Showing papers on "Xylanase published in 1981"

A Thermostable Xylanase from a Thermophilic Acidophilic Bacillus sp.

Abstract: Bacillus sp. 11-IS, a strain of thermophilic acidophilic bacteria, produced an extracellular xylanase during growth on xylan. The enzyme purified from the culture supernatant solution was homogeneous on disc-gel electrophoresis. The molecular weight was calculated to be 56,000 by SDS-gel electrophoresis. The enzyme had a pH optimum for activity at 4.0, and its stability range was pH 2.0 ~ 6.0. The temperature optimum was 80°C (10-min assay); however, the enzyme retained full activity after incubation at 70°C for 15 min. The enzyme acted on carboxymethyl cellulose (CMC) and cellulose, as well as on xylan. The Michaelis constants for larchwood xylan and CMC were calculated to be 1.68 mg xylose eq/ml and 0.465 mg glucose eq/ml, respectively. The predominant hydrolysis products from larchwood xylan were xylobiose, xylotriose, and xylose; the release of arabinose from rice-straw arabinoxylan was not detected. CMC was cleaved to cellobiose and larger oligosaccharides. Thus, the enzyme is considered to be an end...

Substrate specificity and mode of action of the cellulases from the thermophilic fungus Thermoascus aurantiacus.

Abstract: The substrate specificities of three cellulases and a beta-glucosidase purified from Thermoascus aurantiacus were examined. All three cellulases partially degraded native cellulose. Cellulase I, but not cellulase II and cellulase III, readily hydrolyzed the mixed beta-1,3; beta-1,6-polysaccharides such as carboxymethyl-pachyman, yeast glucan and laminarin. Both cellulase I and the beta-glucosidase degraded xylan, and it is proposed that the xylanase activity is an inherent feature of these two enzymes. Lichenin (beta-1,4; beta-1,3) was degraded by all three cellulases. Cellulase II cannot degrade carboxymethyl-cellulose, and with filter paper as substrate the end product was cellobiose, which indicates that cellulase II is an exo-beta-1,4-glucan cellobiosylhydrolase. Degradation of cellulose (filter paper) can be catalysed independently by each of the three cellulases; there was no synergistic effect between any of the cellulases, and cellobiose was the principal product of degradation. The mode of action of one cellulase (cellulase III) was examined by using reduced cellulodextrins. The central linkages of the cellulodextrins were the preferred points of cleavage, which, with the rapid decrease in viscosity of carboxymethyl-cellulose, confirmed that cellulase III was an endocellulase. The rate of hydrolysis increased with chain length of the reduced cellulodextrins, and these kinetic data indicated that the specificity region of cellulase III was five or six glucose units in length.

Purification and Properties of Thermostable Xylanase from Talaromyces byssochlamydoides YH-50

Abstract: Thermostable xylanase from Talaromyces byssochlamydoides YH-50 was fractionated into three components, tentatively named X-a, X-b-I and X-b-II during the purification steps. X-a, X-b-I and X-b-II were further purified by consecutive column chromatographies until found to be in homogeneous states on disc electrophoresis. X-a, X-b-I and X-b-II contained 36.6%, 31.5% and 14.2% carbohydrate residues, respectively. The carbohydrate residues were glucose, mannose and fucose. X-a, X-b-I and X-b-II were optimally active at 70 ~ 75°C and pH 4.5 ~ 5.5. X-a, X-b-I and X-b-II retained 65, 54 and 30%, respectively, of the original activity after heating at 95°C for 5 min. The activities of X-a, X-b-I and X-b-II were considerably inhibited by HgCl2 and KMnO4. The hydrolysis products from xylan with X-a were xylose, arabinose, glucose, xylobiose and other xylooligosaccharides, whereas the hydrolysis products from xylan with X-b-I and X-b-II were xylose and xylobiose.

Production and Characterization of Thermostable Xylanase from Talaromyces byssochlamydoides YH-50

Abstract: Strain YH-50 from a thermophilic fungus isolated from compost heaps produced the highest amount of thermostable xylanase among 180 isolates tested. This xylanase-producing strain YH-50 was identified as Talaromyces byssochlamydoides Stolk & Samson by taxonomical characteristics. When it was cultivated in solid wheat bran medium containing xylan as an additive carbon source, the maximal amount of thermostable xylanase was produced after 3 days at 50°C. This culture filtrate hydrolyzed 90 % of xylan as xylose, and the sugars formed were xylose, arabinose, glucose and galactose. The optimal pH and temperature were 5.5 and 70°C, respectively. The enzyme was quite stable after heating at 65°C for 5 min and retained 55% of original activity after heating at 95°C for 5 min.

Production of xylanolytic enzymes by Streptomycesflavogriseus

Abstract: Cultures of Streptomyces flavogriseus produced considerable amounts of xylanase when grown on xylan containing media. Comparatively lower yields of this enzyme were obtained when hay or avicel served as main carbon source, β-xylosidase was synthesized intracellularly and appeared less dependent on the fermentation substrate. The strain produced simultaneously various enzymes of the cellulase complex and the xylose induced glucose isomerase.

Xylan synthetase activity in differentiated xylem cells of sycamore trees (Acer pseudoplatanus).

Abstract: Particulate enzymic preparations obtained from homogenates of differentiated xylem cells isolated from sycamore trees, catalyzed the formation of a radioactive xylan in the presence of UDP-D-[U-14C]xylose as substrate. The synthesized xylan was not dialyzable through Visking cellophane tubing. Successive extraction with cold water, hot water and 5% NaOH dissolved respectively 15, 5 and 80% of the radioactive polymer. Complete acid hydrolysis of the water-insoluble polysaccharide synthesized from UDP-D-[U-14C]xylose released all the radioactivity as xylose. β-1,4-Xylodextrins, degree of polymerization 2, 3, 4, 5 and 6, were obtained by partial acid hydrolysis (fuming HCl or 0.1 M HCl) of radioactive xylan. The polymer was hydrolysed to xylose, xylobiose and xylotriose by Driselase which contains 1,4-β xylanase activities. Methylation and then hydrolysis of the xylan released two methylated sugars which were identified as di-O-methyl[14C]xylose and tri-O-methyl-[14C]xylose, suggesting a 1→4-linked polymer. The linkage was confirmed by periodate oxidation studies. The apparent Km value of the synthetase for UDP-D-xylose was 0.4 mM. Xylan synthetase activity was not potentiated in the presence of a detergent. The enzymic activity was stimulated by Mg2+ and Mn2+ ions, although EDTA in the range of concentrations between 0.01 and 1 mM did not affect the reaction rate. It appears that the xylan synthetase system associated with membranes obtained from differentiated xylem cells of sycamore trees may serve for catalyzing the in vivo synthesis of the xylan main chain during the biogenesis of the plant cell wall.

Production of cellulase, beta-glucosidase, and xylanase by schizophyllum commune grown on a cellulose-peptone medium

Abstract: The carboxymethylcellulase activity in a S. commune culture containing optimal amounts of cellulose and peptone was 52.4 units/ml at pH approximately 5 and temperature 30 degrees. Enzymatic activities of the optimized S. commune culture filtrate were 1.32 and 26.5 units/ml for filter paper cellulase and cellobiase respectively, at 50 degrees. Other enzymatic activities at 30 degrees were: avicelase 0.02, cellobiase 17.9, p-nitrophenyl-beta-glucosidase 12.5, and xylanase 203.0 units/ml. The S. commune enzyme complex with its high cellobiase and low avicelase activities appears to be complementary to the enzyme complex of Trichoderma reesei. Thus, a mixed fungal culture filtrate may be best for cellulose saccharification.

Polysaccharide-hydrolyzing enzymes in the genus Bacillus.

Abstract: The production of α-amylase, glucoamylase, Cx- and C1-cellulase, lichenase, xylanase and mannanase was followed in 118 strains of 25 species of the genusBacillus using specific substrates obtained by crosslinking of polysaccharides with 2-chloromethyloxiran. The α-amylase production was also followed using a chromolytic substrate.

Enzymatic hydrolysis of xylans I. A high xylanase and β-xylosidase producing strain of aspergillus niger

Abstract: Aspergillus niger, strain 110.42 (CBS), has been selected as a producer of high xylanolytic activities. The time course of xylanase and β-xylosidase production as well as the effect of pH and temperature on the activity of these enzymes were studied. HPLC analysis of the enzymatic degradation of arabinoxylan showed a nearly complete conversion to pentose sugars. Aspects of using crude xylanase preparations for enzymatic saccharification of xylans are discussed.

Cellulose and xylan degrading enzymes of Fusarium avenaceum

Abstract: It was found that crude preparation obtained from the culture medium of Fusarium avenaceum degraded cellulose and xylan. After chromatography on CM-Sepharose CL-6B of this preparation six fraction were obtained. The eluted fractions II and V showed xylanase activity, fraction IV — cellulase activity and fraction III — xylanase and cellulase activity. The end products of xylan hydrolysis by all xylanase fractions (II, III, V) were xylobiose, xylose, xylotriose and xylotetrose. The end products of cellulose hydrolysis by fractions III and IV was cellobiose, glucose and cellotriose. The data from gel filtration on Sephacryl S-200 indicated a molecular weight of more than 250,000 for both cellulase IV and xylanase V. After gel filtration in the presence of urea disaggregation of those high molecular xylanase and cellulase particles was observed. Xylanase II in difference from the other fractions contained higher amount of sugar. Digestion of fraction II with cellulase-hemicellulase preparation from Phoma hibernica decreased the content of sugar from 17% to 8%, but did not change its enzymatic properties. Cellulase IV as well as xylanase V were inactivated by N-bromosuccinimide, 2-hydroxy-5-nitrobenzyl bromide and tetranitromethane, hence it is suggested that tryptophan and tyrosine are the essential for the activity of these enzymes.

Cellulase production by the anaerobic digestion process

Abstract: An anaerobic digestion process is described for the production of cellulolytic enzymes using a methanogenic cellulose-enrichment culture. After a heat treatment designed to destroy all but spore-forming bacteria, this culture produced cellulase from a variety of cellulosic materials as well as from cellobiose. The enzyme system contained endo- and exoglucanase, acted on filter paper, and showed cellobiase and xylanase activities. It was stable at 2/sup 0/C under aerobic conditions and showed a pH optimum at 5 and a temperature optimum at 50/sup 0/C. Endoglucanase and filter paper activities were mostly exogenic, whereas cellobiase and xylanase activities were cell associated. The cellulolytic activity produced by this mixed culture was comparable to that of commercially available fungal preparations, and the process could be useful as an alternate source for these enzymes.

Xylanase Activity of Koji Molds

Abstract: 醸造における原料の有効利用や麹菌による着色コントロールを可能にするためには麹菌のヘミセルラーゼの作用を明らかにする必要があり,本報ではまず市販種麹から分離したキシラナーゼ活性について検討し,次の結果を得た。(1) 麹菌のキシラナーゼ活性測定の条件は,pH5.5,40℃ 30分の反応が適当であった。(2) 〓麹におけるキシラナーゼの生産は,散水が60%以上で30℃培養が優れ,40～60時間において急激に増加し,70時間で最高値に達した。(3) 麹菌を形態や種類によってグループ別けした場合には,これらのグループ間にキシラナーゼ平均活性の差を認めたが,いずれのグループにもキシラナーゼの強い菌株と弱い菌株が含まれていた。(4) キシラナーゼ活性と中性及びアルカリ性プロテアーゼ活性との間には高度に有意の相関があり,醤油の醸造等においてヘミセルロースと蛋白質の分解の関連性が推測された。

Preparation of xylose

Abstract: PURPOSE:To prepare high-purity xylose in high yield through simple steps, by hydrolyzing an extract containing a xylan component extracted from the epicarp layer and/ or endocarp layer of a babassu palm with an alkali enzymically to obtain a saccharide. CONSTITUTION:Holocellulose obtained from the epicarp layer and/or endocarp layer of a babassu palm is extracted with an alkali to give an extract containing a xylan component, from which the xylan component is deposited and separated. The xylan component is then subjected to the action of a hydrolyzing enzyme containing a xylanase and hyrolyzed. The resultant hydrolyzate fluid is separated into a neutral and an acidic components. A saccharide liquid consisting of xylose essentially is obtained from the neutral component. The enzymic hydrolysis of the xylan may be carried out by dissolving the isolated xylan in a buffer solution, and hydrolyzing the xylan with a xylanase enzyme. A crude enzyme preparation containing other hydrolyzing enzymes, e.g. cellulase or hemicellulase, as well as xylanase can be used for the hydrolysis.

Production of thermostable cellulases and raw starch-digestible amylases by fungi

Abstract: CMCase, Avicelase, β-glucosidase and xylanase of thermophilic fungi, Humicola insolens YH 8, Mucor miehei YH 10 and Talaromyces byssochlamydoides YH 50 were found to possess high degrees of pH- and thermo-stabilities The stabilities were closely related to its high content of carbohydrate moiety, containing a large amount of N-acetylglucosamine The carbohydrate moiety was found also important in the raw starch-digestivity of glucoamylase of Aspergillus awamori var kawachi The carbohydrate and protein moieties of this enzyme were stepwisely degraded by the combinated actions of proteases and glycosidases, losing the raw starch-digestivity and forming the multiple types and forms of active glucoamylase Contaminant activities of proteases and glycosidases in the fungal cultures were depressed by the selection of fungal strains, the regulations of culture conditions and the preparations of protease-glycosidase-less mutants, for the purpose of the productions of highly thermostable and raw starch-digestive enzymes KEYWORDS Amylase; cellulase; xylanase; enzyme production; glucosidase; thermostable enzyme; multiple forms; thermophilic fungi; koji; Aspergillus