Xylanase from a newly isolated Fusarium verticillioides capable of utilizing corn fiber xylan

A comprehensive method for the sequential separation of extracellular xylanases and β-xylosidases/arabinofuranosidases from a new Fusarium species

Several fungal species produce diverse carbohydrate-active enzymes useful for the xylooligosaccharide biorefinery. These enzymes can be isolated by different purification methods, but fungi usually produce other several compounds which interfere in the purification process. So, the present work has three interconnected aims: (i) compare β-xylosidase production by Fusarium pernambucanum MUM 18.62 with other crop pathogens; (ii) optimise F. pernambucanum xylanolytic enzymes expression focusing on the pre-inoculum media composition; and (iii) design a downstream strategy to eliminate interfering substances and sequentially isolate β-xylosidases, arabinofuranosidases and endo-xylanases from the extracellular media. F. pernambucanum showed the highest β-xylosidase activity among all the evaluated species. It also produced endo-xylanase and arabinofuranosidase. The growth and β-xylosidase expression were not influenced by the pre-inoculum source, contrary to endo-xylanase activity, which was higher with xylan-enriched agar. Using a sequential strategy involving ammonium sulfate precipitation of the extracellular interferences, and several chromatographic steps of the supernatant (hydrophobic chromatography, size exclusion chromatography, and anion exchange chromatography), we were able to isolate different enzyme pools: four partially purified β-xylosidase/arabinofuranoside; FpXylEAB trifunctional GH10 endo-xylanase/β-xylosidase/arabinofuranoside enzyme (39.8 kDa) and FpXynE GH11 endo-xylanase with molecular mass (18.0 kDa). FpXylEAB and FpXynE enzymes were highly active at pH 5-6 and 60-50 °C.

Screening of Lignocellulolytic Enzyme Activities in Fungal Species and Sequential Solid-State and Submerged Cultivation for the Production of Enzyme Cocktails

Various fungal species can degrade lignocellulolytic materials with their enzyme cocktails composed of cellulolytic and lignolytic enzymes. In this work, seven fungal species (Mucor indicus DSM 2185, Paecilomyces variotii CBS 372.70, Myceliophthora thermophila CBS 663.74, Thielavia terrestris CBS 456.75, Botryosphaeria dothidea JCM 2738, Fusarium oxysporum f.sp. langenariae JCM 9293, and Fusarium verticillioides JCM 23107) and four nutrient media were used in the screening for effective lignocellulose degrading enzymes. From the seven tested fungi, F. oxysporum and F. verticilliodes, along with nutrient medium 4, were selected as the best medium and producers of lignocellulolytic enzymes based on the determined xylanase (>4 U mg-1) and glucanase activity (≈2 U mg-1). Nutrient medium 4 supplemented with pretreated corn cobs was used in the production of lignocellulolytic enzymes by sequential solid-state and submerged cultivation of F. oxysporum, F. verticilliodes, and a mixed culture of both strains. F. oxysporum showed 6 times higher exoglucanase activity (3.33 U mg-1) after 5 days of cultivation in comparison with F. verticillioides (0.55 U mg-1). F. oxysporum also showed 2 times more endoglucanase activity (0.33 U mg-1). The mixed culture cultivation showed similar endo- and exoglucanase activities compared to F. oxysporum (0.35 U mg-1; 7.84 U mg-1). Maximum xylanase activity was achieved after 7 days of cultivation of F. verticilliodes (≈16 U mg-1), while F. oxysporum showed maximum activity after 9 days that was around 2 times lower compared to that of F. verticilliodes. The mixed culture achieved maximum xylanase activity after only 4 days, but the specific activity was similar to activities observed for F. oxysporum. It can be concluded that both fungal strains can be used as producers of enzyme cocktails for the degradation of lignocellulose containing raw materials, and that corn cobs can be used as an inducer for enzyme production.

Effects of xylanase supplementation on growth performance, nutrient digestibility, blood parameters, fecal microbiota, fecal score and fecal noxious gas emission of weaning pigs fed corn-soybean meal-based diet

This study was conducted to evaluate the effects of xylanase supplementation on nutrient digestibility, growth performance, blood parameters, fecal microflora shedding, fecal score and fecal noxious gas emission of weaning pigs fed corn-soybean meal based diet. A total of 150 weaning pigs with an average initial body weight (BW) of 7.85 ± 0.93 kg were randomly allocated to three treatments based on BW and sex (10 replicate pens with five pigs, two gilts and three barrows) were used in this 42-day trial. Dietary treatments were: (1) CON, basal diet; (2) X1, basal diet +0.005% xylanase; (2) X2, basal diet +0.01% xylanase. The xylanase supplementation linearly increased (P < 0.05) average daily gain (ADG), and gain : feed ratio (G:F) from days 29 to 42 and the in overall period, dry matter, nitrogen and energy digestibility, and fecal Lactobacilli counts, and linearly decreased (P < 0.05) blood urea nitrogen (BUN) concentration, fecal NH3 and H2 S emission. Additionally, at weeks 5 and 6, there was a linear decrease in fecal score with xylanase supplementation. In conclusion, dietary supplementation of xylanase improved growth performance, nutrient digestibility, shifted microbiota by increasing fecal Lactobacillus counts, decreased BUN concentration, fecal score, and fecal NH3 and H2 S emission in weaning pigs.

Towards enzymatic breakdown of complex plant xylan structures: State of the art

Significant progress over the past few years has been achieved in the enzymology of microbial degradation and saccharification of plant xylan, after cellulose being the most abundant natural renewable polysaccharide. Several new types of xylan depolymerizing and debranching enzymes have been described in microorganisms. Despite the increasing variety of known glycoside hydrolases and carbohydrate esterases, some xylan structures still appear quite recalcitrant. This review focuses on the mode of action of different types of depolymerizing endoxylanases and their cooperation with β-xylosidase and accessory enzymes in breakdown of complex highly branched xylan structures. Emphasis is placed on the enzymatic hydrolysis of alkali-extracted deesterified polysaccharide as well as acetylated xylan isolated from plant cell walls under non-alkaline conditions. It is also shown how the combination of selected endoxylanases and debranching enzymes can determine the nature of prebiotic xylooligosaccharides or lead to complete hydrolysis of the polysaccharide. The article also highlights the possibility for discovery of novel xylanolytic enzymes, construction of multifunctional chimeric enzymes and xylanosomes in parallel with increasing knowledge on the fine structure of the polysaccharide.

Effect of dietary supplementation of xylanase on apparent ileal digestibility of nutrients, viscosity of digesta, and intestinal morphology of growing pigs fed corn and soybean meal based diet

This study was to determine apparent ileal digestibility of acid detergent fiber (ADF), neutral detergent fiber (NDF), dry matter (DM), energy, organic matter (OM), crude ash, digesta viscosity, and gut morphology in nursery pigs fed diets containing xylanase (Lohmann Animal Nutrition GmbH, Cuxhaven, Germany). The diet (61% corn, 35% soybean meal, 1% poultry fat, and 3% minerals and vitamins) was mixed with 3 levels of xylanase (0, 700, and 1400 LXU/kg). Thirty-six barrows (17.6 ± 3.3 kg) received one of 3 treatment diets based on a randomized complete block design with the initial body weight (BW) as a block. Pigs were individually housed and received experimental diets twice daily (0700 and 1700 h) at a fixed amount based on BW of pigs (0.09 × BW^0.75 kg). Pigs were fed diets for 10 d, and chromium oxide (0.3%) was added to the diets from d 6 as an indigestible external marker. Pigs were euthanized at the end of d 10 for the collection of digesta and tissues. Jejunal digesta were centrifuged to measure viscosity using a viscometer (Brookfield Engineering Laboratories, Stoughton, MA). Diets and freeze-dried ileal digesta were used to measure ADF, NDF, and chromium to calculate apparent ileal digestibility of ADF and NDF. Villus height and crypt depth of jejunum were measured using a microscope (Fisher Scientific, Hampton, NH). Data were analyzed using polynomial contrasts in the MIXED procedure of SAS version 9.3 (SAS Inc., Cary, NC, USA). Morphological measurements and ileal ADF digestibility were not affected by increasing xylanase. However, increasing xylanase supplementation from 0 to 1400 LXU/kg enhanced ileal digestibility of NDF (P < 0.042, linear) from 27.9 to 40.3%, DM (P < 0.006, linear) from 55.4 to 64.6%, OM (P < 0.006, linear) from 59.2 to 67.7%, and energy (P < 0.003, linear) from 58.8 to 68.0%. Viscosity of jejunal digesta decreased (P < 0.023) in a non-linear manner from 2.9 to 2.5 centipoises (cP). In conclusion, the usage of xylanase in corn and soybean meal based pig diets linearly enhanced digestibility of nutrients and affected viscosity of digesta in a non-linear manner.

Switchgrass for bioethanol and other value-added applications: a review

Switchgrass is a promising feedstock for value-added applications due to its high productivity, potentially low requirements for agricultural inputs and positive environmental impacts. The objective of this paper is to review published research on the conversion of switchgrass into bioethanol and other value-added products. Environmental benefits associated with switchgrass include the potential for carbon sequestration, nutrient recovery from runoff, soil remediation and provision of habitats for grassland birds. Pretreatment of switchgrass is required to improve the yields of fermentable sugars. Based on the type of pretreatment, glucose yields range from 70% to 90% and xylose yields range from 70% to 100% after hydrolysis. Following pretreatment and hydrolysis, ethanol yields range from 72% to 92% of the theoretical maximum. Other value-added uses of switchgrass include gasification, bio-oil production, newsprint production and fiber reinforcement in thermoplastic composites. Future prospects for research include increased biomass yields, optimization of feedstock composition for bioenergy applications, and efficient pentose fermentation to improve ethanol yields.

Expression of an AT-rich xylanase gene from the anaerobic fungus Orpinomyces sp. strain PC-2 in and secretion of the heterologous enzyme by Hypocrea jecorina

The catalytic domain encoded by an adenine-thymine (AT)-rich xylanase gene (xynA) of the anaerobic fungus Orpinomyces was expressed in Hypocrea jecorina under the control of the cel7A promoter and terminator. No XynA protein was detected in H. jecorina culture supernatants when the original sequence was fused to the H. jecorina cel5A region coding for its signal peptide, carbohydrate-binding module, and hinge. Replacing the xynA (56% AT content) with a synthetic sequence containing lower AT content (39%) supported the extracellular production (150 mg l(-1)) of the fusion xylanase by H. jecorina. Northern analysis revealed that successful production after the decrease in AT content was related to higher levels of the xylanase-specific mRNA. Another construct with an RDKR-coding sequence inserted between the cel5A linker and the xynA catalytic domain allowed production of the fully processed active xylanase catalytic domain. Both the fusion (40 kDa) and the fully processed (28 kDa) forms displayed enzymatic properties of family 11 xylanases. Both the R and the Kex2-like KR sites were recognized during secretion, resulting in a mixture of two amino termini for the 28-kDa xylanase. The work demonstrated for the first time that glycoside hydrolases derived from anaerobic fungi can be produced by H. jecorina.

Isolation and properties of Aspergillus niger IBT-90 xylanase for bakery

Xylanase of low molecular weight (K II) was isolated from the fungus Aspergillus niger IBT-90 cultivated in medium with wheat bran. K II was purified by precipitation with ammonium sulphate (20-80% saturation) and gel filtration on Biogel P-10. This enzyme is most active in hydrolysis of birchwood xylan at 50 degrees C and pH 5.5. Xylanase K II has an ability to degrade 1,4-beta-bonds and to debranch substrates. It degrades not only xylans but also cellulose, an important factor for its application in bakery. Ag+, Fe3+ and NBS are strong inhibitors of the enzyme. DTT and Na+ activate xylanase K II by 24 and 13%, respectively. Enzyme K II used as additive to flour improves dough properties, increases the volume of wheat-rye and whole meal bread, and increases the porosity of crumb and the moisture of the final product, consequently extending the shelf life of bread.

Peptides and proteins from fungi

The peptides and proteins secreted by fungi are reviewed in this article. They include ribosome inactivating peptides and proteins, antifungal peptides and proteins, lectins, ubiquitin-like peptides and proteins, peptides and proteins with nucleolytic activity, proteases, xylanases, cellulases, sugar oxidoreductases, laccases, invertases, trehalose phosphorylases, and various enzymes with applications in food industry, chemical production and the medical sector.

Purification and properties of an extracellular beta-xylosidase from a newly isolated Fusarium proliferatum

An extracellular beta-xylosidase from a newly isolated Fusarium proliferatum (NRRL 26517) capable of utilizing corn fiber xylan as growth substrate was purified to homogeneity from the culture supernatant by DEAE-Sepharose CL-6B batch adsorption chromatography, CM Bio-Gel A column chromatography, Bio-Gel A-0.5 m gel filtration and Bio-Gel HTP Hydroxyapatite column chromatography. The purified beta-xylosidase (specific activity, 53 U/mg protein) had a molecular weight of 91,200 as estimated by SDS-PAGE. The optimum temperature and pH for the action of the enzyme were 60 degrees C and 4.5, respectively. The purified enzyme hydrolyzed xylobiose and higher xylooligosaccharides but was inactive against xylan substrates. It had a Km value of 0.77 mM (p-nitrophenol-beta-D-xyloside, pH 4.5, 50 degrees C) and was competitively inhibited by xylose with a Ki value of 5 mM. The enzyme did not require any metal ion for activity and stability. Comparative properties of this enzyme with other fungal beta-xylosidases are presented.

Biochemical and catalytic properties of an endoxylanase purified from the culture filtrate of Sporotrichum thermophile

An endo-beta-1,4-xylanase (1,4-beta-D-xylan xylanoxydrolase, EC 3.2.1.8) present in culture filtrates of Sporotrichum thermophile ATCC 34628 was purified to homogeneity by Q-Sepharose and Sephacryl S-200 column chromatographies. The enzyme has a molecular mass of 25,000 Da, an isoelectric point of 6.7, and is optimally active at pH 5 and at 70 degrees C. Thin-layer chromatography (TLC) analysis showed that endo-xylanase liberates mainly xylose (Xyl) and xylobiose (Xyl2) from beechwood 4-O-methyl-D-glucuronoxylan, O-acetyl-4-O-methylglucuronoxylan and rhodymenan (a beta-(1-->4)-beta(1-->3)-xylan). Also, the enzyme releases an acidic xylo-oligosaccharide from 4-O-methyl-D-glucuronoxylan, and an isomeric xylotetraose and an isomeric xylopentaose from rhodymenan. Analysis of reaction mixtures by high performance liquid chromatography (HPLC) revealed that the enzyme cleaves preferentially the internal glycosidic bonds of xylooligosaccharides, [1-3H]-xylooligosaccharides and xylan. The enzyme also hydrolyses the 4-methylumbelliferyl glycosides of beta-xylobiose and beta-xylotriose at the second glycosidic bond adjacent to the aglycon. The endoxylanase is not active on pNPX and pNPC. The enzyme mediates a decrease in the viscosity of xylan associated with a release of only small amounts of reducing sugar. The enzyme is irreversibly inhibited by series of omega-epoxyalkyl glycosides of D-xylopyranose. The results suggest that the endoxylanase from S. thermophile has catalytic properties similar to the enzymes belonging to family 11.