Enzymatic Hydrolysis Of Xylan Research Articles

Xylanases of Trichoderma koningii and Trichoderma pseudokoningii: Production, characterization and application as additives in the digestibility of forage for cattle

The work optimized the production of xylanases by solid-state cultivation by Trichoderma koningii and Trichoderma pseudokoningii. The xylanases were biochemically characterized, the catalytic potential of enzymatic extracts and their use as an additive in the feeding of ruminants were evaluated. The higher production of xylanases by T. koningii, approximately 524.3 U g−1 (or 52.43 UmL−1), was obtained for cultivation in a substrate composed of wheat bran and sugarcane bagasse in a 4:1 g ratio, respectively, containing 60% initial moisture, and kept at 20 °C for 120 h. The xylanase used by T. koningii showed excellent activity at pH 4.5 and 50 °C and remained stable at pH 3.0–9.5 and for 1 h at 45 °C. T. pseudokoningii had a higher production of xylanase, 721.0 U g−1 (72.10 UmL−1), when grown in wheat bran, with 50% initial moisture, at 25 °C for 96 h. The xylanases produced by T. pseudokoningii showed greater catalytic activity at pH 4.5 and 55 °C and were stable at pH 3.0–9.5 and for 1 h at 50 °C. The best results of in vitro digestibility were obtained in Mombaça grass containing the enzymatic extract of T. koningii, reaching a maximum gain of 12% in digestibility, expressed in dry mass. The chromatographic profile of the products resulting from the enzymatic hydrolysis of xylan indicated the predominant action of endoxylanases. Additionally, the enzymatic extracts showed reduced cellulolytic activity, which enables its use in cellulose pulp bio-bleaching processes.

Xylose Release from Sunflower Stalk by Coupling Autohydrolysis and Enzymatic Post-Hydrolysis

PurposeIn this study, to obtain xylose-based fermentation media from autohydrolysis liquors of sunflower stalk by using commercial xylanase formulation was aimed. Xylose is generally produced from xylan by diluted acid hydrolysis that causes the formation of some unwanted compounds during the process. As an alternative to dilute acid hydrolysis method, enzymatic hydrolysis of xylan can provide more specific hydrolysis under moderate conditions and does not cause the formation of undesirable compounds.MethodsXylose production was carried out with Trichoderma longibrachiatum xylanase on solubilized xylan form of sunflower stalk, which was hydrothermally pretreated for 1 h at 160 °C. The effects of substrate concentration and enzyme activity were investigated for the production of xylose. To obtain a high xylose yield and selectivity, the optimization study was conducted by the response surface methodology.ResultsThe optimum substrate concentration and enzyme activity were found as 60 mg ds/mL CAL and 234 U/mL, respectively. Under the optimum condition, xylose yield and selectivity were found to be 69.5% and 8.2 g/g, respectively.ConlusionThis study showed that xylose could be produce with a high yield without requiring a neutralization process and corrosive chemical reagent apart from water.Graphic Abstract

Pistachio (Pistacia vera) shell as a new candidate for enzymatic production of xylooligosaccharides

Every year, considerable amount of pistachio by-products is generated in pistachio processing industry which their disposal is an important challenge. Our study aimed to produce valuable prebiotic xylooligosaccharides (XOS) from pistachio shell (PS) that have no particular uses. Alkaline hydrogen peroxide application yielded 32.85% xylan with low residual lignin content (2.48%). Structural characterization of mentioned xylan determined. Enzymatic hydrolysis of xylan with commercial endoxylanase afforded breakdown into XOS containing xylobiose and xylotriose. Response surface methodology (RSM) disclosed the optimized condition as: enzyme dose of 85 (U/g), the concentration of substrate (6%) and the reaction time (10 h) corresponding to maximum yield of xylobiose (1.86 mg/ml) and xylotriose (0.818 mg/ml). Application of the two-step process consisting of xylan extraction pursued by enzymatic hydrolysis enabled prebiotic XOS production for food and pharmaceutical industrial uses, from the pistachio shell as a novel raw material.

Enzymatic Hydrolysis of Xylan from Coffee Parchment in Membrane Bioreactors

Xylooligosaccharides (XOs) production from xylan, extracted from coffee parchment, using two stirred tank reactors (STRs) and two membrane bioreactors (MBRs) was studied for the first time. In the reactors, xylanase either free in a solution (E-STR, E-MBR) or covalently immobilized on magnetic nanoparticles (MNP-STR, MNP-MBR) was used. A continuous production of reducing sugars in both MBRs was obtained. In the E-MBR, the same conversion of E-STR at a low substrate concentration (1 mg mL–1) (97%) was obtained. At higher substrate concentration, the conversion increases by a quarter in E-MBR on increasing the residence time and doubles in MNP-MBR by increasing the amount of immobilized enzyme. The unchanged apparent KM (about 8 mg mL–1) showed that the affinity of the enzyme for the substrate was not altered by the immobilization process. In E-MBR, the enzyme/substrate affinity is even improved (KM: 2.58 mg mL–1), thanks to the continuous removal of the inhibition products, present in the initial xylan solution, by the membrane process.

Optimized use of hemicellulose within a biorefinery for processing high value-added xylooligosaccharides

Wheat straw was used to produce xylooligosaccharides (XOS) for its prebiotic effect. Steam explosion (SE) pre-treatment has been used to separate the main components of lignocellulosic material: cellulose, hemicellulose and lignin. SE conditions used gave a cellulose recovery as solid fraction (91%) and a xylan recovered in the liquid fraction (LF) (36%). Previously to XOS production by enzymatic hydrolysis of xylan, the LF was subjected to a cleaning step with ion exchange resin to remove soluble inhibitors. The commercial enzyme endo-1,4-β-xylanase was used individually and in combination with β-glucosidase to produce compounds with a low degree of polymerization (DP2-DP6). The process achieved a conversion rate of 91% to XOS with 5h of hydrolysis supplementation, whatever generated 8.9g of XOS per 100g of raw material.

Extremophilic Bacterial Xylanases: Production, Characteristics and Applications

Xylan is the most abundant polysaccharide among hemicelluloses and it has a linear backbone of β-1, 4-linked D-xylopyranose residues. Complete biodegradation of xylan into constituent sugars requires the action of several xylanolytic enzymes. A wide variety of microbes produces xylanolytic enzymes in order to achieve xylan hydrolysis. Immense interest in the enzymatic hydrolysis of xylan is due to its multiple applications. The thermo-alkali-stable xylanases have potential applications in pulping and bleaching processes, food and feed industry, textile processing, enzymatic saccharification of lignocellulosic materials and waste treatment. Most of the available commercial xylanases are from mesophilic microbes, which fail to function at alkaline pH and elevated temperatures prevailing in industrial processes. Alkaliphilic and thermophilic bacteria are very important sources of xylanases with the desirable twin characteristics of thermostability and alkalistability, and therefore, very important in developing environment-friendly pulp bleaching process.

Production of xylooligosaccharides from enzymatic hydrolysis of xylan by white-rot fungi Pleurotus

Hemicellulose consists of non-cellulosic polysaccharides, with xylans and mannans as their main examples. In nature, xylan can be first degraded to xylooligosaccharides and finally to xylose by certain microorganisms. White-rot fungi basidiomycetes Pleurotus sp. BCCB068 and Pleurotus tailandia were used to degrade oat-spelts xylan under submerged fermentation for a period of 40 days. The study obtained activities of endo-1,4-β-xylanase and β-xylosidase and determination of xylan products by degradation. The fungi reached significant levels of xylan degradation by Pleurotus sp. BCCB068 (75.1%) and P. tailandia (73.4%), following formations of xylooligosaccharides and sugar monomers. These Pleurotus strains proved to be a feasible alternative for biotechnological processes related to degradation of hemicellulose sources

Production of xylooligosaccharides from enzymatic hydrolysis of xylan by the white-rot fungi Pleurotus

The white-rot fungi basidiomycetes Pleurotus sp. BCCB068 and Pleurotus tailandia were used to degrade oat-spelt xylan under submerged fermentation over a period of 40 days. Activities of endo-1,4-β-xylanase and β-xylosidase and xylan degradation products were determined. Xylan degradation by Pleurotus sp. BCCB068 and P. tailandia reached 75.1% and 73.4%, respectively. The formation of xylooligosaccharides and the simple sugars xylose, arabinose, cellobiose, mannose, and maltose were observed for both strains. The xylan degradation exhibited by these Pleurotus strains indicates they have potential for use in biotechnological processes related to degradation of hemicellulose sources.

Polarized‐Light‐Stimulated Enzymatic Hydrolysis of Xylan

The 1- to 2-h illumination of xylanase with visible polarized light (PL) prior to the action of that enzyme upon beechwood xylan significantly increased its activity. The activity only negligibly decreased on 3 months storage. The hydrolysis of xylan proceeded in three well-distinguished stages. In the first and fastest stage the effect of illumination was only slightly positive. The effect of the stimulation was noted in the second, slower stage. Enzyme stimulated with PL, preferably by means of the 2-h illumination, performed better than enzyme stimulated with nonpolarized light and non-stimulated enzyme. In the last, the slowest stage, the rates of the reaction were nearly the same using either stimulated or non-stimulated enzyme.

A novel cellulase free alkaliphilic xylanase from alkali tolerant Penicillium citrinum: production, purification and characterization

The enzymatic hydrolysis of xylan has potential economic and environment-friendly applications. Therefore, attention is focused here on the discovery of new extremophilic xylanase in order to meet the requirements of industry. An extracellular xylanase was purified from the culture filtrate of P. citrinum grown on wheat bran bed in solid substrate fermentation. Single step purification was achieved using hydrophobic interaction chromatography. The purified enzyme showed a single band on SDS-PAGE with an apparent molecular weight of c. 25 kDa and pI of 3.6. Stimulation of the activity by beta mercaptoethanol, dithiotheritol (DTT) and cysteine was observed. Moderately thermostable xylanase showed optimum activity at 50 degrees C at pH 8.5. Xylanase purified from P. citrinum was alkaliphilic and moderately thermostable in nature. The present work reports for the first time the purification and characterization of a novel endoglucanase free alkaliphilic xylanase from the alkali tolerant fungus Penicillium citrinum. The alkaliphilicity and moderate thermostability of this xylanase may have potential implications in paper and pulp industries.

Influence of lignin and its degradation products on enzymatic hydrolysis of xylan

The influence of lignin, lignin model compounds, and black liquor from the kraft pulping process on the hydrolysis of xylan by xylanase was investigated. Addition of vanillic acid, acetovanillone, and protocatechuic acid increased the rate of hydrolysis of xylan by as much as 18–50% at low concentrations, but reached maxima at about 0.05% concentration. Addition of vanillin caused a 15% improvement in xylan hydrolysis, while addition of guaiacol more than doubled the hydrolysis rate. Increasing concentrations of either lignin or black liquor also increased the hydrolysis rate of xylan. Circular dichroism spectroscopy indicated a change in the structure of xylanase in the presence of black liquor.

Xylanase ofChaetomium cellulolyticum: Its nature of production and hydrolytic potential

Maximum xylanase production byChaetomiumcellulolyticum was obtained in the culture supernatant after 30 h of growth at 37°C in basal medium containing 1% xylan at pH maintained between 6.5 and 7.5. Addition of 0.05% Tween 80 to the medium increased the enzyme production considerably. Xylanase production was found to be growth associated. The optimal conditions for enzymatic hydrolysis of xylan were found to be pH 6.0 and 50°C. During enzymatic hydrolysis, xylose, xylobiose and other xylooligosaccharides were liberated from xylan. The pH values for xylanase production and for xylan hydrolysis were closely related to the utilization of hemicelluloses of aspen wood for fungal protein production by this organism as reported in our earlier work.

Enzymatic Hydrolysis of Xylan1

Enzymatic Hydrolysis of Xylan¹

Enzymatic hydrolysis of xylan.

A PREVIOUS investigation1 has shown that enzymes from Chœtomium globosum are able to hydrolyse wheat straw xylan to xylose with the formation of a series of intermediates, designated a,b,c, … g, which appear on paper-chromatograms with regularly decreasing RF-values, and which are believed to be oligosaccharides with regularly increasing xylose units: xylobiose2, xylotriose, xylotetraose …etc. By heating or storing the enzyme preparations, it was possible to arrest the hydrolysis at the xylobiose stage, indicating that two enzymes are present, (A) hydrolysing the xyloside chain to xylobiose and (B) hydrolysing xylobiose to xylose.