Search

Sourdough fermentation of bran can overcome the technological problems encountered in bread making but favors the activity of endogenous β-glucanase leading to a degradation of β-glucans. This study investigated the effects of high-intensity ultrasound (US) pretreatment of oat bran (OB) and barley bran (BB) on its β-glucans content, properties, and preservation in processing, as well as on the acidification kinetics of bran sourdough fermentation and on its application in flatbread. To reduce β-glucanase activity, OB and BB (15% water suspensions) were US-pretreated prior to sourdough fermentation. The acidification kinetics, the microbial viable cell count, and the total titratable acidity (TTA) of the sourdough were determined. The total β-glucans content of bran, sourdough, and bread, as well as water solubility and the molecular weight (Mw) of untreated and US-pretreated bran, were investigated. The physical properties of control wheat and composite flatbreads were compared. The US-pretreatment increased the acidification rate (30%) and TTA (51%) of OB sourdough, however, decreased the acidification rate of BB (18%). After the US-pretreatment of OB and BB, the total (11.5–12.3%) and water-soluble β-glucans (31–40%) increased while their Mw decreased (7–21.7%). In sourdough and flatbread prepared with US-pretreated OB/BB, 93–95% and 90–98% of β-glucans were retained, respectively, compared to 64–72% and 82–92% in control samples. The US-pretreatment and/or sourdough fermentation of OB and BB resulted in flatbreads of higher specific volume (8–22%) and cohesiveness (11–20%) while reduced hardness (40–55%) and chewiness (51–73%) compared to their control bread. [ABSTRACT FROM AUTHOR]

Arabinoxylan (AX) and resistant starch (RS) are essential components of dietary fiber, that affect the nutritional value, health benefits, and end-use quality of wheat. Fully understanding their genetic basis is crucial for enhancing wheat quality through marker-assisted selection or other means. In this study, a genome-wide association study of AX-related traits i.e., total-arabinoxylan (TAX), water-extractable arabinoxylan (WEAX), and water un-extractable arabinoxylan (WUAX) of whole wheat flour (WWF) and refined wheat flour (RWF), as well as RS content was conducted using 205 elite wheat varieties (lines) with a composite map (24,355 SNPs) constructed with 90 K single nucleotide polymorphism (SNP) arrays. The broad-sense heritability (H2) of RS was 48.50%, whereas that of AX-related traits ranged from 55.66 to 77.23%. A total of 115 loci for RS and AX related traits, comprising 322 marker-trait associations (MTAs), were identified on all 21 chromosomes across four environments, explaining 5.52–12.40% of the phenotypic variance. Among them, 19 stable loci were significant in two or more environments, including one for RWF-TAX, six for RWF-WEAX, four for RWF-WUAX, three for WWF-TAX, two for WWF-WUAX, and three for RS. Furthermore, 17 co-located chromosomal regions related to the measured traits were stably detected in multiple environments. These findings may be used for further research and to improve wheat quality in wheat breeding programs. [ABSTRACT FROM AUTHOR]

Bifidobacterium adolescentis gene BAD_1527 has previously been suggested to code for a β-xylosidase (Kobayashi et al., Mar Drugs 18:174, 2020). Our detailed investigation of the substrate specificity of the GH43_22 protein using a wide spectrum of natural and artificial substrates showed that the enzyme hydrolyzed neither linear xylooligosaccharides nor glucuronoxylan. Xylose was released only from the artificial 4-nitrophenyl β-D-xylopyranoside (1.58 mU/mg). The corresponding α-L-arabinofuranoside was by three orders of magnitude better substrate (2.17 U/mg). Arabinose was the only monosaccharide liberated from arabinoxylan and α-1,3- or α-1,2-singly arabinosylated xylooligosaccharides. Moreover, the enzyme efficiently debranched sugar beet arabinan and singly arabinosylated α-1,5-L-arabinooligosaccharides, although short linear α-1,5-L-arabinooligosaccharides were also slowly degraded. On the other hand, debranched arabinan, arabinogalactan as well as 2,3-doubly arabinosylated main chain residues of arabinan and arabinoxylan did not serve as substrates. Thus, the enzyme encoded by the BAD_1527 gene is a typical α-L-arabinofuranosidase of AXH-m specificity. Key points: BAD_1527 gene encodes a protein releasing xylose from NPX, but not natural substrates L-Arabinose is released from natural substrates, similarly to other GH43_22 members The enzyme debranches arabinoxylan, branched arabinan and derived oligosaccharides [ABSTRACT FROM AUTHOR]

The xylanolytic enzymes Clocl_1795 and Clocl_2746 from glycoside hydrolase (GH) family 30 are highly abundant in the hemicellulolytic system of Acetivibrio clariflavus (Hungateiclostridium, Clostridium clariflavum). Clocl_1795 has been shown to be a xylobiohydrolase AcXbh30A releasing xylobiose from the non-reducing end of xylan and xylooligosaccharides. In this work, biochemical characterization of Clocl_2746 is presented. The protein, designated AcXyn30B, shows low sequence similarity to other GH30 members and phylogenetic analysis revealed that AcXyn30B and related proteins form a separate clade that is proposed to be a new subfamily GH30_12. AcXyn30B exhibits similar specific activity on glucuronoxylan, arabinoxylan, and aryl glycosides of linear xylooligosaccharides suggesting that it is a non-specific xylanase. From polymeric substrates, it releases the fragments of degrees of polymerization (DP) 2-6. Hydrolysis of different xylooligosaccharides indicates that AcXyn30B requires at least four occupied catalytic subsites for effective cleavage. The ability of the enzyme to hydrolyze a wide range of substrates is interesting for biotechnological applications. In addition to subfamilies GH30_7, GH30_8, and GH30_10, the newly proposed subfamily GH30_12 further widens the spectrum of GH30 subfamilies containing xylanolytic enzymes. Key points: Bacterial GH30 endoxylanase from A. clariflavus (AcXyn30B) has been characterized AcXyn30B is non-specific xylanase hydrolyzing various xylans and xylooligosaccharides Phylogenetic analysis placed AcXyn30B in a new GH30_12 subfamily [ABSTRACT FROM AUTHOR]

The economically viable and sustainable production of xylo-oligosaccharides (XOS) still challenges researchers. The enzymatic hydrolysis of the hemicellulosic fraction is one of the most investigated methods, since it is a more efficient process, easier to control, and less harmful to the environment, which are the main variables to be investigated. This study evaluated the application of the bamboo culm of Dendrocalamus latiflorus in optimizing xylo-oligosaccharides production by the enzymatic hydrolysis of arabinoxylan extracted from this plant matrix using a low-cost commercial enzyme cocktail. Applying a 2% substrate load, 50 °C temperature, pH 5.0, enzymatic load of 7.5 mg of protein/g of xylan, for only 24 h of hydrolysis were the ideal conditions to obtain a high concentration of short-chain xylo-oligosaccharides, especially xylobiose and xylotriose (oligomers with greater prebiotic effect). The low amount of xylose and the lack of inhibitory compounds such as furfural and hydroxymethylfurfural also indicate the high purity of the XOS obtained (~ 97%) without the need for purification processes that could raise costs and make the process economically unfeasible. [ABSTRACT FROM AUTHOR]

Arabinoxylans (AXs) are hemicellulosic polysaccharides consisting of a linear backbone of β-1,4-linked xylose residues branched by high content of α-L-arabinofuranosyl (Araf) residues along with other side-chain substituents, and are abundantly found in various agricultural crops especially cereals. The efficient bioconversion of AXs into monosaccharides, oligosaccharides and/or other chemicals depends on the synergism of main-chain enzymes and de-branching enzymes. Exo-α-L-arabinofuranosidases (ABFs) catalyze the hydrolysis of terminal non-reducing α-1,2-, α-1,3- or α-1,5- linked α-L-Araf residues from arabinose-substituted polysaccharides or oligosaccharides. ABFs are critically de-branching enzymes in bioconversion of agricultural biomass, and have received special attention due to their application potentials in biotechnological industries. In recent years, the researches on microbial ABFs have developed quickly in the aspects of the gene mining, properties of novel members, catalytic mechanisms, methodologies, and application technologies. In this review, we systematically summarize the latest advances in microbial ABFs, and discuss the future perspectives of the enzyme research. [ABSTRACT FROM AUTHOR]

Brewers' spent grain is an important source of non-starch polysaccharides, such as arabinoxylans. In this paper, a fraction rich in arabinoxylans was extracted from brewers' spent grain (BSG-AX) by alkaline medium; was characterized by FTIR spectroscopy, scanning electronic microscopy (SEM), and zeta potential; and was used to prepare fourteen thermoplastic films by addition of two plasticizers (glycerol and polypropylene glycol) and a defoamer agent (coconut oil). All films were characterized by FTIR spectroscopy, SEM, and thermogravimetric analysis (TGA). Activation energy (Ea) of the thermal film's degradation were determined using four models (Broido, Horowitz-Metzger, Coats-Redfern, and Kissigner-Akahira-Sunose), which provide overall kinetic data. Likewise, microbiological analysis of films was performed for assessing their safety. FTIR spectra of BSG-AX films confirm the presence of distinctive functional groups for arabinoxylan, whereas their morphology shows a homogeneous surface structure. Zeta-potential measures suggest that BSG-AX can be considered as a neutral polysaccharide between pH 3 to 10 (values from − 3.44 to − 9.17 mV). Two stages of mass loss were observed in the plasticized films and three for the control (at 113–174 °C, 215–350 °C, and 487–598 °C). The addition of the plasticizer and defoamer agents increases the Ea of the films; namely, the films show greater thermal stability. Besides, the microbiological analysis suggests that the BSG-AX films are safe (absence of total coliforms and 102 CFU g−1 of aerobic mesophylls). In conclusion, plasticized films prepared with BSG-AX have characteristics such as resistance to a wide range of temperatures and can be used as packaging materials. [ABSTRACT FROM AUTHOR]

Purpose: Prebiotic foods can be used to increase production of short-chain fatty acids (SCFA) in the gut. Of the SCFA, propionate is credited with the strongest anorectic activity. In previous work, a 50/50 blend of inulin and arabinoxylan was produced (I + AX) that significantly increased propionate production in an in vitro gut model. This study sought to establish whether chronic consumption of a prebiotic blend of I + AX decreases appetite and energy intake and increases intestinal propionate production in human participants. Methods: MIXSAT (clinicaltrials.gov id: NCT02846454, August 2016) was a double-blind randomised acute-within-chronic crossover feeding trial in healthy adult men (n = 20). Treatments were 8 g per day I + AX for 21 days or weight-matched maltodextrin control. The primary outcome measure was perceived satiety and appetite during an acute study visit. Secondary outcomes were energy intake in an ad libitum meal, faecal SCFA concentration, and faecal microbiota composition. Results: Perceived satiety and appetite were not affected by the intervention. I + AX was associated with a reduction in energy intake in an ad libitum meal, increased faecal SCFA concentration, and an increase in cell counts of Bifidobacteria, Lactobacilli, and other microbial genera associated with health. Implications: Chronic consumption of this blend of prebiotics decreased energy intake in a single sitting. Further studies are needed to confirm mechanism of action and to determine whether this might be useful in weight control. [ABSTRACT FROM AUTHOR]

α-L-Arabinofuranosidases (Abfs) play a crucial role in the degradation of hemicelluloses, especially arabinoxylans (AX). Most of the available characterized Abfs are from bacteria, while fungi, as natural decomposers, contain Abfs with little attention given. An arabinofuranosidase (ThAbf1), belonging to the glycoside hydrolase 51 (GH51) family, from the genome of the white-rot fungus Trametes hirsuta, was recombinantly expressed, characterized, and functionally determined. The general biochemical properties showed that the optimal conditions for ThAbf1 were pH 6.0 and 50°C. In substrate kinetics assays, ThAbf1 preferred small fragment arabinoxylo-oligosaccharides (AXOS) and could surprisingly hydrolyze di-substituted 23,33-di-L-arabinofuranosyl-xylotriose (A2,3XX). It also synergized with commercial xylanase (XYL) and increased the saccharification efficiency of arabinoxylan. The crystal structure of ThAbf1 indicated the presence of an adjacent cavity next to the catalytic pocket which led to the ability of ThAbf1 to degrade di-substituted AXOS. The narrow binding pocket prevents ThAbf1 from binding larger substrates. These findings have strengthened our understanding of the catalytic mechanism of GH51 family Abfs and provided a theoretical foundation for the development of more efficient and versatile Abfs to accelerate the degradation and biotransformation of hemicellulose in biomass. Key points: • ThAbf1 from Trametes hirsuta degraded di-substituted arabinoxylo-oligosaccharide. • ThAbf1 performed detailed biochemical characterization and kinetics. • ThAbf1 structure has been obtained to illustrate the substrate specificity. [ABSTRACT FROM AUTHOR]

Ultrasound-assisted extraction (UAE) was used to obtain arabinoxylan (AX) from brewers' spent grain (BSG) with a higher yield, altered structural characteristics, and improved techno-functional properties. Results showed that an UAE procedure working at 400 W for 15 min under a 60% duty cycle could increase the AX yield by 52.41% compared with a traditional alkaline extraction without sonication. Concomitantly, UAE-AX developed a degraded Mw of 2741 kDa, a changed conformation of less molecular asymmetry and a decreased mean particle size from 12.56 to 4.993 μm. The rheological properties of UAE-AX aqueous solution were improved, leading to higher viscosity and gel-forming capacity of the AX stabilized emulsions. As a result, UAE-AX addition could reduce the mean droplet size to 6.40 μm and better stabilize the emulsion under various conditions than traditional alkaline extracted AX. Thus, the results proved UAE to be a promising method for extracting AX with increased emulsifying capacity from BSG. [ABSTRACT FROM AUTHOR]

Xylose is an abundant bioresource for obtaining diverse chemicals and added-value products. The production of xylose from green alternatives like enzymatic hydrolysis is an important step in a biorefinery context. This research evaluated the synergism among four classes of hydrolytic purified enzymes—endo-1,4-β-xylanase, α-l-arabinofuranosidase, β-xylosidase, and α-d-glucuronidase—over hydrolysis of glucuronoarabinoxylan (GAX) obtained from brewers' spent grain (BSG) after alkaline extraction and ethanol precipitation. First, monosaccharides, uronic acids and glycosidic-linkages of alkaline extracted GAX fraction from BSG were characterized, after that different strategies based on the addition of one or two families of enzymes—endo-1,4-β-xylanase (GH10 and GH11) and α-l-arabinofuranosidase (GH43 and GH51)—cooperating with one β-xylosidase (GH43) and one α-d-glucuronidase (GH67) into enzymatic hydrolysis were assessed to obtain the best yield of xylose. The xylose release was monitored over time in the first 90 min and after a prolonged reaction up to 48 h of reaction. The highest yield of xylose was 63.6% (48 h, 40 ℃, pH 5.5), using a mixture of all enzymes devoid of α-l-arabinofuranosidase (GH43) family. These results highlight the importance of GH51 arabinofuranosidase debranching enzyme to allow a higher cleavage of the xylan backbone of GAX from BSG and their synergy with 2 endo-1,4-β-xylanase (GH10 and GH11), one β-xylosidase (GH43) and the inclusion of one α-d-glucuronidase (GH67) in the reaction system. Therefore, this study provides an environmentally friendly process to produce xylose from BSG through utilization of enzymes as catalysts. [ABSTRACT FROM AUTHOR]

Valorisation of bio-based materials derived from agricultural and industrial side-streams or waste-streams is a basis of circular economy. However, the success of it depends on the full understanding of materials and finding their optimal way of processing. Barley husk is a side-stream waste material derived from the starch and ethanol production. This study is focused on the processability of the arabinoxylan extracted from barley husk using the electrospinning technique to produce thin xylan-poly(vinyl alcohol) fibres. As a comparison, lignin-free xylan of beech wood was used. The properties of spinning solutions and resulting nanofibrous mats were assessed by using rheological measurements, FTIR spectroscopy, scanning electron microscopy and contact angle measurements. It was found that solubility plays a crucial role in the spinnability of xylan extracts. Decrease in viscosity of arabinoxylan achieved by decreasing its concentration was found to improve the jet stability but at the same time, to reduce the diameter of spun fibre. Hydrophilicity of nanofibrous mats were strongly affected by the type of xylan and solvent used. The xylan-based nanofibres have specific properties that could be used for developing value-added applications, such as material for scaffolds for tissue engineering, drug delivery, medical implants, biosensors, wound dressing, water filtration and packaging or further process into carbon nanofibres. [ABSTRACT FROM AUTHOR]

Main conclusion: The feruloylarabinoxylan deposition was initiated at the formation of the secondary cell wall, especially S2 layer in moso bamboo, which may affect crosslinking between cell wall components and plant growth. Hemicelluloses, major components of plant cell walls that are hydrogen bonded to cellulose and covalently bound to lignin, are crucial determinants of cell wall properties. Especially in commelinid monocotyledons, arabinoxylan is often esterified with ferulic acid, which is essential to crosslinking with cell wall components. However, the deposition patterns and localization of ferulic acid during cell wall formation remain unclear. In this study, developing moso bamboo (Phyllostachys pubescens) culms were used to elucidate deposition patterns of hemicelluloses including feruloylarabinoxylan. Ferulic acid content peaked with cessation of elongation growth, and thereafter decreased and remained stable as culm development proceeded. During primary cell wall (PCW) formation, xyloglucan and (1,3;1,4)-β-glucan signals were detected in all tissues. Along with culm development, arabinoxylan and feruloylarabinoxylan signals were sequentially observed in the protoxylem, vascular fibers and metaxylem, and parenchyma. Feruloylarabinoxylan signals were observed slightly later than arabinoxylan signals. Arabinoxylan signals were observed throughout the compound middle lamella and secondary cell wall (SCW), whereas the feruloylarabinoxylan signal was localized to the S2 layer of the SCW. These results indicate that the biosynthesis of hemicelluloses is regulated in accordance with cell wall layers. Feruloylarabinoxylan deposition may be initiated at the formation of SCW, especially S2 layer formation. Ferulic acid-mediated linkages of arabinoxylan-arabinoxylan and arabinoxylan-lignin would arise during SCW formation with the cessation of elongation growth. [ABSTRACT FROM AUTHOR]

Polysaccharides are polymers of sugars linked by glycosidic bonds. They have many nutritional benefits, including prebiotic effects, anti-inflammation, and gut microbiota modulation. Molecular structure investigation helps to understand polysaccharides' functional, conformational properties and biological activities, facilitating their applications in food and nutraceuticals products. Date fruit (Phoenix dactylifera L.) is an ancient plant cultivated in tropical and subtropical areas. The most abundant bioactive compounds of date fruit are polysaccharides. Several investigations reported that date polysaccharides are biologically active compounds. Date flesh contains around 14% polysaccharide; it constitutes 80% of date seed weight (dry based). Date flesh polysaccharides consist of a particular type of (1→3)-β-D-glucopyranosyl residues with (1→6)-linked branched saccharide residues. Date seed also contains xylan as the primary hemicellulose polymer. Xylan structurally consists of β-1,4-linked D-xylose as the main string with different side chains like L-arabinose, D-galactose, and acetyl groups. The structural analysis of polysaccharides is possible through several specialized techniques. Molecular weight-based separation, monosaccharide composition, linkage patterns, anomeric configuration, and sequences of monosaccharides are the essential properties to be characterized in these investigations. The current review collects comprehensive information about date polysaccharides' chemical and nutritional properties. [ABSTRACT FROM AUTHOR]

Purpose: Brewers' spent grain (BSG) represents the largest by-product of the brewing industry. Its utilisation as an animal feed has become less practical today; however, its high fibre and protein content make it a promising untapped resource for human nutrition. BSG contains mainly insoluble fibre. This fibre, along with protein, is trapped with the complex lignocellulosic cell structure and must be solubilised to release components which may be beneficial to health through modulation of the gut microbiota. Methods: In this study, the application of a simultaneous saccharification and fermentation process for the extraction and solubilisation of arabinoxylan from BSG is demonstrated. Results: Processing of the BSG was varied to modulate the physicochemical and molecular characteristic of the released arabinoxylan. The maximum level of arabinoxylan solubilisation achieved was approximately 21%, compared to the unprocessed BSG which contained no soluble arabinoxylan (AX). Concentration of the solubilised material produced a sample containing 99% soluble AX. Samples were investigated for their microbiome modulating capacity in in-vitro faecal fermentation trials. Many samples promoted increased Lactobacillus levels (approx. twofold). One sample that contained the highest level of soluble AX was shown to be bifidogenic, increasing the levels of this genus approx. 3.5-fold as well as acetate (p = 0.018) and propionate (p < 0.001) production. Conclusion: The findings indicate that AX extracted from BSG has prebiotic potential. The demonstration that BSG is a source of functional fibre is a promising step towards the application of this brewing side-stream as a functional food ingredient for human nutrition. [ABSTRACT FROM AUTHOR]

Among different cereals, oat is becoming more popular due to its unique composition and health benefits. The increase in oat production is associated with an increase in related side streams, comprising unutilized biomass that is rich in valuable components, such as polysaccharides, proteins, and antioxidants. To valorize such biomass, it is fundamental that side streams enter back into the food production chain, in respect of the circular economy model. Here, we propose the use of soluble and insoluble oat-production side-stream in suspensions and emulsions, avoiding any further extraction, fractionation, and/or chemical derivatization. Our approach further increases the value of these side streams. To this aim, we first studied the effect of thermal and mechanical processes on the behavior and properties of both soluble and insoluble oat side-stream fractions in water and at air/water interface. Then, we characterized the emulsifying and stabilizing abilities of these materials in oil-in-water emulsions. Interestingly, we found that the insoluble fraction was able to form stable suspensions and emulsions after mechanical treatment. The oil droplets in the emulsions were stabilized by anchoring at the surface of the insoluble particles. On the other hand, the soluble fraction formed only stable viscous solutions. Finally, we demonstrated that the two fractions can be combined to increase the storage stability of the resulting emulsion. Our results highlight that oat production side streams can be used as novel bio-based emulsifiers, showing the great potential behind the underutilized cereal-side-stream biomass. [ABSTRACT FROM AUTHOR]

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

Enzymatic extraction of arabinoxylans (AXs) is an attractive and environmentally friendly extraction option, in which technical considerations (yield and purity) have been coupled with environmental concerns. Amano HC 90 and Cellulase were combined to evaluate their interactive effects on AX extraction from destarched, deproteinised bran (DSDPB). A response surface methodology was used to obtain the optimal extraction conditions. The experimental data fit well with the predicted values and the model adequately represented the actual relationship among the measured parameters. The extraction yield and AX content in the extract under optimal conditions (double-enzyme dose of 920 U/g, pH of 3.0, extraction temperature of 35.0 °C; extraction time of 6 h; and DSDPB to liquid ratio of 1:30) were 40.73 ± 0.09% and 75.88 ± 0.11%, respectively. The double-enzymatic extraction method of AX from fresh corn fibre was more efficient than the chemical method. [ABSTRACT FROM AUTHOR]

Radioactive gold-198 is a useful diagnostic and therapeutic agent. Gold in the form of nanoparticles possesses even more exciting properties. This work aimed at arabinoxylan-mediated synthesis and biodistribution study of radioactive gold nanoparticles (198AuNPs). The particles were synthesized by mixing suspension of arabinoxylan with H198AuCl4 without use of any additional reducing and stabilizing agents. An aqueous suspension of arabinoxylan was added to a H198AuCl4 solution, which resulted in reduction of Au3+ to 198AuNPs. Biodistribution was studied in vitro and in rabbit. The particles having exceptional stability were readily formed. Highest radioactivity was recorded in spleen after 3 h followed by liver, heart, kidney, and lungs after i.v. administration. After 24 h, the activity was not detectable in the spleen; it accumulated in the liver. However, after oral administration, the activity mainly accumulated in the colon. In serum proteins, the distribution was α1-globulin 6.5%, α2-globulin ~ 2%, β-globulin ~ 1%, γ-globulin 0.7%, and albumin 0.7% of the administered dose. This indicates a low protein binding implying high bioavailability of the particles. The cytotoxicity study showed that the particles were inactive against HeLa cell line and Agrobacteriumtumefaciens. Highly stable 198AuNPs reported in this work have the potential for targeting the colon. They show affinity for globulins, the property that can be used in the study of the immune system. [ABSTRACT FROM AUTHOR]

The main components of the non-starch polysaccharide (NSP) fraction of wheat flour are arabinoxylan (AX) and β-glucan. These are also present in other cereal grains, but their proportions vary with AX being the major component in wheat and rye and β-glucan in barley and oats. Therefore, it was hypothesised that these NSPs could act synergistically when fermented in vitro at the ratios present in the major foods consumed, resulting in increased prebiotic activity. AX and β-glucan were therefore tested in in vitro fermentation studies to assess their prebiotic activity when used individually and/or in different ratios. Short-chain fatty-acids (SCFAs) produced from in vitro fermentation were measured using HPLC and bacterial populations were measured using flow cytometry with fluorescence in situ hybridisation (Flow-FISH). Fermentation of AX alone resulted in a significant bifidogenic activity and increased concentrations of SCFAs, mainly acetate, after 8–24 h of fermentation, however β-glucan alone did not show prebiotic activity. The greatest prebiotic activity, based on concentration of total SCFAs and increases in total bacteria as well as beneficial Bifidobacterium and Clostridium coccoides/Eubacterium groups, was observed when AX and β-glucan were combined at a 3:1 ratio, which corresponds to their ratios in wheat flour which is major source of cereal fibre in the diet. This indicates that the population of bacteria in the human GI tract may be modulated by the composition of the fibre in the diet, to maximise the prebiotic potential. [ABSTRACT FROM AUTHOR]

Water-extracted arabinoxylans (WEAXs) of different varieties and structures have important effects on wheat end products. However, the functional performances of WEAXs, particularly relating to prebiotic potential, are not yet clear. The present study compared the structural features, physicochemical properties, and prebiotic potential of WEAXs from three wheat varieties, which were used as special wheat varieties to make steamed buns, bread flour, and noodles. The results showed that WEAX-1, WEAX-2, and WEAX-3, derived from Jinqiang wheat, American red hard spring wheat, and Australian white wheat, respectively, had different structural properties, gelation properties, and prebiotic potential. WEAX-3 had a low arabinose to xylose (A/X) ratio (0.49), high ferulic acid content (2300 μg/g), and excellent gelation capacity. WEAX-2 had a high A/X ratio (0.62), low ferulic acid content (1300 μg/g), and poor gelation capacity. When fermented with human feces, WEAX-3 significantly increased the numbers of bifidobacteria and lactobacilli and increased the production of short-chain fatty acids (SCFAs), while WEAX-2 had weaker effects on the number of beneficial bacteria and SCFAs production (P < 0.05). The physicochemical properties and prebiotic potential of WEAXs depended strongly on their structural properties. WEAX with a low A/X ratio and a high ferulic acid content showed excellent gelation property and a strong prebiotic potential. [ABSTRACT FROM AUTHOR]

Chemical characterization of arabinoxylan extracted using a novel combination of alkali extraction and purification methods provides insight into the effectiveness of this novel combination of methods. Arabinoxylan was extracted from three byproducts of the cereal industry: wheat (Triticum aestivum L.) bran, maize (Zea mays L.) bran, and dried distillers grain. The proximate composition, sugar profile, molecular weight, polydispersity index, and linkages were determined for all three types of arabinoxylan. The purities of the extracted arabinoxylan were as follows: 730 g kg−1 for wheat bran arabinoxylan, 850 g kg−1 for maize bran arabinoxylan, and 580 g kg−1 for dried distillers grain arabinoxylan. The arabinose to xylose ratio for all arabinoxylan extracts was 0.51. The maize bran arabinoxylan had the highest MW (7700333), and the dried distillers grain arabinoxylan had the lowest MW (5900000). The purity of the arabinoxylan obtained in this experiment is a clear indication of the effectiveness of the novel combination of alkali extraction and purification methods developed in this study. [ABSTRACT FROM AUTHOR]

Arabinofuranosidase plays an essential role in the process of hydrolysis of arabinoxylan (AX). Thermostable, versatile, and efficient arabinofuranosidase is thus of great interest for the biorefinery industry. A GH51 arabinofuranosidase, Abf51, from Hungateiclostridium clariflavum DSM 19732 was heterogeneously expressed in Escherichia coli. Abf51 was found to have an optimal pH and temperature of 6.5 and 60 °C, respectively, with very high thermostability. At the optimal working temperature (60 °C), Abf51 retained over 90% activity after a 2-day incubation and over 60% activity after a 6-day incubation. Abf51 could effectively remove the arabinofuranosyls from three kinds of AX oligosaccharides [23-α-l-arabinofuranosyl-xylotriose (A2XX), 32-α-l-arabinofuranosyl-xylobiose (A3X), and 2333-di-α-l-arabinofuranosyl-xylotriose (A2 + 3XX)], which characterized as either single substitution or double substitution by arabinofuranosyls on terminal xylopyranosyl units. The maximal catalytic efficiency (Kcat/Km) was observed using p-nitrophenyl-α-l-arabinofuranoside (pNPAF) as a substrate (205.0 s−1 mM−1), followed by using A3X (22.8 s−1 mM−1), A2XX (6.9 s−1 mM−1), and A2 + 3XX (0.5 s−1 mM−1) as substrates. Moreover, the presence of Abf51 significantly stimulated the saccharification level of AX (18.5 g L−1) up to six times along with a β-xylanase as well as a β-xylosidase. Interestingly, in our survey of top thermostable arabinofuranosidases, most members were found from GH51, probably due to their owning of (β/α)8-barrel architectures. Our results suggested the great importance of GH51s as candidates for thermostable, versatile, and efficient arabinofuranosidases toward industry application. [ABSTRACT FROM AUTHOR]

The effects of water-extractable arabinoxylans (WEAXs) with different molecular weights on the physicochemical properties and structure of wheat gluten were studied, a transition between β-turns in β-leaves in the structure of gluten has been demonstrated by Fourier transform infrared spectroscopy when WEAX samples were added. The ratio of weakly hydrogen-bonded β-sheets to strongly hydrogen-bonded β-sheets tended to decrease with increasing WEAX content. FT-Raman analysis demonstrated other changes in the structure of gluten concerning β-structures, the conformation of the disulfide bridges, and aromatic amino acid environments; these changes were dependent on the molecular weight of the WEAX. Native WEAXs of different molecular weights that are present as discrete fragments of the cell wall have had a negative effect on the properties of gluten. However, low molecular weight WEAX has helped gluten maintain the left-left conformation of its disulfide bonds. In addition, the gluten elasticity was reduced by the native WEAX to make it softer, but the WEAX low molecular weight impeded this process and improved the gluten network. [ABSTRACT FROM AUTHOR]

Main conclusion: Uneven distribution of AX and BG in lateral and longitudinal dimensions of a wheat grain was observed by three-dimensional MS imaging, presumably related to specific physicochemical properties of cell walls.Arabinoxylans (AX) and β-glucans (BG) are the main hemicelluloses that comprise the primary walls of starchy endosperm. These components are not evenly distributed in the endosperm, and the impact of their distribution on cell wall properties is not yet fully understood. Combined with on-tissue enzymatic degradation of the cell walls, mass spectrometry imaging (MSI) was used to monitor the molecular structure of AX and BG in thirty consecutive cross-sections of a mature wheat grain. A 3D image was built from the planar images, showing the distribution of these polymers at the full-grain level, both in lateral and longitudinal dimensions. BGs were more abundant at the vicinity of the germ and in the central cells of the endosperm, while AX, and especially highly substituted AX, were more abundant close to the brush and in the cells surrounding the crease (i.e., the transfer cells). Compared with the previously reported protocol, significant improvements were made in the tissue preparation to better preserve the shape of the fragile sections. This allowed to us achieve a good-quality 3D reconstruction from the consecutive 2D images. By providing a continuous view of the molecular distribution of the cell wall components across and along the grain, the three-dimensional images obtained by MSI may help understand the structure-function relationships of cell walls. The method should be readily extendable to other parietal polymers by selecting the appropriate enzymes. [ABSTRACT FROM AUTHOR]

Main conclusion: Methyl-jasmonate induces large increases in p-coumarate linked to arabinoxylan in Brachypodium and in abundance of GT61 and BAHD family transcripts consistent with a role in synthesis of this linkage.Jasmonic acid (JA) signalling is required for many stress responses in plants, inducing large changes in the transcriptome, including up-regulation of transcripts associated with lignification. However, less is known about the response to JA of grass cell walls and the monocot-specific features of arabinoxylan (AX) synthesis and acylation by ferulic acid (FA) and para-coumaric acid (pCA). Here, we show that methyl-jasmonate (MeJA) induces moderate increases in FA monomer, > 50% increases in FA dimers, and five-sixfold increases in pCA ester-linked to cell walls in Brachypodium callus. Direct measurement of arabinose acylated by pCA (Araf-pCA) indicated that most or all the increase in cell-wall pCA was due to pCA ester-linked to AX. Analysis of the RNA-seq transcriptome of the callus response showed that these cell-wall changes were accompanied by up-regulation of members of the GT61 and BAHD gene families implicated in AX decoration and acylation; two BAHD paralogues were among the most up-regulated cell-wall genes (seven and fivefold) after 24 h exposure to MeJA. Similar responses to JA of orthologous BAHD and GT61 transcripts are present in the RiceXPro public expression data set for rice seedlings, showing that they are not specific to Brachypodium or to callus. The large response of AX-pCA to MeJA may, therefore, indicate an important role for this linkage in response of primary cell walls of grasses to JA signalling. [ABSTRACT FROM AUTHOR]

Objectives: To optimize the expression of type A ferulic acid esterase (FaeA) from Aspergillus niger in Pichia pastoris X-33 using codon optimization.Results: Recombinant FaeA was purified from the fermentation broth, with the maximum specific activity of 48.4 ± 0.1 U mg−1. Adding it during mashing process for beer brewing raised the filtration rate by 14.5% while the turbidity and viscosity declined by 22 and 6.9%, respectively. Addition of FaeA increased the concentrations of free ferulic acid (FA) and arabinoxylan (AX) in the wort, while the polymeric arabinoxylans content declined significantly.Conclusions: Recombinant FaeA was capable to prevent the oxidative gelation of PAX formation by breaking the cross-linking of FA among AX chains and improve the filtration performance of wort. [ABSTRACT FROM AUTHOR]

Improving the nutritional quality and health benefits of food has been of increasing interest globally over the last decade. Staple cereal foods are the major sources of dietary fiber and a recent study identified the Chinese wheat cultivar Yumai-34 as having unusually high levels of water-extractable arabinoxylan (WE-AX) and total arabinoxylan (TOT-AX) in flour. Crosses were therefore made between this variety and three Central European varieties (Lupus, Mv-Mambo, Ukrainka) and the physical properties (test weight, thousand-kernel weight, flour yield, kernel hardness), composition (protein, gluten, WEAX, total AX) and processing quality (gluten index, Zeleny sedimentation, Farinograph parameters) of the grain were compared for thirty-one breeding lines (F7–F9) and the four parents in a 3-year field experiment (2013–2015). Increases of 0.5% in the WE-AX content and 1% in the content of total AX content of the flour were achieved, with an improvement in dough properties. The thousand-kernel weight, protein content, gluten content, Zeleny sedimentation and water absorption of the flour also increased in many lines, while three of the lines had yields that were competitive with the official control varieties, making them suitable for registration. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the effects of two cereal soluble dietary fibres (SDF), wheat arabinoxylan (AX) and oat-mixed linkage glucans (MLG), on fermentative end-products and bacterial community profiles of the porcine caecum (Cae) and distal colon (DC). We hypothesised that feeding pigs these SDF would stimulate Cae and DC carbohydrate fermentation, resulting in a modification of the resident bacterial communities. Methods: Five groups of six pigs were each fed one diet based on wheat starch (WS) only, or treatment diets in which some WS was replaced by 10 % AX, or 10 % MLG, a combination of 5 % AX:5 % MLG (AXMLG), or completely replaced with ground whole wheat. Post-euthanasia, Cae and DC digesta were collected for analysis of fermentative end-products, and bacterial community profiles were determined by 16S rRNA gene amplicon 454 pyrosequencing. Results: Across all the SDF-containing diets, predominantly in the proximal region of the large intestine, Prevotella, Lactobacillus, Mitsuokella and Streptococcus were most significantly influenced ( P < 0.05), while notable changes were observed for the Ruminococcaceae and Lachnospiraceae families in the Cae and DC. The addition of MLG or AXMLG had the greatest effect of influencing bacterial profiles, reducing sequence proportions assigned to the genus Clostridium, considered detrimental to gut health, with associated increases in short-chain fatty acid and reduced ammonia concentrations. Conclusions: This study demonstrated how the cereal SDF AX and MLG altered the large intestinal bacterial community composition, particularly proximally, further giving insights into how diets rich in specific complex carbohydrates shift the bacterial population, by increasing abundance and promoting greater diversity of those bacteria considered beneficial to gut health. [ABSTRACT FROM AUTHOR]

Background: Rye arabinoxylans (AXs) might be used as baking improvers for gluten-free (GF) bread. However, their extraction process still needs to be improved. Objective and methods: The aim of this study was to simplify AX extraction of rye bran by varying temperature and pH and evaluate its chemical and rheological properties for application in GF bread. Results and conclusion: The results demonstrated that higher amounts of AX and impurities were extracted with the increasing pH and temperature. AX yield reached values up to 3.3 g AX/100 g bran. Highest ferulic acid (FA) content (117.27 ± 1.46 mg/100 g) was achieved at the mildest extraction conditions (30 °C and 0.17 M NaOH). A/X ratio of isolates ranged between 0.53 and 0.57 and the gluten content between 81.30 and 216.78 ppm. Rheological measurements revealed typical pseudoplastic behavior of isolates. AX extracted at 30 °C and 0.17 M NaOH showed a slightly higher initial viscosity in comparison with the other isolates but was still inferior to carboxylmethylcellulose (CMC) and hydroxypropyl methylcellulose (HPMC). [ABSTRACT FROM AUTHOR]

Background: Mucoadhesion is an important property that helps oral drug delivery system to remain attached with buccal mucosa and hence to improve the delivery of the drug. The current study was designed to achieve the thiol modification of Arabinoxylan (ARX) and to develop a mucoadhesive oral film for the improved delivery of tizanidine hydrochloride (TZN HCl). Method: Synthesis of thiolated arabinoxylan (TARX) was accomplished by esterification of ARX with thioglycolic acid (TGA). TARX was further used for the development of mucoadhesive oral films which were prepared by using a solvent casting technique. Formulation of the films was designed and optimized by using central composite design (CCRD), selecting TARX (X1) and glycerol (X2) as variables. Prepared film formulations were evaluated for mechanical strength, ex-vivo mucoadhesion, in-vitro drug release, ex-vivo drug permeation, surface morphology anddrug contents. Results: Thiolation of ARX was confirmed by fourier transform infra-red spectroscopy (FTIR) as a peak related to thiol group appeared at 2516 cm-1. The claim of successful thiolation of ARX was strengthened by the presence of 2809.003 ± 1.03 μmoles of thiol contents per gram of the polymer, which was determined by Ellman's reagent method. From the results, it was observed that the films were of satisfactory mechanical strength and mucoadhesiveness with folding endurance greater than 300 and mucoadhesive strength 11.53 ± 0.17 N, respectively. Reasonable drug retention was observed during in-vitro dissolution (85.03% cumulative drug release) and ex-vivo permeation (78.90% cumulative amount of permeated drug) studies conducted for 8 h. Effects of varying concentrations of both polymer and plasticizer on prepared mucoadhesive oral films were evaluated by ANOVA and it was observed that glycerol can enhanced the dissolution as well as permeation of the drug while TARX has opposite impact on these parameters. Conclusion: In nutshell, TARX in combination with glycerolwas found to be suitable for the development of controlled release mucoadhesive oral films of TZN HCl. [ABSTRACT FROM AUTHOR]

α- l-Arabinofuranosidases, belonging to the glycoside hydrolase family (GH) 62, hydrolyze the α-1,2- or α-1,3-bond to liberate l-arabinofuranose from the xylan backbone. Here, we determined the structure of the C-terminal catalytic domain of CcAbf62A, a GH62 α- l-arabinofuranosidase from Coprinopsis cinerea. CcAbf62A is composed of a five-bladed β-propeller, as observed in other GH62 enzymes. The structure near the active site of CcAbf62A is also highly homologous to those of other GH62 enzymes. However, a calcium atom in the catalytic center interacts with an asparagine residue, Asn279, which is not found in other GH62 enzymes. In addition, some residues in subsites +3R, +2NR, +3NR, and +4NR of CcAbf62A are not conserved in other GH62 enzymes. In particular, a histidine residue, His221, is uniquely observed in subsite +2NR of CcAbf62A, which is likely to influence the substrate specificity. The results obtained here suggest that the amino acid residues that interact with the xylan backbone vary among the GH62 enzymes, despite the high similarity of their overall structures. [ABSTRACT FROM AUTHOR]

An α- l-arabinofuranosidase of GH62 from Aspergillus nidulans FGSC A4 ( AnAbf62A-m2,3) has an unusually high activity towards wheat arabinoxylan (WAX) (67 U/mg; k = 178/s, K = 4.90 mg/ml) and arabinoxylooligosaccharides (AXOS) with degrees of polymerisation (DP) 3-5 (37-80 U/mg), but about 50 times lower activity for sugar beet arabinan and 4-nitrophenyl-α- l-arabinofuranoside. α-1,2- and α-1,3-linked arabinofuranoses are released from monosubstituted, but not from disubstituted, xylose in WAX and different AXOS as demonstrated by NMR and polysaccharide analysis by carbohydrate gel electrophoresis (PACE). Mutants of the predicted general acid (Glu) and base (Asp) catalysts, and the general acid p K modulator (Asp) lost 1700-, 165- and 130-fold activities for WAX. WAX, oat spelt xylan, birchwood xylan and barley β-glucan retarded migration of AnAbf62A-m2,3 in affinity electrophoresis (AE) although the latter two are neither substrates nor inhibitors. Trp and Tyr, situated about 30 Å from the catalytic site as seen in an AnAbf62A-m2,3 homology model generated using Streptomyces thermoviolaceus SthAbf62A as template, participate in carbohydrate binding. Compared to wild-type, W23A and W23A/Y44A mutants are less retarded in AE, maintain about 70 % activity towards WAX with K of WAX substrate inhibition increasing 4-7-folds, but lost 77-96 % activity for the AXOS. The Y44A single mutant had less effect, suggesting Trp is a key determinant. AnAbf62A-m2,3 seems to apply different polysaccharide-dependent binding modes, and Trp and Tyr belong to a putative surface binding site which is situated at a distance of the active site and has to be occupied to achieve full activity. [ABSTRACT FROM AUTHOR]

Arabinofuranosidase Abf43A from Bacillus sp. BP-7 is a newly discovered arabinoxylan arabinofuranohydrolase (AXH). It is a modular enzyme comprised of a GH43 catalytic domain and a carbohydrate-binding module of family CBM6. Recombinant Abf43A showed high activity on arabinoxylans, being rye arabinoxylan the preferred substrate on which the purified enzyme exhibited a K of 10.6 ± 3.3 mg/ml and a V of 29.2 ± 3.4 U/mg. Thin-layer chromatography analysis of hydrolysis products showed arabinose as the only sugar released by the enzyme from its substrates. The GH43 and CBM6 modules of the enzyme were individually cloned and expressed in Escherichia coli. While the isolated catalytic GH43 module did not show hydrolytic activity, the purified CBM6 bound to soluble arabinoxylan in affinity gel electrophoresis analysis. Evaluation of cooperative activity of arabinofuranosidase Abf43A with xylanases from families GH10, GH11, and GH30, (Xyn10A, Xyn11E, and Xyn30D from Paenibacillus barcinonensis) on arabinoxylan depolymerization revealed that the studied enzyme showed synergism with Xyn11E, a 2.54-fold increase in the amount of sugars released. On the contrary, Abf43A did not show synergism with the xylanases of families GH10 or GH30 evaluated. The enzyme characterized contributes to understanding the role of this class of enzymes in the catalytic depolymerization of arabinoxylans and their potential for the production of valuable xylooligosaccharides from these abundant plant polymers. [ABSTRACT FROM AUTHOR]

This study investigated the possibility of substituting petroleum-based polymers with biopolymers for films and paper coatings. Arabinoxylan (AX) was extracted from distillers' grains, a low-value corn ethanol byproduct, and modified through crosslinking with glutaraldehyde (GA) which was made into films and paper coatings. The effects of degree of substitution (DS) on film and coating properties of GA cross-linked AX, referred to as GAX, were investigated. The GAX films had markedly higher tensile strength, approximately 3 times higher than the unmodified AX films at low DS, with higher DS causing a negative effect on the film tensile strength. Compared to unmodified AX coating, paper coated with GAX also had significantly higher tensile index, presumably due to high adhesion between the coating and paper interface. When used as a coating binder with calcium carbonate pigments, GAX showed comparable performance to polyvinyl alcohol, a common industrial binder, demonstrating the potential to be substituted for the petroleum-based paper coating binder. [ABSTRACT FROM AUTHOR]

Arabinoxylan (AX) microspheres were formulated by ionotropic gelation for extended drug delivery. AX from Plantago ovata was tested for gelation with aluminium, barium, calcium, magnesium, and iron(III) chloride. Only calcium was found to lead to weak gelation with AX. The conventional needle extrusion produced fragile AX beads with calcium and hence the spray drying process was adopted for the preparation of metronidazole hydrochloride (MH) loaded AX microspheres. MH loading in AX microspheres was 30.8 mass %, 31.9 mass %, and 29.3 mass % in formulations gelled with 0.05 g, 0.1 g, and 0.15 g of calcium chloride per 100 mL of solution, respectively. Scanning electron microscopy revealed the crystallinity reduction of MH in microspheres. The surface of drug loaded calcium gelled AX microsphere was rougher than that of an ungelled one. Interactions of calcium with AX and the amorphous nature of the drug in the microspheres were evidenced by infrared spectroscopy and X-ray diffraction studies. Calcium-induced gelation can extend the drug release to over 90 min in 0.1 M HCl despite the hydrophilic nature of AX and the high solubility of metronidazole. [ABSTRACT FROM AUTHOR]

Brewer's spent grain (BSG) is the most abundant by-product of the brewing industry, constituting approximately 85 % (w/w) of the total by-products generated during beer production. Rich in cellulose and non-cellulosic polysaccharides, lignin, and proteins, BSG provides extra nutritional value, thereby arousing the interest of the food industry. Annually, around 3.4 million t of BSG are produced within the European Union, and Germany contributes approximately 2 million t. BSG is reused either substantial or energetic. However, its main application has been limited to animal feeding. Based on the intense global pressure toward green environmental technology and increasing regulations in the feed sector, alternative application fields have gained importance. Because of its high protein and fiber contents, BSG can be an attractive source for value-added products in human nutrition. The focus is on the reported health effects of (1-3,1-4)-β- d-glucan and arabinoxylan (AX). Several scientific studies have shown that barley (1-3,1-4)-β- d-glucan reduces blood cholesterol levels. A cause and effect relationship has been established between the consumption of AX from wheat endosperm and the reduction of postprandial glycemic responses. The intention of this review is to focus on the extraction of (1-3,1-4)-β- d-glucan and AX from BSG as a source of value-added compounds for use as a nutraceutical. In view of AX and (1-3,1-4)-β- d-glucan yield, different methods of extraction are presented. Finally, technological trends and future perspectives to expand this market are discussed, focusing on promising strategies such as the use of pressurized hot water extraction. [ABSTRACT FROM AUTHOR]

Biological activities of alkali extracted (Barium hydroxide: BE-480 kDa, Potassium hydroxide: KE1-1080 and KE2-40 kDa), purified arabinoxylans (AX) from the finger millet bran varying in their molecular weight, phenolic acid content, arabinose to xylose ratios were evaluated for their immune-stimulatory activities using murine lymphocytes and peritoneal exudate macrophages. All three purified AX displayed significant ( p < 0.001) mitogenic activity and activation of macrophages including phagocytosis. Among these BE has shown higher enhancing lymphocyte proliferation (>2 fold) and macrophage phagocytosis than KE1 and KE2. The above results clearly documented that the immunostimulatory activity of arabinoxylans is directly proportional to the amount of ferulic acid content (0.11 mg/100 g), whereas molecular weight as well as arabinose/xylose ratio, did not have any bearing. Purified AX from the finger millet bran can be explored as a potent natural immunomodulator. [ABSTRACT FROM AUTHOR]

The presence of xylan is a detriment to the enzymatic saccharification of cellulose in lignocelluloses. The inhibition of the processive cellobiohydrolase Cel7A by soluble wheat arabinoxylan is shown here to increase by 50 % following enzymatic treatment with a commercially-purified α- l-arabinofuranosidase. The enhanced inhibitory effect was shown by T relaxation time measurements via low field NMR to coincide with an increasing degree of constraint put on the water in xylan solutions. Furthermore, quartz crystal micro-balance with dissipation experiments showed that α- l-arabinofuranosidase treatment considerably increased the rate and rigidity of arabinoxylan mass association with cellulose. These data also suggest significant xylan-xylan adlayer formation occurs following initial binding of debranched arabinoxylan. From this, we speculate the inhibitory effects of xylan to cellulases may result from reduced enzymatic access via the dense association of xylan with cellulose. [ABSTRACT FROM AUTHOR]

Plant cell walls display a highly complex organization that confers resistance (recalcitrance) to enzymatic hydrolysis. This poses a barrier to the development of technologies for second-generation bioenergy production due to the difficulty of enzymes in accessing wall polymers. Here, we examine the fine structure of some of the main cell wall hemicelluloses and present some evidences that lend support to the idea of a glycomic code, which can be defined as the diversity of encrypted results of the biosynthetic mechanisms of plant cell wall polysaccharides that give rise to fine-structural domains containing information in polysaccharides. These are responsible for the formation of polymer composites with different levels of polymer-polymer interactions and recalcitrance to hydrolysis. Polysaccharide motifs that are recalcitrant to hydrolysis are here called pointrons, and the ones that are available to enzyme attack are named pexons. From the biotechnological viewpoint, the understanding of the glycomic code will require further identification of pointrons and possibly the transformation of them into pexons so that walls would become suitable to hydrolysis. This is thought to be key for tackling the cell wall recalcitrance, therefore opening the way for efficient biomass disassembly and efficient bioenergy production. [ABSTRACT FROM AUTHOR]

Streptomyces sp I10-1 α-L-arabinofuranosidase efficiently produced L-arabinose from high arabinose-content corn hull arabinoxylan (ratio of arabinose to xylose, 0.6). The optimum pH at 40 °C was around 6, and the enzyme was stable from pH 5 to 11. The optimum temperature was 50 °C at pH 5, and the activity was stable at 40 °C. The enzymatic activity against corn hull arabinoxylan was 2.3 times higher than towards p-nitrophenyl-α-L-arabinofuranoside. Approximately 45 % L-arabinose recovery was achieved from corn hull arabinoxylan. It was considered that L-arabinose residues not removed by the enzyme were attributable to those linked with ferulic acid. The open reading frame of the enzyme gene consisted of 1,224 bp, and the predicted peptide was 408 amino acids, which corresponded to a molecular size of 45, 248 Da. It was presumed that the smaller molecular size (31,000 Da) estimated on SDS-PAGE resulted from proteolysis by proteases. I10-1 α-L-arabinofuranosidase belongs to the Alpha-L-AF C superfamily, which is associated with glycoside hydrolase family 51, but the properties were unique. [ABSTRACT FROM AUTHOR]

A pair of ice nucleation and fluorescence reporter strains induced specifically by d-xylose were developed and optimized, to monitor d-xylose content in hydrolyzed arabinoxylans samples. Reporter strains were developed by fusing the Escherichia coli xylose isomerase promoter P to the promoterless native inaZ gene of Pseudomonas syringae and synthetic gfp gene of Aequorea victoria and transferring final constructs to E. coli DH5α. Because of relatively low initial response toward the target analyte, signal improvement by promoter region length adjustment has been implemented. In both cases, this approach proved to be successful, although the manner in which reporter strains have responded to it was dissimilar. The specificity and quantitative response of obtained reporter strains have been confirmed, and the response ranges for NIxylA100 and gfpxylA300 have been established as 9 × 10-9 × 10 g l and 9 × 10-9 g l, respectively. The performance of developed reporter strains has been assessed in comparison with high-performance anion-exchange chromatography and demonstrated 15-18 % difference between data obtained with reporter strains and chromatography analysis, which for microbial sensors is an acceptable dissimilarity. The developed microbial reporter strains present an alternative for other analytical methods used for monosaccharide quantification and enable quantification of d-xylose in arabinoxylans samples. [ABSTRACT FROM AUTHOR]

BACKGROUND/OBJECTIVES: Several studies emphasise that arabinoxylan and β-glucan have more beneficial effects on glucose metabolism than low-dietary fibre (DF) meals. Less attention has been paid to the effects of concentrated DF compared with whole grain. We compared the effects of DF and whole grain on glucose, hormone responses and appetite in subjects with the metabolic syndrome (MetS). SUBJECTS/METHODS: Fifteen subjects with MetS participated in this acute, randomised, cross-over intervention study. The test breads provided 50 g of digestible carbohydrate: wheat bread with concentrated arabinoxylan (AX) or β-glucan (BG), rye bread with kernels (RK) and wheat bread (WB) as control. Blood samples were drawn for 270 min to determine glucose, insulin, glucagon-like peptide-1, glucose-dependent insulinotropic peptide (GIP) and ghrelin. Appetite score was addressed every 30 min. Ad libitum energy intake (EI) was measured 270 min after test meals. RESULTS: Compared with WB, BG and RK induced lower initial glycaemic responses (P<0.001), whereas AX only reduced the glucose peak value (P<0.001). RK reduced insulin (P<0.001) and GIP responses (P<0.001) compared with the other breads. BG lowered insulin responses more than AX (P<0.001). AX, BG and RK increased satiety feeling (P<0.001) more than WB, but did not differ significantly in terms of subsequent EI (P=0.089). CONCLUSION: BG and RK had beneficial impact on the glucose response, whereas AX had only effect on the postprandial glucose peak. The impact of the AX bread was influenced by higher protein content. Whether the metabolic effects of the breads are still present to mixed meals remains to be tested. [ABSTRACT FROM AUTHOR]

A method based on gas chromatography-mass spectrometry analysis of acetylated methyl glycosides was developed in order to analyze monosaccharides obtained from various hemicelluloses. The derivatives of monosaccharide standards, arabinose, glucose, and xylose were studied in detail and C-labeled analogues were used for identification and quantitative analysis. Excellent chromatographic separation of the monosaccharide derivatives was found and identification of the anomeric configuration was feasible through a prepared and identified pure methyl 2,3,4,6-tetra- O-acetyl-β- d-glucopyranoside. The electron ionization mass spectrum and fragmentation path was studied for each monosaccharide derivative. Fragment ion pairs of labeled and unlabeled monosaccharides were used for quantification; m/ z 243/248 for glucose, 128/132 for xylose, and 217/218 for arabinose. Using the intensity ratios obtained from the extracted ion chromatograms, accurate quantification of monosaccharide constituents of selected hemicelluloses was demonstrated. [ABSTRACT FROM AUTHOR]

The chemical structure of rye arabinoxylan (rAX) was systematically modified, exploiting selective enzymes to mimic different naturally occurring xylans, i.e., its degree of substitution (DS) was decreased using α- l-arabinofuranosidase, and a controlled decrease in the degree of polymerization (DP) was performed using endo-1,4-β- d-xylanase. The arabinose to xylose ratio was decreased from 0.45 to 0.27 and the weight-average molar mass was decreased from 184,000 to 49,000 g/mol. The resulting samples were used to prepare films, as such, and with 15% (wt. − %) softwood-derived microfibrillated cellulose (MFC) to obtain novel plant-derived biocomposite materials. The enzymatic tailoring of rAX increased the crystallinity of films, evidenced by X-ray diffraction studies, and the addition of MFC to the debranched, low DS rAX induced the formation of ordered structures visible with polarizing optical microscopy. MFC decreased the moisture uptake of films and increased the relative humidity of softening of the films, detected with moisture scanning dynamic mechanical analysis. For the first time, the chemical structure of xylan was proven to significantly affect the reinforcement potential of nano-sized cellulose, as the tensile strength of films from high DP rAXs, but not that of low DP rAXs, clearly increased with the addition of MFC. At the same time, MFC only increased the Young's modulus of films from rAX with high arabinose content, regardless of DP. [ABSTRACT FROM AUTHOR]

Previously, it has been demonstrated that the glycoside hydrolase family 8 xylanase from the psychrophylic bacterium Pseudoalteromonas haloplanktis (XPH) can bind substrate non-catalytically on the surface of its catalytic module. In the present study, the functional relevance of this secondary binding site (SBS) for the enzyme is investigated by site-directed mutagenesis and evaluation of activity and binding properties of mutant variants on a range of structurally different homoxylan and heteroxylan substrates. The SBS had an impact on the activity on insoluble substrates, whereas the activity on soluble substrates remained unaffected. Unexpectedly, the activity on a soluble oligomeric substrate was also affected for some mutants and results on a chromophoric polymeric model substrate were in contrast with the trends observed on the corresponding natural substrate. All in all, results show that the impact of the SBS on the activity of XPH is in part analogous to the functioning of some carbohydrate-binding modules in modular enzymes. [ABSTRACT FROM AUTHOR]

process was developed to fractionate and isolate the hemicellulose B component of corn fiber generated by corn wet milling. The process consisted of pretreatment by soaking in aqueous ammonia followed by enzymatic cellulose hydrolysis, during which the hemicellulose B was solubilized by cleavage into xylo-oligosaccharides and subsequently recovered by precipitation with ethanol. The pretreatment step resulted in high retention of major sugars and improvement of subsequent enzymatic hydrolysis. The recovered hemicellulose B was hydrolyzed by a cocktail of enzymes that consisted of β-glucosidase, pectinase, xylanase, and ferulic acid esterase (FAE). Xylanase alone was ineffective, demonstrating yields of less than 2% of xylose and arabinose. The greatest xylose and arabinose yields, 44% and 53%, respectively, were obtained by the combination of pectinase and FAE. A mass balance accounted for 87% of the initially present glucan, 91% of the xylan, and 90% of the arabinan. The developed process offered a means for production of corn fiber gum as a value-added co-product and C5 sugars, which could be converted to other valuable co-products through fermentation in a corn wet-milling biorefinery. [ABSTRACT FROM AUTHOR]

The propensity for xylanase to convert insoluble to soluble arabinoxylan is an important parameter in many applications. Current methods for determining xylanase activity on insoluble substrates are nonspecific or utilize artificial substrates which may provide much different results from native substrates. Therefore, a new method for the determination of xylanase activity on insoluble substrates was developed. This method involved incubation of the enzyme with a material containing insoluble arabinoxylan. Arabinoxylan released by the enzyme was quantified as total pentose sugars colorimetrically by reaction with phloroglucinol upon heating in acetic-hydrochloric acid. Absorbance was determined at 552 nm, and interfering hexoses were accounted for by subtracting the absorbance at 510 nm. Because the method measured total pentose sugars released by the enzyme, (arabino)xylanase activity, rather than xylanase activity, was recommended for expressing results. The method was tested using two xylanases and six insoluble arabinoxylan-containing substrates. Sodium acetate and sodium citrate buffers (50 mM) were suitable for the reaction; sodium phosphate buffer substantially interfered with quantification of reaction products by reducing color development. The enzymic release of soluble arabinoxylan was linear for at least 5 min under all reaction conditions tested. Contaminating amylase and cellulase activity did not influence the results, despite the presence of starch and cellulose in many substrate sources. Relative standard deviations were <5% between reactions assayed on different days. Activity on substrates from different botanical origin differed by up to 100-fold, emphasizing the need for the use of application-specific substrates to obtain accurate estimations of enzyme activity. [ABSTRACT FROM AUTHOR]

In addition to the starchy endosperm, a specialized tissue accumulating storage material, the endosperm of wheat grain, comprises the aleurone layer and the transfer cells next to the crease. The transfer cells, located at the ventral region of the grain, are involved in nutrient transfer from the maternal tissues to the developing endosperm. Immunolabeling techniques, Raman spectroscopy, and synchrotron infrared micro-spectroscopy were used to study the chemistry of the transfer cell walls during wheat grain development. The kinetic depositions of the main cell wall polysaccharides of wheat grain endosperm, arabinoxylan, and (1-3)(1-4)-β-glucan in transfer cell walls were different from kinetics previously observed in the aleurone cell walls. While (1-3)(1-4)-β-glucan appeared first in the aleurone cell walls at 90°D, arabinoxylan predominated in the transfer cell walls from 90 to 445°D. Both aleurone and transfer cell walls were enriched in (1-3)(1-4)-β-glucan at the mature stage of wheat grain development. Arabinoxylan was more substituted in the transfer cell walls than in the aleurone walls. However, arabinoxylan was more feruloylated in the aleurone than in the transfer cell walls, whatever the stage of grain development. In the transfer cells, the ferulic acid was less abundant in the outer periclinal walls while para-coumarate was absent. Possible implications of such differences are discussed. [ABSTRACT FROM AUTHOR]