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|Stability:||> 10 years under recommended storage conditions|
|Substrate For (Enzyme):||endo-1,4-β-Xylanase|
High purity Xylohexaose for use in research, biochemical enzyme assays and in vitro diagnostic analysis.
(Trichoderma longibrachiatum) E-XYAN4 - endo-1,4-β-Xylanase M4 (Aspergillus niger) E-XYRU6 - endo-1,4-β-Xylanase (rumen microorganism) E-XYNBS - endo-1,4-β-Xylanase
(Bacillus stearothermophilus T6) E-XYNACJ - endo-1,4-β-Xylanase (Cellvibrio japonicus) E-XYLNP - endo-1,4-β-Xylanase (Neocallimastix patriciarum) E-XYLATM - endo-1,4-β-Xylanase (Thermotoga maritima) E-BXSEBP - β-Xylosidase (Bacillus pumilus) E-BXSR-1KU - β-D-Xylosidase (Selenomonas ruminantium)
McCleary, B. V. & McGeough, P. (2015). Appl. Biochem. Biotechnol., 177(5), 1152-1163.
The most commonly used method for the measurement of the level of endo-xylanase in commercial enzyme preparations is the 3,5-dinitrosalicylic acid (DNS) reducing sugar method with birchwood xylan as substrate. It is well known that with the DNS method, much higher enzyme activity values are obtained than with the Nelson-Somogyi (NS) reducing sugar method. In this paper, we have compared the DNS and NS reducing sugar assays using a range of xylan-type substrates and accurately compared the molar response factors for xylose and a range of xylo-oligosaccharides. Purified beechwood xylan or wheat arabinoxylan is shown to be a suitable replacement for birchwood xylan which is no longer commercially available, and it is clearly demonstrated that the DNS method grossly overestimates endo-xylanase activity. Unlike the DNS assay, the NS assay gave the equivalent colour response with equimolar amounts of xylose, xylobiose, xylotriose and xylotetraose demonstrating that it accurately measures the quantity of glycosidic bonds cleaved by the endo-xylanase. The authors strongly recommend cessation of the use of the DNS assay for measurement of endo-xylanase due to the fact that the values obtained are grossly overestimated due to secondary reactions in colour development.Hide Abstract
Versatile high resolution oligosaccharide microarrays for plant glycobiology and cell wall research.
Pedersen, H. L., Fangel, J. U., McCleary, B., Ruzanski, C., Rydahl, M. G., Ralet, M. C., Farkas, V., Von Schantz, L., Marcus, S. E., Andersen, M.C. F., Field, R., Ohlin, M., Knox, J. P., Clausen, M. H. & Willats, W. G. T. (2012). Journal of Biological Chemistry, 287(47), 39429-39438.
Microarrays are powerful tools for high throughput analysis, and hundreds or thousands of molecular interactions can be assessed simultaneously using very small amounts of analytes. Nucleotide microarrays are well established in plant research, but carbohydrate microarrays are much less established, and one reason for this is a lack of suitable glycans with which to populate arrays. Polysaccharide microarrays are relatively easy to produce because of the ease of immobilizing large polymers noncovalently onto a variety of microarray surfaces, but they lack analytical resolution because polysaccharides often contain multiple distinct carbohydrate substructures. Microarrays of defined oligosaccharides potentially overcome this problem but are harder to produce because oligosaccharides usually require coupling prior to immobilization. We have assembled a library of well characterized plant oligosaccharides produced either by partial hydrolysis from polysaccharides or by de novo chemical synthesis. Once coupled to protein, these neoglycoconjugates are versatile reagents that can be printed as microarrays onto a variety of slide types and membranes. We show that these microarrays are suitable for the high throughput characterization of the recognition capabilities of monoclonal antibodies, carbohydrate-binding modules, and other oligosaccharide-binding proteins of biological significance and also that they have potential for the characterization of carbohydrate-active enzymes.Hide Abstract
Valorization of peach palm (Bactris gasipaes Kunth) waste: Production of antioxidant xylooligosaccharides.
Vieira, T. F., Corrêa, R. C. G., Moreira, R. D. F. P. M., Peralta, R. A., de Lima, E. A., Helm, C. V., Garcia, J. A. A., Bracht, A. & Peralta, R. M. (2021). Waste and Biomass Valorization, 1-14.
In Brazil, the production and consumption of palm heart, especially from the Bactris gasipaes Kunth, generates a large number of lignocellulosic by-products. This study reports the obtainment of xylooligosaccharides (XOS) from xylans extracted from these residues. Xylans from peach palm waste (inner sheath and peel) were extracted using a mild alkali treatment with recovery yields of 82% and 80%, respectively. XOS were obtained through enzymatic hydrolysis employing a commercial xylanase with yields from xylan inner sheath and xylan peel of 50.1% and 48.8%, respectively. The antioxidant potential of XOS was measured employing five of the most commonly used procedures. In overall terms, the XOS from the xylans of peach palm wastes showed higher antioxidant capacity than the XOS obtained from the commercial xylans. The chemical structures of the XOS were determined by mass spectrometry (ESI–MS). The ESI-MS spectra suggest that XOS with grouped xylose or arabinose units ranging from 2 to 5 (differing by 132 Da) and as sodium adduct ions [M + Na]+ in the range of 100-1000 m/z. These results indicate that peach palm wastes can be explored to XOS production, which could be applied as natural antioxidants in functional food and pharmaceutical preparations.Hide Abstract
Phylogenetic, functional and structural characterization of a GH10 xylanase active at extreme conditions of temperature and alkalinity.
Talens-Perales, D., Jiménez-Ortega, E., Sánchez-Torres, P., Sanz-Aparicio, J. & Polaina, J. (2021). Computational and Structural Biotechnology Journal, 19, 2676-2686.
Endoxylanases active under extreme conditions of temperature and alkalinity can replace the use of highly pollutant chemicals in the pulp and paper industry. Searching for enzymes with these properties, we carried out a comprehensive bioinformatics study of the GH10 family. The phylogenetic analysis allowed the construction of a radial cladogram in which protein sequences putatively ascribed as thermophilic and alkaliphilic appeared grouped in a well-defined region of the cladogram, designated TAK Cluster. One among five TAK sequences selected for experimental analysis (Xyn11) showed extraordinary xylanolytic activity under simultaneous conditions of high temperature (90°C) and alkalinity (pH 10.5). Addition of a carbohydrate binding domain (CBM2) at the C-terminus of the protein sequence further improved the activity of the enzyme at high pH. Xyn11 structure, which has been solved at 1.8 Å resolution by X-ray crystallography, reveals an unusually high number of hydrophobic, ionic and hydrogen bond atomic interactions that could account for the enzyme’s extremophilic nature.Hide Abstract
Xylanase-polymer conjugates as new catalysts for xylooligosaccharides production from lignocellulose.
Hu, Y., Shi, C. Y., Xun, X. M., Huang, B. R., You, S., Wu, F. A. & Wang, J. (2021). Biochemical Engineering Journal, 171, 108025.
In the past few years, xylooligosaccharides produced from lignocellulosic biomass have attracted great attention. Enzyme catalysis is widely used because of its mild reaction conditions. In order to solve the shortcomings of poor stability and high cost of enzyme, a carrier-free enzyme immobilization technology was introduced. For this purpose, protein-polymer conjugates, kinds of carrier-free immobilized enzymes, were first established by growing poly (N-isopropylacrylamide) chains on xylanase using a grafting-from method, to obtain reusable and high-value xylanase. SDS-PAGE and circular dichroism spectra showed the successful preparation of xylanase-PNIPAAm conjugates, and the integrity of the protein secondary structure. The remaining activity of the xylanase-PNIPAAm conjugates after heat treatment (90°C) for 60 min was approximately 20 % higher than that of the free xylanase, and a higher pH stability was obtained in the pH range of 2-8. The remaining activity of xylanase-PNIPAAm conjugates was more than 60 % after recycling 5 times. In addition, the mulberry bark synergistic treated by xylanase-PNIPAAm conjugates and cellulase was studied. More than 99.95 % yield of XOS in the degree of polymerization range of 1-3 was produced from mulberry bark. Overall, the construction of xylanase-PNIPAAm conjugates provides a novel method to produce xylooligosaccharides from waste biomass.Hide Abstract
Valorisation of walnut shell and pea pod as novel sources for the production of xylooligosaccharides.
Cebin, A. V., Ralet, M. C., Vigouroux, J., Karača, S., Martinić, A., Komes, D. & Bonnin, E. (2021). Carbohydrate Polymers, 263, 117932.
According to the high interest in agro-industrial waste reutilisation, underutilised lignocellulosic materials, such as walnut shell (WS) and pea pod (PP), come in focus. The aim of this paper was to evaluate WS and PP as sources for the production of xylooligosaccharides (XOS). Hemicelluloses from WS and PP were recovered by combining varying parameters of delignification and alkaline extraction. At optimal recovery conditions, the fractions were further hydrolysed to XOS using GH11 endo-xylanase, by varying time and enzyme concentration. Xylose was predominant in the monomeric composition of the obtained hemicelluloses, building low-branched (arabino)glucuronoxylan, in WS exclusively, while in PP some xyloglucan as well. Delignification was essential for high recovery of total xylose from the materials, up to at least 70%. High xylan conversions were obtained for 24 h hydrolysis, resulting in xylobiose and xylotriose when using low enzyme concentration, while in xylose and xylobiose with high enzyme concentration.Hide Abstract
Evaluation of Xylooligosaccharides Production for a Specific Degree of Polymerization by Liquid Hot Water Treatment of Tropical Hardwood.
Jang, S. K., Kim, J. H., Choi, J. H., Cho, S. M., Kim, J. C., Kim, H. & Choi, I. G. (2021). Foods, 10(2), 463.
Eucalyptus pellita is known as attractive biomass, and it has been utilized for eucalyptus oil, furniture, and pulp and paper production that causes a significant amount of byproducts. Liquid hot water treatment depending on combined severity factor (CSF) was subjected to isolate hemicellulose fraction from E. pellita and to produce xylooligosaccharides (XOS). The xylan extraction ratio based on the initial xylan content of the feedstock was maximized up to 77.6% at 170°C for 50 min condition (CSF: 1.0), which had accounted for XOS purity of 76.5% based on the total sugar content of the liquid hydrolysate. In this condition, the sum of xylobiose, xylotriose, and xylotetraose which has a low degree of polymerization (DP) of 2 to 4 was determined as 80.6% of the total XOS. The highest XOS production score established using parameters including the xylan extraction ratio, XOS purity, and low DP XOS ratio was 5.7 at CSF 1.0 condition. XOS production score evaluated using the CSF is expected to be used as a productivity indicator of XOS in the industry (R-squared value: 0.92).Hide Abstract
Structure-based substrate specificity analysis of GH11 xylanase from Streptomyces olivaceoviridis E-86.
Fujimoto, Z., Kishine, N., Teramoto, K., Tsutsui, S. & Kaneko, S. (2021). Applied Microbiology and Biotechnology, 1-10.
Although many xylanases have been studied, many of the characteristics of xylanases toward branches in xylan remain unclear. In this study, the substrate specificity of a GH11 xylanase from Streptomyces olivaceoviridis E-86 (SoXyn11B) was elucidated based on its three-dimensional structure. Subsite mapping suggests that SoXyn11B has seven subsites (four subsites on the - side and three subsites on the + side), and it is one longer than the GH10 xylanase from S. olivaceoviridis (SoXyn10A). SoXyn11B has no affinity for the subsites at either end of the scissile glycosidic bond, and the sugar-binding energy at subsite - 2 was the highest, followed by subsite + 2. These properties were very similar to those of SoXyn10A. In contrast, SoXyn11B produced different branched oligosaccharides from bagasse compared with those of SoXyn10A. These branched oligosaccharides were identified as O-β-D-xylopyranosyl-(1→4)-[O-α-L-arabinofuranosyl-(1→3)]-O-β-D-xylopyranosyl-(1→4)-β-D-xylopyranosyl-(1→4)-β-D-xylopyranose (Ara3Xyl4) and O-β-D-xylopyranosyl-(1→4)-[O-4-O-methyl-α-D-glucuronopyranosyl-(l→2)]-β-D-xylopyranosyl-(1→4)-β-D-xylopyranosyl-(1→4)-β-D-xylopyranose (MeGlcA3Xyl4) by nuclear magnetic resonance (NMR) and electrospray ionization mass spectrometry (ESI-MS) and confirmed by crystal structure analysis of SoXyn11B in complex with these branched xylooligosaccharides. SoXyn11B has a β-jerryroll fold structure, and the catalytic cleft is located on the inner β-sheet of the fold. The ligand-binding structures revealed seven subsites of SoXyn11B. The 2- and 3-hydroxy groups of xylose at the subsites + 3, + 2, and – 3 face outwards, and an arabinose or a glucuronic acid side chain can be linked to these positions. These subsite structures appear to cause the limited substrate specificity of SoXyn11B for branched xylooligosaccharides.Hide Abstract
Optimized bioconversion of xylose derived from pre-treated crop residues into xylitol by using Candida boidinii.
Bedő, S., Fehér, A., Khunnonkwao, P., Jantama, K. & Fehér, C. (2021). Agronomy, 11(1), 79.
Crop residues can serve as low-cost feedstocks for microbial production of xylitol, which offers many advantages over the commonly used chemical process. However, enhancing the efficiency of xylitol fermentation is still a barrier to industrial implementation. In this study, the effects of oxygen transfer rate (OTR) (1.1, 2.1, 3.1 mmol O2/(L × h)) and initial xylose concentration (30, 55, 80 g/L) on xylitol production of Candida boidinii NCAIM Y.01308 on xylose medium were investigated and optimised by response surface methodology, and xylitol fermentations were performed on xylose-rich hydrolysates of wheat bran and rice straw. High values of maximum xylitol yields (58-63%) were achieved at low initial xylose concentration (20-30 g/L) and OTR values (1.1-1.5 mmol O2/(L × h)). The highest value for maximum xylitol productivity (0.96 g/(L × h)) was predicted at 71 g/L initial xylose and 2.7 mmol O2/(L × h) OTR. Maximum xylitol yield and productivity obtained on wheat bran hydrolysate were 60% and 0.58 g/(L × h), respectively. On detoxified and supplemented hydrolysate of rice straw, maximum xylitol yield and productivity of 30% and 0.19 g/(L × h) were achieved. This study revealed the terms affecting the xylitol production by C. boidinii and provided validated models to predict the achievable xylitol yields and productivities under different conditions. Efficient pre-treatments for xylose-rich hydrolysates from rice straw and wheat bran were selected. Fermentation using wheat bran hydrolysate and C. boidinii under optimized condition is proved as a promising method for biotechnological xylitol production.Hide Abstract
Multiple transporters and glycoside hydrolases are involved in arabinoxylan-derived oligosaccharide utilization in Bifidobacterium pseudocatenulatum.
Saito, Y., Shigehisa, A., Watanabe, Y., Tsukuda, N., Moriyama-Ohara, K., Hara, T., Matsumoto, S., Tsuji, H. & Matsuki, T. (2020). Applied and Environmental Microbiology, 86(24).
Arabinoxylan hydrolysates (AXH) are the hydrolyzed products of the major components of the dietary fiber arabinoxylan. AXH include diverse oligosaccharides varying in xylose polymerization and side residue modifications with arabinose at the O-2 and/or O-3 position of the xylose unit. Previous studies have reported that AXH exhibit prebiotic properties on gut bifidobacteria; moreover, several adult-associated bifidobacterial species (e.g., Bifidobacterium adolescentis and Bifidobacterium longum subsp. longum) are known to utilize AXH. In this study, we tried to elucidate the molecular mechanisms of AXH utilization by Bifidobacterium pseudocatenulatum, which is a common bifidobacterial species found in adult feces. We performed transcriptomic analysis of B. pseudocatenulatum YIT 4072T, which identified three upregulated gene clusters during AXH utilization. The gene clusters encoded three sets of ATP-binding cassette (ABC) transporters and five enzymes belonging to glycoside hydrolase family 43 (GH43). By characterizing the recombinant proteins, we found that three solute-binding proteins of ABC transporters showed either broad or narrow specificity, two arabinofuranosidases hydrolyzed either single- or double-decorated arabinoxylooligosaccharides, and three xylosidases exhibited functionally identical activity. These data collectively suggest that the transporters and glycoside hydrolases, encoded in the three gene clusters, work together to utilize AXH of different sizes and with different side residue modifications. Thus, our study sheds light on the overall picture of how these proteins collaborate for the utilization of AXH in B. pseudocatenulatum and may explain the predominance of this symbiont species in the adult human gut.Hide Abstract
Xylooligosaccharides production by commercial enzyme mixture from agricultural wastes and their prebiotic and antioxidant potential.
Ávila, P. F., Martins, M., de Almeida Costa, F. A. & Goldbeck, R. (2020). Bioactive Carbohydrates and Dietary Fibre, 24, 100234.
Advancement in industrial biotechnology offers potential opportunities for economic utilization of agro industrial biomass for the production of value-added products. Xylooligosaccharides (XOS) are non-digestible food ingredients with prebiotic properties for selectively promoting the growth of probiotics providing many health benefits and several applications on food and pharmaceutical industry. The present study deal with enzymatic production of XOS from xylan extracted from different agroindustrial wastes, namely sugarcane straw (SS) and coffee husk (CH) using an optimized enzymatic mixture with endo-xylanase (GH11), α-l-arabinofuranosidase (GH51) and Feruloyl Esterase (CE1). The XOS profile concentration was quantified by HPAEC-PAD using standard (X2-X6) from Megazyme®. The efficient enzymatic mixture achieved a high total XOS concentration using SS xylan (10.23 ± 0.56 g/L) and CH xylan (8.45 ± 0.65 g/L). Three of four probiotic cultures of Lactobacillus and Bifidobacterium tested were able to utilize XOS produced from agricultural wastes and showed remarkable growth in the media containing XOS, consuming preferentially the X2 and X3 fractions as the sole source of carbon. The XOS produced also exhibited a considerable resistance to hydrolysis of digestive enzymes, as well as an concentration dependent anti-oxidant activity achieving until 78% in a XOS concentration of 2 g. L−1. Thus, the results showed that XOS produced from these agricultural residues have great prebiotic potential and good antioxidant activity; therefore, it can be used in food-related applications as functional ingredients.Hide Abstract
Improved development in magnetic Xyl-CLEAs technology for biotransformation of agro-industrial by-products through the use of a novel macromolecular cross-linker.
Hero, J. S., Morales, A. H., Perotti, N. I., Romero, C. M. & Martinez, M. A. (2020). Reactive and Functional Polymers, 154, 104676.
Cross-Linked Enzyme Aggregates (CLEAs) technologies for enzyme immobilization are influenced by mass transference problems as the degree of molecular crosslinking achieved strongly affects the enzyme exposure to the substrates. Therefore, this work seeks to improve the accessibility of high molecular weight substrates by using macromolecular cross-linkers to the synthesis of a xylanolytic biocatalyst. After confirming that commercial polymers used as macromolecular cross-linkers significantly upgraded the xylanase activity from a crude preparation, a novel biopolymer/amyloid protein complex (BPAP) extracted from a microbial biofilm was used producing a remarkable recovery (83%) of the enzyme activity. A response surface methodology was applied to contrast the features of a previously developed biocatalyst with glutaraldehyde (GA@Xyl-CLEAs) and a novel one synthesized with BPAP combined with functionalized magnetic nanoparticles: mBPAP@Xyl-CLEAs. It was observed that the crosslinking agent used was the factor that most affected the enzyme activity. Also, the mBPAP system showed a similar and higher hydrolytic activity than those synthesized with GA, which was not affected by the mNPs/protein ratio. Finally, the mBPAP@Xyl-CLEAs were successfully tested for xylooligosaccharides production from agroindustrial-derived substrates, making this technology a promising practice to obtain green and suitable biocatalysts.Hide Abstract
An integrated process to produce prebiotic xylooligosaccharides by autohydrolysis, nanofiltration and endo-xylanase from alkali-extracted xylan.
Lian, Z., Wang, Y., Luo, J., Lai, C., Yong, Q., & Yu, S. (2020). Bioresource Technology, 314, 123685.
Alkali-extracted xylan from lignocellulosics is a promising feedstock for production of prebiotic xylooligosaccharides (XOS). An integrated process was established combining autohydrolysis, nanofiltration and xylanase hydrolysis. Results show that after autohydrolysis 48.37% of xylan was degraded into oligomers and dissolved into the autohydrolysate, of which 57.83% were XOS. By-products and xylose were removed by nanofiltration with discontinuous diafiltration, while high recovery yields of XOS (84.15%) and xylan (87.45%) were obtained. High yields of XOS were obtained by adding xylanase to the autohydrolysates; after enzymatic hydrolysis an XOS yield of 96-98% was obtained. The enzymatic hydrolysates showed positive prebiotic effects on B. adolescentis with an increase in cell concentration by 4.8-fold after fermentation for 24 h. The main products were short-chain fatty acids with carbon balanced during the whole fermentation process. This integrated strategy resulted in a final XOS conversion of 41.22% contrasted to the initial xylan in raw alkali-extracted xylan.Hide Abstract
Enzyme synergy for the production of arabinoxylo-oligosaccharides from highly substituted arabinoxylan and evaluation of their prebiotic potential.
Bhattacharya, A., Ruthes, A., Vilaplana, F., Karlsson, E. N., Adlecreutz, P. & Stålbrand, H. (2020). LWT, 131, 109762.
Wheat bran arabinoxylan can be converted by enzymatic hydrolysis into short arabinoxylo-oligosaccharides (AXOS) with prebiotic potential. Alkali extraction of arabinoxylan from wheat-bran offers advantages in terms of yield and results in arabinoxylan with highly-substituted regions which has been a challenge to hydrolyse using endoxylanases. We show that this hurdle can be overcome by selecting an arabinoxylanase that attacks these regions. The yield of AXOS can be increased by enzyme synergy, involving the hydrolysis of some arabinoxylan side groups. Thus, arabinoxylanase (CtXyl5At) from Clostridium thermocellum, belonging to subfamily 34 of glycoside hydrolase (GH) family 5 was investigated pertaining to its specificity for highly-substituted regions in the arabinoxylan-backbone. CtXyl5At preferentially hydrolysed the water-soluble fraction of alkali-extracted arabinoxylan. AXOS with DP 2-4 were determined as major products from CtXyl5At catalyzed hydrolysis. Increase in AXOS yield was observed with enzyme synergy, involving an initial treatment of soluble arabinoxylan with a GH43 α-l-arabinofuranosidase from Bifidobacterium adolescentis termed BaAXHd3 (30°C, 6h), followed by hydrolysis with CtXyl5At (50°C, 24h). The prebiotic potential of AXOS was shown by growth analysis using the human gut bacteria Bifidobacterium adolescentis ATCC 15703 and Roseburia hominis DSM 6839. Importantly, AXOS were utilized by the bacteria and short-chain fatty acids were produced.
CaXyn30B from the solventogenic bacterium Clostridium acetobutylicum is a glucuronic acid-dependent endoxylanase.
Crooks, C., Long, L. & St John, F. J. (2020). BMC Research Notes, 13(1), 1-6.
Objective: We previously described the structure and activity of a glycoside hydrolase family 30 subfamily 8 (GH30-8) endoxylanase, CaXyn30A, from Clostridium acetobutylicum which exhibited novel glucuronic acid (GA)-independent activity. Immediately downstream from CaXyn30A is encoded another GH30-8 enzyme, CaXyn30B. While CaXyn30A deviated substantially in the highly conserved β7-α7 and β8-α8 loop regions of the catalytic cleft which are responsible for GA-dependence, CaXyn30B maintains these conserved subfamily 8 amino acid residues thus predicting canonical GA-dependent activity. In this report, we show that CaXyn30B functions as a canonical GA-dependent GH30-8 endoxylanase in contrast to its GA-independent neighbor, CaXyn30A. Results: A clone expressing the catalytic domain of CaXyn30B (CaXyn30B-CD) exhibited GA-dependent endoxylanase activity. Digestion of glucuronoxylan generated a ladder of aldouronate limit products as anticipated for canonical GA-dependent GH30-8 enzymes. Unlike the previously described CaXyn30A-CD, CaXyn30B-CD showed no activity on arabinoxylan or the generation of appreciable neutral oligosaccharides from glucuronoxylan substrates. These results are consistent with amino acid sequence comparisons of the catalytic cleft and phylogenetic analysis.Hide Abstract
Enzyme-aided xylan extraction from alkaline-sulfite pretreated sugarcane bagasse and its incorporation onto eucalyptus kraft pulps.
Cornetti, A. A. A., A., Ferraz, A. & Milagres, A. M. (2020). Carbohydrate Research, 108003.
Hemicellulose-rich substrates produced in the lignocellulose biorefinery context can yield macromolecular xylan structures with assorted application in the chemical industry. Xylan presents natural affinity to cellulose and its incorporation onto fibers increases the physical processability of pulp; however, current studies diverge on how molar mass affects xylan interaction with cellulose. In the current work, xylans with varied structural characteristics were prepared from alkaline-sulfite pretreated sugarcane bagasse with aid of an alkaline-active xylanase and selective precipitations using different ethanol concentrations. Prepared xylan fractions, containing low levels of lignin contamination (4-9%) and molar masses ranging from 2.3 kDa to 34 kDa, were incorporated onto eucalyptus pulp fibers up to 4.7 g xylan/100 g pulp. The efficiency of xylan incorporation onto cellulosic fibers was dependent on the xylan structures, where low molar mass and low substitution degree favored high incorporation levels.Hide Abstract
High Enzymatic Recovery and Purification of Xylooligosaccharides from Empty Fruit Bunch via Nanofiltration.
Wijaya, H., Sasaki, K., Kahar, P., Rahmani, N., Hermiati, E., Yopi, Y., Ogino, C. Prasetya, B. & Kondo, A. (2020). Processes, 8(5), 619.
Xylooligosaccharides (XOS) are attracting an ever-increasing amount of interest for use as food prebiotics. In this study, we used efficient membrane separation technology to convert lignocellulosic materials into a renewable source of XOS. This study revealed a dual function of nanofiltration membranes by first achieving a high yield of xylobiose (a main component of XOS) from alkali-pretreated empty fruit bunch (EFB) hydrolysate, and then by achieving a high degree of separation for xylose as a monosaccharide product. Alkali pretreatment could increase the xylan content retention of raw EFB from 23.4% to 26.9%, which eventually contributed to higher yields of both xylobiose and xylose. Nanofiltration increased the total amount of XYN10Ks_480 endoxylanase produced from recombinant Streptomyces lividans 1326 without altering its specific activity. Concentrated XYN10Ks_480 endoxylanase was applied to the recovery of both xylobiose and xylose from alkali-pretreated EFB hydrolysate. Xylobiose and xylose yields reached 41.1% and 17.3%, respectively, and when unconcentrated XYN10Ks_480 endoxylanase was applied, those yields reached 35.1% and 8.3%, respectively. The last step in nanofiltration was to separate xylobiose over xylose, and 41.3 g.L−1 xylobiose (90.1% purity over xylose) was achieved. This nanofiltration method should shorten the processes used to obtain XOS as a high-value end product from lignocellulosic biomass.Hide Abstract
Production of xylooligosaccharides from xylan catalyzed by endo-1, 4-β-D-xylanase-immobilized nanoscale carbon, silica and zirconia matrices.
Shivudu, G., Chandraraj, K. & Selvam, P. (2020). Molecular Catalysis, 484, 110745.
Nanoscale materials of carbon, silica and zirconia were used to immobilize a recombinant endo-1, 4-β-D-xylanase (XynC) of B. subtilis KCX006. The adsorption of endo-1, 4-β-D-xylanase on nanomaterials of carbon, silica and zirconia followed the pseudo-second-order kinetic model. The activation energies for adsorption of endoxylanase on carbon, silica and zirconia nanomaterials were 9.94 kJ mol−1, 40.44 kJ mol−1 and 16.33 kJ mol−1 respectively. The recovered activity (RA) of endoxylanase immobilized on carbon, silica and zirconia nanomaterials was in the range of 52%–92%. The endoxylanase immobilized on zirconia nanoparticles showed maximum RA. All immobilized endoxylanase showed optimum activity at pH 6.6 similar to that of free/soluble endoxylanase. But compared to free endoxylanase, all immobilized endoxylanase had broad optimum temperature range (50-65°C) for catalytic activity. The Michaelis-Menten constant (Km) increased for all immobilized endoxylanase due to substrate diffusion limit. The endoxylanase immobilized on above nanomaterials was used repeatedly for XOS production from xylan. All immobilized endoxylanase produced X2-X6 and substituted XOS similar to free endoxylanase from beechwood xylan and extracted crude xylans from sorghum and sugarcane bagasse. The endoxylanase immobilized on above nanoparticles did not lose activity after five batches of repeated use. The results showed that endoxylanase immobilized on carbon, silica and zirconia matrices would be useful for production of XOS by enzyme recycling.Hide Abstract
Production of xylooligosaccharides and monosaccharides from hydrogen peroxide-acetic acid-pretreated poplar by two-step enzymatic hydrolysis.
Hao, X., Wen, P., Wang, J., Wang, J., You, J. & Zhang, J. (2020). Bioresource Technology, 297, 122349.
The severe pretreatment of poplar makes xylan difficult to utilize efficiently. In this work, poplar was pretreated by hydrogen peroxide-acetic acid (HPAC) with H2SO4 as catalyst to remove lignin, and the solid residues were used to produce xylooligosaccharides (XOS) and monosaccharides by two-step xylanase and cellulase hydrolysis. The results indicated that higher H2SO4 concentrations in the HPAC pretreatment of poplar afforded stronger lignin removal ability. An increased XOS yield of 19.8% was obtained from 200 mM H2SO4-catalyzed poplar by xylanase and the XOS purity was high, with a very low xylose/XOS ratio of 0.14. Higher glucose (75.2%) and xylose (61.4%) yields were obtained from the HPAC-pretreated poplar using 50 mM H2SO4 as catalyst. Finally, 16.9 g XOS and 296.4 g glucose were produced from 1 kg poplar by xylanase and cellulase. This study provides a method for producing functional XOS and monosaccharides from poplar using a simple reduced-pollution strategy.Hide Abstract
Cytosolic Acetyl-CoA generated by ATP-citrate lyase is essential for acetylation of cell wall polysaccharides.
Zhong, R., Cui, D., Richardson, E. A., Phillips, D. R., Azadi, P., Lu, G. & Ye, Z. H. (2020). Plant and Cell Physiology, 61(1), 64-75.
Plant cell wall polysaccharides, including xylan, glucomannan, xyloglucan and pectin, are often acetylated. Although a number of acetyltransferases responsible for the acetylation of some of these polysaccharides have been biochemically characterized, little is known about the source of acetyl donors and how acetyl donors are translocated into the Golgi, where these polysaccharides are synthesized. In this report, we investigated roles of ATP-citrate lyase (ACL) that generates cytosolic acetyl-CoA in cell wall polysaccharide acetylation and effects of simultaneous mutations of four Reduced Wall Acetylation (RWA) genes on acetyl-CoA transport into the Golgi in Arabidopsis thaliana. Expression analyses of genes involved in the generation of acetyl-CoA in different subcellular compartments showed that the expression of several ACL genes responsible for cytosolic acetyl-CoA synthesis was elevated in interfascicular fiber cells and induced by secondary wall-associated transcriptional activators. Simultaneous downregulation of the expression of ACL genes was demonstrated to result in a substantial decrease in the degree of xylan acetylation and a severe alteration in secondary wall structure in xylem vessels. In addition, the degree of acetylation of other cell wall polysaccharides, including glucomannan, xyloglucan and pectin, was also reduced. Moreover, Golgi-enriched membrane vesicles isolated from the rwa1/2/3/4 quadruple mutant were found to exhibit a drastic reduction in acetyl-CoA transport activity compared with the wild type. These findings indicate that cytosolic acetyl-CoA generated by ACL is essential for cell wall polysaccharide acetylation and RWAs are required for its transport from the cytosol into the Golgi.Hide Abstract