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Glycoside hydrolase (GH) 30 family xylanases are enzymes of biotechnological interest due to their capacity to degrade recalcitrant hemicelluloses, such as glucuronoxylan (GX). This study focuses on a subfamily 7 GH30, TtXyn30A from Thermothelomyces thermophilus, which acts on GX in an "endo" and "exo" mode, releasing methyl‐glucuronic acid branched xylooligosaccharides (XOs) and xylobiose, respectively. The crystal structure of inactive TtXyn30A in complex with 23‐(4‐O‐methyl‐α‐D‐glucuronosyl)‐xylotriose (UXX), along with biochemical analyses, corroborate the implication of E233, previously identified as alternative catalytic residue, in the hydrolysis of decorated xylan. At the −1 subsite, the xylose adopts a distorted conformation, indicative of the Michaelis complex of TtXyn30AEE with UXX trapped in the semi‐functional active site. The most significant structural rearrangements upon substrate binding are observed at residues W127 and E233. The structures with neutral XOs, representing the "exo" function, clearly show the nonspecific binding at aglycon subsites, contrary to glycon sites, where the xylose molecules are accommodated via multiple interactions. Last, an unproductive ligand binding site is found at the interface between the catalytic and the secondary β‐domain which is present in all GH30 enzymes. These findings improve current understanding of the mechanism of bifunctional GH30s, with potential applications in the field of enzyme engineering. [ABSTRACT FROM AUTHOR]

BACKGROUND: Xylobiose, a non‐digestible disaccharide, largely contributes to the beneficial physiological effects of xylooligosaccharides. However, there is insufficient evidence to assess the direct effect of xylobiose on intestinal barrier function. Here, we investigated the intestinal barrier function in human intestinal Caco‐2 cells treated with xylobiose. RESULTS: In total, 283 genes were upregulated and 256 genes were downregulated in xylobiose‐treated Caco‐2 cells relative to the controls. We focused on genes related to intestinal barrier function, such as tight junction (TJ) and heat shock protein (HSP). Xylobiose decreased the expression of the TJ gene Claudin 2 (CLDN2) and increased the expression of the cytoprotective HSP genes HSPB1 and HSPA1A, which encode HSP27 and HSP70, respectively. Immunoblot analysis confirmed that xylobiose suppressed CLDN2 expression and enhanced HSP27 and HSP70 expression. A quantitative reverse transcription‐PCR and promoter assays indicated that xylobiose post‐transcriptionally regulated CLDN2 and HSPB1 levels. Additionally, selective inhibition of phosphatidyl‐3‐inositol kinase (PI3K) inhibited xylobiose‐mediated CLDN2 expression, whereas HSP27 expression induced by xylobiose was sensitive to the inhibition of PI3K, mitogen‐activated protein kinase kinase and Src. CONCLUSION: The results of the present study reveal that xylobiose suppresses CLDN2 and increases HSP27 expression in intestinal Caco‐2 cells via post‐transcriptional regulation, potentially strengthening intestinal barrier integrity; however, these effects seem to occur via different signaling pathways. Our findings may help to assess the physiological role of xylobiose. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Endo-xylanase hydrolyzing xylan in cellulosic residues releasing xylobiose as the major product at neutral pH are desirable in the substitute sweeteners industry. In this study, two endo-xylanases were obtained from Streptomyces rochei and Bacillus velezensis. SrocXyn10 showed the highest identity of 77.22%, with a reported endo-xylanase. The optimum reaction temperature and pH of rSrocXyn10-Ec were pH 7.0 and 60°C, with remarkable stability at 45°C or pHs ranging from 4.5 to 11.0. rBvelXyn11-Ec was most active at pH 6.0 and 50°C, and was stable at 35°C or pH 3.5 to 10.5. Both rSrocXyn10-Ec and rBvelXyn11-Ec showed specific enzyme activities on wheat arabinoxylan (685.83 ± 13.82 and 2809.89 ± 21.26 U/mg, respectively), with no enzyme activity on non-xylan substrates. The Vmax of rSrocXyn10-Ec and rBvelXyn11-Ec were 467.86 U mg-1 and 3067.68 U mg-1, respectively. The determined Km values of rSrocXyn10-Ec and rBvelXyn11-Ec were 3.08 g L-1 and 1.45 g L-1, respectively. The predominant product of the hydrolysis of alkaline extracts from bagasse, corncob, and bamboo by rSrocXyn10-Ec and rBvelXyn11-Ec were xylooligosaccharides. Interestingly, the xylobiose content in hydrolysates by rSrocXyn10-Ec was approximately 80%, which is higher than most reported endo-xylanases. rSrocXyn10-Ec and rBvelXyn11-Ec could be excellent candidates to produce xylooligosaccharides at neutral/near-neutral pHs. rSrocXyn10-Ec also has potential value in the production of xylobiose as a substitute sweetener. [ABSTRACT FROM AUTHOR]

Plant cell wall-derived oligosaccharides, i.e., damage-associated molecular patterns (DAMPs), could be generated after pathogen attack or during normal plant development, perceived by cell wall receptors, and can alter immunity and cell wall composition. Therefore, we hypothesised that xylo-oligosaccharides (XOS) could act as an elicitor and trigger immune responses. To test this, we treated Arabidopsis with xylobiose (XB) and investigated different parameters. XB-treatment significantly triggered the generation of reactive oxygen species (ROS), activated MAPK protein phosphorylation, and induced callose deposition. The combination of XB (DAMP) and flg22 a microbe-associated molecular pattern (MAMP) further enhanced ROS response and gene expression of PTI marker genes. RNA sequencing analysis revealed that more genes were differentially regulated after 30 min compared to 24 h XB-treated leaves, which correlated with ROS response. Increased xylosidase activity and soluble xylose level after 30 min and 3 h of XB-treatment were observed which might have weakened the DAMP response. However, an increase in total cell wall sugar and a decrease in uronic acid level was observed at both 30 min and 24 h. Additionally, arabinose, rhamnose, and xylose levels were increased in 30 min, and glucose was increased in 24 h compared to mock-treated leaves. The level of jasmonic acid, abscisic acid, auxin, and cytokinin were also affected after XB treatment. Overall, our data revealed that the shortest XOS can act as a DAMP, which triggers the PTI response and alters cell wall composition and hormone level. Key message: Xylobiose treatment in Arabidopsis rosette leaf induces plant-triggered immunity (PTI) responses, alters cell wall polysaccharide composition and influences growth hormone levels. [ABSTRACT FROM AUTHOR]

Xylooligosaccharides (XOS) are non‐digestible oligosaccharides with a significant role as functional food ingredients in the food industry. The present research is undertaken to evaluate water soluble xylan (WSX) extraction from eight different sources using water at ambient temperature (25 ± 2 °C) and structural characterization (FTIR, NMR, XRD, and TGA). Enzymatic production of XOS from extracted substrates and its characterization using HPLC‐RID and FTIR is determined. WSX from orange fleshed sweet potato peel shows highest yield (9%), while the least (2.48%) is from Teff seed coat. FTIR structural identification of xylan confirms the presence of β‐glycosidic linkages and acetyl groups; whereas 1H NMR validates the occurrence of β‐D‐1,4‐xylopyranose backbone with α‐L‐arabinofuranose and 4‐O‐methylglucuronic acid substituents. XRD and TGA characteristics of the extracts indicate similarities in the eight sources in comparison with standard beech wood xylan. WSX is hydrolyzed with endoxylanase to obtain XOS (highest yield of 57.16 ± 1.01% in Cassava cake; lowest yield of 21.72 ± 0.72% in Bambara groundnut). HPLC‐RID reveals xylobiose as the main monomeric sugar component (DP 2) and β‐linkages are identified by FTIR in all the sources. The study suggests the potential commercial production of XOS from the analyzed agricultural by‐products. [ABSTRACT FROM AUTHOR]

Resveratrol is a natural polyphenol with antioxidant activity and numerous health benefits. However, in vivo application of this compound is still a challenge due to its poor aqueous solubility and rapid metabolism, which leads to an extremely low bioavailability in the target tissues. In this work, rXynSOS-E236G glycosynthase, designed from a GH10 endoxylanase of the fungus Talaromyces amestolkiae, was used to glycosylate resveratrol by using xylobiosyl-fluoride as a sugar donor. The major product from this reaction was identified by NMR as 3-O-ꞵ-d-xylobiosyl resveratrol, together with other glycosides produced in a lower amount as 4′-O-ꞵ-d-xylobiosyl resveratrol and 3-O-ꞵ-d-xylotetraosyl resveratrol. The application of response surface methodology made it possible to optimize the reaction, producing 35% of 3-O-ꞵ-d-xylobiosyl resveratrol. Since other minor glycosides are obtained in addition to this compound, the transformation of the phenolic substrate amounted to 70%. Xylobiosylation decreased the antioxidant capacity of resveratrol by 2.21-fold, but, in return, produced a staggering 4,866-fold improvement in solubility, facilitating the delivery of large amounts of the molecule and its transit to the colon. A preliminary study has also shown that the colonic microbiota is capable of releasing resveratrol from 3-O-ꞵ-d-xylobiosyl resveratrol. These results support the potential of mutagenic variants of glycosyl hydrolases to synthesize highly soluble resveratrol glycosides, which could, in turn, improve the bioavailability and bioactive properties of this polyphenol. [ABSTRACT FROM AUTHOR]

Cellobiose and xylobiose are disaccharides composed of two glucose or xylose units with β-1,4 linkages. This study aimed to isolate a Trichoderma reesei mutant that lacks β-glucosidase and β-xylosidase activities for the simultaneous production of these disaccharides. Mutagenesis using Fe-ion beam resulted in a mutant strain, T. reesei T1640; the cellulase production in this strain was as high as that in the parent strain. Genomic analysis revealed that T1640 lost both the β-glucosidase and β-xylosidase activities owing to the translocation of the responsible genes. Hydrolysis of alkali-treated bagasse using the enzymes from T1640 leads to high yields (365 mg/g-biomass) and ratios (72.7% of the total sugars) of cellobiose and xylobiose. [Display omitted] • Trichoderma reesei T1640 was developed using Fe ion irradiation mutagenesis. • T1640 lost both β-glucosidase and β-xylosidase activities through translocation. • T1640 showed a high cellulase production similar to that of the wild parent strain. • One-step co-production of cellobiose and xylobiose from bagasse was achieved. [ABSTRACT FROM AUTHOR]

GH30 xylobiohydrolases, an expanding enzyme category, need deeper insights for optimal use. The primary aim of this study was to characterize a new xylobiohydrolase, Ac GH30A of GH30 family from Acetivibrio clariflavus. The gene encoding Ac GH30A was cloned using pET28a(+) vector and expressed in E. coli BL21(DE3) cells. Ac GH30A was purified by immobilized metal-ion affinity chromatography. SDS-PAGE analysis of Ac GH30A showed molecular mass of ~58 kDa. Ac GH30A showed optimum temperature 80 °C and optimum pH 7.0. Ac GH30A was stable (maintaining >80 % of control activity) in pH range, 4–7 and temperature range, 30 °C -70 °C when incubated for 90 min. Ac GH30A displayed melting temperature, 72 °C and half-life, 21 days at 4 °C. The enzyme activity of Ac GH30A was enhanced by 10 mM Ca2+ and Mg2+ ions by 25 % and 21 %, respectively, whereas 10 mM Co2+, Zn2+, Fe2+, and Cu2+ ions significantly reduced it. Ac GH30A showed activity against various xylan polysaccharides displaying highest V max , 139 U.mg−1 and K M , 0.71 mg.ml−1 against 4- O -methyl glucuronoxylan under optimum conditions. TLC, HPLC and LC-MS analyses of Ac GH30A hydrolyzed products from xylan substrates revealed the release of sole product, xylobiose, confirming it as an obligate xylobiohydrolase. Ac GH30A being a highly thermostable enzyme can be potentially utlilized in various biotechnological applications. [Display omitted] • Recombinant Ac GH30A cloned from Acetivibrio clariflavus showed molecular size 58 kDa. • Thermophilic Ac GH30A showed optimum temperature 80 °C and optimum pH 7.0. • Ac GH30A displayed melting temperature, 72 °C and half-life, 21 days at 4 °C. • Ac GH30A gave V max , 139 U.mg−1 and K M , 0.71 mg.ml−1 with 4- O -methyl glucuronoxylan. • Xylobiohydrolase, Ac GH30A released only xylobiose from xylan polysaccharides. [ABSTRACT FROM AUTHOR]

Xylobiohydrolase plays a crucial role in the hydrolysis of xylan, a complex polysaccharide present in the cell walls of plants. This study focuses on the solution structure and substrate binding analysis of a novel xylobiohydrolase, Ac GH30A, from Acetivibrio clariflavus . Secondary structure analysis of Ac GH30A in an aqueous environment using Circular Dichroism and in silico modeling revealed an α/β/α sandwich structure with a central β-barrel comprising eight β-strands. Superposition of the homology-modelled structure of Ac GH30A with its closest homolog showed that the active-site contains Glu175 and Glu268 as the catalytic residues. Molecular docking confirmed xylobiose as the preferred ligand, showcasing polar interactions with the catalytic amino acids, indicating its xylobiohydrolase activity. Ac GH30A displayed a high binding affinity with xylobiose with an association constant ( K a ) of 7.83 × 10 5 M -1 , as determined by isothermal titration calorimetry. Molecular dynamics (MD) simulations of Ac GH30A and Ac GH30A-xylobiose complex in solution showed reduced RMSD, R g and SASA values, confirming the stability and compactness of the complex. MD simulations further highlighted the crucial role of Glu175 in hydrogen bonding with the ligand, which acts as an acid or base. Small-angle X-ray scattering (SAXS) analysis of Ac GH30A showed its molecular shape as an earbud with a globular structure existing in a monodispersed state, which was corroborated by dynamic light scattering (DLS). The hydrodynamic radius ( R h ) of Ac GH30A, determined by DLS, was 3.7 nm. This study significantly contributed valuable insights into the structure and functional aspects of Ac GH30A.

Xylooligosaccharides having various degrees of polymerization such as xylobiose, xylotriose, and xylotetraose positively affect human health by interacting with gut proteins. The present study aimed to identify proteins present in gut microflora, such as xylosidase, xylulokinase, etc., with the help of retrieved whole-genome annotations and find out the mechanistic interactions of those with the above substrates. The 3D structures of proteins, namely Endo-1,4-beta-xylanase B (XynB) from Lactobacillus brevis and beta-d-xylosidase (Xyl3) from Bifidobacterium adolescentis, were computationally predicted and validated with the help of various bioinformatics tools. Molecular docking studies identified the effectual binding of these proteins to the xylooligosaccharides, and the stabilities of the best-docked complexes were analyzed by molecular dynamic simulation. The present study demonstrated that XynB and Xyl3 showed better effectual binding toward Xylobiose with the binding energies of − 5.96 kcal/mol and − 4.2 kcal/mol, respectively. The interactions were stabilized by several hydrogen bonding having desolvation energy (− 6.59 and − 7.91). The conformational stabilities of the docked complexes were observed in the four selected complexes of XynB–xylotriose, XynB–xylotetraose, Xyl3–xylobiose, and Xyn3–xylotriose by MD simulations. This study showed that the interactions of these four complexes are stable, which means they have complex metabolic activities among each other. Extending these studies of understanding, the interaction between specific probiotics enzymes and their ligands can explore the detailed design of synbiotics in the future. [ABSTRACT FROM AUTHOR]

The hemicellulose content present in corn cobs can help in producing a high amount of xylooligosaccharides (XOS) in an eco-friendly manner. In this work, the XOS was produced from alkali pre-treated corn-cobs having a true yield of 38 ± 1.4% via enzymatic hydrolysis with the help of xylanase from T. lanuginosus VAPS-24. The production process was optimized to achieve a high concentration of XOS using innovative multi-objective optimization through machine learning modeling and finding out the most suitable parameters where xylobiose production is higher than xylose. The Multi-objective connected neural networks (MOCNN) model with tangent sigmoid activation function yielded a correlation coefficient of 96.51%; there were six optimal sets where xylobiose concentration was higher than xylose. The best-optimized conditions yielded 3.03 mg/ml of xylobiose and 1.31 mg/ml of xylose. Therefore, this novel approach of machine learning can target the increasing demand for xylooligosaccharides in the growing industrial market of prebiotics. [ABSTRACT FROM AUTHOR]

The Acetivibrioclariflavus (basonym: Clostridium clariflavum) glycoside hydrolase family 30 cellulosomal protein encoded by the Clocl_1795 gene was highly represented during growth on cellulosic substrates. In this report, the recombinantly expressed protein has been characterized and shown to be a non-reducing terminal (NRT)-specific xylobiohydrolase (AcXbh30A). Biochemical function, optimal biophysical parameters, and phylogeny were investigated. The findings indicate that AcXbh30A strictly cleaves xylobiose from the NRT up until an α-1,2-linked glucuronic acid (GA)-decorated xylose if the number of xyloses is even or otherwise a single xylose will remain resulting in a penultimate GA-substituted xylose. Unlike recently reported xylobiohydrolases, AcXbh30A has no other detectable hydrolysis products under our optimized reaction conditions. Sequence analysis indicates that AcXbh30A represents a new GH30 subfamily. This new xylobiohydrolase may be useful for commercial production of industrial quantities of xylobiose.

Typical bacterial GH30 xylanases are glucuronoxylanases requiring 4-O-methylglucuronic acid (MeGlcA) substitution of a xylan main chain for their action. They do not exhibit a significant activity on neutral xylooligosaccharides, arabinoxylan (AraX), or rhodymenan (Rho). In this work, the biochemical characterization of the bacterial Clocl_1795 xylanase from Hungateiclostridium (Clostridium) clariflavum DSM 19732 (HcXyn30A) is presented. Amino acid sequence analysis of HcXyn30A revealed that the enzyme does not contain amino acids known to be responsible for MeGlcA coordination in the -2b subsite of glucuronoxylanases. This suggested that the catalytic properties of HcXyn30A may differ from those of glucuronoxylanases. HcXyn30A shows similar specific activity on glucuronoxylan (GX) and Rho, while the specific activity on AraX is about 1000 times lower. HcXyn30A releases Xyl2 as the main product from the non-reducing end of different polymeric and oligomeric substrates. Catalytic properties of HcXyn30A resemble the properties of the fungal GH30 xylobiohydrolase from Acremonium alcalophilum, AaXyn30A. HcXyn30A is the first representative of a prokaryotic xylobiohydrolase. Its unique specificity broadens the catalytic diversity of bacterial GH30 xylanases. Key points: • Bacterial GH30 xylobiohydrolase from H. clariflavum (HcXyn30A) has been characterized. • HcXyn30A releases xylobiose from the non-reducing end of different substrates. • HcXyn30A is the first representative of bacterial xylobiohydrolase. [ABSTRACT FROM AUTHOR]

The depolymerization of xylo-oligosaccharides to xylose by β-xylosidase and the subsequent ethanol production from xylose are important for reducing inhibition towards cellulase and hemicellulase and for taking full advantage of all sugars in lignocellulose hydrolysate. The activity of β-xylosidase in most cellulases produced by filamentous fungi is usually deficient, and thus recombinant xylose-fermenting Saccharomyces cerevisiae capable of secreting highly active β-xylosidase is increasingly recognized as an excellent candidate for addressing this issue. To this end, a prominent chassis cell, BSPX042, constructed in our previous work with a well-modified downstream metabolic pathway of xylose through multiple chromosome manipulations and beneficial mutations after evolution engineering, was selected as the host. The xylose isomerase coding gene Ru-xylA (where Ru represents the rumen), which was screened from the metagenomics library of bovine rumen contents, was shown to exhibit a high activity level in S. cerevisiae, and the glycoside hydrolase family 3 β-xylosidase gene xyl3A from Penicillium oxalicum was coexpressed in BSPX042. The recombinant strain BSGIBX with the highest extracellular activity of β-xylosidase was determined by comparing different signal peptides. The hydrolysis of xylobiose and xylotriose by BSGIBX culture further confirmed its β-xylosidase activity. BSGIBX can grow and produce ethanol with xylo-oligosaccharides as the sole carbon source. When xylo-oligosaccharides were pretreated by effective xylanase, the majority of the xylo-oligosaccharides were consumed rapidly and produced ~ 19.4 g L−1 ethanol at 48 h with a yield of 0.473 g g−1 consumed sugars in mixture with glucose. These results indicate the successful coexpression of β-xylosidase and xylose isomerase in ethanol-producing S. cerevisiae, and provide theoretical support for our future work in robust industrial yeast strains. [ABSTRACT FROM AUTHOR]

The fast pyrolysis mechanism of xylose, xylobiose and xylan was investigated with combined fast pyrolysis experiments and quantum chemistry calculations. The results indicate that acyclic d -xylose is an important intermediate for the formation of the major pyrolytic products in xylose pyrolysis, i.e., 1,4-anhydro- d -xylopyranose (ADX), furfural (FF) and hydroxyacetaldehyde (HAA). ADX derives from the successive cyclization of d -xylose which is the only source for ADX formation. 3-Deoxy-xylose is the most important intermediate for FF formation. HAA results from the C C bond scission by retro-aldol and cyclic Grob fragment. In addition, the five-membered intermediate derived from the ring-contraction reaction can transform into FF with high selectivity. The dehydrated xylose is also another source for HAA formation. The fast pyrolysis mechanism of xylobiose is similar to that of xylose, and thus similar pyrolytic product distribution can be obtained from them. However, the pyrolytic products of xylan differ significantly from those of xylose and xylobiose, which is ascribed to its high degree of polymerization and the branches in it. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two novel xylanase genes from T. asperellum were expressed for the first time. • XynTR10 and XynTR11 displayed high halophilic and ethanol tolerant. • XynTR11 hydrolyzed xylan/XOS into xylobiose without xylose via transglycosylation. • Glu153/Glu258 and Glu161/Glu252 were the key active sites for XynTR10 and XynTR11. • XynTR11 holds great potential for XOS production from agricultural waste. Effective production of xylooligosaccharides (XOS) with lower proportion of xylose entails unique and robust xylanases. In this study, two novel xylanases from Trichoderma asperellum ND-1 belonging to glycoside hydrolase families 10 (XynTR10) and 11 (XynTR11) were over-expressed in Komagataella phaffii X-33 and characterized to be robust enzymes with high halotolerance and ethanol tolerant. Both enzymes displayed strict substrate specificity towards beechwood xylan and wheat arabinoxylan. (Glu153/Glu258) and (Glu161/Glu252) were key catalytic sites for XynTR10 and XynTR11. Notably, XynTR11 could rapidly degrade xylan/XOS into xylobiose without xylose via transglycosylation. Direct degradation of corncob using XynTR10 and XynTR111 displayed that while XynTR10 yielded 77% xylobiose and 25% xylose, XynTR11 yielded much less xylose (11%) and comparable amounts of xylobiose (63%). XynTR10 or XynTR111 has great potential as a catalyst for bioconversion of xylan-containing agricultural waste into high-value products (biofuel or XOS), which is of significant benefit for the economy and environment. [ABSTRACT FROM AUTHOR]

Bacterial strain Bacillus tequilensis BT21 isolated from marine sediments was found to produce extracellular xylanase. The xynBT21 gene encoding xylanase enzyme was cloned and expressed in Escherichia coli. The gene encoded a protein consisting of 213 amino acid residues with calculated molecular mass of 23.3 kDa. Purified recombinant xylanase had optimum activity at 60 °C and pH=6. The enzyme was highly stable in alkaline pH, at pH=7 it remained 100 % active for 24 h, while its activity increased at pH=8 and 9 during incubation. B. tequilensis BT21 xylanase had alkaline pI of 9.4 and belongs to glycosyl hydrolase family 11. The mode of action of XynBT21 on beechwood xylan and xylooligosaccharides was studied. It hydrolysed xylooligosaccharides and beechwood xylan yielding mainly xylobiose (X2) with a small amount of xylose (X1), indicating that XynBT21 was probably an endo-acting xylanase. Enzymatic hydrolysis using wheat bran as a substrate revealed that xylanase reported here has the potential to produce xylobiose from wheat bran. Xylooligosaccharides, especially xylobiose, have strong bifidogenic properties and are increasingly used as a prebiotic. This is the first report that describes this novel xylanase enzyme from marine B. tequilensis BT21 used for the release of xylobiose from wheat bran.

The present study demonstrates the application of alkali treatment coupled with steam for the extraction of xylan followed by its enzymatic hydrolysis for the production of xylooligosaccharide (XOS) from coconut husk. The chemical analysis of the husk revealed the presence of hemicelluloses, along with cellulose, lignin and ash demonstrating its suitability for XOS extraction. Application of 20% of NaOH coupled with steam treatment for 60 min enabled the fractionation of approximately 93% xylan from the husk. Response surface methodology was employed to optimize the different variables i.e. enzyme concentration, pH, temperature and time for the extraction of XOS from xylan, wherein, enzyme concentration and temperature were the influential variables affecting xylose yield and enzyme concentration, temperature, time and pH were influential variables affecting xylobiose yield significantly. FTIR analysis of the husk also confirmed the presence of hemicelluloses, whereas, the presence of xylan and XOSmix was also confirmed in the extracted mass. In nutshell, the present study was successful in establishing the suitability of coconut husk for extraction of xylan and XOS which can be further used as a prebiotic. [ABSTRACT FROM AUTHOR]

Xylobiose consists of two molecules of xylose and has been highly recognized as a food supplement because it possesses high prebiotic functions. β-xylosidase exhibits enzymatic activity to hydrolyze xylobiose, and the enzyme can also catalyze the reverse reaction in the presence of high concentrations of xylose. Previously, β-xylosidase from Bacillus pumilus IPO (BpXynB), belonging to GH family 43, was employed to produce xylobiose from xylose. To improve the enzymatic efficiency, this study determined the high-resolution structure of BpXynB in a complex with xylobiose and engineered BpXynB based on the structures. The structure of BpXynB deciphered the residues involved in the recognition of the xylobiose. A site-directed mutation at the residue for xylobiose recognition increased the yield of xylobiose by 20% compared to a similar activity of the wild type enzyme. The complex structure of the mutant enzyme and xylobiose provided the structural basis for a higher yield of the engineered protein. This engineered enzyme would enable a higher economic production of xylobiose, and a similar engineering strategy could be applied within the same family of enzymes. [ABSTRACT FROM AUTHOR]

Abstract Obesity is a public concern and is responsible for various metabolic diseases. Xylobiose (XB), an alternative sweetener, is a major component of xylo-oligosaccharide. The purpose of this study was to investigate the effects of XB on obesity and its associated metabolic changes in related organs. For these studies, mice received a 60% high-fat diet supplemented with 15% d-xylose, 10% XB, or 15% XB as part of the total sucrose content of the diet for ten weeks. Body weight, fat and liver weights, fasting blood glucose, and blood lipids levels were significantly reduced with XB supplementation. Levels of leptin and adipokine were also improved and lipogenic and adipogenic genes in mesenteric fat and liver were down-regulated with XB supplementation. Furthermore, pro-inflammatory cytokines, fatty acid uptake, lipolysis, and β-oxidation-related gene expression levels in mesenteric fat were down-regulated with XB supplementation. Thus, XB exhibited therapeutic potential for treating obesity which involved suppression of fat deposition and obesity-related metabolic disorders. [ABSTRACT FROM AUTHOR]

The gene of Pae1263 (2,196 bp, 732 aa) was found from the full-length sequence analysis of bacterium Paenibacillus terrae HPL-003 isolated from soil on Gara Mountain in Korea (CP003107, our previous study). Among the 20 open reading frames (ORFs) related with the xylose substrate, only the recombinant enzyme of ORF Pae1263 showed a 1,4-beta-D-xylosidase activity when all of the ORFs were transformed into E. coli. This gene is considered to be a new 1,4-beta-D-xylosidase because it has up to 93% similarity with other genes of ZP_10240221.1 from Lactococcus raffinolactis 4877 and ZP_11237858.1 from Paenibacillus peoriae in the GenBank blast search. The enzyme activity was confirmed by HPLC in which xylose was produced from xylobiose as a substrate by this recombinant enzyme. Mass production of the recombinant enzyme was done with the construction of the pET22(+)- Pae1263-6H expression vector system from E. coli. This new 1,4-beta-D-xylosidase was highly active at 50°C in a pH range between 6.0 and 8.0 and had thermo-stability for at least 24 h at 50°C and a Km and Vmax of 6.42 mg/mL and 75.76 U/mg on a xylobiose substrate, respectively. [ABSTRACT FROM AUTHOR]

Biotechnological process for co-production of glucose and xylooligosaccharides from sugarcane bagasse generated a xylobiose-rich sugarcane bagasse xylan hydrolysate. However, sugarcane bagasse xylan hydrolysate is a complex mixture and how to isolate and purify xylobiose from sugarcane bagasse xylan hydrolysate is challenging. In the present study, an efficient combined process consisting of resin adsorption and gel filtration chromatography was developed to isolate and purify xylobiose from sugarcane bagasse xylan hydrolysate using a central composite design-based response surface methodology. The process purified xylobiose to 95.74 ± 1.43%, with a recovery of 93.61 ± 3.50%, and achieved decolourization and desalination rates of 77.59 ± 3.79% and 96.85 ± 1.43%, respectively. Mass balance analysis revealed maximum yields of 64.38 ± 3.47 mg (xylobiose), 6.71 ± 2.20 mg (xylotriose) and 6.71 ± 1.70 mg (xylose) from 100 mg of total sugars in sugarcane bagasse xylan hydrolysate. This process may improve the high-value bio-refinery of sugarcane bagasse. [ABSTRACT FROM AUTHOR]

A series of aryl substituted derivatives of xylose and xylobiose was synthesized. Biological tests revealed high insecticidal activity in the resulting compounds. [ABSTRACT FROM AUTHOR]

The feasibility of a simulated moving bed (SMB) technology for the continuous separation of high-purity xylobiose (X2) from the output of a β-xylosidase X1→X2 reaction has recently been confirmed. To ensure high economical efficiency of the X2 production method based on the use of xylose (X1) as a starting material, it is essential to accomplish the comprehensive optimization of the X2-separation SMB process in such a way that its X2 productivity can be maximized while maintaining the X2 product concentration from the SMB as high as possible in consideration of a subsequent lyophilization step. To address this issue, a suitable SMB optimization tool for the aforementioned task was prepared based on standing wave design theory. The prepared tool was then used to optimize the SMB operation parameters, column configuration, total column number, adsorbent particle size, and X2 yield while meeting the constraints on X2 purity, X2 product concentration, and pressure drop. The results showed that the use of a larger particle size caused the productivity to be limited by the constraint on X2 product concentration, and a maximum productivity was attained by choosing the particle size such that the effect of the X2-concentration limiting factor could be balanced with that of pressure-drop limiting factor. If the target level of X2 product concentration was elevated, higher productivity could be achieved by decreasing particle size, raising the level of X2 yield, and increasing the column number in the zones containing the front and rear of X2 solute band. [ABSTRACT FROM AUTHOR]

In order to better understand the pyrolysis behavior of hemicellulose and unveil pyrolytic products distribution at molecular level, xylobiose was selected as a model compound of hemicellulose and relevant degradation processes were theoretically investigated by employing density functional theory (DFT) method. Several important reaction routes including directly bond breaking, Retro-Aldol reaction and Retro-Diels-Alder mechanism were analyzed, and the influence from adjacent xylose on the pyrolytic mechanism of xylobiose was interpreted systematically. The results indicate that the ring-opening of xylose unit dominates in the initial stage, followed by the cleavage of β -1,4-glycosides bond. Retro-Aldol reaction is kinetically favored and therefore leads to the formation of glycolaldehyde. Furfural, on the other hand, is generated via the cleavage of C1 O bond and subsequent ring forming between C2 and C5, which has a lower reaction energy barrier than that of 1-hydroxy-2-propanone. Aldehyde prefers to generate via Retro-Aldol reaction and decarbonylation. Although dehydration reaction is hard to occur in the initial pyrolysis process, it is still the major reaction channel to obtain formaldehyde and 1-hydroxy-2-propanone. [ABSTRACT FROM AUTHOR]

Xylobiose (XB), a xylose dimer, is a low-calorie sweetener with prebiotic activity. Unlike its well-defined biosynthesis and production methods, its sensory characteristics have not been well investigated. This study aims to identify the relative sweetness and sensory profile of XB. XB was prepared as an aqueous solution, and its relative sweetness (RS) compared to 5% sucrose was determined using the 2-alternative forced choice method. The sensory profile was identified by 10 trained panelists using descriptive analysis. The RS of XB was determined to be 0.34. XB was characterized by its yellowness, corn aroma and flavor, and its nurungji (scorched rice) candy flavor. The persistence of sweetness of XB was similar to that of sucrose, but its onset of sweetness was slower. When XB was mixed with sucrose at a ratio of 7:93, the mixture exhibited a similar sensory quality to that of sucrose, thereby making it a useful sucrose complement. [ABSTRACT FROM AUTHOR]

Bacterial strain Bacillus tequilensis BT21 isolated from marine sediments was found to produce extracellular xylanase. The xynBT21 gene encoding xylanase enzyme was cloned and expressed in Escherichia coli. The gene encoded a protein consisting of 213 amino acid residues with calculated molecular mass of 23.3 kDa. Purified recombinant xylanase had optimum activity at 60 °C and pH=6. The enzyme was highly stable in alkaline pH, at pH=7 it remained 100 % active for 24 h, while its activity increased at pH=8 and 9 during incubation. B. tequilensis BT21 xylanase had alkaline pI of 9.4 and belongs to glycosyl hydrolase family 11. The mode of action of XynBT21 on beechwood xylan and xylooligosaccharides was studied. It hydrolysed xylooligosaccharides and beechwood xylan yielding mainly xylobiose (X2) with a small amount of xylose (X1), indicating that XynBT21 was probably an endo-acting xylanase. Enzymatic hydrolysis using wheat bran as a substrate revealed that xylanase reported here has the potential to produce xylobiose from wheat bran. Xylooligosaccharides, especially xylobiose, have strong bifidogenic properties and are increasingly used as a prebiotic. This is the first report that describes this novel xylanase enzyme from marine B. tequilensis BT21 used for the release of xylobiose from wheat bran. [ABSTRACT FROM AUTHOR]

Type 2 diabetes is a major public health concern worldwide. Xylobiose (XB) consists of two molecules of D-xylose and is a major disaccharide in xylooligosaccharides that are used as prebiotics. We hypothesized that XB could regulate diabetes-related metabolic and genetic changes via microRNA expression in db/db mice. For six weeks, C57BL/KsJ-db/db mice received 5% XB as part of the total sucrose content of their diet. XB supplementation improved glucose tolerance with reduced levels of OGTT AUC, fasting blood glucose, HbA1c, insulin, and HOMA-IR. Furthermore, XB supplementation decreased the levels of total triglycerides, total cholesterol, and LDL-C. The expression levels of miR-122a and miR-33a were higher and lower in the XB group, respectively. In the liver, expressions of the lipogenic genes, including, fatty acid synthase (FAS), peroxisome proliferator activated receptor γ (PPARγ), sterol regulatory element-binding protein-1C (SREBP-1C), sterol regulatory element-binding protein-2 (SREBP-2), acetyl-CoA carboxylase (ACC), HMG-CoA reductase (HMGCR), ATP-binding cassette transporter G5/G8 (ABCG5/8), cholesterol 7 alpha-hydroxylase (CYP7A1), and sterol 12-alpha-hydroxylase (CYP8B1), as well as oxidative stress markers, including superoxide dismutase 1 (SOD1), superoxide dismutase 2 (SOD2), glutathione peroxidase (GPX), and catalase, were also regulated by XB supplementation. XB supplementation inhibited the mRNA expressions levels of the pro-inflammatory cytokines, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, interleukin (IL)-6, and monocyte chemoattractant protein (MCP)-1, as well as phosphorylation of c-Jun N-terminal kinase/stress activated protein kinase (JNK/SAPK), p38 mitogen-activated protein kinases (MAPK), and extracellular signal-regulated kinases 1/2 (ERK1/2). These data demonstrate that XB exhibits anti-diabetic, hypolipogenic, and anti-inflammatory effects via regulation of the miR-122a/33a axis in db/db mice. [ABSTRACT FROM AUTHOR]