Showing papers on "Xylanase published in 2003"
TL;DR: The ability of T. lanuginosus to produce high levels of cellulase-free thermostable xylanase has made the fungus an attractive source of thermostably xylan enzyme with potential as a bleach-boosting agent in the pulp and paper industry and as an additive in the baking industry.
Abstract: The non-cellulolytic Thermomyces lanuginosus is a widespread and frequently isolated thermophilic fungus. Several strains of this fungus have been reported to produce high levels of cellulase-free β-xylanase both in shake-flask and bioreactor cultivations but intraspecies variability in terms of β-xylanase production is apparent. Furthermore all strains produce low extracellular levels of other hemicellulases involved in hemicellulose hydrolysis. Crude and purified hemicellulases from this fungus are stable at high temperatures in the range of 50–80°C and over a broad pH range (3–12). Various strains are reported to produce a single xylanase with molecular masses varying between 23 and 29 kDa and pI values between 3.7 and 4.1. The gene encoding the T. lanuginosus xylanase has been cloned and sequenced and is shown to be a member of family 11 glycosyl hydrolases. The crystal structure of the xylanase indicates that the enzyme consists of two β-sheets and one α-helix and forms a rigid complex with the three central sugars of xyloheptaose whereas the peripheral sugars might assume different configurations thereby allowing branched xylan chains to be accepted. The presence of an extra disulfide bridge between the β-strand and the α-helix, as well as to an increase in the density of charged residues throughout the xylanase might contribute to the thermostability. The ability of T. lanuginosus to produce high levels of cellulase-free thermostable xylanase has made the fungus an attractive source of thermostable xylanase with potential as a bleach-boosting agent in the pulp and paper industry and as an additive in the baking industry.
298 citations
TL;DR: The effect of deletion of the Trichoderma reesei ace1 gene encoding the novel cellulase regulator ACEI resulted in an increase in the expression of all the main cellulase genes and two xylanase genes in sophorose- and cellulose-induced cultures, indicating that ACEI acts as a repressor of cellulase and xylanases expression.
Abstract: We characterized the effect of deletion of the Trichoderma reesei (Hypocrea jecorina) ace1 gene encoding the novel cellulase regulator ACEI that was isolated based on its ability to bind to and activate in vivo in Saccharomyces cerevisiae the promoter of the main cellulase gene, cbh1. Deletion of ace1 resulted in an increase in the expression of all the main cellulase genes and two xylanase genes in sophorose- and cellulose-induced cultures, indicating that ACEI acts as a repressor of cellulase and xylanase expression. Growth of the strain with a deletion of the ace1 gene on different carbon sources was analyzed. On cellulose-based medium, on which cellulases are needed for growth, the Δace1 strain grew better than the host strain due to the increased cellulase production. On culture media containing sorbitol as the sole carbon source, the growth of the strain with a deletion of the ace1 gene was severely impaired, suggesting that ACEI regulates expression of other genes in addition to cellulase and xylanase genes. A strain with a deletion of the ace1 gene and with a deletion of the ace2 gene coding for the cellulase and xylanase activator ACEII expressed cellulases and xylanases similar to the Δace1 strain, indicating that yet another activator regulating cellulase and xylanase promoters was present.
249 citations
TL;DR: Leaf biomass was found to be a more suitable substrate compared to pseudostems for enzyme production and very low levels of cellulolytic enzyme activities were detected compared to lignin degrading enzymes by both the organisms.
213 citations
TL;DR: The filamentous fungus Penicillium brasilianum IBT 20888 was cultivated on a mixture of 30 g l−1 cellulose and 10 g xylan for 111 h and the resulting culture filtrate was used for protein purification and revealed similarity in molecular mass, pI and hydrolytic properties suggested that these two enzymes were identical, but the smaller was lacking the cellulose-binding domain or an essential part of it.
134 citations
TL;DR: The high level of fully active recombinant xylanase obtained in P. pastoris makes this expression system attractive for fermentor growth and industrial applications.
Abstract: Highly efficient production of a Thermomyces lanuginosus IOC-4145 β-1,4-xylanase was achieved in Pichia pastoris under the control of the AOX1 promoter. P. pastoris colonies expressing recombinant xylanase were selected by enzymatic activity plate assay, and their ability to secrete high levels of the enzyme was evaluated in small-scale cultures. Furthermore, an optimization of enzyme production was carried out with a 23 factorial design. The influence of initial cell density, methanol, and yeast nitrogen base concentration was evaluated, and initial cell density was found to be the most important parameter. A time course profile of recombinant xylanase production in 1-liter flasks with the optimized conditions was performed and 148 mg of xylanase per liter was achieved. Native and recombinant xylanases were purified by gel filtration and characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, circular dichroism spectroscopy, matrix-assisted laser desorption ionization-time of flight-mass spectrometry and physicochemical behavior. Three recombinant protein species of 21.9, 22.1, and 22.3 kDa were detected in the mass spectrum due to variability in the amino terminus. The optimum temperature, thermostability, and circular dichroic spectra of the recombinant and native xylanases were identical. For both enzymes, the optimum temperature was 75°C, and they retained 60% of their original activity after 80 min at 70°C or 40 min at 80°C. The high level of fully active recombinant xylanase obtained in P. pastoris makes this expression system attractive for fermentor growth and industrial applications.
126 citations
TL;DR: Determination of k(cat)/K(m) revealed that the enzyme hydrolysed methyl sinapinate 6, 21 and 40 times more efficiently than methyl ferulate, methyl coumarate and methyl caffeate, respectively, indicating a synergistic interaction between FAE-II and S. thermophile xylanase.
126 citations
TL;DR: In solid-state fermentation, even at high concentrations of glucose or xylose (10%), catabolic repression was minimized compared to the effect observed in liquid culture, and a combination of yeast extract and peptone as nitrogen sources led to the best xylanase production.
Abstract: Filamentous fungi have been widely used to produce hydrolytic enzymes for industrial applications, including xylanases, whose levels in fungi are generally much higher than those in yeast and bacteria. We evaluated the influence of carbon sources, nitrogen sources, and moisture content on xylanase production by Penicillium canescens 10-10c in solid-state fermentation. Among agricultural wastes tested (wheat bran, untreated wheat straw, treated wheat straw, beet pulp, and soja meal), untreated wheat straw gave the highest production of xylanase. Optimal initial moisture content for xylanase production was 83%. The addition of 0.4 g of xylan or easily metabolizable sugar, such as glucose and xylose, at a concentration of 2 % to wheat straw enhanced xylanase production. In solid-state fermentation, even at high concentrations of glucose or xylose (10%), catabolic repression was minimized compared to the effect observed in liquid culture. Yeast extract was the best nitrogen source among the nitrogen sources investigated: peptone, ammonium nitrate, sodium nitrate, ammonium chloride, and ammonium sulfate. A combination of yeast extract and peptone as nitrogen sources led to the best xylanase production.
122 citations
TL;DR: In alfalfa, it seems that effective enzymes work by removing structural barriers that retard the microbial colonization of digestible fractions, increasing the rate of degradation, which is consistent with previous findings of synergism between exogenous and ruminal enzymes.
Abstract: With the objective of developing a rational approach for the selection of feed enzymes for ruminants, 22 commercial enzyme products were examined in terms of protein concentration, enzymic activities on model substrates, and hydrolytic capacity, the latter determined from the release of reducing sugars from alfalfa hay and corn silage. An in vitro ruminal degradation assessment was carried out using the same substrates, untreated or treated with the 22 enzyme products at 1.5 microL/g forage DM. Stepwise regressions were then performed to establish relationships between these factors. Protein concentration and enzymic activities explained at least 84% (P < 0.01) of the variation in the release of reducing sugars from alfalfa and corn silage. Alfalfa DM degradation after incubation with ruminal fluid for 18 h was positively related to xylanase activity (R2 = 0.29, P < 0.01), but the same activity was negatively related to DM degradation of corn silage (R2 = 0.19, P < 0.05). Protease activity explained a further 10% of the alfalfa DM degradation (P < 0.10). Following sequential steps involving the determination of rate and extent of DM and fiber degradation, the best candidates for alfalfa and corn silage were selected. Enzyme products effective with alfalfa hay seemed to exert part of their effect during the pretreatment period, whereas enzymes effective with corn silage worked exclusively after ruminal fluid was added. This finding suggests that different modes of action of exogenous enzymes are attacking different substrates and may partly explain enzyme-feed specificity. In alfalfa, it seems that effective enzymes work by removing structural barriers that retard the microbial colonization of digestible fractions, increasing the rate of degradation. In corn silage, effective enzymes seem to interact with ruminal enzymes to degrade the forage more rapidly, which is consistent with previous findings of synergism between exogenous and ruminal enzymes.
121 citations
TL;DR: In this article, the white-rot fungus Ceriporiopsis subvermispora grows on wood aggressively and is suitable for biopulping of both soft and hardwoods, and the results showed that wood weight loss ranged from 2.9 to 11.7% for biodegradation periods of 15-90 days.
116 citations
TL;DR: Although synergistic effects on corn cell wall degradation were found in simultaneous reactions with XynA and cellulases, no synergism effects were observed in sequential reactions.
Abstract: Plant cell walls are comprised of cellulose and hemicellulose and other polymers that are intertwined, and this complex structure presents a barrier to degradation by pure cellulases or hemicellulases In this study, we determined the synergistic effects on corn cell wall degradation by the action of cellulosomal xylanase XynA and cellulosomal cellulases from Clostridium cellulovorans XynA minicellulosomes and cellulase minicellulosomes were found to degrade corn cell walls synergistically but not purified substrates such as xylan and crystalline cellulose The mixture of XynA and cellulases at a molar ratio of 1:2 showed the highest synergistic effect of 16 on corn cell wall degradation The amounts both of xylooligosaccharides and cellooligosaccharides liberated from corn cell walls were increased by the synergistic action of XynA and cellulases Although synergistic effects on corn cell wall degradation were found in simultaneous reactions with XynA and cellulases, no synergistic effects were observed in sequential reactions The possible mechanism of synergism between XynA and cellulases is discussed
115 citations
TL;DR: The recombinant FAEA was tested for wheat straw pulp bleaching, with or without a laccase mediator system and xylanase, and yielded very efficient delignification—close to 75%—and a kappa number of 3.9.
Abstract: A well-known industrial fungus for enzyme production, Aspergillus niger, was selected to produce the feruloyl esterase FAEA by homologous overexpression for pulp bleaching application. The gpd gene promoter was used to drive FAEA expression. Changing the nature and concentration of the carbon source nature (maltose to glucose; from 2.5 to 60 g l-1), improved FAEA activity 24.5-fold and a yield of 1 g l-1 of the corresponding protein in the culture medium was achieved. The secreted FAEA was purified 3.5-fold to homogeneity in a two-step purification procedure with a recovery of 69%. The overproduced protein was characterised and presented properties in good agreement with those of native FAEA. The recombinant FAEA was tested for wheat straw pulp bleaching, with or without a laccase mediator system and xylanase. Best results were obtained using a bi-sequential process with a sequence including xylanase, FAEA and laccase, and yielded very efficient delignification - close to 75% - and a kappa number of 3.9. This is the first report on the potential application of recombinant FAEA in the pulp and paper sector. Chemicals/CAS: hemicellulose, 63100-39-0, 63100-40-3, 9034-32-6; laccase, 80498-15-3; xylan endo 1,3 beta xylosidase, 37278-89-0, 9025-55-2; Carboxylic Ester Hydrolases, EC 3.1.1.-; Endo-1,4-beta Xylanases, EC 3.2.1.8; feruloyl esterase, EC 3.1.1.73; Laccase, EC 1.10.3.2; Recombinant Proteins
TL;DR: In testing a variety of stress treatments on tomato cell suspensions, PLDbeta1 mRNA was found to rapidly and specifically accumulate in response to the fungal elicitor xylanase, showing that PLD genes are differentially regulated.
Abstract: Phospholipase D (PLD, EC 3.1.4.4.) has been implicated in a variety of plant processes, including signalling. In Arabidopsis thaliana a PLD gene family has been described and individual members classified into alpha-, beta- and gamma-classes. Here we describe a second PLD gene family in tomato (Lycopersicon esculentum) that includes three alpha- and two beta-classes. Different expression patterns in plant organs were observed for each PLD. In testing a variety of stress treatments on tomato cell suspensions, PLDbeta1 mRNA was found to rapidly and specifically accumulate in response to the fungal elicitor xylanase. The greatest increase was found 2 h after treatment with 100 microg m1(-1) xylanase (ninefold). In vivo PLD activity increased nearly threefold over a 1.5 h period of treatment. When the elicitor was injected into tomato leaves, PLDbeta1 mRNA accumulation peaked at 2 h (threefold increase), before decreasing to background levels within 72 h. Mutant, non-active xylanase was as effective as the active enzyme in eliciting a response, suggesting that xylanase itself, and not the products resulting from its activity, functioned as an elicitor. When chitotetraose was used as elicitor, no PLDbeta1 mRNA accumulation was observed, thus it is not a general response to elicitation. Together these data show that PLD genes are differentially regulated, reflecting potential differences in cellular function. The possibility that PLDbeta1 is a signalling enzyme is discussed.
TL;DR: It was concluded that enzymes enhanced the fermentation of cellulose and xylan by a combination of pre- and postincubation effects, which was reflected in a higher rate of fermentation.
Abstract: A series of in vitro studies was conducted to determine the effects of adding a commercial enzyme product on the hydrolysis and fermentation of cellulose, xylan, and a mixture (1:1 wt/wt) of both. The enzyme product (Liquicell 2500, Specialty Enzymes and Biochemicals, Fresno, CA) was derived from Trichoderma reesei and contained mainly xylanase and cellulase activities. Addition of enzyme (0.5, 2.55 and 5.1 microL/g of DM) in the absence of ruminal fluid increased (P < 0.001) the release of reducing sugars from xylan and the mixture after 20 h of incubation at 20 degrees C. Incubations with ruminal fluid showed that enzyme (0.5 and 2.55 microL/g of DM) increased (P < 0.05) the initial (up to 6 h) xylanase, endoglucanase, and beta-D-glucosidase activities in the liquid fraction by an average of 85%. Xylanase and endoglucanase activities in the solid fraction also were increased (P < 0.05) by enzyme addition, indicating an increase in fibrolytic activity due to ruminal microbes. Gas production over 96 h of incubation was determined using a gas pressure measurement technique. Incremental levels of enzyme increased (P < 0.05) the rate of gas production of all substrates, suggesting that fermentation of cellulose and xylan was enzyme-limited. However, adding the enzyme at levels higher than 2.55 microL/g of DM failed to further increase the rate of gas production, indicating that the maximal level of stimulation was already achieved at lower enzyme concentrations. It was concluded that enzymes enhanced the fermentation of cellulose and xylan by a combination of pre- and postincubation effects (i.e., an increase in the release of reducing sugars during the pretreatment phase and an increase in the hydrolytic activity of the liquid and solid fractions of the ruminal fluid), which was reflected in a higher rate of fermentation.
TL;DR: The results showed that the xylanase expression can reach up to 6% of the total soluble protein, avaluecomparable to high level expression reported for several non-cellulolyticproteins in tobacco chloroplasts, opening up new avenues for large scale production of several other industrially useful cellulolytic enzymes through chloroplast expression.
Abstract: Overproduction of cellulolytic enzymes through conventional nucleartransformation approaches posed a major challenge as they can potentiallydegrade the cell wall components and thereby affect transgenic plant growth anddevelopment. In this study, we have tested the possibility to over produce analkali-thermostable xylanase gene from Bacillus sp. StrainNG-27 in tobacco plants through chloroplast expression. Our results showed thatthe xylanase expression can reach up to 6% of the total soluble protein, avaluecomparable to high level expression reported for several non-cellulolyticproteins in tobacco chloroplasts. The chloroplast-expressed xylanase retainedits activity even when the leaves were dried under sun or at 42°C, offering flexibility in the agricultural system intransport and storage. The recombinant enzyme was purified to homogeneity usingsingle step chromatography with more than 85% recovery. Most importantly,transgenic plants were indistinguishable from the control untransformed plantsin their morphology, growth and in seed setting. These results open up newavenues for large scale production of several other industrially usefulcellulolytic enzymes through chloroplast expression.
TL;DR: An optimized process for carrying out solid-state fermentation (SSF) on pilot-scale by Aspergillus sulphureus was proposed on the basis of balancing the medium temperature and its water activity as mentioned in this paper.
TL;DR: Results showed that Streptomyces actuosus A-151, isolated from northern Taiwan, produced β-xylanase when rice bran was used as the sole carbon source, and addition of xylan, shrimp and crab shell powder, and orange peel to the culture medium was found to enhance the production of x Dylanase.
TL;DR: Activity staining indicated that A. fumigatus AR1 produced multiple xylanase of high molecular weight ranging from 212 to 253 kDa contrasting to other two alkali-tolerant fungal xylanases, which are less than 35 kDa.
TL;DR: It was shown that production of this xylanase was clearly increased when it was produced as a fusion protein with a carrier polypeptide having an intact domain structure compared to the production of fusions to the signal sequence alone or to carriers having incomplete domain structures.
Abstract: A bacterial xylanase gene, Nonomuraea flexuosa xyn11A, was expressed in the filamentous fungus Trichoderma reesei from the strong cellobiohydrolase 1 promoter as fusions to a variety of carrier polypeptides By using single-copy isogenic transformants, it was shown that production of this xylanase was clearly increased (up to 820 mg/liter) when it was produced as a fusion protein with a carrier polypeptide having an intact domain structure compared to the production (150 to 300 mg/liter) of fusions to the signal sequence alone or to carriers having incomplete domain structures The carriers tested were the T reesei mannanase I (Man5A, or MANI) core-hinge and a fragment thereof and the cellulose binding domain of T reesei cellobiohydrolase II (Cel6A, or CBHII) with and without the hinge region(s) and a fragment thereof The flexible hinge region was shown to have a positive effect on both the production of Xyn11A and the efficiency of cleavage of the fusion polypeptide The recombinant Xyn11A produced had properties similar to those of the native xylanase It constituted 6 to 10% of the total proteins secreted by the transformants About three times more of the Man5A core-hinge carrier polypeptide than of the recombinant Xyn11A was observed Even in the best Xyn11A producers, the levels of the fusion mRNAs were only approximately 10% of the level of cel7A (cbh1) mRNA in the untransformed host strain
TL;DR: In this article, the effects of the enzyme combination in lysine-deficient diets containing wheat and sorghum were more pronounced than those of the individual feed enzymes, which may have resulted from phytase and xylanase having complementary modes of action for enhancing amino acid digestibilities and/or facilitating substrate access.
Abstract: Individual and combined supplementation of phosphorus-adequate, wheat-based broiler diets with exogenous phytase and xylanase was evaluated in three experiments. The effects of the enzyme combination in lysine-deficient diets containing wheat and sorghum were more pronounced than those of the individual feed enzymes. The inclusion of phytase plus xylanase improved (p<0.05) weight gains (7.3%) and feed efficiency (7.0%) of broilers (7-28 days post-hatch) and apparent metabolisable energy (AME) by 0.76 MJ/kg DM. Phytase plus xylanase increased (p<0.05) the overall, apparent ileal digestibility of amino acids by 4.5% (0.781 to 0.816); this was greater than the responses to either phytase (3.6%; 0.781 to 0.809) or xylanase (0.7%; 0.781 to 0.784). Absolute increases in amino acid digestibility with the combination exceeded the sum of the individual increases generated by phytase and xylanase for alanine, aspartic acid, glutamic acid, glycine, histidine, isoleucine, phenylalanine, threonine, tyrosine and valine. These synergistic responses may have resulted from phytase and xylanase having complementary modes of action for enhancing amino acid digestibilities and/or facilitating substrate access. The two remaining experiments were almost identical except wheat used in Experiment 2 had a higher phytate concentration and a lower estimated AME content than wheat used in Experiment 3. Individually, phytase and xylanase were generally more effective in Experiment 2, which probably reflects the higher dietary substrate levels present. Phytase plus xylanase increased (p<0.05) gains (15.4%) and feed efficiency (7.0%) of broiler chicks from 4-24 days post-hatch in Experiment 2; whereas, in Experiment 3, the combination increased (p<0.05) growth to a lesser extent (5.6%) and had no effect on feed efficiency. This difference in performance responses appeared to be 'protein driven' as the combination increased (p<0.05) nitrogen retention in Experiment 2 but not in Experiment 3; whereas phytase plus xylanase significantly increased AME in both experiments. In Experiments 2 and 3 the combined inclusion levels of phytase and xylanase were lower that the individual additions, which demonstrates the benefits of simultaneously including phytase and xylanase in wheat-based poultry diets.
TL;DR: An extracellular xylanase produced by a Mexican Aspergillus strain was purified and characterized and showed a higher affinity for 4-O-methyl-d-glucuronoxylan and displayed no activity toward other polysaccharides, including cellulose.
Abstract: An extracellular xylanase produced by a Mexican Aspergillus strain was purified and characterized Aspergillus sp FP-470 was able to grow and produce extracellular xylanases on birchwood xylan, oat spelt xylan, wheat straw, and corncob, with higher production observed on corncob The strain also produced enzymes with cellulase, amylase, and pectinase activities on this substrate A 22-kDa endoxylanase was purified 30-fold Optimum temperature and pH were 60 degrees C and 55, respectively, and isoelectric point was 90 The enzyme has good stability from pH 50 to 100, retaining >80% of its original activity within this range Half-lives of 150 min at 50 degrees C and 65 min at 60 degrees C were found K(m) and activation energy values were 38 mg/mL and 26 kJ/mol, respectively, using birchwood xylan as substrate The enzyme showed a higher affinity for 4-O-methyl-D-glucuronoxylan with a K(m) of 19 mg/mL The enzyme displayed no activity toward other polysaccharides, including cellulose Baking trials were conducted using the crude filtrate and purified enzyme Addition of both preparations improved bread volume However, addition of purified endoxylanase caused a 30% increase in volume over the crude extract
TL;DR: It is suggested that ferulic acid may be located in regions of low substitution on arabinoxylans while the 5,5′ diferulate moiety is located in more branched regions of the xylan chain.
TL;DR: Two commercial enzyme products, Depol 40 and Liquicell 2500, were characterised from a biochemical standpoint and their potential to improve rumen degradation of forages was evaluated in vitro, suggesting that the increase in rate of degradation was achieved through a combined effect of direct enzyme hydrolysis and synergistic action between the exogenous and endogenous enzymes.
TL;DR: Alkalophilic Bacillus licheniformis 77-2 produced an extracellular alkali-tolerant xylanase with negligible cellulase activity in medium containing corn straw, and the effectiveness of crude xylan enzyme on treatment of eucalyptus Kraft pulp was evaluated.
Abstract: Alkalophilic Bacillus licheniformis 77-2 produced an extracellular alkali-tolerant xylanase with negligible cellulase activity in medium containing corn straw. The effectiveness of crude xylanase on treatment of eucalyptus Kraft pulp was evaluated. A biobleaching experiment was carried out to compare the chlorine saving with pulp treated and untreated by the enzyme. Two-stage bleaching was employed, using a ClO2 chlorination and NaOH extraction (DE sequence). With the enzymatic treatment, in order to obtain the same value of Kappa number and brightness, respectively 28.5 and 30% less ClO2 was required in comparison to the enzymatically untreated samples.
TL;DR: Xylanolytic enzymes (enzyme mixture) produced by this Penicillium sp.
Abstract: Renewable natural resources such as xylans are abundant in many agricultural wastes. Penicillium sp. AHT-1 is a strong producer of xylanolytic enzymes. The sequential activities of its xylanase, α-...
TL;DR: Although xylanase inhibitor activity was detected in all parts of the wheat plant throughout development, XIP-I was located predominantly in the grain tissue, where it appears at a late stage in grain development and persists after germination, indicating that the different xylan enzyme inhibitor proteins are under different regulatory controls.
TL;DR: In this paper, the XOAZRP TCF sequence was applied to bleach wheat straw pulp and the performance of the reagents was analyzed through studies of xylanase treatment and crystallinity and scanning electron microscopy of the pulps.
TL;DR: The room-temperature structure of xylanase (EC 3.8) from the bacterial plant pathogen Erwinia chrysanthemi expressed in Escherichia coli, a 45 kDa, 413-amino acid protein belonging to glycoside hydrolase family 5, has been determined by multiple isomorphous replacement and refined to a resolution of 1.2.1.
Abstract: The room-temperature structure of xylanase (EC 3.2.1.8) from the bacterial plant pathogen Erwinia chrysanthemi expressed in Escherichia coli, a 45 kDa, 413-amino acid protein belonging to glycoside hydrolase family 5, has been determined by multiple isomorphous replacement and refined to a resolution of 1.42 A. This represents the first structure of a xylanase not belonging to either glycoside hydrolase family 10 or family 11. The enzyme is composed of two domains similar to most family 10 xylanases and the α-amylases. The catalytic domain (residues 46−315) has a (β/α)8-barrel motif with a binding cleft along the C-terminal side of the β-barrel. The catalytic residues, Glu165 and Glu253, determined by correspondence to other family 5 and family 10 glycoside hydrolases, lie inside this cleft on the C-terminal ends of β-strands 4 and 7, respectively, with an Oe2···Oe1 distance of 4.22 A. The smaller domain (residues 31−43 and 323−413) has a β9-barrel motif with five of the strands interfacing with α-helices...
TL;DR: Wheat and barley could be used more efficiently by turkeys in the presence of an appropriate enzyme preparation in the form of xylanase and β-glucanase enzymes, which significantly improved body weight gain and feed efficiency.
Abstract: The efficiency of a mixture of xylanase and beta-glucanase enzymes was evaluated in two separate experiments on growing turkeys offered diets based on wheat or wheat and barley. 2. In the first experiment, the addition of 560 and 2800 IU of xylanase and beta-glucanase, respectively, per kg of diet significantly improved feed efficiency in turkeys fed on wheat- and barley-based diet throughout the entire experiment (42 d). 3. In the second experiment, the enzyme mixture significantly increased N-corrected apparent metabolisable energy (AMEN) by approximately 5%. 4. Furthermore, the combination of xylanase and beta-glucanase significantly improved body weight gain and feed efficiency. Feed efficiency was increased by 2.94, 2.47 and 5.91% in diets based on 500 then 540 g of wheat/kg of diet, 394 then 384 g of wheat and 100 then 150 g of barley/kg of diet and 180 g of wheat and 300 then 350 g of barley/kg of diet, respectively. 5. This enzyme mixture decreased in vitro viscosity of wheat, barley and soybean meal, the effect being larger for wheat and barley than for soybean meal. 6. In conclusion, the supplementation of diets based on wheat and barley with xylanase and beta-glucanase significantly improved body weight gain and feed efficiency. Therefore, wheat and barley could be used more efficiently by turkeys in the presence of an appropriate enzyme preparation.
TL;DR: Determination of Vmax/KE revealed that the family 10 enzyme hydrolysed two times more efficiently WU-AX than the family 11 enzyme, indicating that different factors govern W U-AX breakdown by the two endoxylanases.
TL;DR: Examination of the enzymic release of reducing sugars from oat hulls by the actions of individual enzymes and the combined action of cellulase indicates that the synergistic interaction between Aspergillus ferulic acid esterase and Trichoderma xylanase on the release of ferulic Acid makes the remainder of the polysaccharides open for further hydrolytic attack and facilitates the accessibility of the main chain of poly Saccharides to cellulase.
Abstract: Hydroxycinnamic acids, mainly ferulic and p-coumaric acids, are believed to be inhibitory to ruminal biodegradability of complex cell wall materials such as oat hulls. Previous studies have shown that a novel enzyme, Aspergillus ferulic acid esterase, and Trichoderma xylanase act synergistically to break the ester linkage between ferulic acid and the attached sugar of feruloyl polysaccharides, releasing ferulic acid from oat hulls. In this paper, we examined the enzymic release of reducing sugars from oat hulls by the actions of individual enzymes (Aspergillus ferulic acid esterase at 13 mU, 6.4 U, and 4678.4 U/assay; cellulase at 20 levels, ranging from 7.8 mU to 2772.7 U/assay; Trichoderma xylanase at 20 levels, ranging from 7.8 mU to 4096 U/assay) and by the combined action of cellulase at six levels (62.5 mU, 2 U, 16 U, 128 U, 1024 U, and 2772.7 U/assay), Aspergillus ferulic acid esterase at 13 mU/assay, and Trichoderma xylanase at two levels (1 U and 256 U/assay). The amount of total acid-extractable reducing sugars in the oat hulls used in this study was 793.8 +/- 8.0 microg/mg. The results show that after a 24-h incubation with Aspergillus ferulic acid esterase alone, no reducing sugars were observed to be released from oat hulls. With cellulase as the sole enzyme, as the concentration increased from 7.8 mU to 2772.7 U/assay, the release of reducing sugars increased (P < 0.01) from 0 to 39% of the total present, with the highest release at 512 U/assay. With Trichoderma xylanase alone, as the concentration increased from 7.8 mU to 4096 U/assay, the release of reducing sugars increased (P < 0.01) from 4.9 to 33%, with the highest release at 2048 U/assay. When incubated together with Trichoderma xylanase (1 U or 256 U/assay) and Aspergillus ferulic acid esterase (13 mU/assay), cellulase at all six levels (62.5 mU, 2 U, 16 U, 128 U, 1024 U and 2772.7 U/assay) significantly increased the release of reducing sugars (P < 0.01) from 8 to 69%. These results indicate that the synergistic interaction between Aspergillus ferulic acid esterase and Trichoderma xylanase on the release of ferulic acid from feruloyl polysaccharides of oat hulls makes the remainder of the polysaccharides open for further hydrolytic attack and facilitates the accessibility of the main chain of polysaccharides to cellulase. This action extends the cell wall hydrolysis, thus releasing a higher yield of reducing sugars. Such enzymic pretreatment of oat hulls may provide a unique advantage to rumen microorganisms for the biodegradation of the complex cell walls of byproduct feeds such as oat hulls.