Unraveling the unique structural motifs of glucuronoxylan from hybrid aspen wood.

Xylan is a fundamental structural polysaccharide in plant secondary cell walls and a valuable resource for biorefinery applications. Deciphering the molecular motifs of xylans that mediate their interaction with cellulose and lignin is fundamental to understand the structural integrity of plant cell walls and to design lignocellulosic materials. In the present study, we investigated the pattern of acetylation and glucuronidation substitution in hardwood glucuronoxylan (GX) extracted from aspen wood using subcritical water and alkaline conditions. Enzymatic digestions of GX with ß-xylanases from glycosyl hydrolase (GH) families GH10, GH11 and GH30 generated xylo-oligosaccharides with controlled structures amenable for mass spectrometric glycan sequencing. We identified the occurrence of intramolecular motifs in aspen GX with block repeats of even glucuronidation (every 2 xylose units) and consecutive glucuronidation, which are unique features for hardwood xylans. The acetylation pattern of aspen GX shows major domains with evenly-spaced decorations, together with minor stretches of highly acetylated domains. These heterogenous patterns of GX can be correlated with its extractability and with its potential interaction with lignin and cellulose. Our study provides new insights into the molecular structure of xylan in hardwood species, which has fundamental implications for overcoming lignocellulose recalcitrance during biochemical conversion.

Improving the catalytic activity and thermostability of Aspergillus niger xylanase through computational design.

Xylanase plays the most important role in catalyzing xylan to xylose moieties. GH11 xylanases have been widely used in many fields, but most GH11 xylanases are mesophilic enzymes. To improve the catalytic activity and thermostability of Aspergillus niger xylanase (Xyn-WT), we predicted potential key mutation sites of Xyn-WT through multiple computer-aided enzyme engineering strategies. We introduce a simple and economical Ni affinity chromatography purification method to obtain high-purity xylanase and its mutants. Ten mutants (Xyn-A, Xyn-B, Xyn-C, E45T, Q93R, E45T/Q93R, A161P, Xyn-D, Xyn-E, Xyn-F) were identified. Among the ten mutants, four (Xyn-A, Xyn-C, A161P, Xyn-F) presented improved thermal stability and activity, with Xyn-F(A161P/E45T/Q93R) being the most thermally stable and active. Compared with Xyn-WT, after heat treatment at 55 °C and 60 °C for 10 min, the remaining enzyme activity of Xyn-F was 12 and 6 times greater than that of Xyn-WT, respectively, and Xyn-F was approximately 1.5 times greater than Xyn-WT when not heat treated. The pH adaptation of Xyn-F was also significantly enhanced. In summary, an improved catalytic activity and thermostability of the design variant Xyn-F has been reported.

Exploring Bacillus species xylanases for industrial applications: screening via thermostability and reaction modelling.

CONTEXT: Xylanases derived from Bacillus species hold significant importance in various large-scale production sectors, with increasing demand driven by biofuel production. However, despite their potential, the extreme environmental conditions often encountered in production settings have led to their underutilisation. To address this issue and enhance their efficacy under adverse conditions, we conducted a theoretical investigation on a group of five Bacillus species xylanases belonging to the glycoside hydrolase GH11 family. Bacillus sp. NCL 87-6-10 (sp_NCL 87-6-10) emerged as a potent candidate among the selected biocatalysts; this Bacillus strain exhibited high thermal stability and achieved a transition state with minimal energy requirements, thereby accelerating the biocatalytic reaction process. Our approach aims to provide support for experimentalists in the industrial sector, encouraging them to employ structural-based reaction modelling scrutinisation to predict the ability of targeted xylanases. METHODS: Utilising crystal structure data available in the Carbohydrate-Active enzymes database, we aimed to analyse their structural capabilities in terms of thermal-stability and activity. Our investigation into identifying the most prominent Bacillus species xylanases unfolds with the help of the semi-empirical quantum mechanics MOPAC method integrated with the DRIVER program is used in calculations of reaction pathways to understand the activation energy. Additionally, we scrutinised the selected xylanases using various analyses, including constrained network analyses, intermolecular interactions of the enzyme-substrate complex and molecular orbital assessments calculated using the AM1 method with the MO-G model (MO-G AM1) to validate their reactivity.

Optimization and Characterization of an Ultra-Thermostable, Acidophilic, Cellulase-Free Xylanase from a New Obligate Thermophilic Geobacillus thermoleovorans AKNT10 and its Application in Saccharification of Wheat Bran.

Microbial xylanases are enzymes of great importance due to their wide industrial applications, especially in the degradation of lignocellulosic biomass into fermentable sugars. This study aimed to describe the production optimization and partial characterization of an ultra-thermostable, acidophilic, cellulase-free xylanase from an obligate thermophilic eubacterium Geobacillus thermoleovorans strain-AKNT10 (Ac.No. LT158229) isolated from a hot-spring of Puga Valley located at an altitude of 4419 m in Ladakh, India. The optimization of cultural conditions improved enzyme yield by 10.49-fold under submerged fermentation. The addition of 1% (w/v) xylose induced the enzyme synthesis by ~ 165 and 371% when supplemented in the fermentation medium containing wheat bran (WB) 1 and 3%, respectively. The supplementation of sucrose reduced the xylanase production by ~ 25%. Results of partial characterization exhibited that xylanase was optimally active at pH 6.0 and 100 °C. Enzyme retained > 75%, > 83%, and > 84% of activity at 4 °C for 28 days, 100 °C for 60 min, and pHs 3-8 for 60 min, respectively. An outstanding property of AKNT10-xylanase, was the retention of > 71% residual activity at extreme conditions (121 °C and 15 psi pressure) for 15 min. Enzymatic saccharification showed that enzyme was also capable to liberate maximum reducing sugars within 4-8 h under optimized conditions thus it could be a potential candidate for the bioconversion of lignocellulosic biomass as well as other industrial purposes. To the best of our knowledge, this is the first report on such an ultra-thermo-pressure-tolerant xylanase optimally active at pH 6 and 100 °C from the genus Geobacillus.

Unleashing the Power of Evolution in Xylanase Engineering: Investigating the Role of Distal Mutation Regulation.

The drive to enhance enzyme performance in industrial applications frequently clashes with the practical limitations of exhaustive experimental screening, underscoring the urgency for more refined and strategic methodologies in enzyme engineering. In this study, xylanase Xyl-1 was used as the model, coupling evolutionary insights with energy functions to obtain theoretical potential mutants, which were subsequently validated experimentally. We observed that mutations in the nonloop region primarily aimed at enhancing stability and also encountered selective pressure for activity. Notably, mutations in this region simultaneously boosted the Xyl-1 stability and activity, achieving a 65% success rate. Using a greedy strategy, mutant M4 was developed, achieving a 12 °C higher melting temperature and doubled activity. By integration of spectroscopy, crystallography, and quantum mechanics/molecular mechanics molecular dynamics, the mechanism behind the enhanced thermal stability of M4 was elucidated. It was determined that the activity differences between M4 and the wild type were primarily driven by dynamic factors influenced by distal mutations. In conclusion, the study emphasizes the pivotal role of evolution-based approaches in augmenting the stability and activity of the enzymes. It sheds light on the unique adaptive mechanisms employed by various structural regions of proteins and expands our understanding of the intricate relationship between distant mutations and enzyme dynamics.

Investigating process parameters to enhance (hemi)cellulolytic enzymes activity produced by Trichoderma reesei RUT-C30 using deoiled oil palm mesocarp fiber in solid-state fermentation.

This study investigates the synthesis of (hemi)cellulolytic enzymes, including endoglucanase (CMCase), xylanase, and ß-glucosidase, employing Trichoderma reesei RUT-C30 and deoiled oil palm mesocarp fiber (OPMF) through solid-state fermentation (SSF). The objective was to determine the optimal process conditions for achieving high enzyme activities through a one-factor-at-a-time approach. The study primarily focused on the impact of the solid-to-liquid ratio, incubation period, initial pH, and temperature on enzyme activity. The effects of OPMF pretreatment, particularly deoiling and fortification, were explored. This approach significantly improved enzyme activity levels compared to the initial conditions, with CMCase increasing by 111.6 %, xylanase by 665.2 %, and ß-Glucosidase by 1678.1 %. Xylanase and ß-glucosidase activities, peaking at 1346.75 and 9.89 IU per gram dry substrate (GDS), respectively, under optimized conditions (1:4 ratio, pH 7.5, 20 °C, 9-day incubation). With lower moisture levels, CMCase reached its maximum activity of 227.84 IU/GDS. The study highlights how important it is for agro-industrial byproducts to support environmentally sustainable practices in the palm oil industry. It also emphasizes how differently each enzyme reacts to changes in process parameters.

Synergistic effect of cellulo-xylanolytic and laccase enzyme consortia for improved deinking of waste papers.

This study reports the cellulo-xylanolytic cocktail production from Hypocrea lixii GGRK4 using multi-objective genetic algorithm-artificial neural network tool, resulting in 8.32 ± 1.07 IU/mL, 51.53 ± 3.78 IU/mL activity of CMCase and xylanase, respectively with more than 85 % residual activity at 60 °C and pH 6.0. Interestingly, metal ions viz. K+ and Ca2+ stimulated the enzyme activity, whereas Fe2+ and Cu2+ reduced the activity. Significant amounts of hydrophobic compounds, chromophores, and phenolics were released after wastepapers deinking. The deinking efficiency of 73.60 ± 2.45 % and 38.60 ± 1.34 % was obtained for photocopier paper and newspaper, respectively, whereas brightness of 89.90 ± 2.10 % ISO and 44.90 ± 1.63 % ISO was reported for both types of waste papers. The physical strength of deinked photocopier paper and newspapers, i.e., tensile index (3.10 and 0.50 %), tearing index (7.10 and 4.83 %), and burst factor (8.61) were enhanced whereas double fold property was decreased proving wastepaper reusability. This consortium showed effective and significant enzymatic deinking efficiency for recycled wastepapers.

Co-administration of xylo-oligosaccharides produced by immobilized Aspergillus terreus xylanase with carbimazole to mitigate its adverse effects on the adrenal gland.

Carbimazole has disadvantages on different body organs, especially the thyroid gland and, rarely, the adrenal glands. Most studies have not suggested any solution or medication for ameliorating the noxious effects of drugs on the glands. Our study focused on the production of xylooligosaccharide (XOS), which, when coadministered with carbimazole, relieves the toxic effects of the drug on the adrenal glands. In addition to accelerating the regeneration of adrenal gland cells, XOS significantly decreases the oxidative stress caused by obesity. This XOS produced by Aspergillus terreus xylanase was covalently immobilized using microbial Scleroglucan gel beads, which improved the immobilization yield, efficiency, and operational stability. Over a wide pH range (6-7.5), the covalent immobilization of xylanase on scleroglucan increased xylanase activity compared to that of its free form. Additionally, the reaction temperature was increased to 65 °C. However, the immobilized enzyme demonstrated superior thermal stability, sustaining 80.22% of its original activity at 60 °C for 120 min. Additionally, the full activity of the immobilized enzyme was sustained after 12 consecutive cycles, and the activity reached 78.33% after 18 cycles. After 41 days of storage at 4 °C, the immobilized enzyme was still active at approximately 98%. The immobilized enzyme has the capability to produce xylo-oligosaccharides (XOSs). Subsequently, these XOSs can be coadministered alongside carbimazole to mitigate the adverse effects of the drug on the adrenal glands. In addition to accelerating the regeneration of adrenal gland cells, XOS significantly decreases the oxidative stress caused by obesity.

Production of a bacterial secretome highly efficient for the deconstruction of xylans.

Bacteria within the Paenibacillus genus are known to secrete a diverse array of enzymes capable of breaking down plant cell wall polysaccharides. We studied the extracellular xylanolytic activity of Paenibacillus xylanivorans and examined the complete range of secreted proteins when grown on carbohydrate-based carbon sources of increasing complexity, including wheat bran, sugar cane straw, beechwood xylan and sucrose, as control. Our data showed that the relative abundances of secreted proteins varied depending on the carbon source used. Extracellular enzymatic extracts from wheat bran (WB) or sugar cane straw (SCR) cultures had the highest xylanolytic activity, coincidently with the largest representation of carbohydrate active enzymes (CAZymes). Scaling-up to a benchtop bioreactor using WB resulted in a significant enhancement in productivity and in the overall volumetric extracellular xylanase activity, that was further concentrated by freeze-drying. The enzymatic extract was efficient in the deconstruction of xylans from different sources as well as sugar cane straw pretreated by alkali extrusion (SCRe), resulting in xylobiose and xylose, as primary products. The overall yield of xylose released from SCRe was improved by supplementing the enzymatic extract with a recombinant GH43 ß-xylosidase (EcXyl43) and a GH62 α-L-arabinofuranosidase (CsAbf62A), two activities that were under-represented. Overall, we showed that the extracellular enzymatic extract from P. xylanivorans, supplemented with specific enzymatic activities, is an effective approach for targeting xylan within lignocellulosic biomass.

Inter domain linker region affects properties of CBM6 in GH5_34 arabinoxylanases and alters oligosaccharide product profile.

Understanding the relation between enzyme domain structure and catalytic activity is crucial for optimal engineering of novel enzymes for lignocellulose bioconversion. Xylanases with varying specificities are commonly used to valorise the hemicellulose arabinoxylan (AX), yet characterization of specific arabinoxylanases remain limited. Two homologous GH5_34 arabinoxylanases, HhXyn5A and CtXyn5A, in which the two domains are connected by a 40-residue linker, exhibit distinct activity on AX, yielding different reaction product patterns, despite high sequence identity, conserved active sites and similar domain composition. In this study, the carbohydrate binding module 6 (CBM6), or the inter domain linker together with CBM6, were swapped to investigate their influence on hydrolytic activity and oligosaccharide product pattern on cereal AXs. The variants, with only CBM6 swapped, displayed reduced activity on commercial wheat and rye AX, as well as on extracted oat fibre, compared to the original enzymes. Additionally, exchange of both linker and CBM6 resulted in a reduced ratio of enzyme produced in soluble form in Escherichia coli cultivations, causing loss of activity of both HhXyn5A and CtXyn5A variants. Analysis of oligosaccharide product patterns applying HPAEC-PAD revealed a decreased number of reaction products for CtXyn5A with swapped CBM6, which resembled the product pattern of HhXyn5A. These findings emphasize the importance of the CBM6 interactions with the linker and the catalytic domain for enzyme activity and specificity, and underlines the role of the linker in enzyme structure organisation and product formation, where alterations in linker interactions with the catalytic and/or CBM6 domains, influence enzyme-substrate association and specificity.

Sugarcane bagasse derived xylooligosaccharides produced by an arabinofuranosidase/xylobiohydrolase from Bifidobacterium longum in synergism with xylanases.

Arabinoxylan is a major hemicellulose in the sugarcane plant cell wall with arabinose decorations that impose steric restrictions on the activity of xylanases against this substrate. Enzymatic removal of the decorations by arabinofuranosidases can allow a more efficient arabinoxylan degradation by xylanases. Here we produced and characterized a recombinant Bifidobacterium longum arabinofuranosidase from glycoside hydrolase family 43 (BlAbf43) and applied it, together with GH10 and GH11 xylanases, to produce xylooligosaccharides (XOS) from wheat arabinoxylan and alkali pretreated sugarcane bagasse. The enzyme synergistically enhanced XOS production by GH10 and GH11 xylanases, being particularly efficient in combination with the latter family of enzymes, with a degree of synergism of 1.7. We also demonstrated that the enzyme is capable of not only removing arabinose decorations from the arabinoxylan and from the non-reducing end of the oligomeric substrates, but also hydrolyzing the xylan backbone yielding mostly xylobiose and xylose in particular cases. Structural studies of BlAbf43 shed light on the molecular basis of the substrate recognition and allowed hypothesizing on the structural reasons of its multifunctionality.

Live performance, nutrient digestibility, immune response and fecal microbial load modulation in Japanese quails fed a Bacillus-based probiotic alone or combination with xylanase.

Animal industry seeks cost-effective solutions to enhance performance and health of domestic animals. This study investigated the effects of supplementing Bacillus spp. probiotics and xylanase on 2000 one-day-old Japanese quails, randomly assigned to four treatment groups (10 replicates). The control group received no supplementation, while the others were supplemented with a Bacillus-based probiotic at 7.5 × 107 cfu/kg of feed, xylanase enzyme (2,000 U/kg) alone or in combination. Quails receiving both probiotic and enzyme exhibited significantly (p < 0.01) higher weekly and overall weight gain, and lower feed conversion ratios compared to the control group. Dressing percentage was higher (p < 0.01), and mortality lower in birds supplemented with a combination of enzyme and probiotic. Antibody titres against infectious bronchitis and infectious bursal disease were significantly (p < 0.01) higher in quails receiving combined probiotic and enzyme supplementation, while titres against Newcastle disease virus were higher (p < 0.01) in groups supplemented with probiotic and enzyme individually or in combination. Additionally, digestibility was significantly (p < 0.01) higher in groups receiving combined enzyme and probiotic supplementation, with higher apparent metabolizable energy compared to the control. The populations of beneficial Lactobacillus increased, while harmful E. coli and Salmonella decreased significantly in quails supplemented with both probiotic and enzyme. In conclusion, supplementing xylanase enzyme and probiotic together in Japanese quails positively influenced growth, nutrient digestibility, immune response, and cecal microbiota.

A novel xylanase from a myxobacterium triggers a plant immune response in Nicotiana benthamiana.

Xylanases derived from fungi, including phytopathogenic and nonpathogenic fungi, are commonly known to trigger plant immune responses. However, there is limited research on the ability of bacterial-derived xylanases to trigger plant immunity. Here, a novel xylanase named CcXyn was identified from the myxobacterium Cystobacter sp. 0969, which displays broad-spectrum activity against both phytopathogenic fungi and bacteria. CcXyn belongs to the glycoside hydrolases (GH) 11 family and shares a sequence identity of approximately 32.0%-45.0% with fungal xylanases known to trigger plant immune responses. Treatment of Nicotiana benthamiana with purified CcXyn resulted in the induction of hypersensitive response (HR) and defence responses, such as the production of reactive oxygen species (ROS) and upregulation of defence gene expression, ultimately enhancing the resistance of N. benthamiana to Phytophthora nicotianae. These findings indicated that CcXyn functions as a microbe-associated molecular pattern (MAMP) elicitor for plant immune responses, independent of its enzymatic activity. Similar to fungal xylanases, CcXyn was recognized by the NbRXEGL1 receptor on the cell membrane of N. benthamiana. Downstream signalling was shown to be independent of the BAK1 and SOBIR1 co-receptors, indicating the involvement of other co-receptors in signal transduction following CcXyn recognition in N. benthamiana. Moreover, xylanases from other myxobacteria also demonstrated the capacity to trigger plant immune responses in N. benthamiana, indicating that xylanases in myxobacteria are ubiquitous in triggering plant immune functions. This study expands the understanding of xylanases with plant immune response-inducing properties and provides a theoretical basis for potential applications of myxobacteria in biocontrol strategies against phytopathogens.

Exploring xylan removal via enzymatic post-treatment to tailor the properties of cellulose nanofibrils for packaging film applications.

Hemicellulose plays a key role in both the production of cellulose nanofibrils (CNF) and their properties as suspensions and films. While the use of enzymatic and chemical pre-treatments for tailoring hemicellulose levels is well-established, post-treatment methods using enzymes remain relatively underexplored and hold significant promise for modifying CNF film properties. This study aimed to investigate the effects of enzymatic xylan removal on the properties of CNF film for packaging applications. The enzymatic post-treatment was carried out using an enzymatic cocktail enriched with endoxylanase (EX). The EX post-treated-CNFs were characterized by LALLS, XRD, and FEG-SEM, while their films were characterized in terms of physical, morphological, optical, thermal, mechanical, and barrier properties. Employing varying levels of EX facilitated the hydrolysis of 8 to 35 % of xylan, yielding CNFs with different xylan contents. Xylan was found to be vital for the stability of CNF suspensions, as its removal led to the agglomeration of nanofibrils. Nanostructures with preserved crystalline structures and different morphologies, including nanofibers, nanorods, and their hybrids were observed. The EX post-treatment contributed to a smoother film surface, improved thermostability, and better moisture barrier properties. However, as the xylan content decreased, the films became lighter (lower grammage), less strong, and more brittle. Thus, the enzymatic removal of xylan enabled the customization of CNF films' performance without affecting the inherent crystalline structure, resulting in materials with diverse functionalities that could be explored for use in packaging films.

Development of a split-luciferase assay to establish optimal protein secretion conditions for protein production by Bacillus subtilis.

Bacillus subtilis is a Gram-positive bacterium that is frequently used in the bioindustry for the production of various proteins, because of its superior protein secretion capacities. To determine optimal conditions for protein secretion by B. subtilis, a quick and sensitive method for measuring protein secretion is crucial. A fast and universal assay is most useful for detecting diverse proteins in a high-throughput manner. In this study, we introduce a split-luciferase-based method for measuring protein secretion by B. subtilis. The NanoBiT system was used to monitor secretion of four different proteins: xylanase A, amylase M, protein glutaminase A, and GFP nanobody. Our findings underscore the split-luciferase system as a quick, sensitive, and user-friendly method.

Identification of a novel glycoside hydrolase family 8 xylanase from Deinococcus geothermalis and its application at low temperatures.

Xylanase is the most important hydrolase in the xylan hydrolase system, the main function of which is ß-1,4-endo-xylanase, which randomly cleaves xylans to xylo-oligosaccharides and xylose. Xylanase has wide ranging of applications, but there remains little research on the cold-adapted enzymes required in some low-temperature industries. Glycoside hydrolase family 8 (GH8) xylanases have been reported to have cold-adapted enzyme activity. In this study, the xylanase gene dgeoxyn was excavated from Deinococcus geothermalis through sequence alignment. The recombinant xylanase DgeoXyn encodes 403 amino acids with a theoretical molecular weight of 45.39 kDa. Structural analysis showed that DgeoXyn has a (α/α)6-barrel fold structure typical of GH8 xylanase. At the same time, it has strict substrate specificity, is only active against xylan, and its hydrolysis products include xylobiose, xylotrinose, xytetranose, xylenanose, and a small amount of xylose. DgeoXyn is most active at 70 â„ƒ and pH 6.0. It is very stable at 10, 20, and 30 â„ƒ, retaining more than 80% of its maximum enzyme activity. The enzyme activity of DgeoXyn increased by 10% after the addition of Mn2+ and decreased by 80% after the addition of Cu2+. The Km and Vmax of dgeox were 42 mg/ml and 20,000 U/mg, respectively, at a temperature of 70 â„ƒ and pH of 6.0 using 10 mg/ml beechwood xylan as the substrate. This research on DgeoXyn will provide a theoretical basis for the development and application of low-temperature xylanase.

Temperature-dependent structural changes in xylanase II from Trichoderma longibrachiatum.

Endo-ß-1,4-xylanases degrade heteroxylans that constitute the lignocellulosic plant cell wall. This enzyme is widely used in the food, paper, textile, and biorefinery industries. Temperature affects the optimum activity of xylanase and is an important factor in its application. Various structural analyses of xylanase have been performed, but its structural influence by temperature is not fully elucidated. To better understand the structural influence of xylanase due to temperature, the crystal structure of xylanase II from Trichoderma longibrachiatum (TloXynII) at room and cryogenic temperatures was determined at 2.1 and 1.9 Å resolution, respectively. The room-temperature structure of TloXynII (TloXynIIRT) showed a B-factor value 2.09 times higher than that of the cryogenic-temperature structure of TloXynII (TloXynIICryo). Subtle movement of the catalytic and substrate binding residues was observed between TloXynIIRT and TloXynIICryo. In TloXynIIRT, the thumb domain exhibited high flexibility, whereas in TloXynIICryo, the finger domain exhibited high flexibility. The substrate binding cleft of TloXynIIRT was narrower than that of TloXynIICryo, indicating a distinct finger domain conformation. Numerous water molecule networks were observed in the substrate binding cleft of TloXynIICryo, whereas only a few water molecules were observed in TloXynIIRT. These structural analyses expand our understanding of the temperature-dependent conformational changes in xylanase.

Advances in the understanding of the production, modification and applications of xylanases in the food industry.

Xylanases have broad applications in the food industry to decompose the complex carbohydrate xylan. This is applicable to enhance juice clarity, improve dough softness, or reduce beer turbidity. It can also be used to produce prebiotics and increase the nutritional value in foodstuff. However, the low yield and poor stability of most natural xylanases hinders their further applications. Therefore, it is imperative to explore higher-quality xylanases to address the potential challenges that appear in the food industry and to comprehensively improve the production, modification, and utilization of xylanases. Xylanases, due to their various sources, exhibit diverse characteristics that affect production and activity. Most fungi are suitable for solid-state fermentation to produce xylanases, but in liquid fermentation, microbial metabolism is more vigorous, resulting in higher yield. Fungi produce higher xylanase activity, but bacterial xylanases perform better than fungal ones under certain extreme conditions (high temperature, extreme pH). Gene and protein engineering technology helps to improve the production efficiency of xylanases and enhances their thermal stability and catalytic properties.

Total replacement of soybean meal with alternative plant-based ingredients and a combination of feed additives in broiler diets from 1 day of age during the whole growing period.

The capacity of combinations of feed enzymes, natural betaine and a probiotic, combined with alternative plant-based ingredients, to totally replace soybean meal (SBM) in a broiler diet was evaluated. Day-old Ross 308 males (2,574) were assigned to 9 treatments (13 pens/treatment, 22 birds/pen) in a completely randomized design. All diets were pelleted and fed ad libitum in 4 phases: starter, grower, finisher 1, finisher 2 (0-10, 10-21, 21-35, and 35-42 d of age, respectively). Treatments included: 1) control diet containing SBM (SBM control), supplemented with phytase (PhyG), at 2,000, 1,500, 1000 and 1,000 FTU/kg in each phase and xylanase (X) at 750 U/kg, [crude protein (CP): 23.5%, 22.0%, 20.2% and 19.3% in each phase]; 2) to 5), alternative (ALT), SBM-free diets, containing the same CP level as the control ("CP high"), supplemented with PhyG as in the control, protease (P, 800 U/kg) and in 2) xylanase (750 U/kg) (ALT+PhyG+P+X), 3) xylanase-ß-glucanase (XB, 1,200 U/kg and 152 U/kg) (Alt+PhyG+P+XB), 4) XB plus betaine (800 g/ton) (ALT+PhyG+P+XB+Bet), and 5) XB plus a probiotic [150,000 colony forming units (CFU)/g] (ALT+PhyG+P+XB+Prob); 6) to 9) as treatments 2) to 5) but with CP reduced by -2.0 to -1.5% points vs. control ('CP low'). Final (d 42) BW and overall (d 0-42) feed conversion ratio (FCR) of birds fed the SBM control exceeded breeder objectives (+3.8% and -1.9%, respectively). Overall FCR was reduced and d 42 BW increased in birds fed "low" vs. "high" CP (P < 0.01). Overall FCR and feed intake were not different in ALT+PhyG+XB+P+Bet and ALT+PhyG+XB+P+Prob vs. the control, whereas final BW was reduced (P < 0.05) in all ALT treatments but close to breeder objectives (98.3%) in ALT+PhyG+XB+P+Prob. Feed costs of this treatment were similar to the control. Total replacement of SBM with alternative plant-based ingredients in a CP-low diet supplemented with hydrolytic enzymes and probiotics can achieve growth performance outcomes close to commercial breeder objectives.

Digestibility and nutritional parameters of maize ethanol coproducts and xylanase for broiler diets.

1. The objective of this study was to determine the nutritional and energy values of four maize distiller's dried grains with solubles (DDGS) and one maize high protein distiller's dried grains (HP-DDG) from ethanol production plants in Brazil; to evaluate the digestibility, performance, nitrogen balance and energy values for broiler chickens fed diets containing these coproducts (Experiment I); and to evaluate the effects of xylanase inclusion in diets containing maize DDGS for broilers on energy availability, digestibility, nitrogen balance and gastrointestinal morphometry (Experiment II).2. For each experiment, 180 broiler chickens aged 17 and 30 days with initial weights of 450 ± 18 g and 1228 ± 33 g, respectively, were used; the chickens were distributed into 36 metabolism cages. The experimental design consisted of complete randomised blocks, with six replications per treatment and five birds per experimental unit. The treatments consisted of a basal diet (BD) and five test diets containing maize ethanol coproducts (Experiment I) one BD and five test diets containing DDGS with inclusions of 0, 8,000, 16,000, 24,000 and 32,000 BXU/kg xylanase (Experiment II). In Experiment I, HP-DDG and DDGS2 presented higher AME and AMEn values (14.1 and 13.9 MJ/kg and 13.4 and 13.3 MJ/kg, respectively), than did the other coproducts (p < 0.05). Compared with DDGS1 and DDGS3, DDGS4 and HP-DDG had higher digestible CP values (p < 0.05). In Experiment II, the inclusion of the enzyme quadratically affected the values of digestible CP and digestible EE (p < 0.05), with the maximum values occurring with the inclusion of 18 750 and 22,170 BXU/kg of xylanase, respectively.3. The digestible NDF and digestible MM values linearly increased with the inclusion of xylanase (p < 0.05). The addition of xylanase had no effect on gastrointestinal morphometry (p > 0.05). It was concluded that the inclusion of between 18,000 and 22,000 BXU/kg of xylanase resulted in better digestible CP and digestible EE values.