Showing papers on "Xylanase published in 1997"
TL;DR: This is the first report on xylanase production by a thermophilic bacterial strain in SSF and wheat bran was found to be the best substrate among a few easily available lignocellulosics tested.
238 citations
TL;DR: Freshly harvested whole cells from cultures of P. bryantii B(1)4 shown less than 25% of the enzyme activity against oat spelt xylan (OSX) as an energy source showed that much of this hydrolytic activity is either periplasmic, membrane-associated or intracellular and may be concerned with the processing of transported oligosaccharides.
167 citations
TL;DR: It is demonstrated that FAE-III and XYLD specifically release only esters of 5-5'diFA from either xylanase-treated or insoluble fractions of cell walls, even though other esterified dimers were solubilized by preincubation with x Dylanase.
Abstract: Diferulate esters strengthen and cross-link primary plant cell walls and help to defend the plant from invading microbes. Phenolics also limit the degradation of plant cell walls by saprophytic microbes and by anaerobic microorganisms in the rumen. We show that incubation of wheat and barley cell walls with ferulic acid esterase from Aspergillus niger (FAE-III) or Pseudomonas fluorescens (Xy1D), together with either xylanase I from Aspergillus niger, Trichoderma viride xylanase, or xylanase from Pseudomonas fluorescens (XylA), leads to release of the ferulate dimer 5-5' diFA [(E,E)-4,4'-dihydroxy-5,5'-dimethoxy-3,3'-bicinnamic acid]. Direct saponification of the cell walls without enzyme treatment released the following five identifiable ferulate dimers (in order of abundance): (Z)-beta-(4-[(E)-2-carboxyvinyl]-2-methoxyphenoxy)-4-hydroxy-3-methoxycinnamic acid, trans-5-[(E)-2-carboxyvinyl]-2-(4-hydroxy-3-methoxy-phenyl) -7-methoxy-2, 3-dihydrobenzofuran-3-carboxylic acid, 5-5' diFA, (E,E)-4, 4'-dihydroxy-3, 5'-dimethoxy-beta, 3'-bicinnamic acid, and trans-7-hydroxy-1-(4-hydroxy-3-methoxyphenyl) -6-methoxy-1, 2-dihydronaphthalene-2, 3-dicarboxylic acid. Incubation of the wheat or barley cell walls with xylanase, followed by saponification of the solubilized fraction, yielded 5-5'diFA and, in some cases, certain of the above dimers, depending on the xylanase used. These experiments demonstrate that FAE-III and XYLD specifically release only esters of 5-5'diFA from either xylanase-treated or insoluble fractions of cell walls, even though other esterified dimers were solubilized by preincubation with xylanase. It is also concluded that the esterified dimer content of the xylanase-solubilized fraction depends on the source of the xylanase.
118 citations
TL;DR: The structure of BacillusD3 xylanase reveals an unusual feature of surface aromatic residues, which form clusters or “sticky patches” between pairs of molecules that are responsible for the tendency of the protein to aggregate at high concentrations in the absence of reagents such as ethylene glycol.
Abstract: A thermophilic xylanase from Bacillusstrain D3 suitable for use as a bleach booster in the paper pulping industry has been identified and characterized. The enzyme is suited to the high temperature and alkaline conditions needed for using xylanases in the pulp industry. The xylanase is stable at 60°C and relatively stable at high temperatures, with a temperature optimum of 75°C. The pH optimum is 6, but the enzyme is active over a broad pH range. The xylanase has been cloned and sequenced, and the crystal structure has been determined. The structure of BacillusD3 xylanase reveals an unusual feature of surface aromatic residues, which form clusters or “sticky patches” between pairs of molecules. These “sticky patches” on the surface of the enzyme are responsible for the tendency of the protein to aggregate at high concentrations in the absence of reagents such as ethylene glycol. The formation of dimers and higher order polymers via these hydrophobic contacts may also contribute to the thermostability of this xylanase. Proteins 29:77–86, 1997. © 1997 Wiley-Liss, Inc.
102 citations
TL;DR: The effects of two enzyme preparations containing beta-glucanase and xylanase activities on barley- and wheat-based diets, respectively, for broilers, in combination with flavomycin were determined.
99 citations
96 citations
TL;DR: The products observed on TLC after a 23-h hydrolysis of the enzyme on oat spelt xylan were xylobiose, xylotetraose, and xylooligosaccharides with greater chain length.
90 citations
TL;DR: The immobilized xylanase has been immobilized in hydrogel beads prepared by complexation between chitosan and xanthan and shows a predominantly fibrilar microstructure within which there are regions having globular shapes where the enzymes are lodged.
Abstract: endo-1,4-β-Xylanase (E.C. 3.2.1.8) has been immobilized in hydrogel beads prepared by complexation between chitosan and xanthan. The enzyme immobilization efficiency is between 88 and 98% within a wide range of concentrations of xylanase. The optimum xylanase activity requires a pH between 5.0 and 5.5. The immobilized enzymes show 60-70% higher activity than free enzymes. The K m of the immobilized xylanase increases with the concentration of the enzyme in the beads. The latter show, by electron microscopy, a predominantly fibrilar microstructure within which there are regions having globular shapes where the enzymes are lodged.
87 citations
TL;DR: A [beta]-D-xylosidase and an endo-xylanase that hydrolyzed p-nitrophenyl-[alpha]-L-arabinofuranoside was partially purified and appeared to need at least five or more consecutive unsubstituted xylose units.
Abstract: A [beta]-D-xylosidase and an endo-xylanase were purified from European wheat (Triticum aestivum) flour. The [beta]-D-xylosidase had a molecular weight of approximately 64,000 and an isoelectric point of 5.5. It hydrolyzed p-nitrophenyl-[beta]-D-xylopyranoside and xylo-oligosaccharides and released D-xylose units from wheat arabinoxylan and oat spelts xylan. An endo-xylanase with a molecular weight of approximately 55,000 was also obtained and it consisted of a number of isoforms with isoelectric points between 4.0 and 5.0. The action of the isolated endo-xylanase depended on the degree of substitution of the polysaccharide. Unbranched polymers were preferentially hydrolyzed. Since xylo-oligosaccharides were not hydrolyzed, the enzyme appeared to need at least five or more consecutive unsubstituted xylose units. Finally, an [alpha]-L-arabinofuranosidase that hydrolyzed p-nitrophenyl-[alpha]-L-arabinofuranoside was partially purified.
79 citations
TL;DR: It was shown that the enzyme immobilized on oil-bodies could be recycled by flotation several times without loss of activity and the functioning of the xylanase as a fusion protein.
Abstract: Canola seed oil-bodies were investigated as a production vehicle and immobilization matrix for xylanases. A recombinant xynC gene from Neocallimastix patriciarum encoding a xylanase (XynC) was fused to an oleosin coding sequence suitable for targeting the xylanase to the oil-body membrane. This fusion gene was introduced into Brassica napus using Agrobacterium-mediated transformation. Transgenic Canola plants were obtained expressing xylanase which was targeted to the oil-bodies of seeds as shown by analysis with XynC-specific antibodies. Oil-bodies extracted from transgenic seeds exhibited xylanase activity, indicating the immobilization of XynC on the surface of oil bodies and the functioning of the xylanase as a fusion protein. The immobilized XynC retained its optimal temperature, Km value and specificity. However, it exhibited reduced sensitivity to pH. Furthermore, it was shown that the enzyme immobilized on oil-bodies could be recycled by flotation several times without loss of activity.
79 citations
01 Sep 1997
TL;DR: In this paper, commercial enzyme preparations and two laboratory-designed mixes with amylase and/or pentosanase/xylanase activity were used to prepare bread samples, and the effects on bread quality and keeping properties were determined.
Abstract: Nine commercial enzyme preparations and two laboratory-designed mixes with amylase and/or pentosanase/xylanase activity were used to prepare bread samples, and the effects on bread quality and keeping properties were determined. With the doses added, enzymes significantly shortened fermentation time without affecting the pH or the machinability of the doughs. Bread with an improved volume, a greater intensity of aroma and a softer texture was obtained. Loaves had a less intense and characteristic taste and, in some cases, an uneven grain. All enzymes delayed bread firming, but rates varied with each preparation. Factor analysis classified bread samples according to their composition and source.
TL;DR: Fat digestibility was improved by xylanase in both fat type groups but to a greater extent for the tallow diets, and the deposition of the fat soluble vitamins A and E in livers was significantly increased byxylanase supplementation and was also better for soya oil than for tallow.
Abstract: 1. The interactions between dietary fat type and xylanase supplementation of rye‐based diets were investigated using a 2×2 factorial design in which a rye‐based diet (610 g rye/kg) was combined with 100 g/kg of soya oil or beef tallow, with or without xylanase supplementation at 3000 IU/kg, and fed to 1‐d‐old male broilers for 35 d. Growth, nutrient digestibility and AMEn values were determined and the vitamin status of livers assessed at various ages. 2. There were significant interactions between crude fat and xylanase supplementation on the faecal digestibility of crude fat and crude protein. Fat digestibility was improved by xylanase in both fat type groups but to a greater extent for the tallow diets. However, the effects were found to be significant only for oleic, linoleic and linolenic acids. Similarly, protein digestibility and AMEn values were significantly improved by xylanase, but only for the tallow diet. 3. Heal digestibility of nitrogen and amino acids also were affected by enzyme ...
TL;DR: Comparisons of the activities, yields and productivities of cellulase and xylanase obtained in shake-flask, stirred-tank, bubble-column, and air-lift reactors show that better yield and productivity were shown in a bubble- column and an external-loop air- lift than in the stirred- Tank reactor.
TL;DR: Hemicellulases and an endoglucanase from seven different fungi were assessed for their potential to solubilze mannan and xylan from softwood sulfite dissolving pulps and a xylanase from Thermomyces lanuginosus and a mannanase from Sclerotium rolfsii acted synergistically on the pulpsolubilizing 50% more mannanand 11% more xylan than did the individual enzymes.
Abstract: Hemicellulases and an endoglucanase from seven different fungi were assessed for their potential to solubilze mannan and xylan from softwood sulfite dissolving pulps. A xylanase from Thermomyces lanuginosus and a mannanase from Sclerotium rolfsii acted synergistically on the pulp solubilizing 50% more mannan and 11% more xylan than did the individual enzymes. The addition of an endoglucanase further increased both the amount of xylan and mannan that was solubilized from the pulp.
TL;DR: The results demonstrated that the individual cellulases have profoundly different modes of action in modifying pulp carbohydrates, and the exploitation of cellulases for fibre treatments requires careful optimization of both enzyme composition and dosage.
Abstract: Four purified cellulases, a xylanase and mannanase from Trichoderma reesei were used to treat never-dried bleached pine kraft pulp prior to refining, and the effects on pulp properties were evaluated. The enzymatic treatments hydrolysed up to 0.8% of pulp dry weight. The results demonstrated that the individual cellulases have profoundly different modes of action in modifying pulp carbohydrates. This is especially clear when comparing their effects at the same level of hydrolysis. Pretreatment with cellobiohydrolases I (CBH I) and II (CBH II) had virtually no effect on the development of pulp properties during refining, except for a slight decrease in strength properties. On the contrary, endoglucanase I (EG I) and endoglucanase II (EG II) improved the beatability of the pulp as measured by Schopper--Riegler value, sheet density and Gurley air resistance. Of the endoglucanases, EG II was most effective in improving the beating response. The combinations of CBH I with EG I and EG II had similar effects on the pulp properties as the endoglucanases alone, although the amount of hydrolysed cellulose was increased. Pretreatments with xylanase or mannanase did not appear to modify the pulp properties. The same enzyme treatments which improved the beatability, however, slightly impaired the pulp strength, especially tear index at the enzyme dosages used. When compared at a given level of cellulose hydrolysis, the negative effect of EG II on strength properties was more pronounced compared with EG I. Thus, the exploitation of cellulases for fibre treatments requires careful optimization of both enzyme composition and dosage. Since the endoglucanases had no positive effect on the development of tensile strength, it is suggested that the explanation for the increased beating response is increased fibre breakage and formation of fines, rather than improved flexibilization.
TL;DR: The antibodies against the catalytic domain peptide reacted specifically with the xylanases of Orpinomyces and Neocallimastix, while the antibodies against a noncatalytic repeated peptide domain (NCRPD) reacted with many (at least eight) extracellular proteins of Orpinsomyce and NeOCallimastsix, suggesting that the NCRPD is present in a number of polypeptides.
Abstract: Cellulase and xylanase cDNAs were isolated from a cDNA library of the polycentric anaerobic fungus Orpinomyces sp. strain PC-2 constructed in Escherichia coli. The cellulase cDNA (celB) was 1.8 kb long with an open reading frame (ORF) coding for a polypeptide of 471 amino acids, and the xylanase cDNA (xynA) was 1.2 kb long with an ORF encoding a polypeptide of 362 amino acids. Single transcripts of 1.9 kb for celB and 1.5 kb for xynA were detected in total RNA of Orpinomyces grown on Avicel. Genomic DNA regions coding for CelA and XynA were devoid of introns. The enzymes were highly homologous (80 to 85% identity) to the corresponding enzymes of the monocentric anaerobic fungus Neocallimastix patriciarum and, like those, contained in addition to a catalytic domain, a noncatalytic repeated peptide domain (NCRPD). The Orpinomyces xylanase contained one catalytic domain and thus differed from the Neocallimastix xylanase, which had two similar catalytic domains (H. J. Gilbert, G. P. Hazlewood, J. I. Lauie, C. G. Orpin, and G. P. Xue, Mol. Microbiol. 6:2065-2072, 1992). Two peptides corresponding to the catalytic domain and the NCRPD of XynA were synthesized, and antibodies against them were raised and affinity column purified. The antibodies against the catalytic domain peptide reacted specifically with the xylanases of Orpinomyces and Neocallimastix, while the antibodies against the NCRPD reacted with many (at least eight) extracellular proteins of Orpinomyces and Neocallimastix, suggesting that the NCRPD is present in a number of polypeptides.
TL;DR: Sagohampas, the fibrous pith residue left after starch extraction from sago palm, is abundant at sago-processing factories and can be used as a substrate for the production of laccase by solid substrate fermentation (SSF) with Pleurotus sajorcaju, an edible mushroom.
Abstract: Sagohampas, the fibrous pith residue left after starch extraction from sago palm, is abundant at sago-processing factories and can be used as a substrate for the production of laccase by solid substrate fermentation (SSF) withPleurotus sajorcaju, an edible mushroom. The fungus grown onhampas with an adjusted carbon : nitrogen ratio of 35:1, exhibited high laccase activity together with variable cellulase (0.3-2.8 U/g) and xylanase (0.9-10.1 U/g) activity. The maximum amount of laccase produced was approximately 17.7 U/g after 6 days of SSF using 4-week-old inoculum at a density of 10%. With the mature four-week inoculum, laccase activity increased 12-fold compared to that achieved with two-week-old inoculum. The optimum pH and temperature of the crude laccase were 6.0 and 50‡C, respectively. The apparent Km and Vmax values obtained were 0.073 mM and 0.962 U/min, respectively. The maximum laccase activity could be almost doubled after 6 days of fermentation by addition of 0.2 mM vanillin or ferulic acid; the cellulose to lignin ratio increased significantly during the 12 days of SSF, from 2.74 in the control to 3.3, when 0.2 mM of either vanillin or ferulic acid was added to the substrate.
TL;DR: In this article, a combined mixture of commercial amylase, xylanase, and cellulase enzyme preparations were used to extract xylans from corn fiber and wheat germ.
Abstract: Corn fiber is a coproduct produced during the corn wet-milling process and is similar to other high hemicellulose/cellulose-containing biomass such as grasses, straws, or bagasse, all of which represent potential fermentation feedstock for conversion into biofuels or other products. Corn fiber was subjected to ammonia-explosion (AFEX) treatment to increase degradability and then enzymatically digested with a combined mixture of commercial amylase, xylanase, and cellulase enzyme preparations. Whereas the starch and cellulose components were converted solely to glucose, oligosaccharides represented 30–40% of the xylan degradation products. This enzyme mixture also produced substantial oligosaccharides with xylans purified from corn fiber, corn germ, beechwood, oatspelt, or wheat germ. Commercial xylan-degrading enzyme preparations containing xylanase, xylosidase, and arabinosidase activities were then used alone or in varying combinations to attempt to maximize degradation of these isolated xylans of differing chemical compositions. The results showed that oatspelt and beechwood xylans were degraded most extensively (40–60%) with substantial amounts of xylose, xylobiose, and xylotriose as products depending on the enzyme combination used. Corn fiber and wheat germ xylans, which contain large amounts of arabinose and uronic acid sidechains, were poorly degraded and only small amounts of arabinose and xylose and large amounts of pentamer or longer oligosaccharides were produced by enzymatic degradation. The data suggest that whereas enzymatic digestion of biomass hemicellulose does not produce toxic products, the process is not effective in producing a suitable fermentable substrate stream because of the low levels of monosaccharides and high levels of oligosaccharides produced.
TL;DR: The properties of the xylanase enzyme qualify the enzyme to be novel and potentially important for application in some industrial processes.
Abstract: A. GESSESSE AND B.A. GASHE. 1997. An alkaline xylanase-producing alkaliphilic Bacillus sp. AR-()09 was isolated from an alkaline soda lake in Ethiopia. The enzyme was optimally active at pH 9 and was stable over a broad pH range. The optimum temperature for xylanase activity, assayed at pH 9, was 60°-65°C. Measured at pH 8 and 9, the enzyme had good stability at 55° and 60°C. At both pH values, over 80% of its original activity was retained after heating for 2.5 h at 55°C. At 60°C, the enzyme maintained 63% of its original activity after 2.5 h incubation while at pH 9 it retained 54% of its original activity after 1 h heating. These properties qualify the enzyme to be novel and potentially important for application in some industrial processes.
TL;DR: The interactions between fat type and xylanase supplementation of rye-based diets were investigated using a 2 x 2 factorial design and a significant increase in pH after enzyme addition was detected in the proximal ileum; this was independent of fat source.
Abstract: 1. The interactions between fat type and xylanase supplementation of rye-based diets were investigated using a 2 x 2 factorial design in which a rye-based diet (610 g rye/kg) was combined with 100 g/kg of soya oil or beef tallow, with and without xylanase supplementation at 3000 IU/kg, and fed to 1-d-old male broilers. Food passage time, viscosity of digesta supernatant, xylanase activity and pH in different segments of the digestive tract were examined. 2. Food passage throughout the digestive tract was accelerated by enzyme addition regardless of fat type. The time taken for 50% of the marker to be excreted was reduced from 8.4 to 6.7 h in animals receiving the rye-soya oil diets and from 8.0 to 6.9 h with the rye-tallow diets. 3. Viscosity in the supernatant of the jejunal and ileal digesta was markedly decreased after enzyme addition. Viscosities were generally higher in the ileal than in the jejunal supernatant, and fell as the birds aged from 14 to 28 d. The effect of enzyme was also reduced in older chicks. There was not a clear effect of the fat source on viscosity. 4. Xylanase activity was still found at the end of the ileum in digesta of birds fed on the enzyme-supplemented diets but not in control animals. Xylanase activity was also detected in the caeca of all groups. 5. Significantly lower pH values were found in tallow-fed birds in some segments of the digestive tract. A significant increase in pH after enzyme addition was detected in the proximal ileum; this was independent of fat source.
TL;DR: Of the six enzymes tested, two xylanases belonging to family 11 were most effective at increasing bleachability and improving final paper brightness, and the efficiency of individual xylanase as bleach enhancers was not dependent on the source microorganism, and could not be predicted solely on the basis of the quantity or nature of products released from pulp xylan.
Abstract: Enzyme-aided bleaching of softwood and hardwood kraft pulps by glycosyl hydrolase family-10 and -11 xylanases and a family-26 mannanase was investigated. The ability to release reducing sugar from pulp xylan and to enhance bleachability is not a characteristic shared by all xylanases. Of the six enzymes tested, two xylanases belonging to family 11 were most effective at increasing bleachability and improving final paper brightness. None of the enzymes had a deleterious effect on pulp fibre integrity. The efficiency of individual xylanases as bleach enhancers was not dependent on the source microorganism, and could not be predicted solely on the basis of the quantity or nature of products released from pulp xylan. Cooperative interactions between xylanase/xylanase and xylanase/mannanase combinations, during the pretreatment of softwood and hardwood pulps, were investigated. Synergistic effects on reducing-sugar release and kappa number reduction were elicited by a combination of two family-10 xylanases. Pretreatment of kraft pulp with mannanase A from Pseudomonas fluorescens subsp. cellulosa and any one of a number of xylanases resulted in increased release of reducing sugar and a larger reduction in kappa number than obtained with the xylanases alone, confirming the beneficial effects of family-26 mannanases on enzyme-aided bleaching of paper pulp.
TL;DR: One of the thermophilic actinomycetes isolated from urban solid waste, Thermomonospora alba ULJB1, showed a broad degradative activity on xylan, cellulose, starch and other polymers and was able to degrade xylans form different origins but not lichenam or carboxymethylcellulose.
Abstract: Several thermophilic actinomycetes were isolated from urban solid waste. One of them, Thermomonospora alba ULJB1, showed a broad degradative activity on xylan, cellulose, starch and other polymers. Xylanase and cellulase activities were quantified and compared with those Thermomonospora fusca. Genes encoding two different endo-beta-1,4-xylanase were cloned from T. alba ULJB1. One of them, xylA, was sequenced, subcloned and overexpressed in Streptomyces lividans. It encodes a protein of 482 amino acids with a deduced molecular mass of 48,456 Da. The protein contains a 38-amino-acid leader peptide with six Arg+ residues in its amino-terminal end, a catalytic domain and a cellulose-binding domain connected by a linker region rich in proline and glycine. The XylA protein was purified to near homogeneity from S. lividans/XylA cultures. Two forms of the extracellular xylanase, of 48 kDa and 38 kDa, were produced that differed in their cellulose-binding ability. The 48-kDa protein showed a strong binding to cellulose whereas the 38-kDa form did not bind to this polymer, apparently because of the removal during processing of the cellulose-binding domain. Both forms were able to degrade xylans form different origins but not lichenam or carboxymethylcellulose. The major degradation product was xylobiose with traces of xylose. The xylanase activity was thermostable, showing a good activity up to 95 degrees C, and had broad pH stability in the range from pH 4.0 to pH 10.0.
TL;DR: In the early stages of hydrolysis, four purified mannanases and four xylanases from fungal and bacterial origin, examined in this study, showed a different pattern of released oligomers (determined up to the pentamers) and some of these enzymes showed a preference for cleaving the polysaccharides in the middle of the chain while others acted more at the end.
Abstract: Endo-mannanases and endo-xylanases cleave different heteromannans and xylans yielding mainly dimers and trimers of the corresponding sugars as end-products. However, in the early stages of hydrolysis, four purified mannanases and four xylanases from fungal and bacterial origin, examined in this study, showed a different pattern of released oligomers (determined up to the pentamers). Furthermore, some of these enzymes showed a preference for cleaving the polysaccharides in the middle of the chain while others acted more at the end. When the increase in the specific fluidity of mannan and xylan solutions per reducing sugar released (K
v) was measured against the bleaching effect of the enzymes on softwood kraft pulp, a correlation was found. A xylanase from Penicillium simplicissimum (K
v = 0.15 l mPa−1s−1g−1) and a mannanase from Sclerotium rolfsii (K
v = 0.12 l mPa−1s−1g−1) applied in a O(QX)P bleaching sequence (O = oxygen delignification, X = treatment with hemicellulolytic enzymes, Q = chelation of metals, P = treatment with hydrogen peroxide in alkaline solution) gave a high brightness increase of 3.0% and 1.9% ISO respectively. A less significant brightness increase was obtained with enzymes showing lower K
v values, such as a xylanase from Schizophyllum commune (Kv = 0.051 l mPa−1s−1g−1, 0.2% ISO) and a bacterial mannanase (K
v = 0.061 l mPa−1s−1g−1,0.5% ISO).
Patent•
10 Oct 1997TL;DR: In this article, a process for upgrading paper-grade wood pulp to dissolving grade pulp which is suitable for use in the preparation of viscose rayon, cellulose ethers and cellulose esters such as cellulose acetate is described.
Abstract: Disclosed is a process for upgrading paper-grade wood pulp to dissolving grade pulp which is suitable for use in the preparation of viscose rayon, cellulose ethers and cellulose esters such as cellulose acetate. The process utilizes a sequence of caustic extraction, xylanase treatment and caustic extraction to remove most of the xylan, which may be recovered for use in the production of xylose, xylitol, and furans.
TL;DR: Extracellular xylanase activity and cell‐bound β‐xylosidase production by a selected strain of Streptomyces sp.
Abstract: Extracellular xylanase activity and cell-bound β-xylosidase production by a selected strain of Streptomyces sp. CH-M-1035 was characterized during growth on three xylans, sugar cane bagasse pith and lemon peel as sole carbon source. The cell-bound β-xylosidase and extracellular endoxylanase had pH optima of 6·0 and 5·0, and temperature optima of 50°C and 60°C, respectively. The highest level of β-xylosidase activity was obtained when Streptomyces sp. CH-M-1035 was grown on larchwood xylan, whereas the maximal endoxylanase production was found on lemon peel. Reducing sugars accumulated in the culture media when Streptomyces sp. CH-M-1035 was grown on xylans, but not on agroindustrial residues.
Patent•
05 Sep 1997TL;DR: In this article, a modified xylanase of Family 11 was shown to have improved thermophilicity, alkalicity, and thermostability as compared to the natural xylan enzyme.
Abstract: Producing a xylanase enzyme of superior performance in the bleaching of pulp. More specifically, a modified xylanase of Family 11 that shows improved thermophilicity, alkalophilicity, and thermostability as compared to the natural xylanase. The modified xylanases contain any of three types of modifications: (1) changing amino acids 10, 27, and 29 of Trichoderma reesei xylanase II or the corresponding amino acids of another Family 11 xylanase, where these amino acids are changed to histidine, methionine, and leucine, respectively; (2) substitution of amino acids in the N-terminal region with amino acids from another xylanase enzyme. In a preferred embodiment, substitution of the natural Bacillus circulans or Trichoderma reesei xylanase with a short sequence of amino acids from Thermomonospora fusca xylanase yielded chimeric xylanases with higher thermophilicity and alkalophilicity; (3) an extension upstream of the N-terminus of up to 10 amino acids. In a preferred embodiment, extension of the N-terminus of the xylanase with the tripeptide glycine-arginine-arginine improved its performance.
TL;DR: Comparison of the T. maritima recombinant enzyme with a commercially available xylanase, Pulpzyme, indicated that the hyperthermophilic enzyme has several advantages that make it an attractive biotechnological reagent.
TL;DR: Solid-substrate cultivation was a better method for the production of enzyme, particularly xylanase, from A. niger ATCC 6275 and was comparable to the result achieved from using the commercial xylase preparation Meicelase and superior to the effect of Sumyzyme.
Abstract: Optimization of enzyme production from Aspergillus niger ATCC 6275 under both submerged and solid-substrate cultivation was investigated. Results from submerged cultivation using palm oil mill effluent revealed that pretreatment of ground palm cake did not improve enzyme production. Addition of 0.60g NH4NO3/l generated maximum activity of xylanase and cellulase (CMCase). The optimum aeration rate was 1.2 v/v min. Under solid-substrate cultivation, the results indicated that heating and alkali treatment of the ground palm cake gave no further improvement in enzyme production. The optimal N-source was 2% urea. Optimal initial moisture contents for xylanase and CMCase activities were 60% and 50% respectively, with temperature optima of 30°C and 35°C, respectively. The optimal inoculum size was 1× 108 spores/g palm cake with an initial pH of 4.5–5.0. The maximum activities of xylanase (282.9U/g) and CMCase (23.8U/g) were obtained under the optimum conditions. Solid-substrate cultivation was a better method for the production of enzyme, particularly xylanase, from A. niger ATCC 6275. The application of these enzymes to decanter effluent showed the separation of oil and grease and suspended solids from the effluent. This is comparable to the result achieved from using the commercial xylase preparation Meicelase and superior to the effect of Sumyzyme.
TL;DR: Data suggest that the primary function of the calcium binding domain is to increase the stability of the enzyme against thermal unfolding and proteolytic attack, and the possible mechanism by which the domain evolved is discussed.
TL;DR: Three strictly aerobic strains were isolated from a hot-spring in Kobe, Japan, and a facultative anaerobic strain LB3A was isolated from sediments collected from the alkaline Lake Bogoria, Kenya, which were thermophilic and capable of growth on xylan.
Abstract: Three strictly aerobic strains (K-1, K-3d and K-4) were isolated from a hot-spring in Kobe, Japan, and a facultative anaerobic strain LB3A was isolated from sediments collected from the alkaline Lake Bogoria, Kenya. All strains were thermophilic and capable of growth on xylan. On the basis of morphological, physiological and phylogenetic studies the new aerobic isolates resemble the thermophilic species Bacillus thermoleovorans while the facultative anaerobic isolate LB3A resembles the facultative anaerobic thermophilic species Bacillus flavothermus. When grown on xylan as sole carbon source, all isolates produce thermoactive xylanases. Xylanases from strains K-3d and LB3A are active at temperatures between 40 and 90°C and pH values between 5.0 and 9.0. Applying SDS-PAGE the crude xylanase complex of isolate K-3d was shown to be composed of two active bands, with molecular masses of 40 and 69 kDa. The crude xylanase complex of isolate LB3A, on the other hand, is composed of at least four activity bands with molecular masses ranging from 80 to 130 kDa. Due to the product pattern of xylan hydrolysis both enzymes are classified as endoxylanases. The xylanolytic enzyme system of isolate K-3d produces xylotriose, xylotetraose and larger xylooligosacharides, whereas the xylanases from isolate LB3A release xylotetraose as the major product of hydrolysis.