• Journal of Microbiology and Biotechnology
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• 제14권5호
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• pp.1014-1021
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• 2004

Two thermostable xylanases, designated XynA and XynB, were purified to homogeneity from the culture supernatant of Paenibacillus sp. DG-22 by ion-exchange and gel-filtration chromatography. The molecular masses of xylanases A and B were 20 and 30 kDa, respectively, as determined by SDS-PAGE, and their isoelectric points were 9.1 and 8.9, respectively. Both enzymes had similar pH and temperature optima (pH 5.0-6.5 and $70^{\circ}C$), but their stability at various temperatures differed. Xylanase B was comparatively more stable than xylanase A at higher temperatures. Xylanases A and B differed in their $K_m$ and $V_{max}$ values. XynA had a $K_m$ of 2.0 mg/ml and a $V_{max}$ of 2,553 U/mg, whereas XynB had a K_m$ of 1.2 mg/ml and a $V_{max}$, of 754 U/mg. Both enzymes were endo-acting, as revealed by their hydrolysis product profiles on birchwood xylan, but showed different modes of action. Xylotriose was the major product of XynA activity, whereas XynB produced mainly xylobiose. These enzymes utilized small oligosaccharides such as xylotriose and xylotetraose as substrates, but did not hydrolyzed xylobiose. The amino terminal sequences of XynA and XynB were determined. Xylanase A showed high similarity with low molecular mass xylanases of family 11.

• Journal of Microbiology
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• 제33권2호
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• pp.109-114
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• 1995

Alkalophilic Cephalosporium sp. RYM-202 produced multiple xylanases extracellularly. One of these xylanases was purified to electrophoretical homogeneity by chromatography with DEAE-Sephadex A-50, Sephacryl S-200 HR and Superose 12 HR. The purified xylanase differed from most other microbial xylanases in that it had low-molecular weight and acidic isoelectric point. The molecular weight of the xylanase in that it had low-molecular weight and acidic isoelectric point. The molecular weight of the xylanase was 23 kDa by SDS-polyacrylamide electrophoresis and 24 kDa by gel permeation chromatography, and the isoelectric point was 4.3. The xylanase had the highest activity permentation chromatography, and the isoelectric point was 4.3. The xylanase had the highest activity permeation chromatography, and the isoelectric point was 4.3. The xylanase had the highest activity at pH 8.0 and 50 .deg.C. It was stable over a wide range of pH and retained more than 80% of its original activity after 24 h of incubation even at pH 12. The Km values of this enzyme on birchwood xylan and oat spelts xylan were 2.33 and 3.45 mg/ml, respectively. The complete inhibition of the enzyme of n-bromosuccinimide suggests the involvement of tryptophan in the active site. The sylanase lacked activity towards crystalline cellulose and carboxymethyl cellulose.

• Journal of Microbiology and Biotechnology
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• 제3권3호
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• pp.139-145
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• 1993

The nucleotide sequence of the xylanase gene (xynS) from alkali-tolerant Bacillus sp. YA.14 was determined and analyzed. A 639 base pairs open reading frame for xynS gene was observed and encoded for a protein of 213 amino acids with a molecular weight of 23, 339. S1 nuclease mapping showed that the transcription initiation site of the xynS gene did not exist in the cloned DNA. Ribosome binding site sequence with the free energy of -18.8 Kcal/mol was observed 8 base pairs upstream from the initiation codon, ATG. The proposed signal sequence consisted of 28 amino acids, of which 3 were basic amino acid residues and 21 were hydrophobic amino acid residues. When the amino acid sequences of xylanases were compared, Bacillus sp. YA-14 xylanase showed 48% homology with Bacillus sp. YC-335 xylanase and 96% homology with xylanases from B. subtilis and B. circulans.

• 한국동물학회:학술대회논문집
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• 한국동물학회 1995년도 한국생물과학협회 학술발표대회
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• pp.99-99
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• 1995

No Abstract, See Full Text

• 한국미생물생명공학회소식지:생물산업
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• 제13권1호
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• pp.19-24
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• 2000

• Journal of Microbiology and Biotechnology
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• 제11권3호
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• pp.534-538
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• 2001

The xynA gene encoding an alikali-tolerant endo-1,4-${\beta}$-xylanase (XYN) was cloned from the alkalophilic Bacillus pumilus A-30. The nucleotide sequence of a 974-bp DNA fragment containing the xynA was determined. An ORF of 684 nucleotides that encoded a protein of 228 amino aicds was detected. Asparagine-71 of XYN from B. Pumilus A-30 showed to be highly conservative in alkaline xylanases of family G/11, upon comparing the amino acid sequences of 17 family G/11 xylanases. Site-directed mutation of N71D of the xynA gene resulted in a decrease of 12.4% in the specific acitivity and a significant decline in the enzyme activity in the alkaline pH range.

• BMB Reports
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• 제39권1호
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• pp.105-110
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• 2006

We have screened 766 strains of fungi from the BIOTEC Culture Collection (BCC) for xylanases working in extreme pH and/or high temperature conditions, the so-called extreme xylanases. From a total number of 32 strains producing extreme xylanases, the strain BCC7928, identified by using the internal transcribed spacer (ITS) sequence of rRNA to be a Marasmius sp., was chosen for further characterization because of its high xylanolytic activity at temperature as high as $90^{\circ}C$. The crude enzyme possessed high thermostability and pH stability. Purification of this xylanase was carried out using an anion exchanger followed by hydrophobic interaction chromatography, yielding the enzyme with >90% homogeneity. The molecular mass of the enzyme was approximately 40 kDa. The purified enzyme retained broad working pH range of 4-8 and optimal temperature of $90^{\circ}C$. When using xylan from birchwood as substrate, it exhibits $K_m$ and $V_{max}$ values of $2.6{\pm}0.6\;mg/ml$ and $428{\pm}26\;U/mg$, respectively. The enzyme rapidly hydrolysed xylans from birchwood, beechwood, and exhibited lower activity on xylan from wheatbran, or celluloses from carboxymethylcellulose and Avicel. The purified enzyme was highly stable at temperature ranges from 50 to $70^{\circ}C$. It retained 84% of its maximal activity after incubation in standard buffer containing 1% xylan substrate at $70^{\circ}C$ for 3 h. This thermostable xylanase should therefore be useful for several industrial applications, such as agricultural, food and biofuel.

• 한국미생물·생명공학회지
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• 제29권4호
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• pp.221-226
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• 2001

S. thermocyaneoviolaceus 가 생산하는 xylanases를 황산암모늄에 의한 염석 및 투석에 의해 조제한 효소를 이용하여 자일로오리고당을 생산하기 위한 최적 반응조건을 설정하였다. 자알로올리고당 생산을 위한 기질로는 oat spelt xyaln 보다 birchwood xylan을 사용하는 것이 더 좋았다. 반응온도의 영향을 조사한 결과 효소의 열 안정성과 자일로올리고당의 생선량 등을 고려할 때 $60^{\circ}C$에서 반응하는 것이 가장 좋았다 효소의 농도 pH의 영향및 반응시간의 영향을 조사한 결과 10 unit/ml xylanases를 첨가하여 pH 6.0에서 12 시간 반응시켰을 때 가장 많은 양의 자일로올리고당을 생산할 수 있었다. 이러한 최적 반응 조건에서 10% birchwood xylan 으로 부터 생산할 수 있는 자일로올리고당의 조성는 X2, X3, X4, X5 및 X6가 각각 20.1, 8.9 , 4.5, 16.2 및 9.1 g/I 이었으며 이때 생산되는 총 자일로올리고당 (X2~X6)은 58.8 g/I 이었다.

• 한국미생물·생명공학회지
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• 제14권6호
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• pp.447-453
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• 1986

고온, 알칼리성 Bacillus K17이 생성하는 extracellular xylanase를 각종 resin으로 정제하여 비흡착 분획에서 xylanase I과 흡착 분획에서 xylanase II를 분리정제하였고, SDS-Polyacrylamide gel electrophoresis에 의하여 분자량을 측정하였던바 xylanase I은 23,000, xylanase II는 47,000으로 추정되었다. Xylanase I 및 II는 최적온도, 최적 pH, 열 안정성, pH 안정성, 기질 친화력에서 차이가 있었으며 Cu$^{++}$, Ag$^+$, Fe$^{++}$, Hg$^{++}$에 의해 다같이 저해되었다. Xylanase I은 xylan을 Xylobiose, xylotriose, xylotetraose로 분해시키며 그 분해율이 22%로 나타났다. 그리고 xylanase II xylose, xylobiose, xylotriose로 분해시키며 그 분해율이 30%이었다. 효소적 분석은 효소가 갖는 기질특이성으로 인해 다성분계의 분석재료로부터 측정한 성분만을 정량 가능하므로 생체성분의 분석에 널리 활용되고 있다.

• Journal of Microbiology and Biotechnology
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• 제22권4호
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• pp.462-469
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• 2012

A metagenomic fosmid library was constructed from genomic DNA isolated from the microbial community residing in hindguts of a wood-feeding higher termite (Microcerotermes sp.) collected in Thailand. The library was screened for clones expressing lignocellulolytic activities. Fourteen independent active clones (2 cellulases and 12 xylanases) were obtained by functional screening at pH 10.0. Analysis of shotgun-cloning and pyrosequencing data revealed six ORFs, which shared less than 59% identity and 73% similarity of their amino acid sequences with known cellulases and xylanases. Conserved domain analysis of these ORFs revealed a cellulase belonging to the glycoside hydrolase family 5, whereas the other five xylanases showed significant identity to diverse families including families 8, 10, and 11. Interestingly, one fosmid clone was isolated carrying three contiguous xylanase genes that may comprise a xylanosome operon. The enzymes with the highest activities at alkaline pH from the initial activity screening were characterized biochemically. These enzymes showed a broad range of enzyme activities from pH 5.0 to 10.0, with pH optimal of 8.0 retaining more than 70% of their respective activities at pH 9.0. The optimal temperatures of these enzymes ranged from $50^{\circ}C$ to $55^{\circ}C$. This study provides evidence for the diversity and function of lignocellulose-degrading enzymes in the termite gut microbial community, which could be of potential use for industrial processes such as pulp biobleaching and denim biostoning.