Application Of Xylanase Research Articles

An insight into microbial sources, classification and industrial applications of xylanases: A rapid review.

Endo 1,4-β-d- xylanases (EC3.2.1.8) are one of the key lignocellulose hydrolyzing enzymes. Xylan, which is present in copious amounts on earth, forms the primary substrate of endo-xylanases which can unchain the constituent monosaccharides linked via β-1,4 glycosidic bonds from the xylan backbone. Researchers have shown keen interest in the xylanases belonging to glycoside hydrolase families 10 and 11 whereas those placed in other GH families are yet to be investigated. Various microbes such as bacteria and fungi harbor these enzymes for the metabolism of their lignocellulose fibers. These microbes can be used as miniature biofactories of xylanase enzymes for a plethora of environmentally benign applications in pulp and paper industry, biofuel production and for improving the quality of food in bread baking and fruit juice industry. This review highlights the potential of microbes in production of xylanase for industrial biotechnology. This article is protected by copyright. All rights reserved.

Effects of Graded Levels of Xylanase-Treated Rice Husk on Nutrient Digestibility and Growth Performance of Broiler Chickens

This study investigated the feeding value of Aspergillus tubingensis xylanase-treated rice husk in broiler chickens. The objectives of the study are (I) to investigate the effect of xylanase treatment on the utilization of rice husk in broiler chickens and (II) to determine the optimum level of xylanase-treated rice husk that can be tolerated by broiler chickens. Xylanases are hydrolytic enzymes that degrade xylan and hemicelluloses located in plant cell walls, into xylose which is a reducing sugar and enhancing nutrient digestibility in animal feeds. The production of extracellular xylanase by a locally isolated Aspergillus tubingensis was conducted using solid-state fermentation. The selected isolate was identified by cultural techniques and verified by molecular identification. Conventional feed ingredients such as maize is the primary cereal as source of energy in broiler diet. High cost, availability and competition existing among man, industry and livestock has necessitated the need to find cheap and available alternative feedstuffs for maize in poultry diet. Rice husk is one of the alternative feedstuffs but characterized by high fibre content and Non-Starch Polysaccharide (NSP) (Dalibord, 2006). Thus, addition of the xylanase enzyme breaks the NSPs resulting in plant cell wall destruction after releasing the trapped nutrients such as starches and proteins within fibre-rich cell walls (Gade et al., 2017). Crude xylanase produced was used for enzymatic degradation of rice husk to improve its nutritional value. The rice husk was initially subjected to physical pre-treatment by soaking in water for 24 hours or ground to increase the surface area. Pre-treated rice husk was treated by spraying xylanase onto the rice husk at 100g/ 0.2mL representing the concentration level that recorded the best degradation of fibre content in the treated rice husk. Xylanase-treated rice husk (XTRH) was used with other ingredients in formulating a broiler chicken diet at different inclusion levels. The experiment was a complete randomized design with five experimental diets containing xylanase-treated rice husk at different inclusion levels 0, 5, 10, 15 and 20 kg/100kg. The control diet contained no xylanase-treated rice husk (XTRH). There were five (5) treatments each with three (3) replicate cages of eight (8) broiler chicks totalling 120 birds for the feeding trial. One hundred and twenty (120) day-old chicks with an average weight of 54.85g were randomly allotted to five dietary treatments formulated with 0 (control), 5%, 10%, 15% and 20% (XTRH), and fed for eight weeks. There were three replicates of eight (8) birds per treatment. Results showed that the performance of Broiler chickens such as feed intake, and weight gain feed fed diet containing a 20% inclusion level of xylanase-treated rice husk was significantly higher (p<0.05) compared to other treatment diets. This showed an improvement in the utilization of a high-fibre diet, nutrient digestibility, growth performance, and carcass characteristics which can be beneficial to farmers in reducing the cost of feed, and increasing savings and profit margin. Conclusively, the application of xylanase produced by Aspergillus tubingensis on rice husk may have enhanced efficient enzymatic hydrolysis of its fibre fractions and improved its nutritional values. Supplementation of rice husk treated with xylanase at 100g/0.2mL concentration level and included at 20% in broiler chicken may enhance nutrient digestion and utilization and improve the growth performance of broiler chickens.

The Benefits of Exogenous Xylanase in Wheat–Soy Based Broiler Chicken Diets, Consisting of Different Soluble Non-Starch Polysaccharides Content

Four wheat-based diets with either a low soluble content of non-starch polysaccharides (NSPs, 13 g/kg); low viscosity, LV) or a high content of NSPs (33.5 g/kg; high viscosity, HV), with and without exogenous xylanase (XYL), were fed to male Ross 308 broiler chickens from 7 to 21 days age. The enzyme was supplemented at 100 FXU/kg diet, and its preparation was based on endo-1,4-beta-xylanase produced by Aspergillus oryzae. Each diet was fed to eight pens, with five birds in each pen, following randomisation. Chicks fed XYL had an improved feed efficiency, hepatic coenzyme Q10, caecal butyric acid concentration, nitrogen digestibility (p < 0.05) and increased dietary ME (p < 0.001). Compared to HV, birds fed LV diets had reduced weight of proventriculus, gizzard and the pancreas and higher blood glutathione peroxidase and dietary ME (p < 0.05), but no differences were observed on nutrient digestibility and growth performance variables. This also suggests that birds may tolerate a greater dietary NSPs content; thus, further benefits may be obtained by the application of XYL in low energy wheat-based diets.

Immobilization of mutated xylanase from Neocallimastix patriciarum in E. coli and application for kraft pulp biobleaching.

As an important enzyme, xylanase is widely used in the food, pulp, and textile industry. Different applications of xylanase warrant specific conditions including temperature and pH. This study aimed to carry out sodium alginate beads as carrier to immobilize previous reported mutated xylanase from Neocallimastix patriciarum which expressed in E. coli, the activity of immobilization of mutated xylanase was elevated about 4% at pH 6 and 13% at 62 °C. Moreover, the immobilized mutated xylanase retained a greater proportion of its activity than the wide type in thermostability. These properties suggested that the immobilization of mutated xylanase has potential to apply in biobleaching industry.

Influence of Particle Size and Xylanase Pretreatment of Proso Millet Bran on Physical, Sensory and Nutritive Features of Gluten-Free Bread.

Millet bran is a by-product rich in dietary fibre, micronutrients and bioactive compounds which are often deficient in a gluten-free diet. Previously, cryogenic grinding has been shown to improve the functionality of bran to some extent, although it offered limited benefits for bread making. This study aims to investigate the effects of adding proso millet bran depending on its particle size and xylanase pretreatment on the physicochemical, sensory and nutritional properties of gluten-free pan bread. Coarse bran (d50=223 μm) was ground to medium size (d50=157 μm) using an ultracentrifugal mill or to superfine particles (d50=8 μm) using a cryomill. Millet bran presoaked in water (for 16 h at 55 °C) with or without the addition of fungal xylanase (10 U/g) replaced 10% of the rice flour in the control bread. Bread specific volume, crumb texture, colour and viscosity were measured instrumentally. Along with proximate composition, the content of soluble and insoluble fibre, total phenolic compounds (TPC) and phenolic acids as well as total and bioaccessible minerals of bread were assessed. Sensory analysis of the bread samples included a descriptive, hedonic and ranking test. Dietary fibre content (7.3-8.6 g/100 g) and TPC (42-57 mg/100 g) on dry mass basis of the bread loaves depended on bran particle size and xylanase pretreatment. The effect of xylanase pretreatment was most evident in the loaves with medium bran size in terms of higher content of fibre soluble in ethanol (45%) and free ferulic acid content (5%), improved bread volume (6%), crumb softness (16%) and elasticity (7%), but lower chewiness (15%) and viscosity (20-32%). Bread bitterness and dark colour were increased after adding medium-sized bran but its bitter aftertaste, crust crookedness, crumb hardness and graininess were reduced with xylanase pretreatment. Although bran addition impaired protein digestibility, it enriched the bread with iron (341%), magnesium (74%), copper (56%) and zinc (7.5%). Xylanase pretreatment of the bran resulted in the improved bioaccessibility of zinc and copper of the enriched bread compared to the control and bread without xylanase. Application of xylanase to medium sized bran obtained by ultracentrifugal grinding was more successful than its application to superfine bran obtained by the multistage cryogrinding as it resulted in more soluble fibre in gluten-free bread. Moreover, xylanase was proven beneficial in maintaining desirable bread sensory properties and mineral bioaccessibility.

Improving sorghum digestion in broilers by targeting fermentation of xylan.

This study was to examine if it is possible to accelerate sorghum digestion in broiler chickens by targeting fermentation of the xylan. Cobb 500 broilers (n = 960, 80 birds per treatment) were fed 12 sorghum-soybean meal-based dietary treatments fed as 3 phases (starter d 0 to 12, grower d 13 to 23, finisher d 24 to 35), with 8 replicate pens of 10 birds per treatment. For half of the treatments (n = 6), 10% of the sorghum in the diet was directly replaced with 10% wheat bran, as a source of fermentable fibre. The diets were supplemented with either 0, 50 or 2,000 mg/kg xylo-oligosaccharides (XOS), with or without xylanase application. Body weight gain (BWG), feed intake (FI) and feed conversion corrected for mortality (cFCR) was determined at d 0 to 35, and male and female body weight were measured on d 35. On d 35, ileum and caeca samples were collected from 2 birds per pen, for determination of caecal cellulase and xylanase activity, microbiota composition and short chain fatty acid (SCFA) concentration, and ileal XOS concentration. Supplementation with 2,000 mg/kg XOS caused increased BWG at d 0 to 35 (P = 0.007) and enhanced caecal propionic, valeric and succinic acid concentration (P < 0.05). Wheat bran increased FI (P = 0.018) and BWG (P = 0.016), as well as caecal Bifidobacteria concentration (P < 0.001). Ileal XOS concentration was greatest when feeding combined wheat bran, 2,000 mg/kg XOS, and xylanase, resulting in increased caecal total SCFA, acetic acid and butyric acid concentration, and xylanase and cellulase activity (P < 0.05). Results from this study present that feed efficiency in birds fed sorghum-based diets is improved as a consequence of supplementing with fermentable fibre, xylanase and XOS.

Fusion of a proline-rich oligopeptide to the C-terminus of a ruminal xylanase improves catalytic efficiency

ABSTRACT Xylanases are widely used in the degradation of lignocellulose and are important industrial enzymes. Therefore, increasing the catalytic activity of xylanases can improve their efficiency and performance. In this study, we introduced the C-terminal proline-rich oligopeptide of the rumen-derived XynA into XylR, a GH10 family xylanase. The optimum temperature and pH of the fused enzyme (XylR-Fu) were consistent with those of XylR; however, its catalytic efficiency was 2.48-fold higher than that of XylR. Although the proline-rich oligopeptide did not change the enzyme hydrolysis mode, the amount of oligosaccharides released from beechwood xylan by XylR-Fu was 17% higher than that released by XylR. This increase may be due to the abundance of proline in the oligopeptide, which plays an important role in substrate binding. Furthermore, circular dichroism analysis indicated that the proline-rich oligopeptide might increase the rigidity of the overall structure, thereby enhancing the affinity to the substrate and catalytic activity of the enzyme. Our study shows that the proline-rich oligopeptide enhances the catalytic efficiency of GH10 xylanases and provides a better understanding of the C-terminal oligopeptide-function relationships. This knowledge can guide the rational design of GH10 xylanases to improve their catalytic activity and provides clues for further applications of xylanases in industry.

Purification and Characterization of Thermostable Alkaline Xylanase by Aspergillus terreus from Elephant Dung

Aims: Purification and characterization of xylanase by Aspergillus terreus isolated from elephant dung.&#x0D; Study Design: Xylanase enzyme produced by A. terreus was extracted from the fermented solid medium using solid state fermentation and purified using chromatographic techniques. The purified enzyme was characterized for physio-chemical and kinetic properties.&#x0D; Place and Duration of Study: Experiments were performed at the School of Biotechnology, Devi Ahilya University, Indore, INDIA and Maharaja Ranjit Singh College of Professional Sciences, Indore, INDIA, between June, 2019 and September, 2021.&#x0D; Methodology: The enzyme was extracted and purified using ammonium sulphate precipitation, ion exchange chromatography using DEAE cellulose and gel filtration chromatography (GFC) using Sephadex G-200. The molecular weight of the purified enzyme was determined using native poly acrylamide gel electrophoresis (Native PAGE) and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The purified enzyme was characterized to determine pH and temperature optima. Thermostability, pH stability and substrate kinetics were studied for purified xylanase. Effect of several metal ions and detergents were also studied.&#x0D; Results: The alkali-thermo xylanase of Aspergillus terreus was purified to 14.6-fold with a 39.48% recovery through IEC on DEAE-cellulose and GFC using Sephadex G-200. The purified enzyme had a specific activity, 111.6 U/mg. The SDS-PAGE revealed that the enzyme was monomeric with a molecular weight of 87 kDa. The optimum pH and temperature were 8 and 60⁰C, respectively. The Km and Vmax values of the partially purified xylanase were found to be 0.016 mg/l and 102.64 U/mg protein, respectively with birch wood xylan as substrate.&#x0D; Conclusion: The enzyme was active over a wide pH range of 6-11 and temperature range of 40⁰C to 80ºC, indicating its alkali tolerant and thermostable characteristics which is the requirement of different industries. Several ions namely Zn2+ enhanced xylanase activity by 187% followed by Ca2+ (129%), Mg2+ (123%), NH4+ (146%) and Fe3+ (118%) at 10 mM concentration. However, Cu2+ and Hg2+ completely inhibited xylanase activity. This research provides the basis for application of xylanase and improves its biotechnological potential in mainly in paper pulp industry, biofuel generation and in bread baking.

Statistical Optimization of Media Components for Xylanase Production by Aspergillus spp. Using Solid State Fermentation and its Application in Fruit Juice Clarification

Xylanases are enzymes that convert xylan into xylose, xylobiose, and xylotriose. The present study deals with the production and optimization of xylanase through Solid-State Fermentation (SSF) using different agricultural wastes by Aspergillus spp. The Plackett Burman (PB) design was used to screen significant media components affecting the xylanase production. The carbon sources screened were wheat bran, rice bran, sugarcane bagasse, corn cob, and orange peel. The nitrogen sources screened were yeast extract, peptone, (NH4)2SO4, Na2NO3, and urea. Also, nine different salts such as KCl, MgSO4, Na2HPO4, CaCl2, FeSO4, ZnSO4, Na2CO3, KH2PO4, and NaH2PO4 which act as trace elements were screened. The results showed that wheat bran, yeast extract, Na2NO3 and KCl are the significant factors that affect xylanase production. A 33 Full Factorial Design (FFD) was performed to optimize the significant media components (wheat bran, KCl, yeast extract) obtained from PB design using Response Surface Methodology (RSM). Statistical analysis of results showed that wheat bran, KCl, yeast extract, and interaction between wheat bran and yeast extract were found to be significant. The optimum concentration of wheat bran, KCl, yeast extract was 8 g/L, 0.1 g/L and 3 g/L. The Partial purification of xylanase was carried out using ammonium salt precipitation and dialysis. Gel filtration chromatography was performed to optimize the elution time, which was found to be 6 minutes. Application of xylanase in orange juice clarification was studied at 40 °C, 50 °C, and 60 °C. The optimum temperature obtained was 60 ºC.

Dietary soluble non-starch polysaccharide level and xylanase influence the gastrointestinal environment and nutrient utilisation in laying hens

ABSTRACT 1. The objective of this study was to examine the influence of dietary soluble non-starch polysaccharide (sNSP) level and xylanase supplementation on productive performance, viscosity and pH along the gastrointestinal tract in laying hens. Excreta moisture content, ileal and caecal microbiota and short-chain fatty acid (SCFA) composition and apparent total tract nutrient utilisation were measured. 2. Hyline Brown laying hens (n = 144) were housed individually at 25 weeks of age and allocated to one of the four wheat-based dietary treatments in a 2 × 2 factorial arrangement, consisting of two levels of sNSP (High 13.40 g/kg or Low 11.22 g/kg), with or without xylanase (0 or 12,000 BXU/kg). Birds were fed the dietary treatments for 56 d. 3. Increasing dietary sNSP increased jejunum viscosity, degradability of total NSP, total tract flow of insoluble arabinose, and succinic acid concentration in the caeca (P < 0.05). Feeding high sNSP decreased excreta moisture content, total tract energy retention and free oligosaccharide, total tract flow of soluble and insoluble galactose and insoluble rhamnose and fucose, and ileal acetic and lactic acid concentrations (P < 0.05), and tended to reduce egg production (P = 0.058). 4. Supplementation with xylanase resulted in reduced jejunum and ileum viscosity, caecal pH, excreta moisture, flow of soluble arabinose and glucose and insoluble arabinose and xylose, caecal concentration of Lactobacillus sp. and isobutyric and succinic acid, and ileal concentration of Bacillus sp. and total anaerobic bacteria (P < 0.05). Xylanase application also increased energy retention and insoluble and total NSP degradation, and caecal abundance of Bifidobacteria sp. and valeric acid (P < 0.05). 5. These results reiterated the ability of xylanase to improve nutrient digestibility and reduce excreta moisture content in laying hens, and highlighted the importance of considering dietary sNSP level in laying hen diets.

Zeolite-based nanocomposite as a smart pH-sensitive nanovehicle for release of xylanase as poultry feed supplement

Xylanase improves poultry nutrition by degrading xylan in the cell walls of feed grains and release the entrapped nutrients. However, the application of xylanase as a feed supplement is restricted to its low stability in the environment and gastrointestinal (GI) tract of poultry. To overcome these obstacles, Zeozyme NPs as a smart pH-responsive nanosystem was designed based on xylanase immobilization on zeolitic nanoporous as the major cornerstone that was modified with L-lysine. The immobilized xylanase was followed by encapsulating with a cross-linked CMC-based polymer. Zeozyme NPs was structurally characterized using TEM, SEM, AFM, DLS, TGA and nitrogen adsorption/desorption isotherms at liquid nitrogen temperature. The stability of Zeozyme NPs was evaluated at different temperatures, pH, and in the presence of proteases. Additionally, the release pattern of xylanase was investigated at a digestion model mimicking the GI tract. Xylanase was released selectively at the duodenum and ileum (pH 6–7.1) and remarkably preserved at pH ≤ 6 including proventriculus, gizzard, and crop (pH 1.6–5). The results confirmed that the zeolite equipped with the CMC matrix could enhance the xylanase thermal and pH stability and preserve its activity in the presence of proteases. Moreover, Zeozyme NPs exhibited a smart pH-dependent release of xylanase in an in vitro simulated GI tract.

Isolation of Corncob Xylan-Degrading Fungi and Its Application in Xylobiose Production

In the present study, a potential corncob xylan degradation fungi was isolated and screened from soil to produce xylanase, and was identified as Fusarium oxysporum. The production of xylanase by F. oxysporum under solid state fermentation using corncob powder as the solid substrate reached the maximum xylanase activity when using particle size of substrate of 60 mesh, water content ratio of 2 mL/g substrate, incubation temperature of 30°C, initial pH of 6.0, size of inoculum of 5x107 spore/3 g substrate, and incubation time of 2 days. The xylanase activity increased about 4 times up to 7.92 U/mL after optimization. The potential application of xylanase of F. oxysporum in hydrolyzing alkali-treated corncob xylan to produce xylobiose was also demonstrated. Hydrolysis of 6% of corncob xylan using 100 U/g substrate of enzyme loading under optimum pH and temperature conditions (pH 5.5 and 50°C, respectively) achieved the yield of xylobiose up to 28.7 g/100 g pure xylan after 12 h incubation. The purification of hydrolysate could retain 91.1% of xylobiose. Further separation step using activated charcoal column chromatography was able to get a pure xylobiose, but could only recover 59.3% of xylobiose.

Dietary soluble non-starch polysaccharide level and xylanase supplementation influence performance, egg quality and nutrient utilization in laying hens fed wheat-based diets

The aim of this study was to evaluate the effects of dietary soluble non-starch polysaccharide (sNSP) content and xylanase supplementation on production performance, egg quality parameters, and nutrient digestibility in Hy-line Brown layers from 25 to 32 wk of age. A total of 144 Hy-line Brown laying hens (25 wk of age) were randomly allocated to 1 of 4 wheat-based dietary treatments in a 2 × 2 factorial experimental design, with 36 replicates of individual hens per treatment. The diets were formulated to contain either a high or low sNSP level (at 13.3 or 10.8 g/kg) and were supplemented with either 0 or 12,000 BXU/kg exogenous xylanase. Birds were fed these treatment diets for an 8-wk period, and hen production performance, including daily egg production, average egg weight, daily egg mass, feed conversion ratio and proportion of dirty and abnormal eggs were measured at bird age 25 to 28 wk and 29 to 32 wk. An interaction between sNSP content of the diet and xylanase supplementation was observed on daily egg production from 25 to 28 wk of age (P = 0.018); birds fed the high sNSP diet without xylanase had lower egg production than those fed any other treatment. An interaction between the 2 dietary factors was also observed on hen weight gain at 29 to 32 wk of age (P = 0.014), with birds fed the low sNSP diet with 12,000 BXU/kg xylanase presenting greater weight gain compared to those fed the high sNSP diet with 12,000 BXU/kg xylanase. Feed intake at 29 to 32 wk of age was reduced by xylanase supplementation (P = 0.047). Xylanase supplementation also increased yolk colour score at both 28 and 32 wk of age, and decreased yolk weight at 32 wk of age (P = 0.014, 0.037 and 0.013, respectively). Birds fed the low sNSP diet presented lower protein digestibility (P = 0.024) than those fed the high sNSP diet. Additionally, birds fed high sNSP presented higher shell reflectivity at both 28 and 32 wk of age (P = 0.05 and 0.036, respectively). The influence of duration of feeding the treatment diets on egg quality was also determined. It was observed that egg weight, yolk weight and yolk colour score consistently increased over time, regardless of experimental treatment effects. In contrast, Haugh Unit and albumen height significantly decreased throughout the study period in all treatments, although this was less pronounced in hens fed the treatment with high sNSP and no supplemental xylanase. A reduction in shell breaking strength over time was observed only in hens fed the treatments without xylanase addition, and shell thickness was improved over time only in birds fed the low sNSP diet with xylanase. The impacts of the dietary treatments were largely inconsistent in this study, so a solid conclusion cannot be drawn. However, these findings do indicate that dietary NSP level influences layer production performance, and thus should be considered when formulating laying hen diets. It also proved that further research is warranted into how to optimize the benefits of xylanase application in laying hens.

Micronized whole wheat flour and xylanase application: dough properties and bread quality.

The micronization process by jet mill of whole wheat flour in addition to xylanase application may be used to improve dough properties and baking quality. This study aimed to evaluate the dough formation and bakery performance of whole wheat flour micronized using jet mill and having different particle sizes and xylanase content A decrease in particle size increased water absorption and increased dough stability by 3.7 units. Increase in xylanase content decreased the dough stability and mixture tolerance, resulting in reduced strength. Although the dough quality reduced, this was not evident in bread quality. In bread, the increase in xylanase content increased the specific volume and improved the texture profile. The 158 and 261μm particle sizes with 60 and 100mgkg-1 xylanase content reduced the undesirable effects of fibers in the dough, which may lead to improved bread making, thus enhancing improved consumer acceptance.

Taguchi optimization and scale up of xylanase from Bacillus licheniformis isolated from hot water geyser

BackgroundXylanase is one of the widely applied industrial enzymes with diverse applications. Thermostability and alkali tolerance are the two most desirable qualities for industrial applications of xylanase. In this paper, we reveal the statistical Taguchi optimization strategy for maximization of xylanase production. The important process parameters pH, temperature, concentration of wheat bran, and concentration of yeast extract were optimized using the Taguchi L8 orthogonal array where the 4 factors were considered at 2 levels (high and low). ResultsThe optimized conditions given by model were obtained as follows: (i) pH 6, (ii) culture temperature 35 °C, (iii) concentration of xylan 2% w/v, (iv) concentration of wheat bran 2.5% w/v. The production was scaled upto 2.5 L bioreactor using optimized process parameters. A high xylanase titer of 400 U/ml could be achieved in less than 60 h of culture in the reactor. ConclusionOptimization was successful in achieving about threefold increase in the yield of xylanase. The optimized conditions resulted in a successful scale up and enhancement of xylanase production.

3D-printed xylanase within biocompatible polymers as excellent catalyst for lignocellulose degradation

As a key hemicellulase, xylanase has great potential as catalyst of degrading lignocellulose. However, the practical application of xylanase in the industrial sector is limited by its instability, high production cost and difficulties of recycling. In this study, three-dimensional (3D) printing technology was used to immobilize xylanase. The optimum immobilization conditions were determined by single-factor experiments and response surface methods: sodium alginate (SA) concentration was 1 wt%, the CaCl2 concentration was 2 wt%, the cross-linking time was 10 min, and the reaction temperature was 52℃. As a biocompatible adhesive, calcium alginate (CA) can be easily printed. The structural programmability of 3D printing technology endowed the immobilized xylanase with sphere, hook, quadrangle and hexagon shapes. The immobilized xylanase exhibited the excellent reusability with recovered 60% enzyme activity after 7 times using compared with free xylanase. Moreover, the ability of 3D printed xylanase to degrade lignocellulose of corn cob at the large-scale indicated the great potential in the application of industrial production, which can provide a certain reference for the biological intelligent manufacturing of high value-added chemicals.

Cloning, expression and characterization of C. crescentus xynA2 gene and application of Xylanase II in the deconstruction of plant biomass.

Biotechnology offers innovative alternatives for industrial bioprocesses mainly because it uses enzymes that biodegrade the hemicellulose releasing fermentable sugars. Caulobacter crescentus (C. crescentus) has seven genes responsible for xylanolytic cleavage, 5 to β-xylosidases (EC 3.2.1.37) and 2 for endoxylanases, like xynA2 (CCNA_03137) that encodes Xylanase II (EC 3.2.1.8) of the glycohydrolases-GH10 group. The xynA2 gene was amplified by PCR, cloned into the pTrcHisA vector e efficiently overexpressed in E. coli providing a His-tag fusion protein. Recombinant xylanase (XynA2) was purified by affinity chromatography using a nickel sepharose column and exhibited a single 43kDa band on SDS-PAGE gel. XynA2 showed an optimum alkaline pH (8) and stability at alkaline pH for 24h. Although C. crescentus is mesophilic, XynA2 has optimum temperature of 60°C and is thermo-resistance at 65°C. XynA maintains 66% of the enzymatic activity at high temperatures (90°C) without being denatured.The enzyme displayed a xylanolitic activity free of cellulase to xylan from beechwood and it was not inhibited in the presence of 50μmolmL-1 of xylose. In addition, dithiothreitol (DTT) induced XynA2 activity, as it improved its kinetic parameters by lowering the KM (5.78μmolmL-1) and increasing the KCat/KM ratio (1.63 U s-1). Finally, C. crescentus XynA2 efficiently hydrolyzed corn straw with high release of reducing sugars that can be applied in different branches of the industry.

Effect of enzymatic treatment on the thermal stability of cellulose nanofibrils

In this work, bagasse pulp was used to prepare cellulose nanofibrils (CNFs) by enzymatic assisted mechanical treatment. A xylanase pretreatment was applied for varying the hemicellulose content in the pulp fibers, and the contribution of this pretreatment to the post-mechanical treatment was investigated. The results showed that CNFs prepared after xylanase pretreatment exhibited enhanced thermal stability with an increase in crystallinity. However, the overall thermal stability of the CNFs decreased significantly after xylanase was applied directly to the mechanical treated CNFs. The results indicate that the presence of hemicellulose in the fiber could affect the thermal stability of CNFs. The direct application of xylanase to CNFs could affect both the hydrogen bond between the hemicellulose and the cellulose and the covalent bond between the hemicellulose molecules, which partially destroys the internal network structure and reduces of thermal stability of CNFs.

Immobilization of xylanase and xylanase–β-cyclodextrin complex in polyvinyl alcohol via electrospinning improves enzyme activity at a wide pH and temperature range

Xylanase (EC 3.2.1.8) is a key enzyme for degradation of xylan. A limitation of xylanase application in food and beverage industries is the low enzyme activity and stability at a wide pH and temperature range. In the present study, different levels of pure xylanase (XY) and xylanase–β-cyclodextrin (XY–β-CD) inclusion complex were immobilized in polyvinyl alcohol (PVA) via electrospinning. Morphological and structural characteristics of obtained fibers were investigated by Fourier-transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X–ray diffraction (XRD) analyzes. Inclusion complex formation was evaluated by FTIR, XRD, and differential scanning calorimetry (DSC) analyzes. Obtained electrospun fibers showed a smooth surface with average diameter from around 200 to 600 nm. Greater diameters were observed at higher xylanase levels. In addition, inclusion complex provided thicker fibers than pure xylanase. Optimum xylanase activity changed from 60 to 70 °C when enzyme was immobilized in PVA. FTIR results suggest a more efficient enzyme conformation after immobilization. The greatest xylanase efficiency of immobilization was achieved at 0.5%-XY, with specific activity of 59.73 μM/min/mg of immobilized xylanase. Xylanase immobilized in PVA fibers exhibited higher activity at extremer pH conditions (4, 5, 7, and 8), as compared to free xylanase.

Solid-state cultivation of recombinant Aspergillus nidulans to co-produce xylanase, arabinofuranosidase, and xylooligosaccharides from soybean fibre

Abstract Solid-state cultivations of genetically modified strains of Aspergillus nidulans A773, using soybean fibre as substrate, were carried out to produce xylanase and arabinofuranosidase, and these enzymes were subsequently used to obtain xylooligosaccharides using the same agro-residue. First, the best fungi cultivation conditions (moisture content, pH, temperature and addition of maltose) were optimized one-by-one for obtain the crude enzyme extracts. Subsequently, the application of xylanase on soybean fibre to obtain xylooligosaccharides was optimized by central composite design, defining best enzyme concentration and reaction temperature. The best condition obtained (50 °C and 117 U g−1 of soybean fibre) was used to evaluate the co-production of xylooligosaccharides by the addition of different concentrations of arabinofuranosidase. The highest yield of xylooligosaccharides obtained was 28% (mass fraction of xylan), showing final concentrations (in mg g−1 arabino-xylan) of 138.36 xylobiose (X2), 96.96 xylotriose (X3), and 53.04 xylotetraose (X4), in 9 h enzymatic reactions. The conversion of arabino-xylans into different xylooligosaccharides suggests the potential to use recombinant A. nidulans A773 enzymes to obtain prebiotics using a sugar-rich, low-cost soybean residue.