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1.
An xylanase producing alkaliphilic Micrococcus sp was isolated from an alkaline soda lake. Xylose and xylan induced enzyme production but no activity was detected when
it was grown using other carbohydrate sources. The level of xylanase production was higher in the presence of xylose than
in the presence of xylan. The enzyme was purified to homogeneity and its molecular weight was estimated to be 56 kD on SDS-PAGE.
The optimum temperature and pH for xylanase activity were 55°C and 7.5–9.0, respectively. Sixty per cent of the maximum activity
was displayed at pH 11. The enzyme was very stable in the pH range of 6.5–10 and up to a temperature of 40°C. Xylanase activity
was inhibited by Cu2+ and Hg2+.
Received 03 October 1997/ Accepted in revised form 03 February 1998 相似文献
2.
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 endoenzyme which degrades the β-1,4-glycosyl linkages in xylan and cellulose. 相似文献
3.
Summary Xylanase from Scytalidium thermophilum was immobilized on Eudragit L-100, a pH sensitive copolymer of methacrylic acid and methyl methacrylate. The enzyme was non-covalently
immobilized and the system expressed 70% xylanase activity. The immobilized preparation had broader optimum temperature of
activity between 55 and 65 °C as compared to 65 °C in case of free enzyme and broader optimum pH between 6.0 and 7.0 as compared
to 6.5 in case of free enzyme. Immobilization increased the t1/2 of enzyme at 60 °C from 15 to 30 min with a stabilization factor of 2. The Km and Vmax values for the immobilized and free xylanase were 0.5% xylan and 0.89 μmol/ml/min and 0.35% xylan and 1.01 μmol/ml/min respectively. An Arrhenius plot showed an increased value of activation energy for immobilized xylanase (227 kcal/mol)
as compared to free xylanase (210 kcal/mol) confirming the higher temperature stability of the free enzyme. Enzymatic saccharification
of xylan was also improved by xylanase immobilization. 相似文献
4.
Satoshi Nakamura Yutaka Ishiguro Ryuichiro Nakai Kenji Wakabayashi Rikizo Aono Koki Horikoshi 《Journal of Molecular Catalysis .B, Enzymatic》1995,1(1)
Thermoalkaliphilic Bacillus sp. strain TAR-1 isolated from soil produced an extracellular xylanase. The enzyme (xylanase R) was purified to homogeneity by ammonium sulfate fractionation and anion-exchange chromatography. The molecular mass of xylanase R was 40 kDa and the isoelectric point was 4.1. The enzyme was most active over the range of pH 5.0 to 10.0 at 50°C. The optimum temperatures for activity were 75°C at pH 7.0 and 70°C at pH 9.0. Xylanase R was stable up to 65°C at pH 9.0 for 30 min in the presence of xylan. Mercury(ll) ion at 1 mM concentration abolished all the xylanase activity. The predominant products of xylan-hydrolysate were xylobiose, xylotriose, and higher oligosaccharides, indicating that xylanase R was an endo-acting enzyme. Xylanase R had a Km of 0.82 mg/ml and a Vmax of 280 μmol min−1 mg−1 for xylan at 50°C and pH 9.0. 相似文献
5.
The novel fungus Aspergillus niveus RS2 isolated from rice straw showed relatively high xylanase production after 5 days of fermentation. Of the different xylan-containing
agricultural by-products tested, rice husk was the best substrate; however, maximum xylanase production occurred when the
organism was cultured on purified xylan. Yeast extract was found to be the best nitrogen source for xylanase production, followed
by ammonium sulfate and peptone. The optimum pH for maximum enzyme production was 8 (18.2 U/ml); however, an appreciable level
of activity was obtained at pH 7 (10.9 U/ml). Temperature and pH optima for xylanase were 50°C and 7.0, respectively; however
the enzyme retained considerably high activity under high temperature (12.1 U/ml at 60°C) and high alkaline conditions (17.2 U/ml
at pH 8 and 13.9 U/ml at pH 9). The enzyme was strongly inhibited by Hg2+, while Mn2+ was slight activator. The half-life of the enzyme was 48 min at 50°C. The enzyme was purified by 5.08-fold using carboxymethyl-sephadex
chromatography. Zymogram analysis suggested the presence of a single candidate xylanase in the purified preparation. SDS-PAGE
revealed a molecular weight of approximately 22.5 kDa. The enzyme had K
m and V
max values of 2.5 and 26 μmol/mg per minute, respectively. 相似文献
6.
Yin Li Zhiqiang Liu Fengjie Cui Yingying Xu Hui Zhao 《World journal of microbiology & biotechnology》2007,23(6):837-843
A new strain of Penicillium sp. ZH-30 that produces xylanase was isolated from soil. According to the morphology and comparison of internal transcribed
spacer (ITS) rDNA gene sequence, the strain Penicillium sp. ZH-30 was identified as a strain of Penicillium oxalicum. When xylan or wheat bran was used as substrate at 30°C for 3 days under submerged cultivation, xylanase production was 5.3
and 13.3 U ml−1, respectively. The temperature and pH for optimum activity were 50°C and 5.0–6.0, respectively. 相似文献
7.
A. Mandal S. Kar P. K. Das Mohapatra C. Maity B. R. Pati K. C. Mondal 《Applied Biochemistry and Microbiology》2011,47(3):250-255
An extracellular xylanase from the fermented broth of Bacillus cereus BSA1 was purified and characterized. The enzyme was purified to 3.43 fold through ammonium sulphate precipitation, DEAE cellulose
chromatography and followed by gel filtration through Sephadex-G-100 column. The molecular mass of the purified xylanse was
about 33 kDa. The enzyme was an endoxylanase as it initially degraded xylan to xylooligomers. The purified enzyme showed optimum
activity at 55°C and at pH 7.0 and remained reasonably stable in a wide range of pH (5.0–8.0) and temperature (40–65°C). The
K
m
and V
max
values were found to be 8.2 mg/ml and 181.8 μmol/(min mg), respectively. The enzyme had no apparent requirement of cofactors,
and its activity was strongly inhibited by Cu2+, Hg2+. It was also a salt tolerant enzyme and stable upto 2.5 M of NaCl and retained its 85% activity at 3.0 M. For stability and
substrate binding, the enzyme needed hydrophobic interaction that revealed when most surfactants inhibited xylanase activity.
Since the enzyme was active over wide range of pH, temperature and remained active in higher salt concentration, it could
find potential uses in biobleaching process in paper industries. 相似文献
8.
S. Prakash Y. Veeranagouda L. Kyoung K. Sreeramulu 《World journal of microbiology & biotechnology》2009,25(2):197-204
A halophilic and alkali-tolerant Chromohalobacter sp. TPSV 101 with an ability to produce extracellular halophilic, alkali-tolerant and moderately thermostable xylanase was
isolated from solar salterns. Identification of the bacterium was done based upon biochemical tests and 16S rRNA sequence.
The culture conditions for higher xylanase production were optimized with respect to NaCl, pH, temperature, substrates and
metal ions and additives. Maximum xylanase production was achieved in the medium with 20% NaCl, pH-9.0 at 40°C supplemented
with 1% (w/v) sugarcane bagasse and 0.5% feather hydrolysate as carbon and nitrogen sources. Sugarcane bagasse (250 U/ml)
and wheat bran (190 U/ml) were the best inducer of xylanase when used as carbon source as compared to xylan (61 U/ml). The
xylanase that was partially purified by protein concentrator had a molecular mass of 15 kDa approximately. The xylanase from
Chromohalobacter sp. TPSV 101 was active at pH 9.0 and required 20% NaCl for optimal xylanolytic activity and was active over a broad range
of temperature 40–80°C with 65°C as optimum. The early stage hydrolysis products of sugarcane bagasse were xylose and xylobiose,
after longer periods of incubation only xylose was detected. 相似文献
9.
Murat Kacagan Sabriye Canakci Cemal Sandalli Kadriye Inan Dilsat N. Colak Ali O. Belduz 《Biologia》2008,63(5):599-606
A facultatively anaerobic, thermophilic, xylanolytic bacterium was isolated from a sample collected from the Diyadin Hot Springs,
Turkey. According to morphological, biochemical and molecular identification, this new strain was suggested to be representative
of the Anoxybacillus pushchinoensis and it was designated as Anoxybacillus pushchinoensis strain A8. It exhibited 97% similarity to 16S rRNA gene sequence of A. pushchinoensis and 77% DNA homology by DNA-DNA hybridization studies. Q-sepharose and CM-sepharose chromatography was used to purify an
extracellular xylanase to >90% purity from this species. The enzyme had a molecular mass of approximately 83 kDa. The enzyme
showed optimum activity at pH 6.5 and it was 96% stable over a broad pH range of 6.5–11 for 24 hours. The enzyme had optimum
activity at 55°C and it was 100% stable at temperature between 50–60°C up to 24 hours. Kinetic characterization of the enzyme
was performed at temperature optima (55°C) and Vmax and K
m were found to be 59.88 U/mg protein and 0.909 mg/mL, respectively. Oat spelt xylan but not xylooligosaccharides was degraded
by the enzyme and xylose was the only product detected from oat xylan degradation. This suggested that the enzyme was an exo-acting
xylanase. 相似文献
10.
Jing Wang Wei-wei Zhang Jin-ni Liu Yao-ling Cao Xiao-ting Bai Yue-sheng Gong Pei-lin Cen Ming-ming Yang 《Molecular biology reports》2010,37(7):3297-3302
An alkaline active xylanase, XynBYG, was purified from an alkaliphilic Bacillus pumilus BYG, which was newly isolated from paper mill effluent. It had an optimum pH of 8.0–9.0, and showed good stability after
incubated at pH 9.0 for 120 min. The optimum temperature for the activity was 50°C, and the enzyme retained below 55% of its
original activity for 30 min at 55°C. The gene coding for XynBYG consists of 687 bp and encodes 229 amino acids. Similarity
analysis indicated that XynBYG belong to family 11 glycosyl hydrolases. Site-directed mutagenesis was performed to replace
five sites (Tyr/Ser) to Arg/Glu and the results demonstrated that the optimum temperature of the mutant Y7 (S39R-T146E) increased
5°C and the half-life of inactivation (T1/2) at 60 and 65°C was 1 h and 25 min, respectively. Thus, it provides a potential
xylanase that can meet the harsh conditions in the industrial applications. 相似文献
11.
Efficient utilization of hemicellulose entails high catalytic capacity containing xylanases. In this study, proline rich sequence was fused together with a C-terminal of xylanase gene from Geobacillus thermodenitrificans C5 and designated as GthC5ProXyl. Both GthC5Xyl and GthC5ProXyl were expressed in Escherichia coli BL21 host in order to determine effect of this modification. The C-terminal oligopeptide had noteworthy effects and instantaneously extended the optimal temperature and pH ranges and progressed the specific activity of GthC5Xyl. Compared with GthC5Xyl, GthC5ProXyl revealed improved specific activity, a higher temperature (70 °C versus 60 °C) and pH (8 versus 6) optimum, with broad ranges of temperature and pH (60–80 °C and 6.0–9.0 versus 40–60 °C and 5.0–8.0, respectively). The modified enzyme retained more than 80% activity after incubating in xylan for 3 h at 80 °C as compared to wild −type with only 45% residual activity. Our study demonstrated that proper introduction of proline residues on C-terminal surface of xylanase family might be very effective in improvement of enzyme thermostability. Moreover, this study reveals an engineering strategy to improve the catalytic performance of enzymes. 相似文献
12.
Khwanchai Khucharoenphaisan Shinji Tokuyama Vichien Kitpreechavanich 《Mycoscience》2010,51(6):405-410
Highly thermostable β-xylanase produced by newly isolated Thermomyces lanuginosus THKU-49 strain was purified in a four-step procedure involving ammonium sulfate precipitation and subsequent separation on
a DEAE-Sepharose fast flow column, hydroxylapatite column, and Sephadex G-100 column, respectively. The enzyme purified to
homogeneity had a specific activity of 552 U/mg protein and a molecular weight of 24.9 kDa. The optimal temperature of the
purified xylanase was 70°C, and it was stable at temperatures up to 60°C at pH 6.0; the optimal pH was 5.0–7.0, and it was
stable in the pH range 3.5–8.0 at 4°C. Xylanase activity was inhibited by Mn2+, Sn2+, and ethylenediaminetetraacetic acid. The xylanase showed a high activity towards soluble oat spelt xylan, but it exhibited
low activity towards insoluble oat spelt xylan; no activity was found to carboxymethylcellulose, avicel, filter paper, locust
bean gum, cassava starch, and p-nitrophenyl β-d-xylopyranoside. The apparent K
m value of the xylanase on soluble oat spelt xylan and insoluble oat spelt xylan was 7.3 ± 0.236 and 60.2 ± 6.788 mg/ml, respectively.
Thin-layer chromatography analysis showed that the xylanase hydrolyzed oat spelt xylan to yield mainly xylobiose and xylose
as end products, but that it could not release xylose from the substrate xylobiose, suggesting that it is an endo-xylanase. 相似文献
13.
B. Choudhury Sunita Chauhan S.N. Singh P. Ghosh 《World journal of microbiology & biotechnology》2006,22(3):283-288
Summary The production of xylanase from Bacillus coagulans has been studied with respect to the environmental parameters, the carbon source and the concentration of carbon source at
the shake flask level. Among the various carbon sources used, wheat straw powder favoured higher enzyme production. Xylan
isolated from wheat straw gave higher enzyme production as compared to the birchwood xylan. Maximum enzyme activity of 165 IU/ml
was obtained with 2% wheat straw xylan in a shake flask study. Improvement of xylanase production was achieved by increasing
the wheat straw powder concentration up to 3%. Enzyme has optimum activity at a temperature of 55 °C and pH of 7. The concentrated
crude enzyme was found to reduce the kappa number of enzyme-treated eucalyptus pulp by␣5.45% with a marginal increase in the
CED viscosity of the enzyme treated pulp as compared to the non-enzymatically treated pulp. 相似文献
14.
S Canakcı Z Cevher K Inan M Tokgoz F Bahar M Kacagan FA Sal AO Belduz 《World journal of microbiology & biotechnology》2012,28(5):1981-1988
The gene encoding a xylanase from Geobacillus sp. 71 was isolated, cloned, and sequenced. Purification of the Geobacillus sp 7.1 xylanase, XyzGeo71, following overexpression in E. coli produced an enzyme of 47 kDa with an optimum temperature of 75°C. The optimum pH of the enzyme is 8.0, but it is active over
a broad pH range. This protein showed the highest sequence identity (93%) with the xylanase from Geobacillus thermodenitrificans NG80-2. XyzGeo71 contains a catalytic domain that belongs to the glycoside hydrolase family 10 (GH10). XyzGeo71 exhibited
good pH stability, remaining stable after treatment with buffers ranging from pH 7.0 to 11.0 for 6 h. Its activity was partially
inhibited by Al3+ and Cu2+ but strongly inhibited by Hg2+. The enzyme follows Michaelis–Menten kinetics, with Km and Vmax values of 0.425 mg xylan/ml and 500 μmol/min.mg, respectively. The enzyme was free from cellulase activity and degraded xylan
in an endo fashion. The action of the enzyme on oat spelt xylan produced xylobiose and xylotetrose. 相似文献
15.
Effects of aromatic compounds on hemicellulose-degrading enzymes in Aspergillus japonicus 总被引:1,自引:0,他引:1
Sharma A Milstein O Vered Y Gressel J Flowers HM 《Biotechnology and bioengineering》1985,27(8):1095-1101
Aspergillus japonicus was grown in the presence of various aromatic compounds at 0.1 and 1 mg/mL, and extracellular xylanase and arabanase activities were measured. Some of the aromatic compounds tested, especially at the higher concentration, suppressed the appearance of hemicellulase activities, expressed as xylanase or arabanase. Vanillin at 1 mg/mL in the presence of either xylan or araban completely suppressed growth, and guaiacol and p-coumaric acid markedly inhibited the growth of A. japonicus. The effects of the aromatic compounds on the activity of crude enzyme preparations were also ascertained. In vitro arabanase activity was affected more than xylanase activity. 相似文献
16.
Jacob Sonne-Hansen Indra M. Mathrani Birgitte K. Ahring 《Applied microbiology and biotechnology》1993,38(4):537-541
Anaerobic enrichment cultures inoculated with neutral and alkaline (pH 7.0–9.0) sediment and biomat samples from hot-springs in Hveragerdi and Fluir, Iceland, were screened for growth on beech xylan from pH 8.0 to 10.0 at 68° C: no growth occured in cultures above pH 8.4. Five anaerobic xylanolytic bacteria were isolated from enrichment cultures at pH 8.4; all five microbes were Gram-positive rods with terminal spores, and produced CO2, H2, acetate, lactate and ethanol from xylan and xylose. One of the isolates, strain A2, grew from 50 to 75° C, with optimum growth near 68° C, and from pH 5.2 to 9.0 with an optimum between 6.8 and 7.4. Taxonomically, strain A2 was most similar to Clostridium thermohydrosulfuricum. At pH 7.0, the supernatant xylanases of strain A2 had a temperature range from 50 to 78° C with an optimum between 68 and 78° C. At 68° C, xylanase activity occurred from pH 4.9 to 9.1, with an optimum from pH 5.0 to 6.6. At pH 7.0 and 68° C, the K
m of the supernatant xylanases was 2.75 g xylan/l and the V
max was 2.65 × 10–6 kat/l culture supernatant. When grown on xylose, xylanase production was as high as when grown on xylan.
Correspondence to: B. K. Ahring 相似文献
17.
Expression of recombinant Bacillus licheniformis xylanase A in Pichia pastoris and xylooligosaccharides released from xylans by it 总被引:1,自引:0,他引:1
The mature peptide of Bacillus licheniformis xylanase A (BlxA) was successfully expressed in Pichia pastoris under the control of AOX1 promoter. After 96-h 0.25% methanol induction, the activity of recombinant B. licheniformis xylanase A (reBlxA) in culture supernatant was 122.9 U/mg. Enzymatic properties assays showed that the optimum temperature and pH for reBlxA were 60 degrees C and pH 6.0, respectively. When treated at 70 degrees C, pH 6.0 for 2 min, the residual activities of the reBlxA were 76%. Over 80% of reBlxA activity was retained after treatment of the enzyme by preincubation over a pH range of 5.0-9.0 for 1h at 25 degrees C. High performance liquid chromatography (HPLC) analysis revealed that xylotriose (X3) was the main hydrolysis product released from birchwood xylan and wheat bran insoluble xylan by reBlxA. The mode of action studies showed that reBlxA was an endo-acting xylanase and xylobiose (X2), xylotriose, xylotetraose (X4), xylopentaose (X5), and xylohexaose (X6) could be hydrolyzed by it. This is the first report on the expression of reBlxA in yeast and on determining and quantifying the hydrolysis products released from xylans by reBlxA. 相似文献
18.
M Saleem F Aslam MS Akhtar M Tariq MI Rajoka 《World journal of microbiology & biotechnology》2012,28(2):513-522
Delignification efficacy of xylanases to facilitate the consequent chemical bleaching of Kraft pulps has been studied widely.
In this work, an alkaline and thermally stable cellulase-less xylanase, derived from a xylanolytic Bacillus subtilis, has been purified by a combination of gel filtration and Q-Sepharose chromatography to its homogeneity. Molecular weight
of the purified xylanase was 61 kDa by SDS–PAGE. The purified enzyme revealed an optimum assay temperature and pH of 60°C
and 8.0, respectively. Xylanase was active in the pH range of 6.0–9.0 and stable up to 70°C. Divalent ions like Ca2+, Mg2+ and Zn2+ enhanced xylanase activity, whereas Hg2+, Fe2+, and Cu2+ were inhibitory to xylanase at 2 mM concentration. It showed K
m
and V
max
values of 9.5 mg/ml and 53.6 μmol/ml/min, respectively, using birchwood xylan as a substrate. Xylanase exhibited higher values
of turn over number (K
cat) and catalytic efficiency (K
cat/K
m) with birchwood xylan than oat spelt xylan. Bleach-boosting enzyme activity at 30 U/g dry pulp displayed the optimum bio-delignification
of Kraft pulp resulting in 26.5% reduction in kappa number and 18.5% ISO induction in brightness at 55°C after 3 h treatment.
The same treatment improved the pulp properties including tensile strength and burst index, demonstrating its potential application
in pre-bleaching of Kraft pulp. 相似文献
19.
Jia Ouyang Shen Wang Yan Wang Xin Li Mu Chen Qiang Yong Shiyuan Yu 《World journal of microbiology & biotechnology》2011,27(4):751-758
The purpose of this study was to produce a Trichoderma reesei xylanase (XYN2) in Pichia pastoris and to test its potential application for pulp bleaching. The recombinant xylanase was purified by a two-step process of
ultrafiltration and gel filtration chromatography. The molecular mass of the recombinant enzyme was 21 and 25 kDa by SDS–PAGE
analysis, due to different glycosylation of the native protein. The optimum pH and temperature of the recombinant XYN2 was
5.0 and 50 °C. Enzyme activity was stable at 50 °C and at pH 5.0–7.0. The bleaching ability of the recombinant xylanase was
also studied at 50 °C and pH 6.0, using wheat straw pulp. Biobleaching of the xylanase produced chlorine dioxide savings of
up to 60%, while retaining brightness at the control level and led to a lower kappa number and small enhancements in tensile,
burst and tear strength of pulp fibers. 相似文献
20.
V W Yang Z Zhuang G Elegir T W Jeffries 《Journal of industrial microbiology & biotechnology》1995,15(5):434-441
ABacillus sp (V1-4) was isolated from hardwood kraft pulp. It was capable of growing in diluted kraft black liquor at pH 11.5 and produced 49 IU (mol xylose min–1 ml–1) of xylanase when cultivated in alkaline medium at pH 9. Maximal enzyme activity was obtained by cultivation in a defined alkaline medium with 2% birchwood xylan and 1% corn steep liquor at pH 9, but high enzyme production was also obtained on wheat bran. The apparent pH optimum of the enzyme varied with the pH used for cultivation and the buffer system employed for enzyme assay. With cultivation at pH 10 and assays performed in glycine buffer, maximal activity was observed at pH 8.5; with phosphate buffer, maximal activity was between pH 6 and 7. The xylanase temperature optimum (at pH 7.0) was 55°C. In the absence of substrate, at pH 9.0, the enzyme was stable at 50°C for at least 30 min. Elecrophoretic analysis of the crude preparation showed one predominant xylanase with an alkaline pl. Biobleaching studies showed that the enzyme would brighten both hardwood and softwood kraft pulp and release chromophores at pH 7 and 9. Because kraft pulps are alkaline, this enzyme could be used for prebleaching with minimal pH adjustment. 相似文献