• 미생물학회지
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• 제40권2호
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• pp.115-120
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• 2004

시안세균(Anabaena cylindrica)의 생장을 효과적으로 억제하는 세균을 분리하여 NG-2로 구분하였다. 이 세균은 그람 음성의 막대형 세균으로서 1.3∼$1.8{\times}0.35{\mu}m$ 정도의 크기를 보였으며, 카탈라제와 옥시다제 양성 반응을 나타내었고, 35∼$40^{\circ}C$아 pH 9.0의 적정생장 조건을 보였다. A.cylindrica의 NG-2를 JM 배지에서 혼합배양할 경우 두 미생물군은 서로 반비례적으로 성장하였으며, 24시간 이내에 A. cylindrica의 영양세포가 거의 완전히 소멸하였다. NG-2는 빛이 있는 조건에서만 효과적으로 A. cylindrica를 분해하였는데, 이는 NG-2의 A. cylindrica 분해활성이 숙주의 광합성 작용에 매우 의존적임을 의미한다. 분리세균의 A. cylindlica 분해작용을 현미경으로 관찰한 결과 NG-2는 숙주세포에 부착하지 않고 배지 내에 산재한 상태에서 영양세포를 분해하였으며, 이형세포는 분해되지 않았다. 또한 영양세포의 세포벽이 분해되면 분해세균들이 filament 주위에 집중적으로 부착하는 콜로니를 형성함으로써 A. cylindrica를 완전히 분해하는 것이 확인되었다. A. cylindrica에 대한 NG-2의 분해활성은 인공배지 뿐만 아니라 강물에서도 유사한 결과를 나타내었다. 또한 발포 polystyrene 재질의 bead에 세균을 부착함으로써 A. cylindrica 분해 효율을 더 상승시킬 수 있었다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제15권1호
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• pp.1-8
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• 2010

Cometabolic air sparging (CAS) is a new and innovative technology that uses air sparging principles but attempts to optimize in situ contaminant degradation by adding a growth substrate to saturated zone. CAS relies on the degradation of the primary growth substrate and cometabolic substrate transformation in the saturated zone and in the vadose zone for volatilized contaminants. In this study, we have investigated to determine MTBE degradation pattern and microbial activity variation if using propane as a primary substrate at the condition of considering air injection rate and air injection pattern. Laboratory-scale two-dimentional aquifer physical model studies were used and the experimental results were represented that the optimal conditions were as air injection rate of 1,000 mL/min and pulsed air injection pattern (15 min on/off). Over 1,000 mL/min air injection rate and continuous air injection pattern was no affected to increase DO concentration. On the other hand, Injection of propane and propane-utilizing bacteria degraded MTBE partially. And also, injection of propane- and MTBE-utilizing bacteria effectively degraded MTBE and TBA production was observed.

• 대한수의학회지
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• 제33권1호
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• pp.53-60
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• 1993

Anaerobic bacteria are suggested to be potential source for new antibiotics. In order to search for antibiotics from domestic origin, we collected 800 soil samples across Korean locations and could isolate as many as 989 anaerobic strains. Among them 10, strains were found to have good producing capacity of antibiotics. An anaerobe was finally selected due to secreting antibiotics having high antimicrobial activity towards multiple resistant microorganism(E coli JM 83) transformed by genetic engineering technique. Its morphological, physiological and biochemical charateristics were investigated, together with antimicrobial spectrum therefrom. On antimicrobial spectrum study, substance secreted from this strain, had no activities to fungus and yeast. The selected strain showed G(+) and coccal shape, on Gram, staining and electron scanning microscopy, respectively. Biochemically this strain utilized glucose, fructose lactose, sucrose, but did not arabinose, cellulose, rhamnose, sorbitol, trehalose, mannitol. Catalase test showed negative property. Optimal growth temperature was $37^{\circ}C$. The results obtained above suggest this strain Streptococcus faecium subspp. and we named it Streptococcus sp. An-21-1.

• 한국미생물·생명공학회지
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• 제27권2호
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• pp.96-101
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• 1999

Various side-chains are introduced to the 7-amino position of 7-aminocepha-losporanic acid (7-ACA) to make semi-synthetic cephalosporin antibiotics. In order to convert cephalosporin C (CPC) to 7-ACA, two enzymatic reactions are generally imployed. Glutary1-7-aminocephalosporanic acid (Gl-7-ACA) acylase is involved in the second step where the reaction intermediate, Gl-7-ACa is converted into 7-ACA. It was recently reported that CPC amidase can convert CPC directly into 7-ACA in a single enzymatic reaction. A study was undertaken to screen microorganisms conferring enzyme activity to convert Gl-7-ACA or CPC into 7-ACA by one or two enzymatic reactions. In order to screen the microorganisms rapidly, a non-$\beta$-lactam model compund, glutaryl-$\rho$-nitroanilide, was utilized in an early stage, thereafter the selected microorganisms were examined with real substrates. One microorganism exhibiting both Gl-7-ACA acylase and CPC amidase activities was obtained by the colorimetry method and HPLC assay, and was identified as a strain of Serratia species, designated as Serratia sp. N14.4. The optimal fermentation conditions for Serratia sp. N14.4 was pH9.0 and 3$0^{\circ}C$.

• KSBB Journal
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• 제13권4호
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• pp.343-351
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• 1998

About 75 strains which utilize cholesterol as sole carbon and energy source were isolated from 10 samples of Kimchi and 18 samples of fermented fish food (2 Ojingo-jeots, salt-fermented squid ; 5 Changran-jeots, salt-fermented pollack tripe ; 5 Myungran-jeots, salt-fermented Alaska pollack roe ; 3 Gajami-sikhae-jeots, fermented flat fish ; 2 Gul-jeots, salt-fermented oyster ; a Juneo-jeots, salt-fermented shad). Among them tested, the 3T6-5Mj strain isolated from Changran-jeot showed the highest activity on cholesterol degradation. The optimal composition of medium for the producing cholesterol degradation enzyme by 3T6-5Mj strain was 1.0 g/L NH4NO3, 1.0 g/L K2HPO4, 0.1 g/L MgSO4.7H2O, 1.0 g/L FeSO4.7H2O, 1 g/L NaCl, 5 g/L Trypton, 1 g/L Cholesterol, and 5 g/L Maltose at 30$^{\circ}C$, pH 7.5, and the enzyme production reached a maximum level at 140 hours of cultivation.

• 청정기술
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• 제22권3호
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• pp.175-180
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• 2016

본 연구에서는, 저온 및 약산성 조건에서 높은 활성을 보이는 티로시나아제인 tyrosinase-CNK의 반응 안정성을 조사하였다. Tyrosinase-CNK는 지금까지 알려진 중온성(mesophilic) 및 호열성(thermophilic) 환경 유래의 티로시나아제 보다는 열 안정성이 낮았으나 0 ℃에서 효소 안정성이 매우 뛰어났고, 반복적인 동결-해동(freeze-thaw) 과정에서도 효소 활성을 안정적으로 유지하였다. 또한, 물과 ethanol 및 acetonitrile이 혼합된 유기용매 환경에서 초기 상대 활성 값의 변화가 관찰되었으나 유기용매 농도의 증가로 인한 추가적인 활성 저하를 유발하지 않고 활성을 일정하게 유지하였다. 한편, 효소 반응의 염(salt)에 대한 저해는 chaotropic 특성이 많이 나타나는 염일수록 적게 나타났다. 결과적으로, tyrosinase-CNK는 통상의 티로시나아제를 이용하여 반응을 수행하기 어려운 환경에서도 원하지 않는 반응을 억제하고 효소 불활성화를 최소화면서 반응을 촉매할 것으로 기대된다.

• Asian-Australasian Journal of Animal Sciences
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• 제31권4호
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• pp.607-615
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• 2018

Objective: This study was conducted to isolate the cellulolytic microorganism from the rumen of Holstein steers and characterize endoglucanase gene (Cel5A) from the isolated microorganism. Methods: To isolate anaerobic microbes having endoglucanase, rumen fluid was obtained from Holstein steers fed roughage diet. The isolated anaerobic bacteria had 98% similarity with Eubacterium cellulosolvens (E. cellulosolvens) Ce2 (Accession number: AB163733). The Cel5A from isolated E. cellulolsovens sp. was cloned using the published genome sequence and expressed through the Escherichia coli BL21. Results: The maximum activity of recombinant Cel5A (rCel5A) was observed at $50^{\circ}C$ and pH 4.0. The enzyme was constant at the temperature range of $20^{\circ}C$ to $40^{\circ}C$ but also, at the pH range of 3 to 9. The metal ions including $Ca^{2+}$, $K^+$, $Ni^{2+}$,$Mg^{2+}$, and $Fe^{2+}$ increased the endoglucanase activity but the addition of $Mn^{2+}$, $Cu^{2+}$, and $Zn^{2+}$ decreased. The Km and Vmax value of rCel5A were 14.05 mg/mL and $45.66{\mu}mol/min/mg$. Turnover number, Kcat and catalytic efficiency, Kcat/Km values of rCel5A was $96.69(s^{-1})$ and 6.88 (mL/mg/s), respectively. Conclusion: Our results indicated that rCel5A of E. cellulosolvens isolated from Holstein steers had a broad pH range with high stability under various conditions, which might be one of the beneficial characteristics of this enzyme for possible industrial application.

• Applied Biological Chemistry
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• 제36권6호
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• pp.539-546
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• 1993

본 연구에서는 Cheddar 치즈의 숙성기간을 단축시키고 flavor를 증진시키기 위하여 Micrococcus sp. LL3를 치즈 제조시에 첨가할 목적으로 본 균주가 생성하는 aminopeptidase의 특성을 조사하였으며, 또한 본 효소를 정제하였다. L-Leucine-p-nitroanilide를 기질로 사용 하였을 때 본 효소의 최적온도와 pH는 각각 $30^{\circ}C$ 및 7.0이었다. 본 효소는 $50^{\circ}C$까지의 온도에서 10분간 방치하였을 경우에도 안정하였다. $Mg^{++}$ ion에 의해 본 효소의 활성이 촉진되었으나 $Hg^{++}$ ion과 EDTA나 1,10-phenanthroline에 의해서 효소활성이 거의 실활되어 metallopeptidase인 것으로 추정되었다. 본 효소의 기실 특이성은 광범위 하였으나, N-terminal amino acid로서 arginine을 함유한 peptide는 분해하지 못했다. 본 균주가 생성하는 aminopeptidase의 정제를 위하여 DEAE-Sephacel ion chromatography및 gel filtration을 실시하였으며, 이때 분자량 46,500의 효소를 얻을 수 있었다.

• Journal of Microbiology and Biotechnology
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• 제12권6호
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• pp.921-928
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• 2002

Microorganism producing extracellular CFTase was isolated from soil and designated as Bacillus polymyxa MGL21. The gene encoding the CFTase (cft) from B. polymyxa MGL21 was cloned and sequenced. The ORF of the cf gene was composed of 3,999 nucleotides, encoding a protein (1,333 amino acids) with a predicted molecular mass of 149,375 Da. Sequence analysis indicated that CFTase was divided into five distinct regions. CFTase contained three regions of repeat sequences at the N-terminus and C-terminus. The endo-inulinase region of homology (ERH) of CFTase was similar to that of Pseudomonas mucidolens endo-inulinase ($50\%$ identity, 259 amino acids). Furthermore, CFTase possessed a highly conserved core region, which is considered to be functional for the hydrolysis reaction of inulin. The cft gene was expressed in a His-tagged form in Escherichia coli cells, and the His-tagged CFTase was purified to homogeneity. The optimal temperature and pH for CFTase activity were found to be $50^{\circ}C$ and 9.0, respectively. The enzyme activity was completely inhibited by 10 mM $Ag^+\;and\;Cu^2+$. Thin-layer chromatography analyses indicated that CFTase catalyzed not only the cyclization reaction ut also disproportionation and hydrolysis reactions as well.

• Environmental Engineering Research
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• 제19권4호
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• pp.309-316
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• 2014

The water quality improvement of golf course ponds, as representative stagnant stream channels, was evaluated by applying a biological activated carbon (BAC) process composed of four consecutive activated carbon reactors. The study was performed from autumn to winter in order to evaluate the feasibility of the BAC process under low temperature conditions. In the study, water quality of pond A (target pond) and pond B (reference pond) were monitored. Pond water was pumped into the BAC process, and was then returned to the pond after treatment. The optimal conditions were determined to be 2 hr of empty bed contact time (EBCT) at a temperature above $4^{\circ}C$, in which improvements of chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) of pond A compared to pond B were 3.62%, 3.48% and 1.81%, respectively. On the other hand, as the temperature was below $4^{\circ}C$, some degree of water quality improvement was achieved even when EBCT were 1 or 0.5 hr, suggesting that the BAC process can be successfully applied for the improvement of pond water quality in winter months. The values of biomass concentration and microorganism activity in each condition were highest where 2 hr of EBCT was applied at a temperature above $4^{\circ}C$, but values were similar throughout all treatment conditions, and thus, adsorption is considered to be the dominant factor affecting process efficiency. From the denaturing gel gradient electrophoresis (DGGE) results, no significant differences were observed among the activated carbon reactors, suggesting that the number of reactors in the system could be decreased for a more compact application of the system.