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|Substrate For (Enzyme):||β-Xylosidase|
High purity Xylobiose 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)
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
Characterization of a novel GH10 xylanase with a carbohydrate binding module from Aspergillus sulphureus and its synergistic hydrolysis activity with cellulase.
Liu, Y., Wang, J., Bao, C., Dong, B. & Cao, Y. (2021). International Journal of Biological Macromolecules, 182, 701-711.
A study was carried out to investigate the characterization of a novel Aspergillus sulphureus JCM01963 xylanase (AS-xyn10A) with a carbohydrate binding module (CBM) and its application in degrading alkali pretreated corncob, rapeseed meal and corn stover alone and in combination with a commercial cellulase. In this study, the 3D structure of AS-xyn10A, which contained a CBM at C-terminal. AS-xyn10A and its CBM-truncated variant (AS-xyn10A-dC) was codon-optimized and over-expressed in Komagaella phaffii X-33 (syn. Pichia pastoris) and characterized with optimal condition at 70°C and pH 5.0, respectively. AS-xyn10A displayed high activity to xylan extracted from corn stover, corncob, and rapeseed meal. The concentration of hydrolyzed xylo-oligosaccharides (XOSs) reached 1592.26 μg/mL, 1149.92 μg/mL, and 621.86 μg/mL, respectively. Xylobiose was the main product (~70%) in the hydrolysis mixture. AS-xyn10A significantly synergized with cellulase to improve the hydrolysis efficiency of corn stover, corncob, and rapeseed meal to glucose. The degree of synergy (DS) was 1.32, 1.31, and 1.30, respectively. Simultaneously, XOSs hydrolyzed with AS-xyn10A and cellulase was improved by 46.48%, 66.13% and 141.45%, respectively. In addition, CBM variant decreased the yields of xylo-oligosaccharide and glucose in rapeseed meal degradation. This study provided a novel GH10 endo-xylanase, which has potential applications in hydrolysis of biomass.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
Xylanase from marine filamentous fungus Pestalotiopsis sp. AN-7 was activated with diluted salt solution like brackish water.
Koh, S., Mizuno, M., Izuoka, Y., Fujino, N., Hamada-Sato, N. & Amano, Y. (2021). Journal of Applied Glycoscience, 68(1), 11-18.
The genus Pestalotiopsis are endophytic fungi that have recently been identified as cellulolytic system producers. We herein cloned a gene coding for a xylanase belonging to glycoside hydrolase (GH) family 10 (PesXyn10A) from Pestalotiopsis sp. AN-7, which was isolated from the soil of a mangrove forest. This protein was heterologously expressed by Pichia pastoris as a host, and its enzymatic properties were characterized. PesXyn10A was produced as a glycosylated protein and coincident to theoretical molecular mass (35.3 kDa) after deglycosylation by peptide-N-glycosidase F. Purified recombinant PesXyn10A exhibited maximal activity at pH 6.0 and 50°C, and activity was maintained at 90 % at pH 5.0 and temperatures lower than 30°C for 24 h. The substrate specificity of PesXyn10A was limited and it hydrolyzed glucuronoxylan and arabinoxylan, but not β-glucan. The final hydrolysis products from birchwood xylan were xylose, xylobiose, and 1,23-α-D-(4-O-methyl-glucuronyl)-1,4-β-D-xylotriose. The addition of metallic salts (NaCl, KCl, MgCl2, and CaCl2) activated PesXyn10A for xylan degradation, and maximal activation by these divalent cations was approximately 160% at a concentration of 5 mM. The thermostability of PesXyn10A significantly increased in the presence of 50 mM NaCl or 5 mM MgCl2. The present results suggest that the presence of metallic salts at a low concentration, similar to brackish water, exerts positive effects on the enzyme activity and thermal stability of PesXyn10A.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
Xylo-oligosaccharides ameliorate high cholesterol diet induced hypercholesterolemia and modulate sterol excretion and gut microbiota in hamsters.
Abdo, A. A. A., Zhang, C., Lin, Y., Liang, X., Kaddour, B., Wu, Q., Li, X., Fan, G., Yang, R., Teng, C., Xu, Y. & Li, W. (2021). Journal of Functional Foods, 77, 104334.
The present study investigated the cholesterol-lowering activity of xylo- oligosaccharides and its associated underlying mechanisms in hamsters. Twenty-four hamsters were randomly divided into three groups and fed one of three diets, namely a low cholesterol diet, a high cholesterol diet (HCD), and an HCD diet with supplementation of 5% xylo-oligosaccharides for 6 weeks. The changes in gut microbiota, fecal neutral and acidic sterols were examined. Results exhibited that xylo- oligosaccharides could significantly reduce plasma total cholesterol, non-high-density lipoprotein cholesterol and total triacylglycerol by 11.24%, 24.89% and 38.72%, respectively (p < 0.05). Such benefits were associated with an increase in fecal outputs of neutral and acidic sterols as well as SCFAs. Furthermore, dietary supplementation with xylo-oligosaccharides could change the composition of gut microbiota. It was therefore concluded that xylo-oligosaccharides supplementation could reduce plasma cholesterol levels, enhance the excretion of neutral and acidic sterols, and promote the production of SCFAs via changing the gut microbiota composition.Hide Abstract
Maize nutrient composition and the influence of xylanase addition.
Melo-Durán, D., Pérez, J. F., González-Ortiz, G., Villagómez-Estrada, S., Bedford, M. R., Graham, H. & Sola-Oriol, D. (2020). Journal of Cereal Science, 97, 103155.
This study assessed differences in nutrient composition, physical characteristics, and xylo-oligosaccharide content with or without xylanase treatment by maize genotype and the grain position on the cob. Ten cobs each from sixteen maize varieties sowed in the same field were collected and classified considering the grain's position on the cob (basal vs apical). The majority of physicochemical characteristics were influenced by an interaction between genetic background and grain position (P < 0.05); however, moisture, crude protein, starch, ash and soluble arabinose:xylose ratio differed between maize varieties and grain on cob position, without interaction. Xylanase addition increased the concentration of soluble compounds and xylotriose content in the aqueous phase following incubation in vitro (P < 0.05) and in the case of xylotriose the amounts released varied with grain position and variety. In conclusion, maize genotype and grain position on the cob significantly influenced chemical composition and oligosaccharide content when treated with xylanase, which may contribute to nutrient variability between maize samples.Hide Abstract
Efficient production of acetylated xylooligosaccharides from Hawthorn kernels by a xylanase from Paecilomyces aerugineus.
Liu, X., Yang, S., Ma, J., Yu, J., Yan, Q. & Jiang, Z. (2020). Industrial Crops and Products, 158, 112962.
Hawthorn (Crataegus pinnatifida) kernels can be utilized as a good source for production of acetylated XOS. A GH family 10 xylanase gene (PaXyn10A) from Paecilomyces aerugineus was cloned and expressed in Pichia pastoris. PaXyn10A shared the highest identity of 77 % with a xylanase from Aspergillus niger. The highest extracellular xylanase activity of 20,100 U/mL with protein concentration of 19 mg/mL was obtained in a 5-L fermentor. PaXyn10A was most active at pH 5.5 and 55°C, respectively. It hydrolyzed different xylans to produce mainly xylooligosaccharidess (XOS) with degree of polymerization 2-6. To produce XOS, hawthorn kernels (HK) were pretreated by steam explosion at 185°C with 25 min, and then hydrolyzed by PaXyn10A. The highest XOS yield of 18.7 g/100 g HK with hydrolysis ratio of 66.8 % was achieved. Xylooligosaccharides from HK were heavily acetylated at positions of 2-, 3-, and 2, 3-. This is a promising strategy for utilization of HK to produce acetylated XOS in an industrial point of view.Hide Abstract
Impact of the disulfide bond on hydrolytic characteristics of a xylanase from Talaromyces thermophiles F1208.
Fan, G., Wu, Q., Li, Q., Sun, B., Ma, Y., Wu, K., Wang, C., Teng, C., Yang, R. & Li, X. (2020). International Journal of Biological Macromolecules, 164, 1748-1757.
A xylanase from Talaromyces thermophiles F1208 (T-Xyn) was used specifically to explore the effects of disulfide bond on hydrolytic activity. The T-Xyn-C122S-C166S mutant does not have the C122-C166 disulfide bond present in wild-type T-Xyn, whereas T-Xyn-T38C-S50C and T-Xyn-T38C-S50C-C122S-C166S mutants have an introduced disulfide bond, C38-C50, to T-Xyn and T-Xyn-C122S-C166S, respectively. The optimum pH of T-Xyn-T38C-S50C and T-Xyn-T38C-S50C-C122S-C166S was lower than that of T-Xyn and T-Xyn-C122S-C166S. The introduction of a disulfide bond caused a decrease in the optimum temperature and thermal stability of T-Xyn. The existence of a disulfide bond has a strong influence on the hydrolysis characteristics of T-Xyn, which caused changes in the composition and proportion of the hydrolysate products. T-Xyn-T38C-S50C produces the highest level of xylose when using beechwood xylan as the substrate, whereas T-Xyn produces the highest level of xylobiose and T-Xyn-T38C-S50C-C122S-C166S produces the largest amount of xylotriose. When birchwood xylan was used as the substrate, the introduction of a disulfide bond increased the content of xylose, decreased the content of xylotriose and a high degree of polymerization (DP ≥ 5) was observed. The hydrolysis of oat-spelt xylan is more complex with the introduction of the disulfide bond causing an increase in the degradation rate of xylotriose.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.
Novel xylanase producing Bacillus strain X2: molecular phylogenetic analysis and its application for production of xylooligosaccharides.
Dhruw, C., Husain, K., Kumar, V., & Sonawane, V. C. (2020). Biotech, 10(8), 1-15.
A Bacillus strain X2 that produced extracellular endo-xylanase (GH 11) (EC: 220.127.116.11) was isolated from the soil of the Northeast India region. This aerobic culture was Gram positive and endospore forming. Chemotaxonomic characterization showed variance with the fatty acid profile of related species in the Bacillus subtilis group. In Bacillus strain X2, distinct occurrence of iso-C14:0 lipids is absent in other related species. The 16S rRNA gene sequence homology showed 99% similarity with Bacillus subtilis subsp. inaquosorum. The phylogenetic analysis by the multilocus sequence analysis (MLSA) of the nucleotide sequence of six concatenated genes (16S rRNA, groEL, gyrA, polC, purH and rpoB) resolved the taxonomic position of the Bacillus strain X2 in the Bacillus subtilis subsp. group. The MLSA showed that it is a member of a clade that includes Bacillus subtilis subsp. stercoris. In in silico DNA–DNA hybridization (DDH), the highest matching score was obtained with Bacillus subtilis subsp. stercoris (87%). The in silico DDH of the genome (G + C 43.7 mol %) shared 48.5%, with Bacillus subtilis subsp. inaquosorum. The MLSA phylogenetic tree and the highest degree of DNA hybridization, indicating that it belongs to the Bacillus subtilis subspecies stercoris.Hide Abstract
Enzymatic Hydrolysis of Xylan from Coffee Parchment in Membrane Bioreactors.
Acosta-Fernández, R., Poerio, T., Nabarlatz, D., Giorno, L., & Mazzei, R. (2020). Industrial & Engineering Chemistry Research, 59(16), 7346-7354.
Xylooligosaccharides (XOs) production from xylan, extracted from coffee parchment, using two stirred tank reactors (STRs) and two membrane bioreactors (MBRs) was studied for the first time. In the reactors, xylanase either free in a solution (E-STR, E-MBR) or covalently immobilized on magnetic nanoparticles (MNP-STR, MNP-MBR) was used. A continuous production of reducing sugars in both MBRs was obtained. In the E-MBR, the same conversion of E-STR at a low substrate concentration (1 mg mL-1) (97%) was obtained. At higher substrate concentration, the conversion increases by a quarter in E-MBR on increasing the residence time and doubles in MNP-MBR by increasing the amount of immobilized enzyme. The unchanged apparent KM (about 8 mg mL-1) showed that the affinity of the enzyme for the substrate was not altered by the immobilization process. In E-MBR, the enzyme/substrate affinity is even improved (KM: 2.58 mg mL-1), thanks to the continuous removal of the inhibition products, present in the initial xylan solution, by the membrane process.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
Isolation and Characterization of a Novel Cold-Active, Halotolerant Endoxylanase from Echinicola rosea Sp. Nov. JL3085T.
He, J., Liu, L., Liu, X. & Tang, K. (2020). Marine Drugs, 18(5), 245.
We cloned a xylanase gene (xynT) from marine bacterium Echinicola rosea sp. nov. JL3085T and recombinantly expressed it in Escherichia coli BL21. This gene encoded a polypeptide with 379 amino acid residues and a molecular weight of ~43 kDa. Its amino acid sequence shared 45.3% similarity with an endoxylanase from Cellvibrio mixtus that belongs to glycoside hydrolases family 10 (GH10). The XynT showed maximum activity at 40°C and pH 7.0, and a maximum velocity of 62 μmoL min−1 mg−1. The XynT retained its maximum activity by more than 69%, 51%, and 26% at 10°C, 5°C, and 0°C, respectively. It also exhibited the highest activity of 135% in the presence of 4 M NaCl and retained 76% of its activity after 24 h incubation with 4 M NaCl. This novel xylanase, XynT, is a cold-active and halotolerant enzyme that may have promising applications in drug, food, feed, and bioremediation industries.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
Oligosaccharides from rice straw and rice husks produced by glycoside hydrolase family 10 and 11 xylanases.
Pattarapisitporn, A., Jaichakan, P. & Klangpetch, W. (2020). Asia-Pacific Journal of Science and Technology, 25(01).
Rice straw (RS) and rice husks (RH) are the by-products obtained from rice farming, which are the remaining non-starch polysaccharides, called cellulose and hemicellulose. The objectives of this study were to investigate the abilities of the glycoside hydrolase family 10 (GH10) and 11 (GH11) commercial xylanases on the production of oligosaccharides from RS and RH by hydrothermal assisted enzymatic hydrolysis. Firstly, RS and RH were pretreated with acetone/ethanol. Then the pretreated biomass was heated by autoclave at 180˚C for 10-30 min. The oligosaccharides content in the RS and RH hydrolysates (HRS and HRH) were analyzed by High Performance Anion Exchange Chromatography (HPAEC-PAD). The results indicated that RS and RH treated for 10 min had shown the highest total oligosaccharides content. After that, the HRS and HRH were hydrolyzed with Ultraflo Max (UM10) and Ultraflo L (UL11), belonged to GH10 and GH11 respectively, under condition at 50˚C pH of 6.0 for 0-4 h. The highest sugar-reducing content was found while incubating HRS and HRH for 1 h with the aforementioned xylanases. The sugar-reducing contents of HRS and HRH treated with UM10 increased up to 0.24% and 0.17%, respectively, whereas those treated with UL11 increased up to 0.18% and 0.14%, respectively. The results revealed that HRS and HRH treated with UM10 had mainly consisted of xylobiose, while those treated with UL11 had mainly consisted of xylotriose. This study has suggested the potential of GH10 and GH11 xylanases on Xylooligosaccharide (XOS) production using RS and RH as alternative sources.Hide Abstract