• Journal of Microbiology and Biotechnology
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• 제4권2호
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• pp.102-107
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• 1994

The $\beta$-1,4-endoglucanase gene from Actinomyces sp. 40 was cloned into Escherichia coli DH5$\alpha$ with pUC19. Chromosomal DNA from Actinomyces sp. 40 was cleaved with the restriction enzyme Sau3AI and ligated into pUC19 for the transformation of Escherichia coli DH5$\alpha$. Positive clones of $\beta$-1,4-endoglucanase gene were detected as the clear zones on a medium supplemented with carboxymethylcellulose (CMC). This transformant possessed a single plasmid, designated pDS1, which contained the vector DNA and a 3.5 kilobase (kb) Sau3AI insertion fragment encoding endoglucanase. The size of the cloned fragment was reduced to 2.0 kb. The endoglucanase activity produced by the E. coli DH5$\alpha$ (pDS6) was higher than that of Actinomyces sp. 40 strain. The optimum pH and temperature of the cloned enzyme were pH 4.0$\sim$5.0 and 55$^{\circ}C$, respectively. The cloned enzyme was stable at 55$^{\circ}C$ or below and in buffer ranging from pH 4.0 to 7.0. The enzyme degraded CMC but did not degrade xylan, cellobiose, and methyl-umbelliferylcellobiopyranoside (MUC).

• Asian-Australasian Journal of Animal Sciences
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• 제7권3호
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• pp.373-382
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• 1994

A bacterial strain No. 40, which produced extracellular endoglucanase, was isolated from the rumen of Korean native goals and identified to be a genus of Actinomyces sp. The optimum conditions for endoglucanase production in PY-CMC medium were initial pH of 7.0 and 4 days of cultivation at $39^{\circ}C$. When localization of endoglucanase activity of Actinomyces sp. was determined, 68% of the enzyme activity was found in the extracellular fraction, 11% of the activity was detected in the periplasmic space and the remaining activity was in the intracellular and cell-bound fractions. The maximal endoglucanase activity was observed at pH 5.0 and it was most s table at pH 5.0. The optimum temperature of this enzyme activity was $55^{\circ}C$, but enzyme activity was gradually lost at temperature above $60^{\circ}C$. The crude enzyme was activated by addition of 10 mM cysteine and 10 mM DTT. But it was inhibited by addition of 10 mM $Cu^{{+}{+}}$ and $Fe^{{+}{+}}$. This crude enzyme could digest carboxymethylcellulose (CMC), and degrade xylan, avicel, pNPG, and pNPC to a less extent.

• Journal of Animal Science and Technology
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• 제45권4호
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• pp.659-666
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• 2003

다양한 미생물들로부터 유래한 cellulase 중에서, 특히 장내 단백질 가수분해효소에 안정한 Clostridium thermocellum 균주 유래의 endoglucanase를 선별하였다. 그 후 그 유전자의 자체 프로모터에 의해 발현되는 재조합 Lactobacillus용 발현벡터를 구축하였고, 그 발현벡터를 pSD1이라 명명하였다. 이 발현벡터를 L. bulgaricus와 L. plantarum 균주에 각각 전기천공법을 이용하여 형질전환시키는데 성공하였으며 그 재조합 균주들로부터 endoglucanase 효소역가를 조사한 결과 각각 배지 상층액에서 0.12, 0.144 U/ml로 조사되었다. 한편 이들 균주들의 생균제로 갖추어야할 특성인 내산성, 내담즙성 및 항생제내성 여부를 조사한 결과, 이들 균주들은 모두 pH3과 같은 산성 조건하에서도 안정하였으며, 내담즙성에 있어서는 특히 L. plantarum 균주의 경우 0.3, 1% 의 oxgall에서도 안정하였다. 또한 항생제 내성을 조사한 결과 두 균주 모두 amikacin, gentamicin, kanamycin, colistin에 저항성이 높은 것으로 나타났다.

• 한국미생물·생명공학회지
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• 제33권4호
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• pp.267-273
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• 2005

효과적이고 강력한 효모 생균제를 개발하기 위해, Saccharomyces cerevisiae 균주들 에서 섬유소 분해효소를 유전공학적 방법으로 생산하였다. Thermomonospora fusca 유래의 exoglucanase유전자(E3)를 구성적 ADHl promoter 하류에 subcloning하여 구성적 발현계인 plasmid pVT-TE태(8.8 kb)를 제작하였고, 이를 S. cerevisiae 숙주세포 SEY2102에 형질전환 시켜, YPD에서 배양한 결과, 총 생산된 exoglucanase의 avicelase 활성은 190 unit/l에 도달하였고, 분비효율은 $50\%$, plasmid 안정성은 $91\%$로 나타났다. 재조합 exoglucanase의 양은 Clostridium endoglucanase(CelA)와 Trichoderma endoglucanase(C4) 보다 더 높은 avicel 결합능을 나타냈다. 각 혼합비에 대한 avicel분해에 대한 상승효과와 당 생성은, E3와 CelA의 흔합비가 4:1일 때 가장 좋은 포도당 생성이 관찰되었으며 , endoglucanase(CelA)와 exoglucanase(E3)의 혼합물은, 단독으로 처리했을 때보다, 포도당의 생산은 2.5배 향상되었고, avicelase활성은 결과적으로 3.2배 증가하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제27권7호
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• pp.946-950
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• 2014

Bacillus licheniformis was grown in minimal nutrient medium containing 1% (w/v) of distillers dried grain with soluble (DDGS), palm kernel meal (PKM), wheat bran (WB) or copra meal (CM), and the enzyme activity of endoglucanase, ${\beta}$-glucosidase, xylanase and reducing sugars was measured to investigate a possibility of using cost-effective agricultural residues in producing cellulolytic and hemicellulolytic enzymes. The CM gave the highest endoglucanase activity of 0.68 units/mL among added substrates at 48 h. CM yielded the highest titres of 0.58 units/ml of ${\beta}$-glucosidase, compared to 0.33, 0.23, and 0.16 units/mL by PKM, WB, and DDGS, respectively, at 72 h. Xylanase production was the highest (0.34 units/mL) when CM was added. The supernatant from fermentation of CM had the highest reducing sugars than other additional substrates at all intervals (0.10, 0.12, 0.10, and 0.11 mg/mL respectively). It is concluded that Bacillus licheniformis is capable of producing multiple cellulo- and hemicellololytic enzymes for bioethanol production using cost-effective agricultural residues, especially CM, as a sole nutrient source.

• Journal of Microbiology and Biotechnology
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• 제5권1호
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• pp.14-17
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• 1995

Endoglucanase gene of Pseudomonas sp. LBC505 was previously cloned in pUC19 to yield plasmid pLCl. The Pseudomonas sp. LBC505 endoglucanase gene was subcloned in a temperature-regulated Es-cherichia coli expression vector, pAS1, containing the leftward promoter $P_L$ of bacteriophage lambda. The level of gene expression was controlled by the thermal inactivation of the heat-sensitive lambda cI857 repressor. Best yield of endoglucanase was obtained by lowering the incubation temperature to $37^{\circ}C$ after induction at $42^{\circ}C$ for 1h. Under these conditions enzyme production continued for about 5h at a gradually decreasing rate. Ecoli harboring recombinant plasmid pASC10 expressed 4.3 times as much CMCase activity as E.coli containing pLCl. To enhance the expression level of endogl, ucanase gene, we have also changed the presumptive Shine-Dalgamo sequence (AGAGGT) of the gene to consensus sequence (AGGAGGT) by site-directed mutagenesis. The genes mutated were subcloned in pASl resulting in the formation of recombinant plasmid pASS50. E.coli harboring the plasmid pASS50 expressed 6.2-fold higher levels of CMCase activity than that of E.coli harboring pLC1.

• Journal of Microbiology and Biotechnology
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• 제24권4호
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• pp.440-446
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• 2014

The carbohydrate-binding module (CBM) is an important domain of most cellulases that plays a key role in the hydrolysis of cellulose. The neutral endoglucanase (EG1) gene was reconstructed. A redesigned endoglucanase, named EG2, was constructed with a CBM containing a linker from Corticium rolfsii (GenBank Accession No. D49448). The redesigned EG genes were expressed in Escherichia coli, and their characteristics are discussed. Results showed that the degradation of cellulose by EG2 was about double that by EG1. The specific activities of EG1 and EG2 were tested under optimal conditions, and EG2 had higher activity ($169.1{\pm}2.74$ U/mg) toward CMC-Na than did EG1 ($84.0{\pm}1.98$) in the process of cellulose degradation. The optimal pH and temperature, pH stability, and heat stability of EG1 and EG2 were similar. Results indicated that the CBM plays an essential role in the hydrolysis of cellulose. We can improve EG's catalytic power by adding the CBM from Corticium rolfsii.

• Journal of Microbiology and Biotechnology
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• 제17권8호
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• pp.1249-1253
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• 2007

A hyperthermostable endoglucanase from Pyrococcus horikoshii with the capability of hydrolyzing crystalline cellulose was analyzed. A protein engineering study was carried out to obtain a reduced-size mutant. Five amino acid residues at both the N- and C-terminus were found to be removable without any loss of activity or thermal stability. Site-directed mutagenesis was also performed on R102, N200, E201, H297, Y299, E342, and W377, residues possibly involved in the active center or in the recognition and binding of a cellulose substrate. The activity of the resulting mutants was considerably decreased, confirming that the mutated residues were all important for activity. A reduced-size enzyme, as active as the wild-type endoglucanase, was successfully obtained, plus the residues critical for its activity and specificity were confirmed. Consequently, an engineered enzyme with a reduced size was obtained, and the amino acids essential for activity were confirmed by site-directed mutagenesis and comparison with a known three-dimensional structure.

• Journal of Microbiology and Biotechnology
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• 제8권2호
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• pp.141-145
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• 1998

Overproduction of intracellular ${\beta}$-glucosidase was attempted by modifying the promoter region of a ${\beta}$-glucosidase gene cloned from Cellulomonas fimi and expressing it in Bacillus subtilis DB 104. A strong engineered promoter, BJ27UΔ88, was fused to the ${\beta}$-glucosidase gene after removing its native promoter. An effective Shine-Dalgamo sequence (genel0 of phage T7) was inserted between the promoter and the ${\beta}$-glucosidase structural gene. The modified gene was overexpressed in B. subtilis and produced 1121.5 units of ${\beta}$-glucosidase per mg protein which is about $12\%$ of total intracellular protein. Secretion of overproduced intracellular ${\beta}$-glucosidase was attempted by using the signal sequence of the Bacillus endoglucanase gene as well as an in-frame hybrid protein of endoglucanase. The hybrid protein was normally secreted into the culture medium and still retained ${\beta}$-glucosidase activity.

• 미생물학회지
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• 제41권1호
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• pp.81-86
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• 2005

국내에서 분리된 우수섬유소분해 균주인 Trichodema sp. C-4가 생성하는 endoglucanase 중하나를 $(NH_4)_2SO_4$ 침전, Sephacryl S-200 gel filtration, DEAE-Sepharose A-50 ion exchange, Mono-P chromatofocusing (EPLC)의 단계로 정제하고 이를 F-I-III라 명명하였다. 분리된 효소 F-I-III는 분자량 56,000Da, 둥전점 4.9로 측정된 단일 단백질이었다. F-I-III는 $55^{\circ}C$에서 가장 높은 활성을 보였으며, pH 5.0이 반응 최적 조건이었다. $50^{\circ}C$에서 24시간 동안 안정하였으며, pH 4-7의 범위에서 안정하였다. CMC에 대한 비활성은 315.4U/mg 이었으며, PNPG2에 대한 Km 값은 2.69 mM이었다. 이 효소는 같은 균주에서 분리한 다른 endoglucanase와 exoglucanase를 섞었을 때 결정형 섬유소인 Avicel분해에 대한 상승효과를 보였다. $Mg^{2+},\;CO^{2+},\;Fe^{2+},\;Ca^{2+},\;CS^+,\;Li^+$ 등의 이온은 1 mM의 농도에서 효소의 활성에 큰 영향을 미치지 않았고, 1 mM의 환원제 (cystein, EDIA, \beta-mercaptoethanol, dithiothreitol(DTT), L-ascorbic acid)들은 효소의 활성을 증가시켰다. E-I-III의 N-말단 서열을 분석하여 QPGTSTPEVHPKKLTTYK의 서열을 얻었다. 이는 Trichodema reesei의 endoglucanase인 EGI과 $95\%$의 유사도를나타내었다. 분리된 효소 F-I-III는 높은 비활성을 가지고 있어서 활용가치가 높을 것으로 사료되었다.