/kg. The composition of different sections in each cooked sample was then determined. Xylan was isolated from selected samples and analyzed using size exclusion chromatography and HSQC NMR. Most changes in concentration and structure of residual xylan occurred early in the process (<45 min). Furthermore, xylan samples isolated from the tissue of different cooked chips had similar average molecular weights, indicating that temperature and alkali content had little impact over the extent of reactions affecting residual xylan. In contrast, xylan dissolution was significantly dependent on pulping conditions, increasing with hydroxide concentration. The lignin profile inside the cooked chips also varied with alkali content and temperature, and it was shown to be more uniform when applying low cooking temperatures (145 °C). Finally, increased delignification and xylan removal were detected close to the transverse surfaces of chips (likely due to the fast mass transport in vessels/lumen), implying that anatomical features of wood can have a significant impact on pulping. [ABSTRACT FROM AUTHOR]

Alkaline pretreatment has great potential for the separation of biomass components. In this study, taking bamboo and cotton stalk as raw materials, two-stage alkaline pretreatment was designed for evaluating the components fractionation. The chemical structure of isolated xylan from bamboo and cotton stalk have a backbone of (1 → 4)-β-D-Xylp units attached with 4-O-Me-α-D-GlcpA and/or α-L-Araf units as the branched chain, characterized by Fourier transform infrared spectroscopy and Heteronuclear Single Quantum Coherence Nuclear Magnetic Resonance. Its excellent pretreatment performance was mainly due to the alkali solution weakening the hydrogen bond between cellulose and hemicellulose and saponifying the ester bond between hemicellulose and lignin, thus increasing the fiber porosity. The cellulose enzymatic hydrolysis yield of two-stage alkaline pretreatments cotton stalks and bamboo could reach to 74.2% and 82.1%. The recovery of xylan and lignin of two-stage alkaline pretreatments cotton stalks and bamboo was 85.4% and 84.5%, and 85.1% and 85.1%. This technology was a great potential to promote the efficiency of the component separation of nonwood biomass. [ABSTRACT FROM AUTHOR]

The transition towards a sustainable society involves the utilization of lignocellulosic biomass as a renewable feedstock for materials, fuel, and base chemicals. Lignocellulose consists of cellulose, hemicellulose, and lignin, forming a complex, recalcitrant matrix where efficient enzymatic saccharification is pivotal for accessing its valuable components. This study investigated microbial communities from brackish Lauwersmeer Lake, in The Netherlands, as a potential source of xylan-degrading enzymes. Environmental sediment samples were enriched with wheat arabinoxylan (WAX) and beechwood glucuronoxylan (BEX), with enrichment on WAX showing higher bacterial growth and complete xylan degradation compared to BEX. Metagenomic sequencing revealed communities consisting almost entirely of bacteria (>99%) and substantial shifts in composition during the enrichment. The first generation of seven-day enrichments on both xylans led to a high accumulation of Gammaproteobacteria (49% WAX, 84% BEX), which were largely replaced by Alphaproteobacteria (42% WAX, 69% BEX) in the fourth generation. Analysis of the protein function within the sequenced genomes showed elevated levels of genes associated with the carbohydrate catabolic process, specifically targeting arabinose, xylose, and xylan, indicating an adaptation to the primary monosaccharides present in the carbon source. The data open up the possibility of discovering novel xylan-degrading proteins from other sources aside from the thoroughly studied Bacteroidota. [ABSTRACT FROM AUTHOR]

Bifidobacteria are commonly encountered members of the human gut microbiota that possess the enzymatic machinery necessary for the metabolism of certain plant-derived, complex carbohydrates. In the current study we describe differential growth profiles elicited by a panel of 21 newly isolated Bifidobacterium pseudocatenulatum strains on various plant-derived glycans. Using a combination of gene-trait matching and comparative genome analysis, we identified two distinct xylanases responsible for the degradation of xylan. Furthermore, three distinct extracellular α-amylases were shown to be involved in starch degradation by certain strains of B. pseudocatenulatum. Biochemical characterization showed that all three a-amylases can cleave the related substrates amylose, amylopectin, maltodextrin, glycogen and starch. The genes encoding these enzymes are variably found in the species B. pseudocatenulatum, therefore constituting a strain-specific adaptation to the gut environment as these glycans constitute common plant-derived carbohydrates present in the human diet. Overall, our study provides insights into the metabolism of these common dietary carbohydrates by a human-derived bifidobacterial species. [ABSTRACT FROM AUTHOR]

In order to realize the resource conversion and utilization of bamboo shoot processing waste, the xylan in Phyllostachys edulis was extracted by using the alkali extraction and alcohol precipitation method. The extraction process was optimized by the single factor test and orthogonal test. The physicochemical properties of xylan extrated from Phyllostachys edulis were analyzed by high performance liquid chromatography and Fourier transform infrared spectroscopy. The antioxidant activity in vitro of xylans from Phyllostachys edulis was evaluated by DPPH method and ABTS method. The results showed that: Under the conditions of the extraction time of 3.5 h, the alkali mass concentration of 0.1 g·mL-1, the ratio of solid to liquid being 1:25 and the extraction temperature of 100℃, the extraction rate of xylan from Phyllostachys edulis was the highest, reaching 20.86%. The monosaccharide composition and FT-IR analysis showed that the xylose may be the main component of xylan from Phyllostachys edulis. The in vitro anti-oxidation test showed that the xylan extracted from Phyllostachys edulis had certain antioxidant activity. When the concentration was 8 mg·mL-1, the scavenging rate of it on the DPPH free radical reached 94.75%, and the IC50 value was 1.0 mg·mL-1. When the concentration was 20 mg·mL-1, the scavenging rate of it on the ABTS free radical was 93.09%, and the IC50 value was 3.85 mg·mL-1. [ABSTRACT FROM AUTHOR]

In this study, we investigated a deleterious mutation in the β-xylosidase gene, xylA (AkxylA), in Aspergillus luchuensis mut. kawachii IFO 4308 by constructing an AkxylA disruptant and complementation strains of AkxylA and xylA derived from A. luchuensis RIB2604 (AlxylA), which does not harbor the mutation in xylA. Only the AlxylA complementation strain exhibited significantly higher growth and substantial β-xylosidase activity in medium containing xylan, accompanied by an increase in XylA expression. This resulted in lower xylobiose and higher xylose concentrations in the mash of barley shochu. These findings suggest that the mutation in xylA affects xylose levels during the fermentation process. Because the mutation in xylA was identified not only in the genome of strain IFO 4308 but also the genomes of other industrial strains of A. luchuensis and A. luchuensis mut. kawachii , these findings enhance our understanding of the genetic factors that affect the fermentation characteristics. [ABSTRACT FROM AUTHOR]

Abstract Dinizia Excelsa is an Amazonian tree with a wide range of applications as a raw material in the industry. The objective of this study was to extract, characterize, and evaluate the biological activities of xylan extracted from Dinizia excelsa wood. The xylan was obtained in five stages, including delignification, precipitation, purification, and freeze-drying. The physicochemical analysis of xylan included the determination of monosaccharides, elemental composition, FTIR analysis, 2D nuclear magnetic resonance spectroscopy, and the determination of molecular weight. Xylan had an extraction yield of 28.44% and an elemental composition of 35.03% carbon, 5.65% hydrogen, and 59.32% oxygen. FTIR analysis revealed similarities between Dinizia excelsa xylan and commercial xylan. 2D NMR analysis confirmed the presence of characteristic xylan groups. Furthermore, xylan has a low molecular weight. In vitro cytotoxicity tests demonstrated low toxicity, indicating its potential for biological applications. Immunomodulatory activity assays revealed that xylan stimulated cell proliferation and the production of anti-inflammatory cytokines. The anticoagulant activity of xylan was low compared to heparin. The antioxidant activity of xylan was weaker compared to ascorbic acid and butylated hydroxytoluene (BHT). These results indicate that xylan from Dinizia excelsa has potential for several biomedical applications due to its immunomodulatory and anticoagulant properties.

Hemicellulose is one of the most important natural polysaccharides in nature. Hemicellulose from different sources varies in chemical composition and structure, which in turn affects the modification effects and industrial applications. Grain and oil by-products (GOBPs) are important raw materials for hemicellulose. This article reviews the modification methods of hemicellulose in GOBPs. The effects of chemical and physical modification methods on the properties of GOBP hemicellulose biomaterials are evaluated. The potential applications of modified GOBP hemicellulose are discussed, including its use in film production, hydrogel formation, three-dimensional (3D) printing materials, and adsorbents for environmental remediation. The limitations and future recommendations are also proposed to provide theoretical foundations and technical support for the efficient utilization of these by-products. [ABSTRACT FROM AUTHOR]

The present study aimed to prepare a multilayer complex of polysaccharides for encapsulation of β-carotene for delivery into aqueous media. β-carotene, a highly beneficial carotenoid for human health, can be effectively combined with three polysaccharides that serve as prebiotics in the human gut microbiota. The process of preparing the β-carotene-polysaccharides complex involved a three-step method. Firstly, β-carotene was encapsulated using xylan. Subsequently, the encapsulated β-carotene was complexed with chitooligosaccharides. Finally, the resulting double-layer complex was mixed with fucoidan to form a three-layer complex that readily dissolves in aqueous media. The formation of the complex was verified through SEM and spectroscopic analyses. The complex exhibited a favourable loading capacity ranging from 0.144 to 0.293 mg/mL, with sizes varying between 205 and 297 nm. The solubility of the complex ranged from 26.84 to 29.04 mg/mL. Notably, the complex demonstrated antioxidant activity as observed by DPPH and FRAP methods. These remarkable properties make the new complex a potential candidate for incorporation into the food and beverage industries, thanks to its antioxidant capabilities and advantageous features. [ABSTRACT FROM AUTHOR]

Grass xylan consists of a linear chain of β-1,4-linked xylosyl residues that often form domains substituted only with either arabinofuranose (Ara f) or glucuronic acid (GlcA)/methylglucuronic acid (MeGlcA) residues, and it lacks the unique reducing end tetrasaccharide sequence found in dicot xylan. The mechanism of how grass xylan backbone elongation is initiated and how its distinctive substitution pattern is determined remains elusive. Here, we performed biochemical characterization of rice xylan biosynthetic enzymes, including xylan synthases, glucuronyltransferases and methyltransferases. Activity assays of rice xylan synthases demonstrated that they required short xylooligomers as acceptors for their activities. While rice xylan glucuronyltransferases effectively glucuronidated unsubstituted xylohexaose acceptors, they transferred little GlcA residues onto (Ara f)-substituted xylohexaoses and rice xylan 3- O -arabinosyltransferase could not arabinosylate GlcA-substituted xylohexaoses, indicating that their intrinsic biochemical properties may contribute to the distinctive substitution patterns of rice xylan. In addition, we found that rice xylan methyltransferase exhibited a low substrate binding affinity, which may explain the partial GlcA methylation in rice xylan. Furthermore, immunolocalization of xylan in xylem cells of both rice and Arabidopsis showed that it was deposited together with cellulose in secondary walls without forming xylan-rich nanodomains. Together, our findings provide new insights into the biochemical mechanisms underlying xylan backbone elongation and substitutions in grass species. [ABSTRACT FROM AUTHOR]

The content of xylan in sugarcane straw (culm top and leaves) is interesting to produce xylooligosaccharides (XOS), oligomers composed of xylose, which provide numerous health benefits. XOS were produced in this study by two types of treatment using sugarcane leaves: liquid hot water (LHW) and dilute acid (sulfuric and acetic acids), aiming to minimize sugar degradation production. A central composite design with axial points was performed to evaluate the effects of the independent variables on the hydrolysis production of XOS. Hydrolysis with acetic acid resulted in the conversion of xylan into XOS of 22.78% with 2% (%, m/v) of acid at 180 °C for 35 min. Hydrolysis with sulfuric acid resulted in XOS yield of 62.18% with 2% (%, m/v) of acid at 79.55 °C for 35 min. The LHW treatment using leaves resulted in XOS yield of 20.71% at 130 °C for 35 min. The LHW and dilute acid resulted in 0.018% and 0.195% (m/m) of furfural, respectively. For each ton of sugarcane leaves, an XOS production of 206.44 kg, 75.63 kg, and 68.69 kg can be estimated using sulfuric acid, acetic acid, and LHW, successively. The most effective treatment for XOS production was hydrolysis with dilute sulfuric acid; however, LHW generated lower degradation products. [ABSTRACT FROM AUTHOR]

The lignocellulosic residue cassava peel is an unexplored source of bioactive compounds, such as hemicellulose-based xylooligosaccharides (XOS) that present prebiotic properties. In this sense, this work aimed to produce XOS from cassava peels that were pretreated with NaOH (xylan extraction and lignin removal) followed by enzymatic hydrolysis (endo-1–4-β-xylanase). The cassava peels were pretreated sequentially: starch removal, alkaline hydrolysis, and enzymatic hydrolysis. The aqueous-mechanical reduction and sieving for 15 cycles removed ≈16% of starch (iodometric method). The alkaline pretreatments were carried out with 2, 4, and 6% (w/v) NaOH, 1:100/solid:liquid at 121 °C and 1.1 bar for 30 or 60 min. The enzymatic kinetics was evaluated with enzyme concentration at 0.5, 1.5, and 3.0% (v/v). The highest alkaline hydrolysis reached 34.20% of lignin removal (2% (w/v) NaOH for 30 min). The highest XOS yield was 396.5 mg XOS/g xylan after 48 h and 3.0% enzyme concentration. Regarding the mass balance, from 300 g of cassava peels (an agroindustrial residue), it is possible to obtain up to 3.27% XOS. Therefore, the fractionation of hemicellulose from cassava peels was technically viable from the concepts of biorefinery and bioeconomy, being one of the first researches to approach the extraction of xylan from cassava peel to obtain XOS through an enzymatic route with a highly promising yield. Highlights: • The high starch content is a drawback to producing cassava peel-based xylooligosaccharides. • Delignification and extraction of xylan from cassava peels by alkaline hydrolysis were performed. • Xylooligosaccharides were produced by enzymatic hydrolysis with endo-1–4-β-xylanase. • The highest yield of cassava peel-based xylooligosaccharides, already reported. [ABSTRACT FROM AUTHOR]

The absorption and metabolism of indigestible dietary glycans play a crucial role in maintaining the integrity of the intestinal barrier and shaping the gut microbiota. Three chemically modified products of xylan, including carboxymethylated xylan, xylan–zinc complex, and carboxymethylated xylan–zinc complex, were synthesized using xylan from sugarcane bagasse. The potential effects of xylan before and after modification on the intestinal barriers and intestinal microbiota of mice were subsequently investigated and compared, revealing distinct changes in the gut microbiota of mice. The results suggest that the chemically modified xylan products have the potential to induce specific regulatory functions on the gut microbiota. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to investigate the gastrointestinal tolerability, glycemic and insulinemic responses of Plant Fiber Extract (PFE), a mixture comprising of oligosaccharides and polysaccharides derived from cellulose and xylan. Methods: Two double-blind, randomized, controlled, cross-over trials were conducted in healthy adults. In the first trial, participants (n=29) consumed either 25, 35 or 45g per day of PFE or resistant maltodextrin (Control) for 14days. The occurrence and severity of gastrointestinal (GI) symptoms, stool parameters, and safety outcomes were evaluated with a combination of surveys and blood analysis respectively. In the second trial (n=20), the post-prandial glycemic and insulinemic responses after the ingestion of 20g of PFE diluted in water or incorporated into chocolate chips was measured and then compared to that of glucose and regular chocolate, respectively. Results: For all timepoints (0, 7 and 14days), within any given dose group, there was no statistically significant difference in the GI symptoms score between PFE and Control. Further, for each test product (PFE or Control), no difference was observed in the same dose group from days 0 and 14. Stool consistency score and number of participants experiencing loose or watery stools was similar between products. No serious adverse events were reported and neither PFE nor Control significantly altered blood or urine safety parameters. The glycemic and insulinemic responses after PFE ingestion in comparison to glucose were 12% and 8% respectively. The glycemic and insulinemic responses after consuming chocolate containing PFE were 20% of that of regular chocolate. Conclusion: PFE was well-tolerated by healthy volunteers in doses up to 45g/day and it elicited comparatively low glycemic and insulinemic responses when consumed alone or when incorporated into a food product. [ABSTRACT FROM AUTHOR]

Main conclusion: A member of the rice GT61 clade B is capable of transferring both 2-O-xylosyl and 2-O-arabinosyl residues onto xylan and another member specifically catalyses addition of 2-O-xylosyl residue onto xylan. Grass xylan is substituted predominantly with 3-O-arabinofuranose (Araf) as well as with some minor side chains, such as 2-O-Araf and 2-O-(methyl)glucuronic acid [(Me)GlcA]. 3-O-Arabinosylation of grass xylan has been shown to be catalysed by grass-expanded clade A members of the glycosyltransferase family 61. However, glycosyltransferases mediating 2-O-arabinosylation of grass xylan remain elusive. Here, we performed biochemical studies of two rice GT61 clade B members and found that one of them was capable of transferring both xylosyl (Xyl) and Araf residues from UDP-Xyl and UDP-Araf, respectively, onto xylooligomer acceptors, whereas the other specifically catalysed Xyl transfer onto xylooligomers, indicating that the former is a xylan xylosyl/arabinosyl transferase (named OsXXAT1 herein) and the latter is a xylan xylosyltransferase (named OsXYXT2). Structural analysis of the OsXXAT1- and OsXYXT2-catalysed reaction products revealed that the Xyl and Araf residues were transferred onto O-2 positions of xylooligomers. Furthermore, we demonstrated that OsXXAT1 and OsXYXT2 were able to substitute acetylated xylooligomers, but only OsXXAT1 could xylosylate GlcA-substituted xylooligomers. OsXXAT1 and OsXYXT2 were predicted to adopt a GT-B fold structure and molecular docking revealed candidate amino acid residues at the predicted active site involved in binding of the nucleotide sugar donor and the xylohexaose acceptor substrates. Together, our results establish that OsXXAT1 is a xylan 2-O-xylosyl/2-O-arabinosyl transferase and OsXYXT2 is a xylan 2-O-xylosyltransferase, which expands our knowledge of roles of the GT61 family in grass xylan synthesis. [ABSTRACT FROM AUTHOR]

Solid‐state nuclear magnetic resonance (ssNMR) measurements of intact cell walls and cellular samples often generate spectra that are difficult to interpret due to the presence of many coexisting glycans and the structural polymorphism observed in native conditions. To overcome this analytical challenge, we present a statistical approach for analyzing carbohydrate signals using high‐resolution ssNMR data indexed in a carbohydrate database. We generate simulated spectra to demonstrate the chemical shift dispersion and compare this with experimental data to facilitate the identification of important fungal and plant polysaccharides, such as chitin and glucans in fungi and cellulose, hemicellulose, and pectic polymers in plants. We also demonstrate that chemically distinct carbohydrates from different organisms may produce almost identical signals, highlighting the need for high‐resolution spectra and validation of resonance assignments. Our study provides a means to differentiate the characteristic signals of major carbohydrates and allows us to summarize currently undetected polysaccharides in plants and fungi, which may inspire future investigations. [ABSTRACT FROM AUTHOR]

Fluorescent sensors with single reading are generally subject to unpredictable disturbs from environmental and artificial factors. In order to overcome this barrier of detection reliability, a paper-based optical sensor with proportional fluorescence was established and further combined with a smartphone for visual, on-site and quantitative detection of Fe3+, which affects the color, smell and taste of water, and endangers the health of plants and animals. The ratio fluorescent probe was fabricated by rhodamine B and carbon quantum dots derived from xylan. The red fluorescence of rhodamine B was inert to Fe3+, which was referred to as background. And blue emitting carbon quantum dots functioned as signal report units, which would be quenched by Fe3+ and make the fluorescence of the ratio probe change from purple to red. The quantitative detection of Fe3+ was conducted by investigating the RGB value of fluorescent images with a smartphone. With the increase of Fe3+ concentration, the R/B (red/blue) value of the fluorescent paper gradually increased. The linear detection range was 10–180 μM, and the limit of detection was 198.2 nM. The application of ratio fluorescent paper with a smartphone provides a facile method for the rapid detection of ions. [ABSTRACT FROM AUTHOR]

In this study, the α-glucosidase (maltase-glucoamylase: MGAM) and α-amylase inhibitory properties elicited by xylooligosaccharides (XOSs) prepared from dulse xylan were analysed as a potential mechanism to control postprandial hyperglycaemia for type-2 diabetes prevention and treatment. Xylan was purified from red alga dulse powder and used for enzymatic hydrolysis using Sucrase X to produce XOSs. Fractionation of XOSs produced xylobiose (X2), β-(1→3)-xylosyl xylobiose (DX3), xylotriose (X3), β-(1→3)-xylosyl-xylotriose (DX4), and a dulse XOS mixture with n ≥ 4 xylose units (DXM). The different fractions exhibited moderate MGAM (IC50 = 11.41–23.44 mg/mL) and α-amylase (IC50 = 18.07–53.04 mg/mL) inhibitory activity, which was lower than that of acarbose. Kinetics studies revealed that XOSs bound to the active site of carbohydrate digestive enzymes, limiting access to the substrate by competitive inhibition. A molecular docking analysis of XOSs with MGAM and α-amylase clearly showed moderate strength of interactions, both hydrogen bonds and non-bonded contacts, at the active site of the enzymes. Overall, XOSs from dulse could prevent postprandial hyperglycaemia as functional food by a usual and continuous consumption. [ABSTRACT FROM AUTHOR]

Bifidobacteria are commonly encountered members of the human gut microbiota that possess the enzymatic machinery necessary for the metabolism of certain plant-derived, complex carbohydrates. In the current study we describe differential growth profiles elicited by a panel of 21 newly isolated Bifidobacterium pseudocatenulatum strains on various plant-derived glycans. Using a combination of gene-trait matching and comparative genome analysis, we identified two distinct xylanases responsible for the degradation of xylan. Furthermore, three distinct extracellular α-amylases were shown to be involved in starch degradation by certain strains of B. pseudocatenulatum. Biochemical characterization showed that all three α-amylases can cleave the related substrates amylose, amylopectin, maltodextrin, glycogen and starch. The genes encoding these enzymes are variably found in the species B. pseudocatenulatum, therefore constituting a strain-specific adaptation to the gut environment as these glycans constitute common plant-derived carbohydrates present in the human diet. Overall, our study provides insights into the metabolism of these common dietary carbohydrates by a human-derived bifidobacterial species.

Growth suppression and defence signalling are simultaneous strategies that plants invoke to respond to abiotic stress. Here, we show that the drought stress response of poplar trees (Populus trichocarpa) is initiated by a suppression in cell wall derived methanol (MeOH) emissions and activation of acetic acid (AA) fermentation defences. Temperature sensitive emissions dominated by MeOH (AA/MeOH

Corn as one of the world's major food crops, its by-product corn cob is also rich in resources. However, the unreasonable utilization of corn cob often causes the environmental pollution, waste of resources and other problems. As one of the most abundant polymers in nature, xylan is widely used in food, medicine, materials and other fields. Corn cob is rich in xylan, which is an ideal raw material for extracting xylan. However, the intractable lignin is covalently linked to xylan, which increases the difficulty of xylan extraction. It has been reported that the deep eutectic solvent (DES) could preferentially dissolve lignin in biomass, thereby dissolving the xylan. Then, the xylan in the extract was separated by ethanol precipitation method. The xylan precipitate was obtained after centrifugation, while the supernatant was retained. The components of the supernatant after ethanol precipitation were separated by the rotary evaporator. The ethanol, water and DES were collected for the subsequent extraction of corn cob xylan. In this study, a novel way was provided for the green production of corn cob xylan. The DES was used to extract xylan from corn cob which was used as the raw material. The effects of solid-liquid ratio, reaction time, reaction temperature and water content of DES on the extraction rate of corn cob xylan were investigated by the single factor test. Furthermore, the orthogonal test was designed to optimize the xylan extraction process. The structure of corn cob xylan was analyzed and verified. The results showed that the optimum extraction conditions of corn cob xylan were as follows: the ratio of corn cob to DES was 1 : 15 (g : mL), the extraction time was 3 h, the extraction temperature was 60 °C, and the water content of DES was 70%. Under these conditions, the extraction rate of xylan was 16.46%. The extracted corn cob xylan was distinctive triple helix of polysaccharide, which was similar to the structure of commercially available xylan. Xylan was effectively and workably extracted from corn cob by the DES method. This study provided a new approach for high value conversion of corn cob and the clean production of xylan.

Abstract Reduced graphene oxide (rGO) films suffer from low capacitance for inner unreduced oxygen functional groups, restacking of sheets and high contact resistance. Herein, carbon spheres derived from renewable xylan were added to graphene oxide with large sheet area to fabricate film by gelation and filtration, followed by in situ reduction for high-performance flexible supercapacitor. rGO film with transverse size about 13 μm showed a good specific capacitance of 967 mF/cm2 at a scanning rate of 5 mV/s and increased to 1786 mF/cm2 by in situ reducing its inner part, which generally remained oxidized due to outer hindering from hydrophobic graphene. Then, by hydrothermal carbonization of xylan and activation with KOH, activated carbon sphere (aXCS) was prepared, which had a diameter of 150–200 nm and a specific capacitance of 270 F/g. The aXCS acted as spacer and connector to avoid restacking of graphene sheets and decrease interlayer contact resistance, resulting 94% increase in capacitance performance from rGO film to aXCS/rGO film. Therefore, combined in situ reduction and enhancement through compositing aXCS, the final film (aXCS/rGO-AA) showed a boosted specific capacitance of 755 mF/cm2 at 1 mA/cm2 in double electrode system, power density of 22.5–2250 mW/cm2, and energy density of 11.88–25.2 mWh/cm2. Meanwhile, aXCS/rGO-AA had outstanding cycling stability that its specific capacitance maintained 108.7% after 10,000 cycles of charge–discharge, showing promising potential in wearable and portable electronics. Graphical abstract

Abstract Background The abundance of glucuronoxylan (GX) in agricultural and forestry residual side streams positions it as a promising feedstock for microbial conversion into valuable compounds. By engineering strains of the widely employed cell factory Saccharomyces cerevisiae with the ability to directly hydrolyze and ferment GX polymers, we can avoid the need for harsh chemical pretreatments and costly enzymatic hydrolysis steps prior to fermentation. However, for an economically viable bioproduction process, the engineered strains must efficiently express and secrete enzymes that act in synergy to hydrolyze the targeted polymers. Results The aim of this study was to equip the xylose-fermenting S. cerevisiae strain CEN.PK XXX with xylanolytic enzymes targeting beechwood GX. Using a targeted enzyme approach, we matched hydrolytic enzyme activities to the chemical features of the GX substrate and determined that besides endo-1,4-β-xylanase and β-xylosidase activities, α-methyl-glucuronidase activity was of great importance for GX hydrolysis and yeast growth. We also created a library of strains expressing different combinations of enzymes, and screened for yeast strains that could express and secrete the enzymes and metabolize the GX hydrolysis products efficiently. While strains engineered with BmXyn11A xylanase and XylA β-xylosidase could grow relatively well in beechwood GX, strains further engineered with Agu115 α-methyl-glucuronidase did not display an additional growth benefit, likely due to inefficient expression and secretion of this enzyme. Co-cultures of strains expressing complementary enzymes as well as external enzyme supplementation boosted yeast growth and ethanol fermentation of GX, and ethanol titers reached a maximum of 1.33 g L− 1 after 48 h under oxygen limited condition in bioreactor fermentations. Conclusion This work underscored the importance of identifying an optimal enzyme combination for successful engineering of S. cerevisiae strains that can hydrolyze and assimilate GX. The enzymes must exhibit high and balanced activities, be compatible with the yeast’s expression and secretion system, and the nature of the hydrolysis products must be such that they can be taken up and metabolized by the yeast. The engineered strains, particularly when co-cultivated, display robust growth and fermentation of GX, and represent a significant step forward towards a sustainable and cost-effective bioprocessing of GX-rich biomass. They also provide valuable insights for future strain and process development targets.

Abstract Background The recently discovered PcAA14A and B from white-rot basidiomycete Pycnoporus coccineus enriched our understanding of the oxidative degradation of xylan in fungi, however, the unusual mode of action of AA14 LPMOs has sparked controversy. The substrate specificity and functionality of AA14 LPMOs still remain enigmatic and need further investigation. Results In this study, a novel AA14 LPMO was characterized from the ascomycete Talaromyces rugulosus. TrAA14A has a broad substrate specificity with strong oxidative activity on pure amorphous cellulose and xyloglucan. It could simultaneously oxidize cellulose, xylan and xyloglucan in natural hemi/cellulosic substrate such as fibrillated eucalyptus pulp, and released native and oxidized cello-oligosaccharides, xylo-oligosaccharides and xyloglucan oligosaccharides from this substrate, but its cellulolytic/hemicellulolytic activity became weaker as the contents of xylan increase in the alkaline-extracted hemi/cellulosic substrates. The dual cellulolytic/hemicellulolytic activity enables TrAA14A to possess a profound boosting effect on cellulose hydrolysis by cellulolytic enzymes. Structure modelling of TrAA14A revealed that it exhibits a relatively flat active-site surface similar to the active-site surfaces in AA9 LPMOs but quite distinct from PcAA14B, despite TrAA14A is strongly clustered together with AA14 LPMOs. Remarkable difference in electrostatic potentials of L2 and L3 surfaces was also observed among TrAA14A, PcAA14B and NcLPMO9F. We speculated that the unique feature in substrate-binding surface might contribute to the cellulolytic/hemicellulolytic activity of TrAA14A. Conclusions The extensive cellulolytic/hemicellulolytic activity on natural hemi/cellulosic substrate indicated that TrAA14A from ascomycete is distinctively different from previously characterized xylan-active AA9 or AA14 LPMOs. It may play as a bifunctional enzyme to decompose some specific network structures formed between cellulose and hemicellulose in the plant cell walls. Our findings shed new insights into the novel substrate specificities and biological functionalities of AA14 LPMOs, and will contribute to developing novel bifunctional LPMOs as the booster in commercial cellulase cocktails to efficiently break down the hemicellulose-cellulose matrix in lignocellulose.

Summary: There is an increasing need for renewable energy sources to replace part of our fossil fuel‐based economy and reduce greenhouse gas emission. Sugarcane bagasse is a prominent feedstock to produce cellulosic bioethanol, but strategies are still needed to improve the cost‐effective exploitation of this potential energy source. In model plants, it has been shown that GUX genes are involved in cell wall hemicellulose decoration, adding glucuronic acid substitutions on the xylan backbone. Mutation of GUX genes increases enzyme access to cell wall polysaccharides, reducing biomass recalcitrance in Arabidopsis thaliana. Here, we characterized the sugarcane GUX genes and silenced GUX2 in commercial hybrid sugarcane. The transgenic lines had no penalty in development under greenhouse conditions. The sugarcane GUX1 and GUX2 enzymes generated different patterns of xylan glucuronidation, suggesting they may differently influence the molecular interaction of xylan with cellulose and lignin. Studies using biomass without chemical or steam pretreatment showed that the cell wall polysaccharides, particularly xylan, were less recalcitrant in sugarcane with GUX2 silenced than in WT plants. Our findings suggest that manipulation of GUX in sugarcane can reduce the costs of second‐generation ethanol production and enhance the contribution of biofuels to lowering the emission of greenhouse gases. [ABSTRACT FROM AUTHOR]

Spent mushroom substrate (SMS), a lignocellulosic waste after mushroom production is generally discarded without proper management. There is increasing interest in the sustainable transformation of lignocellulosic waste into high-value products. Within this context, the present study investigated the potential of the SMS from the cultivation of Pleurotus pulmonarius and Auricularia auricula on rubber tree wood sawdust as substrates for xylooligosaccharides (XOS) production. SMS samples from these two edible mushrooms were extracted using alkaline xylan extraction, producing maximum true recovery amounts of xylan in the range 34.61%–37.49% using 18% NaOH at 70 °C for 3 h. Production of XOS from alkaline-extracted xylan from the SMS samples of both mushroom species using economically crude xylanases from Aspergillus flavus KUB2 resulted in XOS (X2–X5) production of 241.47–249.04 mg/g, with X3 as the predominant XOS product. The produced XOS had excellent prebiotic activity and 2,2′-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and contained high total phenolic contents. The combined beneficial bioactivities in terms of prebiotic and antioxidant properties suggested that the XOS produced from sawdust-based SMS samples of P. pulmonarius and A. auricula could be promising ingredients for both food and pharmaceutical applications. [ABSTRACT FROM AUTHOR]

1. Xylo-oligosaccharides (XOS) stimulate proliferation of beneficial bacteria in the gastrointestinal tract of broiler chickens. This results in enhanced utilisation of dietary non-starch polysaccharides and increased production of valuable short-chain fatty acids. However, these positive effects do not always translate into improved bird productive performance, with inconsistent performance responses observed between bird trials. 2. A holo-analysis was conducted to determine the effects of supplementing XOS into broiler diets on bird feed intake, body weight gain, feed conversion and mortality. This was done by comparing the XOS supplemented treatment to the control treatment. A total of 53 studies which met the criteria for inclusion were used in the analysis. 3. The results showed that XOS had a notable positive impact on bird mortality; XOS reduced mortality by 0.69% for every 1% increment in the control group. XOS supplementation induced a positive effect on the feed conversion ratio (FCR). However, the efficacy of XOS at improving FCR was dependent on the efficiency of the control group (performance of the flock), and the concentration of total arabinoxylan, protein and phytase in the diet. There were insufficient data points to predict the effect of XOS on body weight and feed intake. 4. In conclusion, the holo-analysis revealed that supplementing XOS to broiler chicken diets reduces bird mortality. XOS can also improve FCR, but the scale of response is dependent on the diet composition and control flock performance. Additional studies are required to confirm the effects of XOS on body weight and feed intake. [ABSTRACT FROM AUTHOR]

Lignocellulose, the most abundant and renewable plant resource, is a complex of polymers mainly composed of polysaccharides (cellulose and hemicelluloses) and an aromatic polymer (lignin). Utilisation of lignocellulosic biomass for biotechnological applications has increased over the past few years. Xylan is the second most abundant carbohydrate in plant cell walls, and structurally, it is a heteropolysaccharide with a backbone composed of β-1,4-d-xylopyranosyl units connected with glycosidic bonds. Xylanases degrade this complex structure of xylan and can be produced by various microorganisms, including fungi, bacteria, and yeasts. Lignocellulosic biomass is the most economical substrate for the production of fungal xylanases. The bioconversion of lignocellulosic biomass to industrially important products, i.e., xylooligosaccharides and biofuels, is possible via the application of xylanases. These enzymes also play a key role in enhancing the nutrition of food and feed and the bio-bleaching of paper and kraft pulp. However, the demand for more potent and efficient xylanases with high activity has increased, which is fulfilled by involving recombinant DNA technology. Hence, in this review, we thoroughly discussed the biotechnological potential of lignocellulosic biomass for the production of fungal xylanases, their purification, molecular strategies for improving their efficiency, and their utilisation for the production of valuable products and in other industrial processes. [ABSTRACT FROM AUTHOR]