• Journal of Microbiology and Biotechnology
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• 제23권6호
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• pp.794-801
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• 2013

This paper reports the production and characterization of crude xylanase from the newly isolated Humicola sp. Ly01. The highest (41.8 U/ml) production of the crude xylanase was obtained under the optimized conditions (w/v): 0.5% wheat bran, 0.2% $KH_2PO_4$, and 0.5% peptone; initial pH 7.0; incubation time 72 h; $30^{\circ}C$; and 150 rpm. A considerable amount of the crude xylanase was induced using hulless barley bran or soybean meal as the carbon source, but a small amount of the enzyme was produced when supplementary urea was used as the nitrogen source to wheat bran. The crude xylanase showed apparent optimal cellulase-free xylanase activity at $60^{\circ}C$ and pH 6.0, more than 71.8% of the maximum xylanase activity in 3.0-30.0% (v/v) ethanol and more than 82.3% of the initial xylanase activity after incubation in 3.0-30.0% (v/v) ethanol at $30^{\circ}C$ for 2 h. The crude xylanase was moderately resistant to both acid and neutral protease digestion, and released 7.9 and 10.9 ${\mu}mol/ml$ reducing sugar from xylan in the simulated gastric and intestinal fluids, respectively. The xylooligosaccharides were the main products of the hydrolysis of xylan by the crude xylanase. These properties suggested the potential of the crude enzyme for being applied in the animal feed industry, xylooligosaccharides production, and high-alcohol conditions such as ethanol production and brewing.

• Journal of Microbiology and Biotechnology
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• 제27권10호
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• pp.1783-1789
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• 2017

Thermostability is an important property of xylanase because high temperature is required for its applications, such as wood pulp bleaching, baking, and animal feedstuff processing. In this study, XynB from Thermobacillus composti, a moderately thermophilic gram-negative bacterium, was modified via site-directed mutagenesis (based on its 3D structure) to obtain thermostable xylanase, and the properties of this enzyme were analyzed. Results revealed that the half-life of xylanase at $65^{\circ}C$ increased from 10 to 50 min after a disulfide bridge was introduced between the ${\alpha}$-helix and its adjacent ${\beta}$-sheet at S98 and N145. Further mutation at the side of A153E named XynB-CE in the C-terminal of this ${\alpha}$-helix enhanced the half-life of xylanase for 60 min at $65^{\circ}C$. Therefore, the mutant may be utilized for industrial applications.

• 미생물학회지
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• 제42권1호
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• pp.67-72
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• 2006

클로닝된 Bacillus circulans ATCC21367 유래 cellulolytic xylanase 유전자(bglBC2)의 염기서열을 결정 분석하였다. 본 유전자는 1,224 bp의 407개 아미노산을 암호하는 open reading frame (ORF)으로 구성되어 있었으며 염기서열로부터 산출된 유전자의 분자량은 45 kDa으로 효소의 SDS-PAGE로부터 측정된 분자량과 일치하였다. ATG 개시 코돈의 9bp 위쪽에 Shine-Dalgarno (SD) 서열로 추정되는 5'-AAAGGAG-3' 서열이 확인되었고 그 상단에 promoter로 추정되는 -35 서열(TTTACA)과 -10 서열(TATACT)이 위치하고 있었으며, 이는 B. subtilis promoter consensus sequence와 유사하였다. 한편, 이 효소의 아미노산 서열은 이미 보고된 B. circulans KSM-N257의 alkaline $endo-\beta-1,4-glucanase$와는 97%, B. circulans WL-12의 $endo-\beta-1,3-1,4-glucanase$와는 75%, Bacillus sp. KSM-330의 $endo-\beta-1,4-glucanase$ (cellulase)와는 45%의 유사성을 나타내었다. 또한 bglBCS 염기서 열의 정보를 GenBank에 등록하였으며 등록번호는 Ar269256이다.

• Mycobiology
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• 제39권2호
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• pp.121-124
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• 2011

The cDNA of endo-1,$4-{\beta}-xylanaseA$, isolated from Phaenerocheate chrysosporium was expressed in Pichia pastoris. Using either the intrinsic leader peptide of XynA or the ${\alpha}$-factor signal peptide of Saccharomyces cerevisiae, xylanaseA is efficiently secreted into the medium at maximum concentrations of 1,946 U/L and 2,496 U/L, respectively.

• 생명과학회지
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• 제17권4호
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• pp.568-574
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• 2007

리그닌 분해 세균인 Pseudomonas sp. LG2는 lignocellulose 기질을 분해하여 APPL 화합물을 생성하는 균주이다. 이 균주를 BSG(brewer's spent grain)가 함유된 배지에서 배양한 배양액에서 APPL 화합물을 확인하였다. 세포외 조효소들의 유도에 관한 여러 가지 탄소원의 영향을 조사한 결과 glucose 배지에서는 xylanase의 효소활성만 확인 되었고 xylose, arabinose에서 배양한 조효소에서는 FAE 및 xylanase의 효소활성이 없었다. Oat spelt xylan, HBSG I(hydrolyzed brewer's spent grain I), HBSG II(hydrolyzed brewer's spent grain II) 및 AFBSG(autoclaved fraction from brewer's spent grain)를 탄소원으로 배양한 조효소에서는 FAE 및 xylanase의 효소활성이 확인됐다. Pseudomonas sp. LG2를 oat spelt xylan, HBSG I, HBSG II 및 AFBSG를 탄소원으로 사용하여 14일 동안 배양하면서 배양기간에 따른 세포외 효소들의 FAE와 xylanase 활성을 조사하였다. Xylanase의 최고 활성은 xylan을 탄소원으로 6일간 배양 했을때 5.3 U/mg으로 가장 높았으며, FAE의 최고 활성은 AFBSG를 탄소원으로 배양했을 때 배양 8일째 15.4 mU/mg으로 가장 높았다. Oat spelt xylan, HBSG I, HBSG II 및 AFBSG를 탄소원으로 사용하여 배양한 배지에 분리된 ferulic acid가 확인되었다. 세포외 효소의 FAE 활성은 methyl ferulic acid, methyl caffeic acid, methyl p-coumaric acid에 대해 esterase의 활성을 보였으나, methyl sinapinic acid, methyl vanillic acid 및 methyl gallic acid에 대해서는 esterase의 활성이 없었다.

• Journal of Microbiology and Biotechnology
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• 제19권12호
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• pp.1514-1519
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• 2009

A gene encoding the xylanase of Bacillus subtilis AMX-4 isolated from soil was cloned into Escherichia coli and the gene product was purified from the cell-free extract of the recombinant strain. The gene, designated xylA, consisted of 639 nucleotides encoding a polypeptide of 213 residues. The deduced amino acid sequence was highly homologous to those of xylanases belonging to glycosyl hydrolase family 11. The molecular mass of the purified xylanase was 23 kDa as estimated by SDS-PAGE. The enzyme had a pH optimum of 6.0-7.0 and a temperature optimum of $50-55^{\circ}C$. Xylanase activity was significantly inhibited by 5 mM $Cu^{2+}$ and 5 mM $Mn^{2+}$, and noticeably enhanced by 5 mM $Fe^{2+}$. The enzyme was active on xylans including arabinoxylan, birchwood xylan, and oat spelt xylan, but it did not exhibit activity toward carboxymethylcellulose or p-nitrophenyl-$\beta$-xylopyranoside. The predominant products resulting from xylan and xylooligosaccharide hydrolysis were xylobiose and xylotriose. The enzyme could hydrolyze xylooligosaccharides larger than xylotriose.

• Asian-Australasian Journal of Animal Sciences
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• 제24권9호
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• pp.1282-1287
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• 2011

The objective of this study was to assess the effect of xylanase on net energy for production, performance, nutrient digestion and gut microflora of broilers fed corn/soy-based diet. Eighty-four day-old male broiler chicks were allocated to two groups receiving two treatments, respectively. Each treatment had six replicate cages with seven broilers per cage. The diets were based on corn and soybean. The treatments were: i) basal diet reduced in apparent metabolizable energy (-0.63 MJ/kg compared to commercial diet specifications); ii) basal diet supplemented xylanase at 4,000 u/kg feed. The experiment used the auto-control, open circuit respiration calorimetry apparatus to examine the heat production and net energy for production. The results revealed that xylanase supplementation did not affect growth performance and diet AME value, but increased $NE_p$ value by 18.2% (p<0.05) and decreased daily heat production per $kg^{0.75}$ by 31.7% (p<0.05). There was no effect (p>0.05) of xylanase supplementation on the ileal digestibility of N and hemicelluloses, but the ileum digestibility of energy was increased by 2% by xylanase supplementation (p<0.05). Xylanase supplementation increased (p<0.05) the count of lactobacillus and bifidobacterial in the caecum.

• Journal of Microbiology and Biotechnology
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• 제20권2호
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• pp.254-264
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• 2010

To obtain an efficient natural lignocellulolytic complex enzyme, we screened an efficient lignocellulose-degrading composite microbial system (XDC-2) from composted agricultural and animal wastes amended soil following a long-term directed acclimation. Not only could the XDC-2 degrade natural lignocelluloses, but it could also secrete extracellular xylanase efficiently in liquid culture under static conditions at room temperature. The XDC-2 degraded rice straw by 60.3% after fermentation for 15 days. Hemicelluloses were decomposed effectively, whereas the extracellular xylanase activity was dominant with an activity of 8.357 U/ml on day 6 of the fermentation period. The extracellular crude enzyme noticeably hydrolyzed natural lignocelluloses. The optimum temperature and pH for the xylanase activity were $40^{\circ}C$ and 6.0. However, the xylanase was activated in a wide pH range of 3.0-10.0, and retained more than 80% of its activity at $25-35^{\circ}C$ and pH 5.0-8.0 after three days of incubation in liquid culture under static conditions. PCR-DGGE analysis of successive subcultures indicated that the XDC-2 was structurally stable over long-term restricted and directed cultivation. Analysis of the 168 rRNA gene clone library showed that the XDC-2 was mainly composed of mesophilic bacteria related to the genera Clostridium, Bacteroides, Alcaligenes, Pseudomonas, etc. Our results offer a new approach to exploring efficient lignocellulolytic enzymes by constructing a high-performance composite microbial system with synergistic complex enzymes.

• Journal of Microbiology and Biotechnology
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• 제13권1호
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• pp.1-8
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• 2003

Strain FJI, a filamentous fungus isolated from rotten wood, showed high ability to hydrolyze cellulosic materials. To identify the strain FJI, ITS sequencing analysis and morphological observation were performed. The strain FJI was identified as Trichoderma harzianum. The strain produced a large amount of CMCase, xylanase, ${\beta}-glucosidase$, and avicelase. Optimal culture conditions for the production of the enzymes, such as pH, temperature, and inoculation concentration, were initial pH 6.0-7.0,$25-30^{\circ}C$, and $10^4$ ea-spores/ml in Mandel's medium, respectively. T.hanzianum FJI utilized various cellulosic materials and organic nitrogen sources to produce cellulases and xylanase, and also considerably a crystalline and/or insoluble material like Avicel and rice straw. The highest levels of CMCase and xylanase were 41.2 and 65.6 U/ml in 7 days of cultivation using 2.5% of carbon source (Avicel+CMC) and 0.5% of nitrogen source (peptone), respectively.

• 한국미생물·생명공학회지
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• 제41권3호
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• pp.263-271
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• 2013

균주 HX-1은 토양샘플로부터 분리된 자일라네이즈 생산 미생물로서 16S rRNA 유전자 염기서열 분석과 이를 이용한 phylogenetic tree 제작을 통하여 Paenibacillus 속의 한 종으로 동정되었다. 그러나 HX-1 균주가 계통발생적 연관관계가 높은 기존에 알려진 표준군주들과는 상당히 다른 생리적-생화학적 특성을 나타내는 사실로부터 HX-1이 신아종일 것으로 판단하고, Paenibacillus sp. HX-1으로 명명하였다. 균주 HX-1로부터의 자일라네이즈 생산을 증가시키는 배지조건을 탐색하여 최적화된 TNX 배지(1% bacto tryptone, 0.7% 자일란, 1% NaCl; pH 7.0)에서 약 7.4배에 달하는 자일라네이즈 생산량의 증가가 가능하였다. 균주 HX-1이 분비하는 자일라네이즈는 pH 7.0과 $45^{\circ}C$에서 최적의 효소활성을 나타냈으며, beechwood 자일란을 기질로 하는 효소반응으로부터 xylobiose를 최종산물로 생산하는 endo-${\beta}$-1,4-xylanase임을 확인하였다. 본 연구로부터 동정된 Paenibacillus sp. HX-1은 다양한 산업에 응용이 가능한 새로운 자일라네이즈를 제공할 수 있는 중요한 균으로 사료된다.