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1.
Jianshe Wang Yingguo Bai Pengjun Shi Huiying Luo Huoqing Huang Jun Yin Bin Yao 《World journal of microbiology & biotechnology》2011,27(2):207-213
A xylanase gene, xynA4-2, was obtained from the genome sequence of thermoacidophilic Alicyclobacillus sp. A4 and expressed in Escherichia coli BL21 (DE3). xynA4-2 encodes a mature protein of 411 residues with a calculated molecular weight of 46.8 kDa. Based on the amino acid sequence
similarities (highest identity of 61%), the enzyme was confined into glycoside hydrolase family 10. The purified recombinant
XynA4-2 exhibited maximum activity at pH 6.2 and 55°C. The enzyme was stable over a broad pH range, retaining more than 90%
of the original activity at pH 5.8–12.0, 37°C for 1 h. The substrate specificity of XynA4-2 was relatively narrow, exhibiting
100, 93, and 35% of the relative activity towards birchwood xylan, oat spelt xylan, and wheat arabinoxylan, respectively.
Supplementation of XynA4-2 to mash caused the reduction of mash filtration rate (5.6%) and viscosity (4.0%). When combined
with the commercial glucanase from Sunson, higher reduction was detected in the filtration rate (12.0%) and viscosity (17.2%).
These favorable properties make XynA4-2 a good candidate in the brewing industry. 相似文献
2.
Junpei Zhou Pengjun Shi Rui Zhang Huoqing Huang Kun Meng Peilong Yang Bin Yao 《Journal of industrial microbiology & biotechnology》2011,38(4):523-530
A pH-stable and protease-resistant xylanase (XynB119) was identified from Streptomyces sp. TN119, a strain isolated from the gut luminal contents of longhorned beetle (Batocera horsfieldi) larvae. Using the GC TAIL-PCR method, the 1,026-bp coding gene (xynB119) with 67.3% GC content was successfully cloned and expressed in Escherichia coli. It encodes a 341-residue polypeptide with a calculated molecular mass of 35.9 kDa, including a putative 41-residue signal
peptide, a catalytic domain of glycosyl hydrolase (GH) family 11, a short Gly/Pro-rich linker, and a family 2 cellulose-binding
domain (CBM 2). The deduced amino acid sequence is most similar to (61.9% identity) an endo-1,4-β-xylanase from Streptomyces thermoviolaceus OPC-520. Purified recombinant XynB119 exhibited peak activity at 50°C and pH 7.0, remained stable over a broad pH range (retaining >70%
activity after incubation at pH 1.0–11.0 for 1 h at 37°C without substrate), had strong protease resistance (retaining >90%
activity after proteolytic treatment at 37°C for 1 h) and SDS resistance (at 100 mM). These properties make XynB119 promising
for application in the feed industry and valuable for basic research. Compared to r-XynB119, the r-XynB119 derivative without
CBM 2 and linker region (r-XynB119d) exhibited a decreased pH stability of >25% at extreme pHs (pH 1.0–3.0 and pH 11.0–12.0). 相似文献
3.
Huiying Luo Jiang Li Jun Yang Hui Wang Yuhui Yang Huoqing Huang Pengjun Shi Tiezheng Yuan Yunliu Fan Bin Yao 《Extremophiles : life under extreme conditions》2009,13(5):849-857
A complete gene, xyl10C, encoding a thermophilic endo-1,4-β-xylanase (XYL10C), was cloned from the acidophilic fungus Bispora sp. MEY-1 and expressed in Pichia pastoris. XYL10C shares highest nucleotide and amino acid sequence identities of 57.3 and 49.7%, respectively, with a putative xylanase
from Aspergillus fumigatus Af293 of glycoside hydrolase family 10. A high expression level in P. pastoris (73,400 U ml−1) was achieved in a 3.7–l fermenter. The purified recombinant XYL10C was thermophilic, exhibiting maximum activity at 85°C,
which is higher than that reported from any fungal xylanase. The enzyme was also highly thermostable, exhibiting ~100% of
the initial activity after incubation at 80°C for 60 min and >87% of activity at 90°C for 10 min. The half lives of XYL10C
at 80 and 85°C were approximately 45 and 3 h, respectively. It had two activity peaks at pH 3.0 and 4.5–5.0 (maximum), respectively,
and was very acid stable, retaining more than 80% activity after incubation at pH 1.5−6.0 for 1 h. The enzyme was resistant
to Co2+, Mn2+, Cr3+ and Ag+. The specific activity of XYL10C for oat spelt xylan was 18,831 U mg−1. It also had wide substrate specificity and produced simple products (65.1% xylose, 25.0% xylobiose and 9.9% xylan polymer)
from oat spelt xylan. 相似文献
4.
Jianshe Wang Yingguo Bai Peilong Yang Pengjun Shi Huiying Luo Kun Meng Huoqing Huang Jun Yin Bin Yao 《World journal of microbiology & biotechnology》2010,26(5):917-924
A xylanase gene, xynE2, was cloned from thermoalkaline Anoxybacillus sp. E2 and was expressed in Escherichia coli BL21 (DE3). The gene consisted of 987 bp and encoded a 328-residue xylanase with a calculated molecular weight of 38.8 kDa.
On the basis of amino acid sequence similarities, this enzyme was assigned as a member of glycoside hydrolase family 10. Purified
recombinant XynE2 showed maximal activity at pH 7.8 and 65°C, and was thermostable at 60°C. The enzyme was highly active and
stable over a broad pH range, showing more than 90% of maximal activity at pH 6.6–pH 8.6 and retaining more than 80% of activity
at pH 4.6–pH 12.0, 37°C for 1 h, respectively. These favorable properties make XynE2 a good candidate in the pulp and paper
industries. This is the first report on gene cloning, expression and characterization of a xylanase from the genus Anoxybacillus. 相似文献
5.
An endoxylanase gene, xynA, was cloned from Bacillus pumilus ARA and expressed in Escherichia coli. The open reading frame of the xynA gene was 687 bp encoding a signal peptide and a mature xylanase with a molecular mass of 23 kDa. The enzyme was categorized
as a glycosyl hydrolase family 11 member based on the sequence analysis of the putative catalytic domain. The recombinant
XynA (Bpu XynA) was purified to homogeneity by Ni–NTA and ion exchange chromatography on DEAE–Sepharose FF. The enzyme exhibited highest
activity at pH 6.6 and 50°C. The purified Bpu XynA was stable for at least 2 h at 45°C, and retained over 50% residual activity after being incubated at 60°C for 1 h.
The activity of the xylanase was not significantly affected by metal ions and EDTA. The K
m
and K
cat
/K
m
of Bpu XynA for oat-spelt xylan were 5.53 mg/ml and 10.14 ml/mg s at 50°C and pH 6.6. The main product of hydrolysis by Bpu XynA was xylooligosaccharide. The results revealed that the consumption of grass xylan by B. pumilus ARA depended on the synergistic reactions of Bpu XynA and Bpu arabinosidase, and that a typical GH11 xylanase e.g. Tla XynA had capability to remove the side chain of xylan. The properties Bpu XynA make it promising for application in the production of Bifidobacterium growth-promoting factors and in feed industry. 相似文献
6.
Yingguo Bai Jianshe Wang Zhifang Zhang Pengjun Shi Huiying Luo Huoqing Huang Chunliang Luo Bin Yao 《Applied microbiology and biotechnology》2010,87(1):251-259
An endo-β-1,3(4)-glucanase gene, Agl9A, was cloned from Alicyclobacillus sp. A4 and expressed in Pichia pastoris. Its deduced amino acid sequence shared the highest identity (48%) with an endo-β-1,4-glucansae from Alicyclobacillus acidocaldarius that belongs to family 9 of the glycoside hydrolases. The purified recombinant Agl9A exhibited relatively wide substrate
specificity, including lichenan (109%), barley β-glucan (100%), CMC-Na (15.02%), and laminarin (6.19%). The optimal conditions
for Agl9A activity were pH 5.8 and 55°C. The enzyme was stable over a broad pH range (>60% activity retained after 1-h incubation
at pH 3.8–11.2) and at 60°C (>70% activity retained after 1-h incubation). Agl9A was highly resistant to various neutral proteases
(e.g., trypsin, α-chymotrypsin, and collagenase) and Neutrase 0.8L (Novozymes), a protease widely added to the mash. Under
simulated mashing conditions, addition of Agl9A (20 U/ml) or a commercial xylanase (200 U/ml) reduced the filtration rate
(26.71% and 20.21%, respectively) and viscosity (6.12% and 4.78%, respectively); furthermore, combined use of Agl9A (10 U/ml)
and the xylanase (100 U/ml) even more effectively reduced the filtration rate (31.73%) and viscosity (8.79%). These characteristics
indicate that Agl9A is a good candidate to improve glucan degradation in the malting and brewing industry. 相似文献
7.
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
8.
Xiaoshuang Liu Zongqing Huang Xiangnan Zhang Zongze Shao Ziduo Liu 《Extremophiles : life under extreme conditions》2014,18(2):441-450
A new xylanase gene (xynA) from the marine microorganism Zunongwangia profunda was identified to encode 374 amino acid residues. Its product (XynA) showed the highest identity (42.78 %) with a xylanase from Bacillus sp. SN5 among the characterized xylanases. XynA exhibited the highest activity at pH 6.5 and 30 °C, retaining 23 and 38 % of the optimal activity at 0 and 5 °C, respectively. XynA was not only cold active, but also halophilic, and both its activity and thermostability could be significantly increased by NaCl, showing the highest activity (180 % of the activity) at 3 M NaCl and retaining nearly 100 % activity at 5 M NaCl, compared to the absence of NaCl. In the presence of 3 M NaCl, the k cat/K m value of XynA exhibited a 3.41-fold increase for beechwood xylan compared to no added NaCl, and the residual activity of XynA increased from 23 % (no added NaCl) to 58 % after 1 h incubation at 45 °C. This may be the first report concerning a cold-adapted xylanase from a non-halophilic species that displays the highest activity at a NaCl concentration range from 3 to 5 M. The features of cold activity and salt tolerance suggest the potential application of XynA in the food industry and bioethanol production from marine seaweeds. 相似文献
9.
A xylanase gene was PCR-cloned from Thermoanaerobacterium saccharolyticum and expressed in Escherichia coli. The xylanase (XynA) consisted of a signal peptide, glycoside hydrolase family 10 domains, carbohydrate-binding modules,
and surface layer homology domains. It was optimally active at 70–73°C and at pH 5–7. It had enhanced activity with NaCl with
optimal activity at 0.4 M but was tolerant up to 2 M NaCl. The thermostable and salt-tolerant properties of this xylanase
suggest that it may be useful for industrial applications. 相似文献
10.
Zhang F Shi P Bai Y Luo H Yuan T Huang H Yang P Miao L Yao B 《Applied microbiology and biotechnology》2011,89(6):1851-1858
An endo-β-1,4-xylanase gene, designated xyn10G5, was cloned from Phialophora sp. G5 and expressed in Pichia pastoris. The 1,197-bp full-length gene encodes a polypeptide of 399 amino acids consisting of a putative signal peptide at residues
1–20, a family 10 glycoside hydrolase domain, a short Gly/Thr-rich linker and a family 1 carbohydrate-binding module (CBM).
The deduced amino acid sequence of XYN10G5 shares the highest identity (53.4%) with a putative xylanase precursor from Aspergillus terreus NIH2624. The purified recombinant XYN10G5 exhibited the optimal activity at pH 4.0 and 70 °C, remained stable at pH 3.0–9.0
(>70% of the maximal activity), and was highly thermostable at 70 °C (retaining ~90% of the initial activity for 1 h). Substrate
specificity studies have shown that XYN10G5 had the highest activity on soluble wheat arabinoxylan (350.6 U mg−1), and moderate activity to various heteroxylans, and low activity on different types of cellulosic substrates. Under simulated
gastric conditions, XYN10G5 was stable and released more reducing sugars from soluble wheat arabinoxylan; when combined with
a glucanase (CelA4), the viscosity of barley–soybean feed was significantly reduced. These favorable enzymatic properties
make XYN10G5 a good candidate for application in the animal feed industry. 相似文献
11.
P Shi Z Qiu Y Bai T Yuan H Huang X Pan P Yang W Zhang B Yao 《World journal of microbiology & biotechnology》2012,28(2):687-692
A new xylanase gene, xynBM4, was cloned from Streptomyces megasporus DSM 41476 and expressed in Pichia pastoris. The full-length gene consists of 1,443 bp and encodes 480 amino acids including a putative 49-residue signal peptide. The
deduced amino acid sequence of xynBM4 shows the highest identity of 66.3% to the xylanase Xys1L from Streptomyces halstedii JM8. The purified recombinant XYNBM4 had a high specific activity of 350.7 U mg-1 towards soluble wheat arabinoxylan, exhibited optimal activity at pH 6.0 and 57°C, showed broad pH adaptability (>75% of
the maximum activity at pH 2.5–9.0), was resistant to neutral proteases and most chemicals, and produced simple products.
The hydrolysis products of birchwood xylan and corncob xylan were predominantly xylobiose (76.9 and 90.8%, respectively) and
no xylose. These characteristics suggest that XYNBM4 has potential in various applications, especially in the food industry. 相似文献
12.
Sushil Nagar Vijay Kumar Gupta Davender Kumar Lalit Kumar Ramesh Chander Kuhad 《Journal of industrial microbiology & biotechnology》2010,37(1):71-83
This paper reports the production of a cellulase-free and alkali-stable xylanase in high titre from a newly isolated Bacillus pumilus SV-85S using cheap and easily available agro-residue wheat bran. Optimization of fermentation conditions enhanced the enzyme
production to 2995.20 ± 200.00 IU/ml, which was 9.91-fold higher than the activity under unoptimized basal medium (302.2 IU/ml).
Statistical optimization using response-surface methodology was employed to obtain a cumulative effect of peptone, yeast extract,
and potassium nitrate (KNO3) on enzyme production. A 23 central composite design best optimized the nitrogen source at the 0 level for peptone and yeast extract and at the −α level
for KNO3, along with 5.38-fold increase in xylanase activity. Addition of 0.1% tween 80 to the medium increased production by 1.5-fold.
Optimum pH for xylanase was 6.0. The enzyme was 100% stable over the pH range from 5 to 11 for 1 h at 37°C and it lost no
activity, even after 3 h of incubation at pH 7, 8, and 9. Optimum temperature for the enzyme was 50°C, but the enzyme displayed
78% residual activity even at 65°C. The enzyme retained 50% activity after an incubation of 1 h at 60°C. Characteristics of
B. pumilus SV-85S xylanase, including its cellulase-free nature, stability in alkali over a long duration, along with high-level production,
are particularly suited to the paper and pulp industry. 相似文献
13.
Ricardo Sposina Sobral Teixeira Félix Gonçalves Siqueira Marcelo Valle de Souza Edivaldo Ximenes Ferreira Filho Elba Pinto da Silva Bon 《Journal of industrial microbiology & biotechnology》2010,37(10):1041-1051
This study presents data on the production, purification, and properties of a thermostable β-xylanase produced by an Aspergillus awamori 2B.361 U2/1 submerged culture using wheat bran as carbon source. Fractionation of the culture filtrate by membrane ultrafiltration
followed by Sephacryl S-200 and Q-Sepharose chromatography allowed for the isolation of a homogeneous xylanase (PXII-1), which
was 32.87 kDa according to MS analysis. The enzyme-specific activity towards soluble oat spelt xylan, which was found to be
490 IU/mg under optimum reaction conditions (50°C and pH 5.0–5.5), was 17-fold higher than that measured in the culture supernatant.
Xylan reaction products were identified as xylobiose, xylotriose, and xylotetraose. K
m values (mg ml−1) for soluble oat spelt and birchwood xylan were 11.8 and 9.45, respectively. Although PXII-1 showed 85% activity retention
upon incubation at 50°C and pH 5.0 for 20 days, incubation at pH 7.0 resulted in 50% activity loss within 3 days. PXII-1 stability
at pH 7.0 was improved in the presence of 20 mM cysteine, which allowed for 85% activity retention for 25 days. This study
on the production in high yields of a remarkably thermostable xylanase is of significance due to the central role that this
class of biocatalyst shares, along with cellulases, for the much needed enzymatic hydrolysis of biomass. Furthermore, stable
xylanases are important for the manufacture of paper, animal feed, and xylooligosaccharides. 相似文献
14.
The cellulolytic myxobacterium Sorangium cellulosum is able to efficiently degrade many kinds of polysaccharides, but none of the enzymes involved have been characterized. In
this paper, a xylanase gene (xynA) was cloned from S. cellulosum So9733-1 using thermal asymmetric interlaced PCR. The gene is composed of 1,209 bp and has only 52.27% G + C content, which
is much lower than that of most myxobacterial DNA reported (67–72%). Gene xynA encodes a 402 amino acid protein that contains a single catalytic domain belonging to the glycoside hydrolase family 10.
The novel xylanase gene, xynA, was expressed in Escherichia coli BL21 (DE3) and the recombinant protein (r-XynA) was purified by Ni-affinity chromatography. The r-XynA had the optimum temperature
of 30–35°C and exhibited 33.3% activity at 5°C and 13.7% activity at 0°C. Approximately 80% activity was lost after 20-min
pre-incubation at 50°C. These results indicate that r-XynA is a cold-active xylanase with low thermostability. At 30°C, the
K
m values of r-XynA on beechwood xylan, birchwood xylan, and oat spelt xylan were 25.77 ± 4.16, 26.52 ± 4.78, and 38.13 ± 5.35 mg/mL,
respectively. The purified r-XynA displayed optimum activity at pH 7.0. The activity of r-XynA was enhanced by the presence
of Ca2+. The r-XynA hydrolyzed beechwood xylan, birchwood xylan, and xylooligosaccharides (xylotriose, xylotetraose, and xylopentose)
to produce primarily xylose and xylobiose. To our knowledge, this is the first report on the characterization of a xylanase
from S. cellulosum. 相似文献
15.
Novel xylanase (EC 3.2.1.8) is in great demand due to its industrial significance. In this study, we have developed and characterized a novel xylanase-producing yeast strain. This mature xylanase gene xyn11A consists of 870 base pairs and belongs to GH11 family. The gene sequence was optimized and synthesized, and was then cloned into yeast vector pGAPZαA under the control of the constitutive GAP promoter. SDS-PAGE analysis indicates that Xyn11A is extracellularly expressed as a glycosylated protein in P. pastoris. Xyn11A is optimally active at 70 °C and pH 7.4. This xylanase retained more than 90% of its activity after incubation at 50 °C and 60 °C for up to 1 h. Xyn11A is also stable over a wide range of pH (2.0–11.0). Most metal ions tested such as copper (Cu2+) and lead (Pb2+) have little inhibitory effects on Xyn11A. It is also resistant to pepsin and proteinase K digestion, retaining 80% and 90% of its activity after digestion at 37 °C for 1 h, respectively. Those superior properties make Xyn11A a robust xylanase with great potential for industrial use. To the best of our knowledge, this is the first report of xylanase from the fungus Corynascus thermophilus. 相似文献
16.
Facchini FD Vici AC Reis VR Jorge JA Terenzi HF Reis RA Polizeli Mde L 《Bioprocess and biosystems engineering》2011,34(3):347-355
Solid-state fermentation obtained from different and low-cost carbon sources was evaluated to endocellulases and endoxylanases
production by Aspergillus japonicus C03. Regarding the enzymatic production the highest levels were observed at 30 °C, using soy bran added to crushed corncob
or wheat bran added to sugarcane bagasse, humidified with salt solutions, and incubated for 3 days (xylanase) or 6 days (cellulase)
with 70% relative humidity. Peptone improved the xylanase and cellulase activities in 12 and 29%, respectively. The optimum
temperature corresponded to 60 °C and 50–55 °C for xylanase and cellulase, respectively, both having 4.0 as optimum pH. Xylanase
was fully stable up to 40 °C, which is close to the rumen temperature. The enzymes were stable in pH 4.0–7.0. Cu++ and Mn++ increased xylanase and cellulase activities by 10 and 64%, respectively. A. japonicus C03 xylanase was greatly stable in goat rumen fluid for 4 h during in vivo and in vitro experiments. 相似文献
17.
P Prakash SK Jayalakshmi B Prakash M Rubul K Sreeramulu 《World journal of microbiology & biotechnology》2012,28(1):183-192
The alkaliphilic Bacillus halodurans strain PPKS-2 was shown to produce extracellular alkaliphilic, thermostable and halotolerent xylanase. The culture conditions
for xylanase production were optimized with respect to pH, temperature, NaCl and inexpensive agro waste as substrates. Xylanase
yield was enhanced more than four fold in the presence of 1% corn husk and 0.5% peptone or feather hydrolysate at pH 11 and
37°C. Xylanase was purified to 11.8-fold with 8.7% yield by using traditional chromatographic methods whereas the same enzyme
purified to 20-fold with 72% yield by using corn husk as ligand. Its molecular mass was estimated to be 24 kDa by SDS–PAGE.
The xylanase had maximal activity at pH 11 and 70°C. The enzyme was active over broad range, 0–20% sodium chloride. The enzyme
was thermostable retaining 100% of the original activity at 70°C for 3 h. The apparent K
m values for oat spelt xylan and brichwood xylan were 4.1 and 4.4 mg/ml respectively. The deduced internal amino acid sequence
of PPKS-2 xylanase resembled the sequence of β-1,4-endoxylanase, which is member of glycoside hydrolase family 11. 相似文献
18.
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
19.
M. Michelin S. C. Peixoto-Nogueira J. H. A. Betini T. M. da Silva J. A. Jorge H. F. Terenzi M. L. T. M. Polizeli 《Bioprocess and biosystems engineering》2010,33(7):813-821
Aspergillus terricola and Aspergillus ochraceus, isolated from Brazilian soil, were cultivated in Vogel and Adams media supplemented with 20 different carbon sources, at
30 °C, under static conditions, for 120 and 144 h, respectively. High levels of cellulase-free xylanase were produced in birchwood
or oat spelt xylan-media. Wheat bran was the most favorable agricultural residue for xylanase production. Maximum activity
was obtained at 60 °C and pH 6.5 for A. terricola, and 65 °C and pH 5.0 for A. ochraceus. A. terricola xylanase was stable for 1 h at 60 °C and retained 50% activity after 80 min, while A. ochraceus xylanase presented a t
50 of 10 min. The xylanases were stable in an alkali pH range. Biobleaching of 10 U/g dry cellulose pulp resulted in 14.3% delignification
(A. terricola) and 36.4% (A. ochraceus). The brightness was 2.4–3.4% ISO higher than the control. Analysis in SEM showed defibrillation of the microfibrils. Arabinase
traces and β-xylosidase were detected which might act synergistically with xylanase. 相似文献
20.
Swarnima Agnihotri Dharm Dutt C. H. Tyagi Alok Kumar J. S. Upadhyaya 《World journal of microbiology & biotechnology》2010,26(8):1349-1359
Fungi producing xylanases are plentiful but alkali-thermo-tolerant fungi producing cellulase-poor xylanase are rare. Out of
12 fungal strains isolated from various sources, Coprinellus disseminatus SW-1 NTCC 1165 yielded the highest xylanase activity (362.1 IU/ml) with minimal cellulase contamination (0.64 IU/ml). The
solid state fermentation was more effective yielding 88.59% higher xylanase activity than that of submerged fermentation.
An incubation period of 7 days at 37°C and pH 6.4 accelerated the xylanase production up to the maximum level. Among various
inexpensive agro-residues used as carbon source, wheat bran induced the maximum xylanase titres (469.45 IU/ml) while soya
bean meal was the best nitrogen source (478.5 IU/ml). A solid substrate to moisture content ratio of 1:3 was suitable for
xylanase production while xylanase titre was repressed with the addition of glucose and lactose. The xylanase and laccase
activities under optimized conditions were 499.60 and 25.5 IU/ml, respectively along with negligible cellulase contamination
(0.86 IU/ml). Biochemical characterization revealed that optimal xylanase activity was observed at pH 6.4 and temperature
55°C and xylanase is active up to pH 9 (40.33 IU/ml) and temperature 85°C (48.81 IU/ml). SDS–PAGE and zymogram analysis indicated
that molecular weight of alkali-thermo-tolerant xylanase produced by C. disseminatus SW-1 NTCC 1165 was 43 kDa. 相似文献