A commercial GH 11 xylanase mediates xylan solubilisation and degradation in wheat, rye and barley as demonstrated by microscopy techniques and wet chemistry methods

Novel thermal stability enhanced xylanase improves the performance and digestibility parameters in broilers

Xylanases require thermal stability to withstand the pelleting process, pH stability to function in the gastrointestinal tract, and resistance to xylanase inhibitors in raw materials to be effective in animal feed. A GH11 family xylanase originating from an anaerobic fungus, Orpinomyces sp. strain PC-2, has high specific activity and resistance to xylanase inhibitors intrinsically. It was engineered using rational protein design methods to obtain a thermal and pH stable enzyme, OXynA-M. OXynA-M showed resistance to three types of xylanase inhibitors, Triticum aestivum xylanase inhibitors TAXI-IB and TAXI-IIA and xylanase inhibitor protein XIP and showed melting temperature of 87.2°C when measured using differential scanning calorimetry. It was stable at all pH between 2.0-10.0 incubated up to 4 h. Xylo-oligosaccharides (XOS) production profile using a wheat arabinoxylan substrate revealed the production of xylobioses up to xylohexaoses, which are known to have prebiotic functionalities. An animal trial was conducted in broiler chickens to evaluate the in vivo efficacy of the xylanase. In total, 600 1-day-old chickens were divided into six dietary treatments, including a positive control (PC) (T1) without the addition of exogenous enzyme and the rest where exogenous xylanase was added at the rates of 1200, 2400, 4800, 9600, and 240000 U/kg of feed from T2-T6. An increase in OXynA-M xylanase improved the performance parameters in the enzyme-treated groups compared with the control. The viscosity of ileal digesta decreased with increasing enzyme dosage. A significantly lower viscosity of 6.54 cP was determined for the minimum dose in T2 (1200 U/kg), and the viscosity was further reduced in T6 (240000 U/kg) (P<0.05) compared to the control treatment. The apparent ileal digestibility of crude protein, fat, and starch improved as the xylanase dosage increased. The application of OXynA-M xylanase improved the apparent ileal digestibility of crude protein when the dose was higher than that of T2 (1200 U/kg). Furthermore, the AMEn of the diets improved when xylanase was supplemented at a rate of 9600 U/kg (T5) compared with the control treatment (P<0.05).

In vitro evaluation of the application of an optimized xylanase cocktail for improved monogastric feed digestibility

Xylanases from glycoside hydrolase (GH) families 10 and 11 are common feed additives for broiler chicken diets due to their catalytic activity on the nonstarch polysaccharide xylan. This study investigated the potential of an optimized binary GH10 and GH11 xylanase cocktail to mitigate the antinutritional effects of xylan on the digestibility of locally sourced chicken feed. Immunofluorescence visualization of the activity of the xylanase cocktail on xylan in the yellow corn of the feed showed a substantial collapse in the morphology of cell walls. Secondly, the reduction in the viscosity of the digesta of the feed by the cocktail showed an effective degradation of the soluble fraction of xylan. Analysis of the xylan degradation products from broiler feeds by the xylanase cocktail showed that xylotriose and xylopentaose were the major xylooligosaccharides (XOS) produced. In vitro evaluation of the prebiotic potential of these XOS showed that they improved the growth of the beneficial bacteria Streptococcus thermophilus and Lactobacillus bulgaricus. The antibacterial activity of broths from XOS-supplemented probiotic cultures showed a suppressive effect on the growth of the extraintestinal infectious bacterium Klebsiella pneumoniae. Supplementing the xylanase cocktail in cereal animal feeds attenuated xylan's antinutritional effects by reducing digesta viscosity and releasing entrapped nutrients. Furthermore, the production of prebiotic XOS promoted the growth of beneficial bacteria while inhibiting the growth of pathogens. Based on these effects of the xylanase cocktail on the feed, improved growth performance and better feed conversion can potentially be achieved during poultry rearing.

Unveiling the influence of adaptation time on xylanase and arabinoxylan-oligosaccharide efficacy: a study on nutrient digestibility, viscosity, and scanning electron microscopy in the small and large intestine of growing pigs fed insoluble fiber

The experiment objective was to evaluate the impact of xylanase over time on viscosity and digestibility in growing pigs fed corn-based fiber. Twenty gilts with an initial body weight of 30.6 ± 0.2 kg (n = 5 per dietary treatment) were fitted with t-cannulae in the medial jejunum and terminal ileum, housed individually, and randomly assigned to one of four dietary treatments: low-fiber control (LF) with 10.4% total dietary fiber (TDF), 30% corn bran high-fiber control (HF; 26.4% TDF), HF + 100 mg xylanase/kg (XY; Econase XT 25P; AB Vista, Marlborough, UK), and HF + 50 mg arabinoxylan-oligosaccharide/kg (AX). Gilts were limit fed for three 17 d periods (P1, P2, P3); each included 5 d adaptation, 2 d fecal collection, 3 d ileal collection, 3 d jejunal collection, and 4 d related rate of passage study. Data were analyzed as repeated measures using a linear mixed model with surgery date as a random effect, and dietary treatment, period, and their interaction as fixed effects. Jejunal and ileal digesta viscosity did not differ among dietary treatments or periods (P > 0.10). There was a dietary treatment × period interaction for the apparent jejunal digestibility (AJD) of dry matter (DM), gross energy (GE), insoluble dietary fiber (IDF), neutral detergent fiber (NDF), total arabinoxylan (T-AX), total non-starch polysaccharide (T-NSP), and TDF (P≤ 0.05). In P1, LF had the greatest AJD of DM (15.5%), and relative to HF and AX, XY decreased it (9.3%, 10.1 %, and 6.3%, respectively). In P2, the AJD of DM in XY was greater than HF (11.7% vs. 9.1%) but did not differ from AX (10.5%). Relative to HF, in P3, XY increased AJD of DM (11.7 vs 15.3%), and AX decreased it (7.2%). For the AJD of NDF, AX performed intermediately in P1; in P2, relative to HF, XY, and AX increased the AJD of NDF (8.4%, 13.1%, and 11.7%, respectively), and in P3, XY, and LF did not differ (13.6 vs. 14.4%). A similar response was observed for the AJD of IDF and TDF, except for XY having the greatest AJD of IDF, T-AX, T-NSP, and TDF in P3 (P < 0.05). Compared to LF, irrespective of period, HF decreased the apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of IDF, TDF, and NDF (P < 0.05). Relative to HF, XY partially mitigated this effect, improving the AID and ATTD of TDF, IDF, and NDF (P < 0.05). Increased corn-based fiber decreased nutrient digestibility, but XY partially mitigated that effect in the small intestine through enhanced fiber digestibility when given sufficient adaptation time.

Barley, an Undervalued Cereal for Poultry Diets: Limitations and Opportunities

Simple Summary

With the ever-increasing demand for poultry products, the continuous supply of conventional cereal grains such as maize has become a challenge. Barley has been recognised as a potential alternative feed ingredient that can replace common cereal grains in poultry diets. However, due to several limitations such as the presence of various anti-nutritive factors and the variability in nutrient composition and quality, the use of barley in poultry diets remains comparatively low. The previous findings on the optimum use of barley in poultry diets are also inconsistent primarily due to differences in research methodologies. The importance of using accurate nutrient profiles for specific barley cultivars to formulate barley-based diets is emphasised in this review. Moreover, the need to adapt feed processing conditions suitable to different barley cultivars to increase the inclusion of barley in poultry diets is highlighted in this review.

Abstract

The supply of conventional cereal grains, especially of maize, will be a significant constraint to the future growth of the poultry industry. Various alternative feed ingredients are being tested to replace maize in poultry diets. Barley (Hordeum vulgare L.) is one such feed ingredient, the use of which remains limited in poultry diets due to its low metabolisable energy, presence of anti-nutritive, soluble non-starch polysaccharides and consequent inter-cultivar variability. Differences in research methodologies used in published studies have also contributed to the inconsistent findings, preventing a good understanding of the nutritional value of barley for poultry. The importance of using accurate nutrient profiles, specifically metabolisable energy and digestible amino acids, for specific barley cultivars to formulate barley-based diets is emphasised. Nutritionists should also pay close attention to feed processing conditions tailored to the specific barley cultivars to increase the barley inclusion in poultry diets.

Effect of an endo-1,4-β-xylanase from wheat malt on water-unextractable arabinoxylan derived from wheat

BACKGROUND

Non-starch polysaccharides in wheat are dominated by arabinoxylan (AX). Endo-1,4-β-xylanase (EC 3.2.1.8) is the most important enzyme for degrading AX. This paper investigated the ability of endo-1,4-β-xylanase extracted from wheat malt to degrade non-water-extractable wheat-derived arabinoxylan (WUAX).

RESULTS

The enzyme was observed to break down wheat-derived WUAX effectively, substantially increasing the concentration of water-extractable arabinoxylan (WEAX) in the system for up to 6 h. A considerable quantity of arabinose xylooligosaccharide (AXOS) was also produced, suggesting that the enzyme could produce oligosaccharides too. The molecular weight of the product WEAX was between 23 and 27 kDa and the content of oligosaccharides changed with degradation time. This suggests that endo-1,4-β-xylanase can not only degrade WUAX into WEAX and xylooligosaccharides but can also degrade the xylooligosaccharides with larger molecular weights into xylobiose and xylotriose. The viscosity of the degradation product increased significantly in the first 2 h, then decreased with longer degradation times. The concentration of WEAX in the reaction system increased throughout the reaction but at gradually lower rates, indicating that the endo-1,4-β-xylanase degraded WEAX better than it degraded WUAX. Rheological tests showed that solutions prepared from the WEAX that was produced had properties of a pseudoplastic fluid.

CONCLUSION

The results showed that the wheat malt endo-1,4-β-xylanase, which we had previously tested on WEAX, was also effective in degrading wheat-derived WUAX. This study can therefore provide a theoretical basis for the subsequent role of the enzyme in other sources of xylan, and provide guidance for the quality control of beer in the brewing process. © 2021 Society of Chemical Industry.

The influence of xylanase on the fermentability, digestibility, and physicochemical properties of insoluble corn-based fiber along the gastrointestinal tract of growing pigs

In theory, supplementing xylanase in corn-based swine diets should improve nutrient and energy digestibility and fiber fermentability, but its efficacy is inconsistent. The experimental objective was to investigate the impact of xylanase on energy and nutrient digestibility, digesta viscosity, and fermentation when pigs are fed a diet high in insoluble fiber (>20% neutral detergent fiber; NDF) and given a 46-d dietary adaptation period. A total of 3 replicates of 20 growing gilts were blocked by initial body weight, individually housed, and assigned to 1 of 4 dietary treatments: a low-fiber control (LF) with 7.5% NDF, a 30% corn bran high-fiber control (HF; 21.9% NDF), HF + 100 mg xylanase/kg (HF + XY [Econase XT 25P; AB Vista, Marlborough, UK]) providing 16,000 birch xylan units/kg; and HF + 50 mg arabinoxylan-oligosaccharide (AXOS) product/kg (HF + AX [XOS 35A; Shandong Longlive Biotechnology, Shandong, China]) providing AXOS with 3–7 degrees of polymerization. Gilts were allowed ad libitum access to fed for 36-d. On d 36, pigs were housed in metabolism crates for a 10-d period, limit fed, and feces were collected. On d 46, pigs were euthanized and ileal, cecal, and colonic digesta were collected. Data were analyzed as a linear mixed model with block and replication as random effects, and treatment as a fixed effect. Compared with LF, HF reduced the apparent ileal digestibility (AID), apparent cecal digestibility (ACED), apparent colonic digestibility (ACOD), and apparent total tract digestibility (ATTD) of dry matter (DM), gross energy (GE), crude protein (CP), acid detergent fiber (ADF), NDF, and hemicellulose (P < 0.01). Relative to HF, HF + XY improved the AID of GE, CP, and NDF (P < 0.05), and improved the ACED, ACOD, and ATTD of DM, GE, CP, NDF, ADF, and hemicellulose (P < 0.05). Among treatments, pigs fed HF had increased hindgut DM disappearance (P = 0.031). Relative to HF, HF + XY improved cecal disappearance of DM (162 vs. 98 g; P = 0.008) and NDF (44 vs. 13 g; P < 0.01). Pigs fed xylanase had a greater proportion of acetate in cecal digesta and butyrate in colonic digesta among treatments (P < 0.05). Compared with LF, HF increased ileal, cecal, and colonic viscosity, but HF + XY decreased ileal viscosity compared with HF (P < 0.001). In conclusion, increased insoluble corn-based fiber decreases digestibility, reduces cecal fermentation, and increases digesta viscosity, but supplementing xylanase partially mitigated that effect.

Multicomponent carbohydrase system from Trichoderma reesei: A toolbox to address complexity of cell walls of plant substrates in animal feed

A diverse range of monocot and dicot grains and their by-products are commonly used in the animal feed industry. They all come with complex and variable cell wall structures which in turn contribute significant fiber to the complete feed. The cell wall is a highly interconnected matrix of various polysaccharides, proteins and lignin and, as such, requires a collaborative effort of different enzymes for its degradation. In this regard, we investigated the potential of a commercial multicomponent carbohydrase product from a wild type fermentation of Trichoderma reesei (T. reesei) (RONOZYME® MultiGrain) in degrading cell wall components of wheat, barley, rye, de-oiled rice bran, sunflower, rapeseed and cassava. A total of thirty-one different enzyme proteins were identified in the T. Reesei carbohydrase product using liquid chromatography with tandem mass spectrometry LC-MS/MS including glycosyl hydrolases and carbohydrate esterases. As measured by in vitro incubations and non-starch polysaccharide component analysis, and visualization by immunocytochemistry and confocal microscopy imaging of immuno-labeled samples with confocal microscopy, the carbohydrase product effectively solubilized cellulolytic and hemicellulolytic polysaccharides present in the cell walls of all the feed ingredients evaluated. The T. reesei fermentation also decreased viscosity of arabinoxylan, xyloglucan, galactomannan and β-glucan substrates. Combination of several debranching enzymes including arabinofuranosidase, xylosidase, α-galactosidase, acetyl xylan esterase, and 4-O-methyl-glucuronoyl methylesterase with both GH10 and GH11 xylanases in the carbohydrase product resulted in effective hydrolyzation of heavily branched glucuronoarabinoxylans. The different β-glucanases (both endo-β-1,3(4)-glucanase and endo-β-1,3-glucanase), cellulases and a β-glucosidase in the T. reesei fermentation effectively reduced polymerization of both β-glucans and cellulose polysaccharides of viscous cereals grains (wheat, barley, rye and oat). Interestingly, the secretome of T. reesei contained significant amounts of an exceptional direct chain-cutting enzyme from the GH74 family (Cel74A, xyloglucan-specific β-1,4-endoglucanase), that strictly cleaves the xyloglucan backbone at the substituted regions. Here, we demonstrated that the balance of enzymes present in the T. reesei secretome is capable of degrading various cell wall components in both monocot and dicot plant raw material used as animal feed.

Improving the digestibility of cereal fractions of wheat, maize, and rice by a carbohydrase complex rich in xylanases and arabinofuranosidases: an in vitro digestion study

BACKGROUND

Cereal co-products rich in dietary fibres are increasingly used in animal feed. The high fibre content decreases the digestibility and reduces the nutrient and energy availability, resulting in lower nutritive value. Therefore, this study investigated the ability of two carbohydrase complexes to solubilize cell-wall polysaccharides, in particular arabinoxylan (AX), from different cereal fractions of wheat, maize, and rice using an in vitro digestion model of the pig gastric and small intestinal digestive system. The first complex (NSPase 1) was rich in cell-wall-degrading enzymes, whereas the second complex (NSPase 2) was additionally enriched with xylanases and arabinofuranosidases. The extent of solubilization of insoluble cell-wall polysaccharides after in vitro digestion was evaluated with gas-liquid chromatography and an enzymatic fingerprint of the AX oligosaccharides was obtained with high-performance anion-exchange chromatography with pulsed amperometric detection.

RESULTS

The addition of carbohydrase increased the digestibility of dry matter and solubilized AX in particular, with the greatest effect in wheat fractions and less effect in maize and rice fractions. The solubilization of AX (expressed as xylose release) ranged from 6% to 41%, and there was an increased effect when enriching with xylanases and arabinofuranosidases in wheat aleurone and bran of 19% and 14% respectively. The enzymatic fingerprint of AX oligosaccharides revealed several non-final hydrolysis products of the enzymes applied, indicating that the hydrolysis of AX was not completed during in vitro digestion.

CONCLUSION

These results indicate that the addition of a carbohydrase complex can introduce structural alterations under in vitro digestion conditions, and that enrichment with additional xylanases and arabinofuranosidases can boost this effect in wheat, maize, and rice. © 2020 Society of Chemical Industry.

Coccidia Vaccine Challenge and Exogenous Enzyme Supplementation in Broiler Chicken 1. Effect on Digesta Viscosity, Diet Energy Utilization, and Apparent Metabolizable Energy Value of Wheat

This study examined the effect of exogenous mixed-enzyme supplementation (xylanase, β-glucanase, and pectinase) to a corn-SBM (CS) and a wheat-CS-based (WCS) diet in birds challenged with coccidia vaccine (Coccivac B-52™). The WCS-based diet was produced by replacing 30% of the energy-yielding portions of the CS-based diet with wheat. On day 14, 448 (n = 7) Cobb by-product breeder male broilers were assigned to a 2 (diet types) × 2 (with or without enzyme supplementation) × 2 (0 or 20 × coccidia vaccine challenge; CVC) factorial arrangement of treatments in a completely randomized design for the determination of the apparent metabolizable energy (AME) value of wheat. Treatment effects on jejunum digesta viscosity and AME corrected for nitrogen (AMEn) of the diets were evaluated within each diet type as a 2 × 2 factorial arrangement of treatments, 7- and 14-day post-challenge. Seven-day post-challenge (day 21), dry matter (DM) and energy utilization, AME, and AMEn of the CS- and WCS-based diets decreased (p < 0.05) with CVC. Both AME and AMEn of wheat decreased (p < 0.05) by about a 20% in CVC-birds 7-day post-challenge. Enzyme and CVC resulted in a decrease (p < 0.05) in jejunal digesta viscosity in birds fed the CS-based diets, while there was an interaction (p < 0.05) between CVC and enzyme, with enzyme lowering (p < 0.05) the viscosity of digesta 7-day post-challenge. Results from this study showed that CVC resulted in a 20% decrease in AMEn 7-day post-challenge, while the interaction between exogenous enzyme supplementation and CVC resulted in an improvement in nitrogen utilization (~6%) in CVC birds fed the corn-SBM-based diet 7-days post challenge.

Xylanase supplementation in corn-based swine diets: a review with emphasis on potential mechanisms of action

Corn is a common energy source in pig diets globally; when financially warranted, industrial corn coproducts, such as corn distiller's dried grains with solubles (DDGS), are also employed. The energy provided by corn stems largely from starch, with some contribution from protein, fat, and non-starch polysaccharides (NSP). When corn DDGS are used in the diet, it will reduce starch within the diet; increase dietary protein, fat, and NSP levels; and alter the source profile of dietary energy. Arabinoxylans (AXs) comprise the majority of NSP in corn and its coproducts. One strategy to mitigate the antinutritive effects of NSP and improve its contribution to energy is by including carbohydrases within the diet. Xylanase is a carbohydrase that targets the β-1,4-glycosidic bonds of AX, releasing a mixture of smaller polysaccharides, oligosaccharides, and pentoses that could potentially be used by the pig. Xylanase is consistently effective in poultry production and moderately consistent in wheat-based swine diets, but its efficacy in corn-based swine diets is quite variable. Xylanase has been shown to improve the digestibility of various components of swine-based diets, but this seldom translates into an improvement in growth performance. Indeed, a review of xylanase literature conducted herein suggests that xylanase improves the digestibility of dietary fiber at least 50% of the time in pigs fed corn-based diets, but only 33% and 26% of the time was there an increase in average daily gain or feed efficiency, respectively. Intriguingly, there has been an abundance of reports proposing xylanase alters intestinal barrier integrity, inflammatory responses, oxidative status, and other health markers in the pig. Notably, xylanase has shown to reduce mortality in both high and low health commercial herds. These inconsistencies in performance metrics, and unexpected health benefits, warrant a greater understanding of the in vivo mechanism(s) of action (MOA) of xylanase. While the MOA of xylanase has been postulated considerably in the literature and widely studied in in vitro settings, in wheat-based diets, and in poultry, there is a dearth of understanding of the in vivo MOA in pigs fed corn-based diets. The purpose of this review is to explore the role of xylanase in corn-based swine diets, discuss responses observed when supplemented in diets containing corn-based fiber, suggest potential MOA of xylanase, and identify critical research gaps.

Carbohydrase Complexes Rich in Xylanases and Arabinofuranosidases Affect the Autofluorescence Signal and Liberate Phenolic Acids from the Cell Wall Matrix in Wheat, Maize, and Rice Bran: An In Vitro Digestion Study

The high fiber content of cereal coproducts used in animal feed reduces the digestibility and nutrient availability. Therefore, the aim of this study was to elucidate the ability of two carbohydrase complexes to degrade the cell wall of wheat, maize, and rice during in vitro digestion. One complex was rich in cell-wall-degrading enzymes (NSPase 1), and the other was similar but additionally enriched with xylanases and arabinofuranosidases (NSPase 2). Degradation of arabinoxylan, the main cereal cell wall polysaccharide, was followed directly by gas-liquid chromatography (GLC) and indirectly through phenolic acid liberation as quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The effect was additionally visualized using a unique multispectral autofluorescence approach. Wheat fractions, in particular aleurone, were susceptible to degradation as judged from the redistribution of arabinoxylan (25% reduction in insoluble arabinoxylan), whereas the highest relative liberation of ferulic acid was observed in rice bran (6%). All cereal fractions, except for maize, had a higher release of ferulic acid with NSPase 2 than NSPase 1 (38% in rice and wheat bran, 30% in wheat whole grain, and 28% in wheat aleurone). Thus, the carbohydrase complexes were able to degrade important cell wall components during in vitro digestion but apparently through different mechanisms in wheat, maize, and rice.

Enzymatic Properties of endo-1,4-β-xylanase from Wheat Malt

BACKGROUND

Arabinoxylan (AX) is the main non-starch polysaccharide in wheat. Wheat malts are traditional raw materials for beer brewing. AX is divided into water-soluble arabinoxylan (WEAX) and waterinsoluble arabinoxylan (WUAX). In the mashing stage of beer production, WUAX in malt is degraded by arabinoxylanase to WEAX, which is further degraded to smaller molecules and retained in the final beer. The viscosity of WEAX is related to its molecular weight. WEAX with higher molecular weight and viscosity can increase viscosity and turbidity and reduce filtration speed of wort and beer; WEAX with moderate molecular weight and viscosity contributes to the foaming characteristics and foam stability, and promotes the taste and texture of a beer; WEAX with small molecular weight has the functions of anti-tumor and lowering blood pressure and is regarded as a prebiotic. Because WEAXs with different molecular weight and properties have different impacts on the beer brewing process and qualities of the final beer, it becomes more important to control the degradation of AX during the brewing process of a beer. Endo-1,4-β-xylanase (EC 3.2.1.8) is the most important AX degrading enzyme, which cleaves the β -xylosidic bond between two d-xylopyranosyl residues linked in β-(1,4). The study of enzymatic properties of endo-1,4-β-xylanase from wheat malt is very important for the rational formulation of the content and molecular weight of WEAX in wort and beer during the mashing procedure when using wheat malt as the main raw materials.

OBJECTIVE

In this article, our motivation is to study the enzymatic properties (including optimum pH and temperature, pH and temperature stability, the effect of inhibitors) of wheat malt endo-1,4-β-xylanase.

METHODS

In this article, we prepared crude enzyme according to the method of Guo with minor modifications. The endo-1,4-β-xylanase activity was determined according to the method of Biely in the previous report with minor modifications. The 0.5 mL crude enzyme sample was mixed with 0.5 mL 1 mg/mL 4-O-methyl-dglucurono- d-xylan dyed with Remazol Brilliant Blue R (RBBR-Xylan) solution, intensively mixed, and incubated at 40 °C for exactly 90 min. The reaction was stopped by precipitation using 2 mL absolute ethanol, and the reaction mixture was stirred acutely and placed at room temperature for 30 min. Then, the mixture was mixed again and centrifuged at 6000 g for 10 min. The supernatant was collected and the absorbance was measured at 590 nm. Absolute ethanol and RBBR-Xylan were added to the control tubes first, and after the reaction was completed, the crude enzyme sample was added. One unit of endo-1,4-β-xylanase was defined as at pH 5.5 and 40 °C liberate 1 μmol xylose equivalents in 1 min per g dry wheat malt.

RESULTS

The results showed that the optimal activity of endo-1,4-β-xylanase was achieved at pH 5.5-6.0, and the enzyme was extremely stable at pH 4.5, 5.5 and 6.5 after incubation for 30, 50 and 60 min, respectively. The optimal temperature was 40-45 °C and the deactivation temperature was 75 °C. Endo-1,4-β-xylanase was stable at 20 °C and 40 °C; the stability was slightly decreased at 50 °C and rapidly decreased at 55 °C. The enzyme activity was mildly inhibited by K+, Na+, and Pb2+, moderately inhibited by Ca2+, Mg2+ and Mn2+ and severely inhibited by Cu2+, Ag+ and EDTA.

CONCLUSION

We have got the enzymatic properties of endo-1,4-β-xylanase from wheat malt, so during wort mashing, we could apply this research result to carry out the rational formulation of the content and molecular weight of WEAX in wort and beer during the mashing procedure when using wheat malt as the main raw materials. Expected to solve the technical problems such as high viscosity, slow filtration speed and so on, but also highlight the typical flavors of WEAX such as rich and persistent foam and mellow texture during the brewing process of a beer.

A novel glucuronoxylan hydrolase produced by fermentation is safe as feed additive: toxicology and tolerance in broiler chickens

The current study presents a safety evaluation of a novel glucuronoxylan hydrolase (EC 3.2.1.136) from Bacillus subtilis produced in Bacillus licheniformis. The glucuronoxylan hydrolase preparation did not exhibit irritative potential to the eye and skin when applied in in vitro models. The glucuronoxylan hydrolase preparation was non-mutagenic and non-clastogenic in in vitro tests. Oral administration of the glucuronoxylan hydrolase preparation to rats did not cause any adverse effect in a 90-days subchronic toxicity study. A tolerance study was performed with broiler chickens and confirmed that this glucuronoxylan hydrolase is safe for broiler chickens when fed at the maximum recommended dose, as well as at the 10 times higher dose. In conclusion, there are no safety concerns with using this novel glucuronoxylan hydrolase as a feed additive as it is toxicologically inert and the glucuronoxylan hydrolase is well tolerated by broiler chickens. The beneficial safety evaluation of glucuronoxylan hydrolase is consistent with the fact that this type of enzyme is ubiquitous in nature.

Effects of mono-component xylanase supplementation on nutrient digestibility and performance of lactating sows fed a coarsely ground diet

The objective of the current study was to investigate the effect of supplementing a mono-component xylanase to a coarsely ground lactation diet (feed fraction particle size above 2 mm was more than 17%) based on wheat, barley, and soybean meal on nutrient digestibility and performance of lactating sows. A total of 30 cross-bred (Danish Landrace × Yorkshire) multiparous sows (parity 2 to 5) were used. Sows were fed a standard gestation diet from mating until day 108 of gestation, and then stratified for BW (295.4 ± 26.1 kg average BW) and parity to receive one of two dietary treatments (n = 15 per treatment), a lactation diet without (control diet) or with supplemented enzyme (enzyme diet). The enzyme applied was a mono-component xylanase dosed at 200 enzyme unit (FXU) per kg of feed, which corresponds to 200 g per ton of feed. The diets were fed until weaning at day 28 of lactation. On day 2 of lactation, litter size of each sow was adjusted to 14 piglets within treatment. Reproductive performance of the sows, growth of the piglets, yield and composition of sow milk, plasma metabolites and apparent total tract digestibility (ATTD) of nutrients were measured. Supplementation of xylanase had no effect (P > 0.05) on total born and live born piglets or stillbirth rate (%) at parturition. Initial parameters on day 2 of lactation including sow BW and back fat thickness, litter size, piglet weight, and litter weight were similar (P > 0.05) between treatments. Piglet weight gain, litter weight gain, litter size, and daily milk yield did not differ (P > 0.05) between treatments. The ADFI was increased by 4.5% (P < 0.01), and BW loss during the whole lactation was reduced from -13.6 to -5.2 kg (P = 0.04) with xylanase addition when compared to control sows. The ATTD of GE (83.9 vs. 82.9, P < 0.01), DM (84.2 vs. 83.4, P < 0.01), N (83.4 vs. 81.7, P = 0.02), OM (86.5 vs. 85.7, P < 0.01) and total nonstarch polysaccharides (NSP; 59.4 vs. 56.7, P = 0.02) were all increased by xylanase supplementation. Milk composition and plasma metabolites were not affected (P > 0.05), except that plasma triglycerides content was increased by xylanase addition (0.23 vs. 0.20 mM, P = 0.04). In conclusion, supplementing a mono-component xylanase to a coarsely ground lactating diet based on wheat, barley, and soybean meal improved sow feed intake and nutrient digestibility, thereby reducing sow BW loss throughout lactation, whereas milk yield and piglet performance were not affected.