• Journal of Microbiology and Biotechnology
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• 제11권4호
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• pp.636-643
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• 2001

Bacillus sp. AIR-5, a strain from soil, produced an extracellular maltopentaose-forming amylase from amylose and soluble starch. This bacterium produced 8.9 g/l of maltopentaose from 40 g/l of soluble starch in a batch fermentation and the maltopentaose made up 90 % of the maltooligosaccharides produced (from maltose to maltoheptaose). The culture supernatant was concentrated using a 30 K molecular weight cut-off membrane and purified by DEAE-Cellulose and Sephadex G-150 column chromatographies. The purified protein showed one band on a native-PAGE and its molecular mass was estimated as 250 kDa. The 250-kDa protein was composed of tetramers of a 63-kDa protein. the isoelectric point of the purified protein was pH 6.9, and the optimum temperature for the enzyme activity was $45^{\circ}C$. The enzyme was quickly inactivated above $55^{\circ}C$, and showed a maximum activity at pH 8.5 and over 90% stability between a pH of 6 to 10. The putative N-terminal amino acid sequence of AIR-5 amylase, ATINNGTLMQYFEWYVPNDG, showed a 96% sequence similarity with that of BLA, a general liquefying amylase.

• 미생물학회지
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• 제26권2호
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• pp.73-81
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• 1988

$\alpha$-Amylase (EC.3.2.1.1) of Neurospora crassa (ATCC9279) was cloned in E. coli HB101 using shotgun method, and the enzymes isolated from both N. crassa and E. coli were compared. Chromosomal DNA isolated from the spores of N. crassa was partially digested with PstI restriction endonuclease and rejoined to pBR322 which had been digested with the same enzyme. The resulting recombinant DNA were introduced into E. coli HB101 which had competancy by treating with $CaCl_{2}$. As the result, about 8000 colonies which showed tetracycline resistance were selected and two of the colonies which had 13.5Kb recombinant plasmid exhibit starch degrading activity on starch-containing plate when treated with D-cycloserine. $\alpha$-Amylases from both N.crassa and E. coli were isolated by using ammonium sulfate precipitation, DEAE-cellulose ion exchange column chromatography and Bio-Gel P150 gel foltration column. As the result, about 81.3 fold and 5.6 fold purifications in specific activities were obtained respectively, and specific activities of the gel filtrates were 6.1u/mg and 85u/mg respectively. The properties of both enzymes were compared and they showed quite the similar patterns in optimal temperature, optimal pH and had same molecular weight about 100,000 daltons on gel filtration method. Optimal temperatures for both enzymes were $70^{\circ}C$ and optimal pH were about 6 and 10.

• BMB Reports
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• 제35권6호
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• pp.568-575
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• 2002

An $\alpha$-amylase (EC 3.2.1.1) was purified that catalyses the production of a high level of maltose from starch without the attendant production of glucose. The enzyme was produced extracellularly by thermophilic Streptomyces sp. that was isolated from Thailand's soil. Purification was achieved by alcohol precipiation, DEAE-Cellulose, and Gel filtration chromatographies. The purified enzyme exhibited maximum activity at pH 6-7 and $60^{\circ}C$. It had a relative molecular mass of 45 kDa, as determined by SDS-PAGE. The hydrolysis products from starch had $\alpha$-anomeric forms, as determined by $^1H$-NMR. This maltose-forming $\alpha$-amylase completely hydrolyzed the soluble starch to produce a high level of maltose, representing up to 90%. It hydrolyzed maltotetrose and maltotriose to primarily produce maltose (82% and 62%, repectively) without the attendant production of glucose. The high maltose level as a final end-product from starch and maltooligosaccharides, and the unique action pattern of this enzyme, indicate an unusual maltose-forming system. After the addition of the enzyme in the bread-baking process, the bread's volume increased and kept its softness longer than when the bread had no enzyme.

• Journal of Microbiology and Biotechnology
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• 제18권9호
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• pp.1555-1563
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• 2008

A novel $\alpha$-amylase ($\alpha$-1,4-$\alpha$-D-glucan glucanohydrolase, E.C. 3.2.1.1), ScAmy43, was found in the culture medium of the phytopathogenic fungus Sclerotinia sclerotiorum grown on oats flour. Purified to homogeneity, ScAmy43 appeared as a 43 kDa monomeric enzyme, as estimated by SDS-PAGE and Superdex 75 gel filtration. The MALDI peptide mass fingerprint of ScAmy43 tryptic digest as well as internal sequence analyses indicate that the enzyme has an original primary structure when compared with other fungal a-amylases. However, the sequence of the 12 N-terminal residues is homologous with those of Aspergillus awamori and Aspergillus kawachii amylases, suggesting that the new enzyme belongs to the same GH13 glycosyl hydrolase family. Assayed with soluble starch as substrate, this enzyme displayed optimal activity at pH 4 and $55^{\circ}C$ with an apparent $K_m$ value of 1.66 mg/ml and $V_{max}$ of 0.1${\mu}mol$glucose $min^{-1}$ $ml^{-1}$. ScAmy43 activity was strongly inhibited by $Cu^{2+}$, $Mn^{2+}$, and $Ba^{2+}$, moderately by $Fe^{2+}$, and was only weakly affected by $Ca^{2+}$ addition. However, since EDTA and EGTA did not inhibit ScAmy43 activity, this enzyme is probably not a metalloprotein. DTT and $\beta$-mercaptoethanol strongly increased the enzyme activity. Starting with soluble starch as substrate, the end products were mainly maltotriose, suggesting for this enzyme an endo action.

• 미생물학회지
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• 제9권4호
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• pp.163-168
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• 1971

Neutral protease which was obtained from a genus of Aspergilli as the crystal form were investigated for their purification and properties. The results of biochemical and enzymatic studies for their purification and properties in this enzyme were as follows. 1) On the wheat media containing 70%-water and $CaCo_{3}$, Aspergilus oryzae S.H.W. 131 is satisfactorily grown under the basic optimum conditions temperature $27^{\circ}C$- $30^{\circ}C$at relative humidity 100% for three days. 2) The enzyme solution extracted with water is successively purified through the passing on column of Asmti-177N for decolorization of it. And ion exchanger such as DEAAE Sphadex A-50 or Shepadex G-100 and fraction collector is necessary for the sepearte treatments of this enzyme. After washing it with organic solvents as aceton-EtOH, etc., it should be dried on the vacuum dryer at $40^{\circ}C$) The protease activity is determined by the amounts of amino acids, tyrosine. 4) The optimum pH of neutral protease is 6.0-8.0. 5) In effectively decomposing with this neutral protease, the optimum temperature is $35^{\circ}C$. 6) It is interesting that the amounts of metal ion affects the activity of neutral protease. For examples, if it were treated with manganic ion, its activity would be more effective than any other that.

• 한국식품과학회지
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• 제42권2호
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• pp.198-203
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• 2010

보리 맥아에는 2종의 $\alpha$-amylase isozyme(AMY1, AMY2)이 존재하며, 이들 효소는 80% 이상의 높은 아미노산 서열 상동성을 보이지만, calcium 의존성 등 효소의 작용특성은 서로 매우 다르다. 따라서 본 연구에서는 AMY2의 활성부위 중 2번째 $\beta\rightarrow\alpha$ loop에 존재하는 42번째 alanine 잔기를 saturation mutagenesis를 이용하여 다양한 아미노산으로 치환하고, 전분 분해활성이 증가한 돌연변이를 선발하였다. 결과적으로 alanine이 proline으로 치환된 AMY2-A42P의 경우에서만 발현도가 2배 증가하는 것을 확인하였으며, 특히 정제 과정에서의 회수율 또한 4배 증가하므로 향후 효소의 생산 및 활용에 유리할 것으로 판단하였다. 이 돌연변이 효소의 calcium 의존성 및 pH 안정성 등은 AMY2와 유사한 것으로 나타났으나, 각종 전분에 대한 기질특이성은 AMY1과 AMY2의 중간적인 특성으로 변화되었다. 결국 42번째 아미노산 잔기의 proline 치환에 의해 상대적으로 발현율이 높고 기질특이성이 변화된 AMY2 유사효소의 생산이 가능하였으며, 향후 이를 이용하여 분자진화기술 등 최신 효소공학적 방법론을 적용한 다양한 연구가 가능할 것으로 기대한다.

• 생명과학회지
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• 제25권2호
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• pp.180-188
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• 2015

김치로부터 분리한 L. sp. KD 28은 펩타이드성 항균물질인 박테리오신을 생산하였다. 이 박테리오신은 ${\alpha}$-chymotrypsin, proteinase K, lipase, ${\alpha}$-amylase, carboxypeptidase A 효소에 대해서 매우 민감한 반응을 보였다. 낮은 pH 2.0에서 약 염기성의 pH 8.0까지는 항균활성을 온전히 유지하였으나 pH 8.0 이상에서는 항균활성이 감소하기 시작하여 pH 12.0에서는 25%로 감소하였다. L. sp. KD 28는 16S rRNA 분자계통학적 분석을 한 결과 L. lactis와 99% 상동성을 보였다. 또한 김치에서 분리한 L. sp. KD 28이 생산하는 박테리오신은 acetonitrile, isopropanol, methanol, chloroform 및 acetone 등의 유기용매 최종 농도 50%에서 항균활성은 영향을 받지 않았다. 열 안정성의 경우 $80^{\circ}C$까지 한 시간의 열처리에 안정하였으나 $100^{\circ}C$에서는 20분 이상의 열처리에 의해 항균활성이 감소하여 50분간 열처리할 경우 항균활성이 나타나지 않았다. 또한 이 박테리오신은 그람 음성보다는 양성 세균인 M. luteus IAM 1056, L. delbrueckii subsp. lactis KCTC 1058, E. faecium KCTC 3095, B. cereus KCTC 1013, B. subtilis KCTC 1023, S. aureus subsp. aureus KCTC 1916, B. megaterium KCTC 1098, B. sphaericus KCTC 1184 및 L. ivanovii subsp, ivanovii KCTC 3444 등에 대해서 항균활성을 보였다. 박테리오신을 SP-Sepharose 이온교환크로마토그래피로 부분 정제한 후 RP-HPLC 를 통해서 최종적으로 정제하여 tricine-SDS-PAGE를 통해 분자량을 확인한 결과 약 3.4 kDa로 나타났다.

• 한국미생물·생명공학회지
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• 제38권1호
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• pp.84-92
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• 2010

B. subtilis MJP1이 생산하는 항균물질을 분리 정제하기 위하여 SPE, IEC, GFC를 통한 정제를 수행하였다. 정제된 항세균 물질은 tricine SDS-PAGE에서 하나의 band임을 확인 한 후 N-말단 아미노산 서열분석을 하였으나 N-말단이 blocking 되어 그 서열을 분석할 수 없였다. 이에 그 내부서열을 알아보기 위한 LC를 이용한 ESI-MS/MS를 시행하였으나 내부서열도 확인할 수 없었고, UPLC를 이용한 ESI-MS/MS를 시행한 결과 항세균 활성 물질은 분자량이 매우 유사한 2개의 peptide(3356.54 Da, 3400.5244 Da)가 존재함을 확인하였다. 정제된 항세균 물질의 항균 spectrum을 조사한 결과, L. monocytogenes에 가장 강한 항균활성을 나타내며 이외에 B. subtilis, S. aureus subsp. aureus, E. faecalis 등의 Gram 양성균에서 항균활성을 나타내였다. 정제된 B. subtilis 항세균 물질은 pH 3.0부터 pH 9.0 범위에서는 안정하였으며 $4^{\circ}C$, $30^{\circ}C$, $50^{\circ}C$에서 24시간, $100^{\circ}C$에서 5분 동안 매우 안정하였고, $70^{\circ}C$에서 24 시간, $100^{\circ}C$에서 30분 동안 처리한 구간부터 역가가 감소하여 $121^{\circ}C$에서 15분 동안 처리한 구간에서는 역가가 완전히 소실되었다. 효소 안정성 실험에서 정제된 항세균 물질은 일부 단백분해효소에 의해 분해되어 역가를 상실하였으며, lipase나 $\alpha$-amylase에서는 안정함을 나타냈다. 이로부터 정제된 항세균 물질이 넓은 pH 범위에서 안정하고, 비교적 높은 온도에서도 활성을 유지한다는 점을 관찰할 수 있었으며, 단백분해효소에 의해 분해되므로 bacteriocin임을 확인하였다. 본 연구를 통하여 B. subtilis MJP1으로부터 분리 정제된 bacteriocin은 class IIa군의 특성과 유사하며, B. subtilis MJP1은 본 분리 bacteriocin 이외에도 다른 항세균 물질과 항진균 물질을 생산하는 균주임을 알 수 있었다.

• 한국식품위생안전성학회지
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• 제33권6호
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• pp.516-520
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• 2018

박테리오신은 미생물이 생산하는 단백질성의 항균물질이다. 본 연구에서는 Enterococcus faecium CJNU 2008 균주로부터 생산되는 박테리오신에 대한 일부 특성을 규명하였다. 부분 정제 박테리오신은 열처리($100^{\circ}C$ 30분, $121^{\circ}C$ 15분) 및 유기용매(메탄올, 에탄올, 아세톤, 아세토니트릴, 클로로포름)에 대한 안정성이 우수하였으며 효소처리의 경우 Lipase와 ${\alpha}-amylase$에 대해서는 안정하였으나 Protease 처리에서 활성이 소실되었다. 이는 E. faecium CJNU 2008균주가 생산하는 항균물질이 단백질성의 박테리오신임을 추가적으로 증명하는 것이다. 병원성 세균인 Listeria monocytogenes 균주를 지시균으로 사용했을 때 박테리오신은 살균(bactericidal)의 작용양상을 보였다. Tricine-SDS-PAGE를 이용한 박테리오신의 분자량은 6.5 kDa 이하로 확인되었다. 부분 정제된 박테리오신을 이용하여 HPLC법을 활용한 정제를 수행하였으며 크로마토그램 상에서 단일 피크를 얻었을 수 있었다. 앞으로 정제된 박테리오신은 생화학적 분석 등에 활용할 계획이다.

• Asian-Australasian Journal of Animal Sciences
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• 제12권1호
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• pp.77-83
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• 1999

Molecular biological techniques that recently developed, have made it possible to realize some of new attempts in the research field of rumen microbiology. Those are 1) cloning of genes from rumen microorganisms mainly in E. coli, 2) transformation of rumen bacteria and 3) ecological analysis with nonculturing methods. Most of the cloned genes are for polysaccharidase enzymes such as endoglucanase, xylanase, amylase, chitinase and others, and the cloning rendered gene structural analyses by sequencing and also characterization of the translated products through easier purification. Electrotransformation of Butyrivibrio fibrisolvens and Prevotella ruminicola have been made toward the direction for obtaining more fibrolytic, acid-tolerant, depoisoning or essential amino acids-producing rumen bacterium. These primarily required stable and efficient gene transfer systems. Some vectors, constructed from native plasmids of rumen bacteria, are now available for successful gene introduction and expression in those rumen bacterial species. Probing and PCR-based methodologies have also been developed for detecting specific bacterial species and even strains. These are much due to accumulation of rRNA gene sequences of rumen microbes in databases. Although optimized analytical conditions are essential to reliable and reproducible estimation of the targeted microbes, the methods permit long term storage of frozen samples, providing us ease in analytical work as compared with a traditional method based on culturing. Moreover, the methods seem to be promissing for obtaining taxonomic and evolutionary information on all the rumen microbes, whether they are culturable or not.