• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.314-316
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• 2000

Urea is detected as an indicator of renal disease in the human body. For these reasons, many biosensors for urea have been developed based on the enzymatic reaction of urea hydrolysis catalyzed by urease. Potentiometric method is applied reversible reaction system. But urea hydrolysis reaction may not has a reversible reaction mechanism in electrode surface. Therefore we applied to voltammtricmethod to obtain a sensitivity curve. The sensitivity of sensors was 34 ${\mu}$A/decade.

• 한국토양비료학회지
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• 제47권6호
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• pp.391-397
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• 2014

Acid mine drainage occurrence is a serious environmental problem by mining industry; it usually contain high levels of metal ions, such as iron, copper, zinc, aluminum, and manganese, as well as metalloids of which arsenic is generally of greatest concern. It causes mine impacted soil pollution with mining and smelting activities, fossil fuel combustion, and waste disposal. In the present study, three bacterial strains capable of producing urease were isolated by selective enrichment of heavy metal contaminated soils from a minei-mpacted area. All isolated bacterial strains were identified Sporosarcina pasteurii with more than 98% of similarity, therefore they were named Sporosarcina sp. KM-01, KM-07, and KM-12. The heavy metals detected from the collected mine soils containing bacterial isolates as Mn ($170.50mg\;kg^{-1}$), As ($114.05mg\;kg^{-1}$), Zn ($92.07mg\;kg^{-1}$), Cu ($62.44mg\;kg^{-1}$), and Pb ($40.29mg\;kg^{-1}$). The KM-01, KM-07, and KM-12 strains were shown to be able to precipitate calcium carbonate using urea as a energy source that was amended with calcium chloride. SEM-EDS analyses showed that calcium carbonate was successfully produced and increased with time. To confirm the calcium carbonate precipitation ability, urease activity and precipitate weight were also measured and compared. These results demonstrate that all isolated bacterial strains could potentially be used in the bioremediation of acidic soil contaminated by heavy metals by mining activity.

• Journal of Microbiology and Biotechnology
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• 제13권5호
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• pp.673-679
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• 2003

Glutamine and urea, abundant in body fluids or plasma, yield net ammonium ions upon hydrolysis by ${\gamma}-glutamyl$ transpeptidase (${\gamma}-GTP$) and urease, respectively, and these two enzymes are largely produced from Helicobacter pylori. To investigate bacterial potential of ammonium production, we first quantified those in whole-cell systems and found that the relative ratio of their amounts varied greatly, especially with pH values and the cell's aging. During the H. pylori cultivation, the ratio appeared to be inversely proportional to each other, showing a progressive increase of the ${\gamma}-GTP$ with decreasing of the urease. Under the urease-defective conditions due to low pH or coccoids, the bacterial cells still possessed a considerable amount of ${\gamma}-GTP$, which was found exclusively in the external compartment, therefore, the cell's ammonium production was found to be solely dependent upon glutamine, and the external ammonium concentration was constant without any contribution of urea concentration. Such ammonium constancy would definitely have an adverse effect on the host, because of its absolute requirement for vacuolar degeneration by H. pylori VacA, maximized at approximately 10 mM $NH_4Cl$. It was also found that, by using the metal-saturated membrane vesicles, ammonium ions were likely to be involved in the pH-dependent cation-flux across the H. pylori membrane, where the role of ${\gamma}-GTP$ in ammonium homeostasis around cells was suggested, especially under the hostile conditions against H. pylori.

• 한국지하수토양환경학회지:지하수토양환경
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• 제20권1호
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• pp.56-64
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• 2015

Acid mine drainage occurrence is a serious environmental problem by mining industry, it usually contains high levels of metal ions, such as iron, copper, zinc, aluminum, and manganese, as well as metalloids of which arsenic is generally of the greatest concern. An indigenous plant extract was used to produce calcium carbonate from Canavalia ensiformis as effective biomaterial, and its ability to form the calcium carbonate under stable conditions was compared to that of purified urease. X-ray diffraction and scanning electron microscopy were employed to elucidate the mechanism of calcium carbonate formation from the crude plant extracts. The results revealed that urease in the plant extracts catalyzed the hydrolysis of urea in liquid state cultures and decreased heavy metal amounts in the contaminated soil. The heavy metal amounts were decreased in the leachate from the treated mine soil; 31.7% of As, 65.8% of Mn, 50.6% of Zn, 51.6% of Pb, 45.1% of Cr, and 49.7% of Cu, respectively. The procedure described herein is a simple and beneficial method of calcium carbonate biomineralization without cultivation of microorganisms or further purification of crude extracts. This study suggests that crude plant extracts of Canavalia ensiformis have the potential to be used in place of purified forms of the enzyme during remediation of heavy metal contaminated soil.

• 대한화학회지
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• 제36권3호
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• pp.393-404
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• 1992

새로운 효소반응기를 쓰는 요소 정량용 연속${\cdot}$자동화 장치의 감응성질을 조사하였다. 효소반응기는 지지체인 nylon-6입자(42∼48 mesh)를 teflon관(안지름 2mm, 길이 20cm)에 충전시키고, 이 지지체의 표면에 공유결합제인 glutaraldehyde로 urease를 고정화시켜서 제작하였다. 연속${\cdot}$자동화장치는 효소반응기, 기체투석기 및 지시전극인 관형 PVC-nonactin막 암모늄 이온 선택성 전극을 차례로 연결하여 만들었다. 이 장치를 써서 요소를 정량할 때 감응특성은 다음과 같다. 곧 직선감응 농도범위는 $5.5{\times}10^{-6}$~$2.4{\times}10^{-3}M$, 감응기울기는 57.8 mV/decade, 검출한계는 $1.5{\times}10^{-6}M$, 효소반응기의 전환백분율은 80.8%이었다. 효소반응기의 최적 완충용액은 0.01M Tris-HCl 완충용액(pH 7.0∼7.8)과 0.01M 인산염 완충용액(pH 6.9∼7.5)이었고, 수명은 150일 정도였다. 또한 다른 생리활성물질의 방해는 없었다.

• 대한화학회지
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• 제36권6호
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• pp.864-871
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• 1992

pH-ISFET와 urease막으로 이루어져 있는 요소센서를 제조하고, 그 감응특성을 조사하였다. pH-ISFET 요소센서는 pH-ISFET의 게이트 위에 glutaraldehyde로 BSA와 urease를 고정화시켜서 제작하였다. pH-ISFET 요소센서의 감응에 미치는 완충용액의 pH 및 농도와 효소의 양의 영향에 대하여 조사하였다. 합성생리염수(pH 7.4)로 만든 요소용액에 대한 감응 특성은 다음과 같다. 곧 직선감응농도범위, 감응기울기(감도) 및 감응시간은 각각 5.0 ${\times}$ $10^{-4}$ ${\sim}$ 5.0 ${\times}$ $10^{-2}$M, 31.6 mV/decade 및 4${\sim}$10분이다.

• 한국식품과학회지
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• 제38권1호
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• pp.93-98
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• 2006

본 연구는 H. pylori를 산란계에 면역화하여 얻은 항-H. pylori 난황항체 분말의 H. pylori에 대한 억제효과를 알아보기 위하여 실시하였다. 마우스의 종에 따라서 H. pylori에 대한 감수성의 차이가 있다고 보고된 바 있다(25). Richard 등의 연구결과에 의하면 C57BL/6 mice는 H. pylori에 대하여 약 70%의 감수성을 가진 것으로 보고하였다(26). 이번 실험에서는 7주째의 urease test 결과 항-H. pylori 난황항체 분말을 급이한 군에서 33%의 낮은 양성율을 보였고, 흡광도 측정결과도 유의적으로 감소하였다. 조직학적 검사에서 접종대조군의 위조직은 염증성 세포의 집적 등 특이적인 염증성 변화를 동반하였지만, 항-H. pylori 난황항체 분말을 급이한 군에서는 특이적 변화를 관찰할 수 없었다. H. pylori의 제균효과를 확인하는 방법중 하나인 ureA 유전자 확인결과, 항-H. pylori 난황항체 분말을 급이한 군에서는 3주째보다 7주째 많이 감소하였다. 항-H. pylori 난황항체 분말의 급이시기는 감염전이나 감염후에 큰 차이를 보이지 않았으며, 급이수준은 5%보다는 10% 첨가수준이 약간 높게 나타났다. 이 연구결과로 동물시험에서 항-H. pylori 난황항체 분말이 H. pylori 억제 효과가 있음이 확인되었다.

• 한국지반공학회논문집
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• 제33권9호
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• pp.61-69
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• 2017

본 연구에서는 사질토에서의 EICP에 의한 탄산칼슘 침전량을 정량적으로 평가하였다. 생성된 탄산칼슘은 염산과의 반응에 수반되는 이산화탄소 기체 압력 증분을 통해 간접적으로 측정하였으며, 이는 반응이 진행됨에 따라 특정 값으로 수렴하는 경향을 보였다. EICP 용액으로 포화된 주문진표준사의 전단파 속도 및 전기전도도값은 측정된 탄산칼슘량의 수렴시간보다 선행하여 일정한 값에 도달함을 확인하였다. 결정화 모델은 탄산칼슘이 흙 입자간 접촉점과 입자표면에서 생성됨을 나타내며, 이를 통해 최종 전단파 속도 및 최종 전기전도도에 도달하는 시간과 탄산칼슘 생성량의 수렴시간 간의 불일치가 설명 가능함을 보였다. 또한, 용액 농도 0.5g/L를 이용한 최종 전단파 속도는 0.1g/L의 것보다 224% 높은 효율을 나타내었다. 더불어 효소의 농도와 무관하게 전기전도도와 전단파 속도의 상관관계가 있음을 확인하였으며 주사전자현미경과 X-ray CT 이미지 분석을 통해 생성된 탄산칼슘의 공간적 분포를 확인하였다.

• Journal of Animal Science and Technology
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• 제64권4호
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• pp.603-620
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• 2022

Human activities have caused an increase in greenhouse gas emissions, resulting in climate change that affects many factors of human life including its effect on water and food quality in certain areas with implications for human health. CH₄ and N₂O are known as potent non-CO₂ GHGs. The livestock industry contributes to direct emissions of CH₄ (38.24%) and N₂O (6.70%) through enteric fermentation and manure treatment, as well as indirect N₂O emissions via NH₃ volatilization. NH₃ is also a secondary precursor of particulate matter. Several approaches have been proposed to address this issue, including dietary management, manure treatment, and the possibility of inhibitor usage. Inhibitors, including urease and nitrification inhibitors, are widely used in agricultural fields. The use of urease and nitrification inhibitors is known to be effective in reducing nitrogen loss from agricultural soil in the form of NH₃ and N₂O and can further reduce CH₄ as a side effect. However, the effectiveness of inhibitors in livestock manure systems has not yet been explored. This review discusses the potential of inhibitor usage, specifically of N-(n-butyl) thiophosphoric triamide, dicyandiamide, and 3,4-dimethylpyrazole phosphate, to reduce emissions from livestock manure. This review focuses on the application of inhibitors to manure, as well as the association of these inhibitors with health, toxicity, and economic benefits.

• 한국미생물·생명공학회지
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• 제28권3호
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• pp.161-166
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• 2000

Monilinia fructicola에 의해 감염되어 미이라화된 복숭아 열매로부터 Monilinia fructicola에 강한 항진균성 물질 chitinase 및 urease을 분비하는 방선균을 분리하였다 선발된 TH-04 균주는 배양적 .형태적 특성 세포벽 성분 및 세포내 당 성분을 분석한 결과 전형적인 Streptomyces속에 속하는 방선균으로 동정되었다. TH-04 균주는 Monilinia fructicola Colletotrichum gloeosporioides Magnaporthe grisea Rhizoctonia solani, Phytophthora capsici, Alternaria kikuchi-ana, Fusarium solani 및 Fusarium oxysporum 등 8종의 식물병원균에 대하여 항진균 활성을 나타냈다. 항생물질 생산을 위한 배양조건은 온도 $20^{\circ}C$, pH 7 및 배양기간 7일로 확인되었다.