Production of xylooligosaccharides from enzymatic hydrolysis of xylan by the white-rot fungi Pleurotus (original) (raw)
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Xylanases from fungi: properties and industrial applications
Applied Microbiology and Biotechnology, 2005
Xylan is the principal type of hemicellulose. It is a linear polymer of β-D-xylopyranosyl units linked by (1-4) glycosidic bonds. In nature, the polysaccharide backbone may be added to 4-O-methyl-α-D-glucuronopyranosyl units, acetyl groups, α-L-arabinofuranosyl, etc., in variable proportions. An enzymatic complex is responsible for the hydrolysis of xylan, but the main enzymes involved are endo-1,4-β-xylanase and β-xylosidase. These enzymes are produced by fungi, bacteria, yeast, marine algae, protozoans, snails, crustaceans, insect, seeds, etc., but the principal commercial source is filamentous fungi. Recently, there has been much industrial interest in xylan and its hydrolytic enzymatic complex, as a supplement in animal feed, for the manufacture of bread, food and drinks, textiles, bleaching of cellulose pulp, ethanol and xylitol production. This review describes some properties of xylan and its metabolism, as well as the biochemical properties of xylanases and their commercial applications.
2011
Humicola lanuginosus produced xylanase 1100 U/ mL in liquid state culture at optimum condition like pH 5, temperature 35°C, inoculum size 2mL, time period 4 days, Vogel's media 160 mL, 1 g corn steep liquir as best nitrogen source using sugar cane bagasse (5g) as a substrate. Xylanase passing from gel filteration obtained with an average specific activity of 379 U/mg protein, purification fold 1.9 and recovery yield of xylanase 10%. Patially purified xylanase has optimum pH 5.0, stability range of pH 6 to 7 and optimum temperature 45°C, stability range of temperature 35 to 40°C for 24 hours incubation. Km and Vmax of partially purified xylanase oxidize xylan were obtained 2 mM, 450 mM/min. MgCl enhanced the activity of partially 2 purified xylanase but silver nitrate strongly inhibited. Crude xylanase (2-10 mL) removed the reducing sugar 20 mg/mL from rice polish as compared with lignocellulosic substrates such as rice husks, corn stover and corn cobs.
Xylan is a principal structural component in plant cell walls and could interfere in many industries and biological activities. Bio-synthesis of the xylan-degrading enzyme xylanase by fungal isolates was investigated, using agricultural wastes as substrates for production. Aspergillus fumigatus was shown to be the superior isolate to produce xylanase, and wheat bran proved to be the most appropriate substrate for enzyme production and activity. Media composition and growth conditions were optimized for the production of fungal xylanase using Plackett-Burman multifactorial mixture design and Box-Behnken experimental design. Characterization of the purified xylanase revealed that the most favorable conditions for the maximum enzyme activity (57 IU/mL) were temperature of 55-60°C with thermal stability for 30 min and pH of 9 with enzyme stability for 20 min. Application of xylanase for biodegradation of sugarcane pulp fibers was examined using scanning electron micrographs, which exhibited a vigorous alteration in the topography of fiber surface and structure with a prolonged enzymatic treatment period.
Xylan decomposition by Aspergillus clavatus endo-xylanase
Protein Expression and Purification, 2009
Agricultural and forest waste products are abundant and low-cost biomass sources useful in renewable fuel energy and feedstock preparation. Hydrolysis of a major biomass component, hemicellulose, is accomplished by the action of endo-xylanases. Reaction products vary in composition and degree of polymerization as a function of both feedstock and the enzyme activities utilized, ranging from monomeric sugars to complex branched polysaccharides. The study herein describes heterologous expression in Aspergillus awamori of a bb-(1-4) endo-xylanase isolated from the whole-genome DNA sequence of A. clavatus along with a comprehensive biochemical and functional analysis of the enzyme, including substrate preference and hydrolysis patterns. The A. clavatus xylanase promotes incomplete hydrolysis of xylan substrates resulting in xylobiose, xylotriose and xylotetraose. Incomplete degradation resulting in xylo-oligomers is appealing for functional foods as the beneficial effect of oligosaccharides on gastrointestinal micro flora includes preventing proliferation of pathogenic intestinal bacteria and facilitating digestion and absorption of nutrients.
Brazilian Journal of Development, 2020
In order to optimize the production of xylanase from a new thermophilic strain of Aspergillus fumigatus (OI-1R-T), Plackett-Burman design (PBD) and central composite rotational design (CCRD) were performed. The response surface plots indicated a trend for increased xylanase biosynthesis with increasing concentrations of corn straw. The optimized xylanase activity was 530 U mL-1 in the presence of 6.5% (w/v) of the residual biomass, which was 11 times (1,157%) higher than that obtained with only the PBD (45.8 U mL-1). Interestingly, xylanase thermostability was maintained at 90% at 50 °C for 6 h. Enzymatic hydrolysis assays conducted for 96 h with 2 U mL-1 of xylanase and crude corn straw, pre-treated corn straw (hemicellulose) and xylan from beechwood, resulted in the net production of 3.89, 20.96 and 21.64 µmol mL-1 of reducing sugars, respectively. Thus, A. fumigatus xylanase was equally able to hydrolyzes hemicellulose from corn straw and xylan from beechwood. The present data indicate that the xylanase activity of A. fumigatus could be applied to the production of low molecular weight sugars for use by pentose-fermenting yeast for the production of fuels and chemicals, among other products.
Journal of Applied Microbiology, 2003
To determine and quantify the products from the degradation of xylan by a range of purified xylandegrading enzymes, endoxylanase, b-xylosidase and a-L L-arabinofuranosidase produced extracellularly by Thermomonospora fusca BD25. Methods and Results: The amounts of reducing sugars released from oat-spelt xylan by the actions of endoxylanase, b-xylosidase and a-L L-arabinofuranosidase were equal to 28AE1, 4AE6 and 7% hydrolysis (as xylose equivalents) of the substrate used, respectively. However, addition of b-xylosidase and a-L L-arabinofuranosidase preparation to endoxylanase significantly enhanced (70 and 20% respectively) the action of endoxylanase on the substrate. The combination of purified endoxylanase, b-xylosidase and a-L L-arabinofuranosidase preparations produced a greater sugar yield (58AE6% hydrolysis) and enhanced the total reducing sugar yield by around 50%. The main xylooligosaccharide products released using the action of endoxylanase alone on oat-spelt xylan were identified as xylobiose and xylopentose. a-L L-Arabinofuranosidase was able to release arabinose and xylobiose from oat-spelt xylan. In the presence of all three purified enzymes the hydrolysis products of oat-spelt xylan were mainly xylose, arabinose and substituted xylotetrose with lesser amount of substituted xylotriose. Conclusions: The addition of the b-xylosidase and a-L L-arabinofuranosidase enzymes to purified xylanases more than doubled the degradation of xylan from 28 to 58% of the total substrate with xylose and arabinose being the major sugars produced. Significance and Impact of the Study: The results highlight the role of xylan de-branching enzymes in the degradation of xylan and suggest that the use of enzyme cocktails may significantly improve the hydrolysis of xylan in industrial processes.
Bioscience Journal, 2016
Xylanases are useful in several industrial segments, including pulp and paper bleaching, animal feed, and bread-making processes. However, the industrial use of these enzymes is closely related to its production cost and its catalytic properties. The process of solid state fermentation enables the use of agro-industrial residues as substrates for microbial cultivation and enzymes production, reducing costs. In the present study, different cultivation parameters were evaluated for the xylanase production by the thermophilic fungus Thermoascus aurantiacus, by solid state fermentation, using agro-industrial residues as substrates. High production of xylanase (1701.9 U g-1 of dry substrate) was obtained using wheat bran containing 65% of initial moisture, at 120 h of cultivation, and 45°C. The xylanase showed optimal activity at pH 5.0 and 75°C; its stability was maintained at pH 3.0-11.0. The enzyme retained its catalytic potential after 1 h, at 75°C. The enzymatic extract produced under optimized conditions showed reduced activities of endoglucanase and FPase. Our results, including the xylanase production by T. aurantiacus in low-cost cultivation medium, high structural stability of the enzyme, and reduced cellulolytic activity, encourage the application of this enzymatic extract in pulp and paper bleaching processes.
Cultural conditions for xylanase production by Pleurotus ostreatus SYJ042 were screened in shake flask cultures. The results indicated that various factors including carbon and nitrogen source, air, pH, and inoculum size influence xylanase secretion. The optimum fermentation medium contained a carbon source (2.5% corn cob + 2.5% wheat bran), nitrogen (0.8% peptone), inoculation level (four disks, 0.5 cm in diameter), aeration rate (1/3 fermentation liquid volume) and initial pH 6.0. Under these culture conditions, the maximum level of xylanase activity (24.98 U ml −1) was reached in 7 days. The enzyme was stable up to 40 • C, with 99.3% of the activity remaining after the enzyme had been incubated for 15 min. The enzyme appeared to be stable over a broad pH range (3.0–9.0) under assay conditions. The majority of the metal ions tested had little effect on enzyme activity with the exception of MnO 4 2− (strong inhibitor) and Ag + (modest inhibitor).
Screening of xylanase producing microorganisms
Research Journal of Agricultural Science, 2016
Hemicellulose, the second most abundant natural polymer on earth, is a mixture of polysaccharides and vegetable gums, found, together with cellulose and lignin, in plant cell walls. Xylanases are enzymes involved in the hydrolysis of xylan, the major component of hemicellulose. These enzymes are able to hydrolyze xylan, by breaking the β-1,4-glycoside linkages, in order to produce xylose and other degradation compounds. Many degrading microorganisms such as fungi, bacteria, yeast etc. have been found to produce xylanases. In this study, our aim was to test different strains regarding their ability to produce xylanases. A screening of the bacterial and fungal strains was performed in order to select the microorganisms that could produce higher amount of xylanases. The strains were cultivated on minimal agar medium with 0.5% oat spelt xylan as the carbon source. The plates were incubated at 28oC, for three to ten days (depending on microorganism) and analyzed at every 24 hours for the...
Isolation of Corncob Xylan-Degrading Fungi and Its Application in Xylobiose Production
Chiang Mai University Journal of Natural Sciences, 2021
In the present study, a potential corncob xylan degradation fungi was isolated and screened from soil to produce xylanase, and was identified as Fusarium oxysporum. The production of xylanase by F. oxysporum under solid state fermentation using corncob powder as the solid substrate reached the maximum xylanase activity when using particle size of substrate of 60 mesh, water content ratio of 2 mL/g substrate, incubation temperature of 30°C, initial pH of 6.0, size of inoculum of 5x107 spore/3 g substrate, and incubation time of 2 days. The xylanase activity increased about 4 times up to 7.92 U/mL after optimization. The potential application of xylanase of F. oxysporum in hydrolyzing alkali-treated corncob xylan to produce xylobiose was also demonstrated. Hydrolysis of 6% of corncob xylan using 100 U/g substrate of enzyme loading under optimum pH and temperature conditions (pH 5.5 and 50°C, respectively) achieved the yield of xylobiose up to 28.7 g/100 g pure xylan after 12 h incubat...