Xylanases are mostly produced through submerged fermentation;nonetheless solid-state fermentation has increased profound attention and consideration of scholars having high conversion level biomass to energy conservat...Xylanases are mostly produced through submerged fermentation;nonetheless solid-state fermentation has increased profound attention and consideration of scholars having high conversion level biomass to energy conservation. This study depicted the purification of xylanases and their possible utilization in industry. The present study was carried out to examine the culture influence of fungal strain Fomes fomentarius (F. fomentarius) using different agro-industrial residues (wheat straw, rice husk, sugarcane bagasse and siris pods). F. fomentarius showed maximum enzyme production after 72 h of fermentation, when grown on wheat straw in solid state fermentation process while maximum activity showed on pH 6.0 at 30°C. The other parameters optimized by statistical design (RSM) showed maximum xylanase activity (146 ± 8 IU/mL) at 65% moisture content, 4 mL inoculums size, 175 mg Ammonium sulphate, 200 mg Calcium carbonate and 1.4 grams of glucose. Xylanase was salted out at 60% ammonium sulphate concentration and enzyme was further purified by Sephadex G-100 gel filtration chromatography with 2.2 fold increase in activity. The purified xylanase from F. fomentarius had optimum pH 6.0 and 40°C. Xylanase showed higher specificity for oat spelt xylan with kinetic constants Km 1.25 mg/mL and Vmax 54 mM/min. Xylanases have an industrial important enzyme used extensively in food, feed and paper industry.展开更多
The enzyme xylanase is more and more widely used in feed production, but different xylanase have different properties, mechanism and application effects. To provide a theoretical basis for choosing more suitable xylan...The enzyme xylanase is more and more widely used in feed production, but different xylanase have different properties, mechanism and application effects. To provide a theoretical basis for choosing more suitable xylanase in feed production, we selected bacterial xylanase(BX), labeled enzyme A, and trichoderma xylanase(TX), labeled enzyme B, and studied the enzymology properties and application effects on growth performance and gut flora in weaned piglets. The results showed that the activity levels of both appear parabolic along with increasing pH or temperature, but the amplitude of enzyme activity changing curves and the pH/temperature of optimal activity level are different, where enzyme A has the optimal activity level at 50 ℃ with a pH value of 5.0. The optimal activity level of enzyme B was achieved at 70 ℃ with a pH around 6.0. Enzyme B suffered very little activity loss with moisture level at16% and temperature from 80℃ to 90 ℃. Enzyme A suffered a big drop in activity level when processed with high temperature from around 80 ℃ to 90 ℃, and it was even completely inactivated at 90 ℃,Enzyme A has very low activity level after being processed in acid environment, but enzyme B has minor changes in activity level with respect to changes in acid level, indicating significantly different enzymatic properties between the two different sources of xylanases. In feeding experiment, the control group, was fed the basal diet, and the BX group and TX group were fed basal diets supplemented with 0,01% bacterial and fungal xylanases, respectively. The results showed that ADG of the BX group and TX group increased by 3.25%(P> 0.05) and 8.22%(P < 0.05), respectively, and the feed conversion ratio decreased by 6.74% and 7.86%(P > 0.05), respectively compared with the control group; TX group had significantly higher(P < 0.05) ADG compared with BX group; BX group and TX group had significantly lower ileum Escherichia coli level than the control group, which were reduced by up to 12.98%(P < 0.05) and 11.68%(P < 0.05), respectively, but the ileal lactic acid bacteria levels were significantly increased by 16.21%(P < 0.01) and 27.02%(P < 0.01),respectively. There were no significant differences(P > 0.05) between BX group and TX group in terms of lactic acid bacteria E. coli level. We concluded that fungal xylanase(enzyme B) has better performances in improving weaned piglet growth and in increasing ileal lactic acid bacteria level compared with bacterial xylanase(enzyme A).展开更多
This study investigated the effects of xylanase supplementations with cereal-based diets on nutrient digestibility and gut microbiota of growing pigs. A total of 96 individually penned pigs(initial BW = 22.7 ± 0....This study investigated the effects of xylanase supplementations with cereal-based diets on nutrient digestibility and gut microbiota of growing pigs. A total of 96 individually penned pigs(initial BW = 22.7 ± 0.65 kg) were allotted to 12 treatments and subjected to a completely randomized block design experiment. Pigs in each treatment were fed an isocaloric wheat-based or corn-based diet with or without 1 of 5 types of xylanase supplements(XA, XB, XC, XD, XE). On d 42, all piglets were euthanized to obtain ileal and cecal digesta for microbial analysis, which involved high-throughput sequencing of the V1 - V3 regions of 16 S rRNA gene. Corn-and wheat-based diets differed(P < 0.05) in digestion characteristics. Dietary treatments affected the alpha-and beta-diversities of microbiota in the cecum but not in the ileum. The wheat-based diet increased(P < 0.05) alphadiversity and clustered separately(P < 0.05) compared with the corn-based diet. Wheat-based diet also promoted the relative abundance of genus(g.) Succinivibrio while corn-based diet promoted the proportion of family(f.) Veillonellaceae in the community. Among xylanases, only XC within the wheat-based diet altered(P < 0.05) the beta-diversity of the cecal microbiota compared with control. For each cereal-based diet and compared with the controls, xylanase treatments affected(P < 0.05) the proportions of 5 bacterial taxa in the ileum(f. Peptostreptococcaceae, order [o.]Streptophyta, f. Clostridiaceae, g. Clostridium and g. Streptococcus) and 8 in the cecum(g. Lactobacillus,g. Streptococcus, class [c.] Clostridia, f. Clostridiaceae, g. Megasphaera, g. Prevotella, g. Roseburia and f.Ruminococcaceae). Network analysis showed that across diets under control treatments, Bacteroidetes was the most influential phylum promoting cooperative relationships among members of the ileum and cecum microbiota. Xylanase treatment, however, reduced the influence of Bacteroidetes and promoted a large number of hub taxa majority of which belonged to the Firmicutes phylum. To maximize the efficiency of xylanase supplementation, our data suggest that xylanase C originated from Bacillus subtilis was more effective when applied to wheat-based diets, while xylanase A originated from Fusarium verticillioides was more beneficial when applied to corn-based diets.展开更多
Background Corn arabinoxylan(AX)is a complicated and multibranched antinutritional factor,thereby proving the use of endo-xylanase(EX)to be marginally valid.This study focused on specific types of AX-degrading enzymes...Background Corn arabinoxylan(AX)is a complicated and multibranched antinutritional factor,thereby proving the use of endo-xylanase(EX)to be marginally valid.This study focused on specific types of AX-degrading enzymes(ADEs)to exert the synergy of debranching enzymes and track the prebiotic potential of enzymatic hydrolysates.This study investigated the effects of ADEs on the growth performance,intestinal histomorphology,absorption functions,changes in polysaccharide components,fermentation,and gut microbiota of broiler chickens.Five hundred seventysix five-day-old Arbor Acres male broiler chickens were randomly allocated into eight treatments with six replicates each.Corn basal diets supplemented with or without enzymes were fed for a 21-day period,specifically including EX,its compatible use with arabinofuranosidase(EXA)or ferulic acid esterase(EXF),and compound groups with the above three enzymes(XAF).Results Specific ADEs stimulated the jejunal villus height and goblet cell number and evidently decreased the crypt depth(P<0.05),while the ratio of ileal villus height to crypt depth was significantly increased in EXF(P<0.05).Maltase activities of ileal mucosa in XAF groups were extremely enhanced(P<0.01),and EX boosted the activity of Na+-K+ATPase in the small intestine(P<0.01).The insoluble AX concentrations comparatively lessened,thereby notably raising the sundry xylooligosaccharide(XOS)yield in the ileal chyme(P<0.05),which was dominant in xylobiose and xylotriose.Improvements in the abundance and diversity of ileal microbial communities within the EXA,EXF,and XAF treatments were observed(P<0.05).Positive correlations between microbiota and XOS were revealed,with xylobiose and xylotriose being critical for ten beneficial bacteria(P<0.05).EXF increased the BWG and FCR of broiler chickens in this phase(P<0.05),which was attributed to the thriving networks modified by Lactobacillus.The intracecal contents of acetic acid,butyric acid,and propionic acid were greatly enhanced in most ADE groups,such as EXF(P<0.05).Conclusions Debranching enzymes appreciably targeted corn AX to release prebiotic XOS in the posterior ileum and facilitated intracaecal fermentation.It was beneficial for improving gut development,digestion and absorption and modulating the microflora to promote the early performance of broiler chickens.展开更多
Background Soybean(Glycine max)meal is one of the important protein sources for fish,but the non-starch polysaccharides(NSP)in soybean meal impair the intestinal barrier function.Here we aimed to investigate whether x...Background Soybean(Glycine max)meal is one of the important protein sources for fish,but the non-starch polysaccharides(NSP)in soybean meal impair the intestinal barrier function.Here we aimed to investigate whether xylanase can alleviate the adverse effects on the gut barrier induced by soybean meal in Nile tilapia and to explore the possible mechanism.Results Nile tilapia(Oreochromis niloticus)(4.09±0.02 g)were fed with two diets including SM(soybean meal)and SMC(soybean meal+3,000 U/kg xylanase)for 8 weeks.We characterized the effects of xylanase on the gut barrier,and the transcriptome analysis was performed to investigate the underlying mechanism.Dietary xylanase improved intestinal morphology and decreased the concentration of lipopolysaccharide(LPS)in serum.The results of transcriptome and Western blotting showed that dietary xylanase up-regulated the expression level of mucin2(MUC2)which may be related to the inhibition of protein kinase RNA-like endoplasmic reticulum kinase(perk)/activating transcription factor 4(atf4)signaling pathways.Microbiome analysis showed that addition of xylanase in soybean meal altered the intestinal microbiota composition and increased the concentration of butyric acid in the gut.Notably,dietary sodium butyrate was supplemented into the soybean meal diet to feed Nile tilapia,and the data verified that sodium butyrate mirrored the beneficial effects of xylanase.Conclusions Collectively,supplementation of xylanase in soybean meal altered the intestinal microbiota composition and increased the content of butyric acid which can repress the perk/atf4 signaling pathway and increase the expression of muc2 to enhance the gut barrier function of Nile tilapia.The present study reveals the mechanism by which xylanase improves the intestinal barrier,and it also provides a theoretical basis for the application of xylanase in aquaculture.展开更多
Cellulose binding domains (CBDs) are present in the majority of fungal cellulases and hemicellulases. Based on the conserved region of CBDs, degenerate primers were designed and used to amplify the 5′ end cDNA fragme...Cellulose binding domains (CBDs) are present in the majority of fungal cellulases and hemicellulases. Based on the conserved region of CBDs, degenerate primers were designed and used to amplify the 5′ end cDNA fragment of xylanase from Volvariella volvacea by 5′ RACE. Gene specific primer was then designed based on extreme region of 5′ end cDNA fragment and used to amplify the full length cDNA of xylanase. The cDNA of xyn 1 was 1 287 bp in length, including 3′ and 5′ non coding region. The xyn 1 cDNA contained an ORF of 1101 bp encoding 367 amino acids, in which there was a putative signal peptide with 19 amino acids. Alignment of the deduced amino acid sequence of xyn 1 with other xylanases showed that the homology with family 10 xylanases from Agaricus bisporus xyl1,Aspergillus sojae xyn1, Aspergillus kawachii xynA, Fusarium oxysporum f.sp xyl3 was 64%,55%,52%,55%, respectively.展开更多
The modification on the fiber structure of bleached eucalyptus kraft pulp is a very attractive alternative for improve- ments in the properties of paper production. The enzymatic treatment by xylanases and ultrassonic...The modification on the fiber structure of bleached eucalyptus kraft pulp is a very attractive alternative for improve- ments in the properties of paper production. The enzymatic treatment by xylanases and ultrassonic treatments modify the characteristics of the fibers, has been reported. Therefore, the purpose of this study was to evaluate the influence of ultrasonic waves as a facilitator of the action of enzymes (hemicellulase) by modifying the physicochemical nature of fiber eucalyptus Kraft pulp, in order to improve the physical and mechanical properties of the paper. But it was observed the that idea of ultrasound acts as facilitator for action of enzymes can’t be affirmed, since in most properties XA-1 and XA-2 were equal statistically. It may be noted that the junction of ultrasound and xylanase provided improves on tensile index, specific elastic modulus and tensile energy absorption and a decrease of tear index on the mechanical properties of handsheet and it increased the opacity when the ultrasound was applied before xylanase.展开更多
A xylanase-producing bacterium, isolated from deep sea sediments, was identified as the cold-adapted marine species Acinetobacter Johnsonii. A cold-adapted marine species Acinetobacter Johnsonii could grow at 4 ℃. Th...A xylanase-producing bacterium, isolated from deep sea sediments, was identified as the cold-adapted marine species Acinetobacter Johnsonii. A cold-adapted marine species Acinetobacter Johnsonii could grow at 4 ℃. The optimum temperature and pH of xylanase from a cold-adapted marine species Acinetobacter Johnsonii were 55 ℃ and pH 6.0. Xylanase from a cold-adapted marine species Acinetobacter Johnsonii remained at 80% activity after incubation for 1 h at 65 ℃. The xylanase activity was 1.2-fold higher in 4% ethanol solution than in ethanol free solution. Gibbs free energy of denaturation, ΔG, was higher in 4% ethanol solution than in ethanol free solution. Thermostable ethanol tolerant xylanase was valuable for bioethanol production by simultaneous saccharification and fermentation process with xylan as a carbon source.展开更多
Industrial applications require enzymes highly stable and economically viable in terms of reusability. Enzyme immobilization is an exciting alternative to improve the stability of enzymatic processes. The immobilizati...Industrial applications require enzymes highly stable and economically viable in terms of reusability. Enzyme immobilization is an exciting alternative to improve the stability of enzymatic processes. The immobilization of two commercial enzymes is reported here (cellulase and xylanase) using three chemical methods (adsorption, reticulation, and crosslinking-adsorption) and two polymeric supports (alginate-chitin and chitosan-chitin). The optimal pH for binding was 4.5 for cellulase and 5.0 for xylanase, and the optimal enzyme concentrations were 170 μg/mL and 127.5 μg/mL respectively, being the chitosan and the ideal support. In some cases, a low concentration of crosslinking agent (glutaraldehyde) improved stability of the immobilization process. Biotechnological characterization showed that the reusability of enzymes was the most striking finding, particularly of immobilized cellulase using glutaraldehyde, which after 19 cycles retained 64% activity. These results confirm the economic and biotechnical advantages of enzyme immobilization for a range of industrial applications.展开更多
Truffle mycelia exhibit a complex interaction pattern with host plants and have been extensively studied over the last years as a source of new bioactive compounds. Fungal enzymes possess a wide use in food industry, ...Truffle mycelia exhibit a complex interaction pattern with host plants and have been extensively studied over the last years as a source of new bioactive compounds. Fungal enzymes possess a wide use in food industry, confectionaries, textiles and leather industries in order to simplify the processing of raw materials. They are often more stable than enzymes derived from other sources. Tuber maculatum and Tuber aestivum mycelia were tested for enzymes production in Petri dishes solid medium conditions. The results showed that Tuber maculatum produced seven extracellular enzymes (amylase, xylanase, laccase, lipase, peroxidase, cellulase and catalase) while Tuber aestivum produced only three enzymes (amylase, peroxidase and catalase).展开更多
Prebiotics are non-digestible food supplements (oligosaccharides) which play an important role in stimulating the growth of beneficial bacteria especially Lactobacilli and Bifidobacteria in the colon of the host. Xylo...Prebiotics are non-digestible food supplements (oligosaccharides) which play an important role in stimulating the growth of beneficial bacteria especially Lactobacilli and Bifidobacteria in the colon of the host. Xylooligosaccharides (XOS) are more effective than other oligosaccharides such as fructo-oligosaccharides as dietary supplements. Chemical methods are preferred to produce XOS mixtures with a wide DP range, while enzymatic methods are preferred in the food or pharmaceutical industries to reduce formation of degradation products. With the growing importance of making fuels fromlignocellulosic biomass (LCM) and the increasing demand for XOS, more opportunities are emerging to utilize xylan-rich component generated in biorefinery into high-value products such as XOS that could further lower the cost of LCM derived biofuels.展开更多
Issues such as fossil fuels and oil supplies have stimulated the search for renewable alternatives such as biofuels. Agricultural crop residues represent an abundant renewable resource for the future of bioethanol. Fo...Issues such as fossil fuels and oil supplies have stimulated the search for renewable alternatives such as biofuels. Agricultural crop residues represent an abundant renewable resource for the future of bioethanol. For it to be a viable alternative, the second-generation ethanol which ought to provide a net energy gain, environmental benefits, should be economically viable, and also be produced in large quantities without reducing food supplies. The current difficulty of lignocellulosic biofuel production is the hydrolysis of biomass into sugar. This is a work in which the white-rot Lentinula edodes fungus secretes substantial amounts of hydrolytic enzymes and is useful for degradation of lignocellulosic biomass which have not been described yet. The objective of this investigation was to evaluate the pH effect (5, 6 and 7), agitation (0, 100 rpm and 200 rpm) and also the cultivation time (6, 9 and 12 days). The culture medium was supplemented with agro-industrial residue and the EF 52 strain of the fungus Lentinula edodes was used as a processing agent. A factorial design 22 repeating the central point was performed. Submerged cultivation was conducted in a synthetic medium and was incubated at 25°C. The total protein content was determined as well as the activity of xylanase and cellulase (endoglucanase, exoglucanase and β-glucosidase). By Pareto diagram, the agitation and pH variables were significant for enzymatic activities. The highest enzyme expression occurred at pH values between 5.0 and 6.0 and above 100 rpm agitation. The exoglucanase was the enzyme which showed the highest activity in terms of cellulases, despite the cultivation time. Regarding the production of other enzymes and proteins, the most significant cultivation time was 12 days.展开更多
Cassava (Manihot esculenta, Crantz) is one of the most important food plants in West Africa. Its peels are made up of cellulose, hemicellulose and lignin. This lignocellulolytic biomass can be converted using microbia...Cassava (Manihot esculenta, Crantz) is one of the most important food plants in West Africa. Its peels are made up of cellulose, hemicellulose and lignin. This lignocellulolytic biomass can be converted using microbial enzymes to fermentable sugars which have wide range of biotechnological relevance in many fermentation processes. The aim of this study is to screen filamentous fungi from decaying cassava peels that are good producers of xylanases and cellulases. Decaying parts of cassava peels were obtained and brought to the laboratory for further work. Fungi were isolated, identified and screened for cellulase and xylanase production. Isolate with highest frequency of occurrence and enzyme production was identified using phenotypic and molecular method. Optimisation of growth conditions for enzymes production was monitored using the DNSA method, also saccharification of cassava peel were carried out using the enzymes obtained from the isolate. Aspergillus terreus KJ829487 was the predominant fungus. It produces cellulases and xylanases optimally at 40°C, pH 6 and 8, utilising carboxymethylcellulose (CMC) or xylose and yeast extracts as its carbon and nitrogen sources respectively. Saccharification of the peels yielded 584 mg/L glucose, 78 mg/L xylose and 66 mg/L rhamnose. Aspergillus terreus KJ829487 obtained from cassava peels have the ability to produce high concentration cellulases and xylanases which effectively hydrolysed the lignocelluloses’ biomass to fermentable sugars.展开更多
480 healthy 1-day-old male yellow-feathered chickens were selected and assigned randomly into groups A and B,each having 6 pens with 40 birds per pen.The birds in group A were fed with wheatbased diet and group B with...480 healthy 1-day-old male yellow-feathered chickens were selected and assigned randomly into groups A and B,each having 6 pens with 40 birds per pen.The birds in group A were fed with wheatbased diet and group B with wheat-based diet supplemented with xylanase(1.2×l0~4 U/kg diet).On day 16,two birds per replication with average live weight were selected and sacrificed.Tissue samples of jejunum and ileum were collected to detect mRNA expression of cationic amino acid transporters using RT-PCR.The results showed that xylanase significantly increased the abundance of mRNA for rBAT and CAT4 in the intestines of broilers fed with wheat-based diets(P<0.05)and had a tendency to increase the mRNA expression of y^+LAT2 and CAT1 in jejunum(P>0.05),y^+LAT2,CAT1 and CAT4 in ileum(P>0.05).The treatment had no effect on the expression of rBAT mRNA in ileum(P>0.05).展开更多
We screened soil samples collected from underneath shrubs and/or large trees at different locations in the Eastern Ghats of Andhra Pradesh for xylanase-producing microorganisms. Xylose-utilizing bacteria were numerica...We screened soil samples collected from underneath shrubs and/or large trees at different locations in the Eastern Ghats of Andhra Pradesh for xylanase-producing microorganisms. Xylose-utilizing bacteria were numerically dominant in soils of most locations whereas xylose-and xylan-utilizing actinobacteria were minor components. Xylan-utilizing fungi constituted a major share of total microbial populations in soil samples collected at half of the sites, whereas xylan-utilizing bacteria were predominant at other sampling locations. Some of the isolates of fungi exhibited xylanase activity with a range of400–4000 U/ml, indicating great potential for their uses in paper, pulping and bioethanol industries for producing value-added products.展开更多
The Aspergillus niger XynB gene and core promoter region of porcine RELMβgene were cloned into pcDNA3.1(-),and an intestine-specific expression vector pcDNA3.1-RELMβ-XynB-Myc-GFP carrying green fluorescence and Myc ...The Aspergillus niger XynB gene and core promoter region of porcine RELMβgene were cloned into pcDNA3.1(-),and an intestine-specific expression vector pcDNA3.1-RELMβ-XynB-Myc-GFP carrying green fluorescence and Myc double tags was constructed.The vector was transfected into human colon cancer cells(HT29)and human liver cancer cells(Bel7402)using liposomes.Fluorescence microscopy revealed that the vector could specifically express green fluorescent protein(GFP)in HT29 cells.RT-PCR and Western Blot were performed on the HT29 cells transfected with the expression vector,and the results showed that the XynB gene was normally transcribed in HT29 cells,and the target protein expression was detected in the cells.展开更多
[Objectives]The paper was to analyze and predict the structure and characteristics of xylanase xynMF13-GH10 gene and its encoded protein.[Methods]xynMF13-GH10 gene was predicted by NCBI and various information analysi...[Objectives]The paper was to analyze and predict the structure and characteristics of xylanase xynMF13-GH10 gene and its encoded protein.[Methods]xynMF13-GH10 gene was predicted by NCBI and various information analysis tools in ExPASy website,as well as SignaIP 5.0,DNAman,TMHMM,SOPMA and SWISS-Model,and the characteristics and functions of protein structure encoded by the gene were predicted.[Results]The gene is 1332 bp in length,the coding region is 1-1332 bp,and the gene encodes 443 amino acids.The xynMF13-GH10 gene has high homology with xylanase in many species,and it has the highest homology with Paraphaeosphaeria sporulosa endoxylanase-like protein,with the consistency reaching 78.91%and e-value reaching 2e-159.The secondary structure consists of 48.31%random curl,30.25%α-helix structure,16.70%extended chain and 4.74%β-corner.[Conclusions]The results provide a reference for revealing the physiological function and expression regulation mechanism of xynMF13-GH10 gene in the future.展开更多
Extracellular cellulase free xylanase from Pseudomonas sp. XPB-6 was purified to homogeneity with 2.15 fold of purity and 60.31% yield, respectively by ammonium sulfate precipitation and DEAE ion exchange chromatograp...Extracellular cellulase free xylanase from Pseudomonas sp. XPB-6 was purified to homogeneity with 2.15 fold of purity and 60.31% yield, respectively by ammonium sulfate precipitation and DEAE ion exchange chromatography. The protein was found to be a homotrimer consisting of three subunits of 41 kDa each and the native molecular weight of 123 kDa. The pH and temperature optimum for enzyme were 7.5 in 100 mM sodium phosphate buffer at 60°C and was stable to a high and broader range of pH and to a temperature up to 75°C. Kinetic experiments at 60°C gave Vmax and Km values of 144.92 U/mg and 0.60 mg·ml-1 respectively for birch wood xylan. The enzyme had no apparent requirement for cofactors, and its activity was strongly inhibited 1 mM Hg2+ and Cu2+ while it was slightly inactivated by 1 mM Mg2+ and Pb2+. Shelf life of xylanase of Pseudomonas sp. XPB-6 was studied both at room temperature and 4°C. The enzyme was stable both at room temperature and at 4°C for 90 and 28 days respectively. The half-life of the enzyme was approximately 40 days at room temperature.展开更多
An alkaline xylanase secreted by Paenibacillus macquariensis RC 1819 has been purified using ammonium sulfate fractionation, ion exchange chromatography using DEAE-cellulose and gel filtration chromatography over Seph...An alkaline xylanase secreted by Paenibacillus macquariensis RC 1819 has been purified using ammonium sulfate fractionation, ion exchange chromatography using DEAE-cellulose and gel filtration chromatography over Sephadex G-200 and Sephadex G-100. The purified enzyme had the specific activity, 25.2 units/mg protein with birchwood xylan as a substrate. The purified enzyme showed a single protein band over sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The molecular weight of the enzyme has been found to be 31,000 ± 2000 as determined by using Sephadex G-200 gel filtration chromatography. The subunit molecular weight has also been found to be ~31,000 as determined using SDS-PAGE indicating monomeric enzyme. The enzyme showed optimum activity at pH 8.6 and temperature, 50°C. The Michaelis constant (Km) of the enzyme for birchwood xylan was 2.2 mg/ml as determined using velocity saturation plot. The metal ions viz. Co+2 and Mn+2 stimulated xylanase enzyme activity whereas Hg+2 inhibited the enzyme activity.展开更多
Xylanase is an important enzyme with potential application in the degradation of xylan component in the lignocellulosic biomass. There are very few reports on the production of cellulase free xylanases especially by y...Xylanase is an important enzyme with potential application in the degradation of xylan component in the lignocellulosic biomass. There are very few reports on the production of cellulase free xylanases especially by yeast strains which have great potential in paper and pulp industry in removing the hemicellulose from the treated or untreated pulp. In this study, P. hubeiensis NCIM 3574 isolated in our laboratory produced significant levels of extracellular cellulase free xylanase (2480 IU/g DSS) in solid state fermentation (SSF) using wheat bran and xylan. It also produced high levels of β-xylosidase (198 IU/g DSS) when grown in SSF using ground nut oil cake and xylan. These highest activities were obtained when fermented Koji was extracted with 1% NaCl supplemented with 0.5% of Triton X-100. These are the highest activities reported so far from yeast strains in the available literature. The crude xylanase preparation of P. hubeiensis produced xylooligosaccharides (XOS) without xylose proving its potential for XOS production with no further requirement of downstream processing. The XOS as prebiotic show beneficial effect on gut microflora such as Lactobacilli and Bifidobacteria which suppress the activity of pathogenic organisms. This xylanase also has a potential application as a bio-bleaching agent in paper and pulp industry.展开更多
文摘Xylanases are mostly produced through submerged fermentation;nonetheless solid-state fermentation has increased profound attention and consideration of scholars having high conversion level biomass to energy conservation. This study depicted the purification of xylanases and their possible utilization in industry. The present study was carried out to examine the culture influence of fungal strain Fomes fomentarius (F. fomentarius) using different agro-industrial residues (wheat straw, rice husk, sugarcane bagasse and siris pods). F. fomentarius showed maximum enzyme production after 72 h of fermentation, when grown on wheat straw in solid state fermentation process while maximum activity showed on pH 6.0 at 30°C. The other parameters optimized by statistical design (RSM) showed maximum xylanase activity (146 ± 8 IU/mL) at 65% moisture content, 4 mL inoculums size, 175 mg Ammonium sulphate, 200 mg Calcium carbonate and 1.4 grams of glucose. Xylanase was salted out at 60% ammonium sulphate concentration and enzyme was further purified by Sephadex G-100 gel filtration chromatography with 2.2 fold increase in activity. The purified xylanase from F. fomentarius had optimum pH 6.0 and 40°C. Xylanase showed higher specificity for oat spelt xylan with kinetic constants Km 1.25 mg/mL and Vmax 54 mM/min. Xylanases have an industrial important enzyme used extensively in food, feed and paper industry.
基金supported by the 'the twelfth five-year-plan' of China national science and technology for the rural development (2013BAD10B00)
文摘The enzyme xylanase is more and more widely used in feed production, but different xylanase have different properties, mechanism and application effects. To provide a theoretical basis for choosing more suitable xylanase in feed production, we selected bacterial xylanase(BX), labeled enzyme A, and trichoderma xylanase(TX), labeled enzyme B, and studied the enzymology properties and application effects on growth performance and gut flora in weaned piglets. The results showed that the activity levels of both appear parabolic along with increasing pH or temperature, but the amplitude of enzyme activity changing curves and the pH/temperature of optimal activity level are different, where enzyme A has the optimal activity level at 50 ℃ with a pH value of 5.0. The optimal activity level of enzyme B was achieved at 70 ℃ with a pH around 6.0. Enzyme B suffered very little activity loss with moisture level at16% and temperature from 80℃ to 90 ℃. Enzyme A suffered a big drop in activity level when processed with high temperature from around 80 ℃ to 90 ℃, and it was even completely inactivated at 90 ℃,Enzyme A has very low activity level after being processed in acid environment, but enzyme B has minor changes in activity level with respect to changes in acid level, indicating significantly different enzymatic properties between the two different sources of xylanases. In feeding experiment, the control group, was fed the basal diet, and the BX group and TX group were fed basal diets supplemented with 0,01% bacterial and fungal xylanases, respectively. The results showed that ADG of the BX group and TX group increased by 3.25%(P> 0.05) and 8.22%(P < 0.05), respectively, and the feed conversion ratio decreased by 6.74% and 7.86%(P > 0.05), respectively compared with the control group; TX group had significantly higher(P < 0.05) ADG compared with BX group; BX group and TX group had significantly lower ileum Escherichia coli level than the control group, which were reduced by up to 12.98%(P < 0.05) and 11.68%(P < 0.05), respectively, but the ileal lactic acid bacteria levels were significantly increased by 16.21%(P < 0.01) and 27.02%(P < 0.01),respectively. There were no significant differences(P > 0.05) between BX group and TX group in terms of lactic acid bacteria E. coli level. We concluded that fungal xylanase(enzyme B) has better performances in improving weaned piglet growth and in increasing ileal lactic acid bacteria level compared with bacterial xylanase(enzyme A).
基金supported by grants from Growing Forward 2-Agricultural Rural Development Initiative Program of the Province of Manitoba,Canada,and DuPont
文摘This study investigated the effects of xylanase supplementations with cereal-based diets on nutrient digestibility and gut microbiota of growing pigs. A total of 96 individually penned pigs(initial BW = 22.7 ± 0.65 kg) were allotted to 12 treatments and subjected to a completely randomized block design experiment. Pigs in each treatment were fed an isocaloric wheat-based or corn-based diet with or without 1 of 5 types of xylanase supplements(XA, XB, XC, XD, XE). On d 42, all piglets were euthanized to obtain ileal and cecal digesta for microbial analysis, which involved high-throughput sequencing of the V1 - V3 regions of 16 S rRNA gene. Corn-and wheat-based diets differed(P < 0.05) in digestion characteristics. Dietary treatments affected the alpha-and beta-diversities of microbiota in the cecum but not in the ileum. The wheat-based diet increased(P < 0.05) alphadiversity and clustered separately(P < 0.05) compared with the corn-based diet. Wheat-based diet also promoted the relative abundance of genus(g.) Succinivibrio while corn-based diet promoted the proportion of family(f.) Veillonellaceae in the community. Among xylanases, only XC within the wheat-based diet altered(P < 0.05) the beta-diversity of the cecal microbiota compared with control. For each cereal-based diet and compared with the controls, xylanase treatments affected(P < 0.05) the proportions of 5 bacterial taxa in the ileum(f. Peptostreptococcaceae, order [o.]Streptophyta, f. Clostridiaceae, g. Clostridium and g. Streptococcus) and 8 in the cecum(g. Lactobacillus,g. Streptococcus, class [c.] Clostridia, f. Clostridiaceae, g. Megasphaera, g. Prevotella, g. Roseburia and f.Ruminococcaceae). Network analysis showed that across diets under control treatments, Bacteroidetes was the most influential phylum promoting cooperative relationships among members of the ileum and cecum microbiota. Xylanase treatment, however, reduced the influence of Bacteroidetes and promoted a large number of hub taxa majority of which belonged to the Firmicutes phylum. To maximize the efficiency of xylanase supplementation, our data suggest that xylanase C originated from Bacillus subtilis was more effective when applied to wheat-based diets, while xylanase A originated from Fusarium verticillioides was more beneficial when applied to corn-based diets.
基金financially supported by the System for Poultry Production Technology,Beijing Agriculture Innovation Consortium(Project Number:BAIC04-2020)。
文摘Background Corn arabinoxylan(AX)is a complicated and multibranched antinutritional factor,thereby proving the use of endo-xylanase(EX)to be marginally valid.This study focused on specific types of AX-degrading enzymes(ADEs)to exert the synergy of debranching enzymes and track the prebiotic potential of enzymatic hydrolysates.This study investigated the effects of ADEs on the growth performance,intestinal histomorphology,absorption functions,changes in polysaccharide components,fermentation,and gut microbiota of broiler chickens.Five hundred seventysix five-day-old Arbor Acres male broiler chickens were randomly allocated into eight treatments with six replicates each.Corn basal diets supplemented with or without enzymes were fed for a 21-day period,specifically including EX,its compatible use with arabinofuranosidase(EXA)or ferulic acid esterase(EXF),and compound groups with the above three enzymes(XAF).Results Specific ADEs stimulated the jejunal villus height and goblet cell number and evidently decreased the crypt depth(P<0.05),while the ratio of ileal villus height to crypt depth was significantly increased in EXF(P<0.05).Maltase activities of ileal mucosa in XAF groups were extremely enhanced(P<0.01),and EX boosted the activity of Na+-K+ATPase in the small intestine(P<0.01).The insoluble AX concentrations comparatively lessened,thereby notably raising the sundry xylooligosaccharide(XOS)yield in the ileal chyme(P<0.05),which was dominant in xylobiose and xylotriose.Improvements in the abundance and diversity of ileal microbial communities within the EXA,EXF,and XAF treatments were observed(P<0.05).Positive correlations between microbiota and XOS were revealed,with xylobiose and xylotriose being critical for ten beneficial bacteria(P<0.05).EXF increased the BWG and FCR of broiler chickens in this phase(P<0.05),which was attributed to the thriving networks modified by Lactobacillus.The intracecal contents of acetic acid,butyric acid,and propionic acid were greatly enhanced in most ADE groups,such as EXF(P<0.05).Conclusions Debranching enzymes appreciably targeted corn AX to release prebiotic XOS in the posterior ileum and facilitated intracaecal fermentation.It was beneficial for improving gut development,digestion and absorption and modulating the microflora to promote the early performance of broiler chickens.
基金supported by the National Key Research and Development Program of China(2019YFE0115000).
文摘Background Soybean(Glycine max)meal is one of the important protein sources for fish,but the non-starch polysaccharides(NSP)in soybean meal impair the intestinal barrier function.Here we aimed to investigate whether xylanase can alleviate the adverse effects on the gut barrier induced by soybean meal in Nile tilapia and to explore the possible mechanism.Results Nile tilapia(Oreochromis niloticus)(4.09±0.02 g)were fed with two diets including SM(soybean meal)and SMC(soybean meal+3,000 U/kg xylanase)for 8 weeks.We characterized the effects of xylanase on the gut barrier,and the transcriptome analysis was performed to investigate the underlying mechanism.Dietary xylanase improved intestinal morphology and decreased the concentration of lipopolysaccharide(LPS)in serum.The results of transcriptome and Western blotting showed that dietary xylanase up-regulated the expression level of mucin2(MUC2)which may be related to the inhibition of protein kinase RNA-like endoplasmic reticulum kinase(perk)/activating transcription factor 4(atf4)signaling pathways.Microbiome analysis showed that addition of xylanase in soybean meal altered the intestinal microbiota composition and increased the concentration of butyric acid in the gut.Notably,dietary sodium butyrate was supplemented into the soybean meal diet to feed Nile tilapia,and the data verified that sodium butyrate mirrored the beneficial effects of xylanase.Conclusions Collectively,supplementation of xylanase in soybean meal altered the intestinal microbiota composition and increased the content of butyric acid which can repress the perk/atf4 signaling pathway and increase the expression of muc2 to enhance the gut barrier function of Nile tilapia.The present study reveals the mechanism by which xylanase improves the intestinal barrier,and it also provides a theoretical basis for the application of xylanase in aquaculture.
文摘Cellulose binding domains (CBDs) are present in the majority of fungal cellulases and hemicellulases. Based on the conserved region of CBDs, degenerate primers were designed and used to amplify the 5′ end cDNA fragment of xylanase from Volvariella volvacea by 5′ RACE. Gene specific primer was then designed based on extreme region of 5′ end cDNA fragment and used to amplify the full length cDNA of xylanase. The cDNA of xyn 1 was 1 287 bp in length, including 3′ and 5′ non coding region. The xyn 1 cDNA contained an ORF of 1101 bp encoding 367 amino acids, in which there was a putative signal peptide with 19 amino acids. Alignment of the deduced amino acid sequence of xyn 1 with other xylanases showed that the homology with family 10 xylanases from Agaricus bisporus xyl1,Aspergillus sojae xyn1, Aspergillus kawachii xynA, Fusarium oxysporum f.sp xyl3 was 64%,55%,52%,55%, respectively.
文摘The modification on the fiber structure of bleached eucalyptus kraft pulp is a very attractive alternative for improve- ments in the properties of paper production. The enzymatic treatment by xylanases and ultrassonic treatments modify the characteristics of the fibers, has been reported. Therefore, the purpose of this study was to evaluate the influence of ultrasonic waves as a facilitator of the action of enzymes (hemicellulase) by modifying the physicochemical nature of fiber eucalyptus Kraft pulp, in order to improve the physical and mechanical properties of the paper. But it was observed the that idea of ultrasound acts as facilitator for action of enzymes can’t be affirmed, since in most properties XA-1 and XA-2 were equal statistically. It may be noted that the junction of ultrasound and xylanase provided improves on tensile index, specific elastic modulus and tensile energy absorption and a decrease of tear index on the mechanical properties of handsheet and it increased the opacity when the ultrasound was applied before xylanase.
基金Supported by the Science and Technology Research Project of Hubei Provincial Department of Education(B2017041)
文摘A xylanase-producing bacterium, isolated from deep sea sediments, was identified as the cold-adapted marine species Acinetobacter Johnsonii. A cold-adapted marine species Acinetobacter Johnsonii could grow at 4 ℃. The optimum temperature and pH of xylanase from a cold-adapted marine species Acinetobacter Johnsonii were 55 ℃ and pH 6.0. Xylanase from a cold-adapted marine species Acinetobacter Johnsonii remained at 80% activity after incubation for 1 h at 65 ℃. The xylanase activity was 1.2-fold higher in 4% ethanol solution than in ethanol free solution. Gibbs free energy of denaturation, ΔG, was higher in 4% ethanol solution than in ethanol free solution. Thermostable ethanol tolerant xylanase was valuable for bioethanol production by simultaneous saccharification and fermentation process with xylan as a carbon source.
文摘Industrial applications require enzymes highly stable and economically viable in terms of reusability. Enzyme immobilization is an exciting alternative to improve the stability of enzymatic processes. The immobilization of two commercial enzymes is reported here (cellulase and xylanase) using three chemical methods (adsorption, reticulation, and crosslinking-adsorption) and two polymeric supports (alginate-chitin and chitosan-chitin). The optimal pH for binding was 4.5 for cellulase and 5.0 for xylanase, and the optimal enzyme concentrations were 170 μg/mL and 127.5 μg/mL respectively, being the chitosan and the ideal support. In some cases, a low concentration of crosslinking agent (glutaraldehyde) improved stability of the immobilization process. Biotechnological characterization showed that the reusability of enzymes was the most striking finding, particularly of immobilized cellulase using glutaraldehyde, which after 19 cycles retained 64% activity. These results confirm the economic and biotechnical advantages of enzyme immobilization for a range of industrial applications.
文摘Truffle mycelia exhibit a complex interaction pattern with host plants and have been extensively studied over the last years as a source of new bioactive compounds. Fungal enzymes possess a wide use in food industry, confectionaries, textiles and leather industries in order to simplify the processing of raw materials. They are often more stable than enzymes derived from other sources. Tuber maculatum and Tuber aestivum mycelia were tested for enzymes production in Petri dishes solid medium conditions. The results showed that Tuber maculatum produced seven extracellular enzymes (amylase, xylanase, laccase, lipase, peroxidase, cellulase and catalase) while Tuber aestivum produced only three enzymes (amylase, peroxidase and catalase).
文摘Prebiotics are non-digestible food supplements (oligosaccharides) which play an important role in stimulating the growth of beneficial bacteria especially Lactobacilli and Bifidobacteria in the colon of the host. Xylooligosaccharides (XOS) are more effective than other oligosaccharides such as fructo-oligosaccharides as dietary supplements. Chemical methods are preferred to produce XOS mixtures with a wide DP range, while enzymatic methods are preferred in the food or pharmaceutical industries to reduce formation of degradation products. With the growing importance of making fuels fromlignocellulosic biomass (LCM) and the increasing demand for XOS, more opportunities are emerging to utilize xylan-rich component generated in biorefinery into high-value products such as XOS that could further lower the cost of LCM derived biofuels.
文摘Issues such as fossil fuels and oil supplies have stimulated the search for renewable alternatives such as biofuels. Agricultural crop residues represent an abundant renewable resource for the future of bioethanol. For it to be a viable alternative, the second-generation ethanol which ought to provide a net energy gain, environmental benefits, should be economically viable, and also be produced in large quantities without reducing food supplies. The current difficulty of lignocellulosic biofuel production is the hydrolysis of biomass into sugar. This is a work in which the white-rot Lentinula edodes fungus secretes substantial amounts of hydrolytic enzymes and is useful for degradation of lignocellulosic biomass which have not been described yet. The objective of this investigation was to evaluate the pH effect (5, 6 and 7), agitation (0, 100 rpm and 200 rpm) and also the cultivation time (6, 9 and 12 days). The culture medium was supplemented with agro-industrial residue and the EF 52 strain of the fungus Lentinula edodes was used as a processing agent. A factorial design 22 repeating the central point was performed. Submerged cultivation was conducted in a synthetic medium and was incubated at 25°C. The total protein content was determined as well as the activity of xylanase and cellulase (endoglucanase, exoglucanase and β-glucosidase). By Pareto diagram, the agitation and pH variables were significant for enzymatic activities. The highest enzyme expression occurred at pH values between 5.0 and 6.0 and above 100 rpm agitation. The exoglucanase was the enzyme which showed the highest activity in terms of cellulases, despite the cultivation time. Regarding the production of other enzymes and proteins, the most significant cultivation time was 12 days.
文摘Cassava (Manihot esculenta, Crantz) is one of the most important food plants in West Africa. Its peels are made up of cellulose, hemicellulose and lignin. This lignocellulolytic biomass can be converted using microbial enzymes to fermentable sugars which have wide range of biotechnological relevance in many fermentation processes. The aim of this study is to screen filamentous fungi from decaying cassava peels that are good producers of xylanases and cellulases. Decaying parts of cassava peels were obtained and brought to the laboratory for further work. Fungi were isolated, identified and screened for cellulase and xylanase production. Isolate with highest frequency of occurrence and enzyme production was identified using phenotypic and molecular method. Optimisation of growth conditions for enzymes production was monitored using the DNSA method, also saccharification of cassava peel were carried out using the enzymes obtained from the isolate. Aspergillus terreus KJ829487 was the predominant fungus. It produces cellulases and xylanases optimally at 40°C, pH 6 and 8, utilising carboxymethylcellulose (CMC) or xylose and yeast extracts as its carbon and nitrogen sources respectively. Saccharification of the peels yielded 584 mg/L glucose, 78 mg/L xylose and 66 mg/L rhamnose. Aspergillus terreus KJ829487 obtained from cassava peels have the ability to produce high concentration cellulases and xylanases which effectively hydrolysed the lignocelluloses’ biomass to fermentable sugars.
基金supported by National Key Basic Research Development Program 973 of China(No.2004CB117501)National Natural Science Foundation of China(No.30671519)Guangdong Province Scientific Technology Research Project(No.2005B20201016)
文摘480 healthy 1-day-old male yellow-feathered chickens were selected and assigned randomly into groups A and B,each having 6 pens with 40 birds per pen.The birds in group A were fed with wheatbased diet and group B with wheat-based diet supplemented with xylanase(1.2×l0~4 U/kg diet).On day 16,two birds per replication with average live weight were selected and sacrificed.Tissue samples of jejunum and ileum were collected to detect mRNA expression of cationic amino acid transporters using RT-PCR.The results showed that xylanase significantly increased the abundance of mRNA for rBAT and CAT4 in the intestines of broilers fed with wheat-based diets(P<0.05)and had a tendency to increase the mRNA expression of y^+LAT2 and CAT1 in jejunum(P>0.05),y^+LAT2,CAT1 and CAT4 in ileum(P>0.05).The treatment had no effect on the expression of rBAT mRNA in ileum(P>0.05).
基金supported by the University Grants Commission,New Delhi,India
文摘We screened soil samples collected from underneath shrubs and/or large trees at different locations in the Eastern Ghats of Andhra Pradesh for xylanase-producing microorganisms. Xylose-utilizing bacteria were numerically dominant in soils of most locations whereas xylose-and xylan-utilizing actinobacteria were minor components. Xylan-utilizing fungi constituted a major share of total microbial populations in soil samples collected at half of the sites, whereas xylan-utilizing bacteria were predominant at other sampling locations. Some of the isolates of fungi exhibited xylanase activity with a range of400–4000 U/ml, indicating great potential for their uses in paper, pulping and bioethanol industries for producing value-added products.
基金Northern Jiangsu Science and Technology Special Project(XZ-SZ201921)the Technology Program of Gaoyou City(GY201914)。
文摘The Aspergillus niger XynB gene and core promoter region of porcine RELMβgene were cloned into pcDNA3.1(-),and an intestine-specific expression vector pcDNA3.1-RELMβ-XynB-Myc-GFP carrying green fluorescence and Myc double tags was constructed.The vector was transfected into human colon cancer cells(HT29)and human liver cancer cells(Bel7402)using liposomes.Fluorescence microscopy revealed that the vector could specifically express green fluorescent protein(GFP)in HT29 cells.RT-PCR and Western Blot were performed on the HT29 cells transfected with the expression vector,and the results showed that the XynB gene was normally transcribed in HT29 cells,and the target protein expression was detected in the cells.
基金Public Service Platform Project for Industrial Chain Collaborative Innovation(ZHC 2017CB82)Public Service Platform Subproject for Research and Development of Marine Biomedical Resources in the South China Sea(XM-202008-01B2).
文摘[Objectives]The paper was to analyze and predict the structure and characteristics of xylanase xynMF13-GH10 gene and its encoded protein.[Methods]xynMF13-GH10 gene was predicted by NCBI and various information analysis tools in ExPASy website,as well as SignaIP 5.0,DNAman,TMHMM,SOPMA and SWISS-Model,and the characteristics and functions of protein structure encoded by the gene were predicted.[Results]The gene is 1332 bp in length,the coding region is 1-1332 bp,and the gene encodes 443 amino acids.The xynMF13-GH10 gene has high homology with xylanase in many species,and it has the highest homology with Paraphaeosphaeria sporulosa endoxylanase-like protein,with the consistency reaching 78.91%and e-value reaching 2e-159.The secondary structure consists of 48.31%random curl,30.25%α-helix structure,16.70%extended chain and 4.74%β-corner.[Conclusions]The results provide a reference for revealing the physiological function and expression regulation mechanism of xynMF13-GH10 gene in the future.
文摘Extracellular cellulase free xylanase from Pseudomonas sp. XPB-6 was purified to homogeneity with 2.15 fold of purity and 60.31% yield, respectively by ammonium sulfate precipitation and DEAE ion exchange chromatography. The protein was found to be a homotrimer consisting of three subunits of 41 kDa each and the native molecular weight of 123 kDa. The pH and temperature optimum for enzyme were 7.5 in 100 mM sodium phosphate buffer at 60°C and was stable to a high and broader range of pH and to a temperature up to 75°C. Kinetic experiments at 60°C gave Vmax and Km values of 144.92 U/mg and 0.60 mg·ml-1 respectively for birch wood xylan. The enzyme had no apparent requirement for cofactors, and its activity was strongly inhibited 1 mM Hg2+ and Cu2+ while it was slightly inactivated by 1 mM Mg2+ and Pb2+. Shelf life of xylanase of Pseudomonas sp. XPB-6 was studied both at room temperature and 4°C. The enzyme was stable both at room temperature and at 4°C for 90 and 28 days respectively. The half-life of the enzyme was approximately 40 days at room temperature.
文摘An alkaline xylanase secreted by Paenibacillus macquariensis RC 1819 has been purified using ammonium sulfate fractionation, ion exchange chromatography using DEAE-cellulose and gel filtration chromatography over Sephadex G-200 and Sephadex G-100. The purified enzyme had the specific activity, 25.2 units/mg protein with birchwood xylan as a substrate. The purified enzyme showed a single protein band over sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The molecular weight of the enzyme has been found to be 31,000 ± 2000 as determined by using Sephadex G-200 gel filtration chromatography. The subunit molecular weight has also been found to be ~31,000 as determined using SDS-PAGE indicating monomeric enzyme. The enzyme showed optimum activity at pH 8.6 and temperature, 50°C. The Michaelis constant (Km) of the enzyme for birchwood xylan was 2.2 mg/ml as determined using velocity saturation plot. The metal ions viz. Co+2 and Mn+2 stimulated xylanase enzyme activity whereas Hg+2 inhibited the enzyme activity.
文摘Xylanase is an important enzyme with potential application in the degradation of xylan component in the lignocellulosic biomass. There are very few reports on the production of cellulase free xylanases especially by yeast strains which have great potential in paper and pulp industry in removing the hemicellulose from the treated or untreated pulp. In this study, P. hubeiensis NCIM 3574 isolated in our laboratory produced significant levels of extracellular cellulase free xylanase (2480 IU/g DSS) in solid state fermentation (SSF) using wheat bran and xylan. It also produced high levels of β-xylosidase (198 IU/g DSS) when grown in SSF using ground nut oil cake and xylan. These highest activities were obtained when fermented Koji was extracted with 1% NaCl supplemented with 0.5% of Triton X-100. These are the highest activities reported so far from yeast strains in the available literature. The crude xylanase preparation of P. hubeiensis produced xylooligosaccharides (XOS) without xylose proving its potential for XOS production with no further requirement of downstream processing. The XOS as prebiotic show beneficial effect on gut microflora such as Lactobacilli and Bifidobacteria which suppress the activity of pathogenic organisms. This xylanase also has a potential application as a bio-bleaching agent in paper and pulp industry.