• Journal of Microbiology and Biotechnology
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• 제31권12호
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• pp.1684-1691
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• 2021

In this study, the physicochemical changes related to fishy smell were determined by storing high hydrostatic pressure (HHP)-treated mackerel (Scomber japonicus) meat in a refrigerator for 20 days. The inhibition of crude urease activity from Vibrio parahaemolyticus using HHP treatment was also investigated. The mackerel meat storage experiment demonstrated that production of trimethylamine (TMA) and volatile basic nitrogen (VBN), the main components of fishy smell, was significantly reduced on the 20th day of storage after the HHP treatment compared to the untreated mackerels. The results demonstrated that the increased ammonia nitrogen rates in the 2000, 3000, and 4000 bar, HHP-treated groups decreased by 23.8%, 23.8%, and 31.0%, respectively, compared to the untreated groups. The enzyme activity of crude urease was significantly reduced in the HHP-treated group compared to that in the untreated group. Measurement of the volatile organic compounds (VOCs) in mackerel meat during storage indicated that the content of ethanol, 2-butanone, 3-methylbutanal, and trans-2-pentenal, which are known to cause off-flavor due to spoilage, were significantly reduced by HHP treatment. Collectively, our results suggested that HHP treatment would be useful for inhibiting the activity of urease, thereby reducing the fishy smells from fish and shellfish.

• Journal of Microbiology and Biotechnology
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• 제32권6호
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• pp.808-815
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• 2022

In this study, gamma-irradiated mackerel (Scomber japonicus) meat was stored in a refrigerator for 20 days to examine the physicochemical changes related to fishy smell. The effect of gamma irradiation on the inhibition of the activity of crude urease extracted from Vibrio parahaemolyticus was also evaluated. Increased levels of trimethylamine (TMA) and volatile basic nitrogen (VBN) content, which are the main components causing fishy smell, were significantly reduced by day 20 of storage after gamma irradiation, indicating that freshness was maintained during storage. The ammonia nitrogen contents of 3, 7, 10, and 20 kGy gamma-irradiated groups were significantly decreased by 6.5, 15.2, 17.4, and 23.9%, respectively, compared to non-irradiated groups on day 20 of storage. In addition, urease activity decreased in a gamma irradiation intensity-dependent manner. Volatile organic compounds (VOCs) were measured during the storage of gamma-irradiated mackerel meat. The contents of ethanol, 2-butanone, 3-methylbutanal, and trans-2-pentenal, which are known to cause off-flavors due to spoilage of fish, were significantly reduced by day 20 of storage. Therefore, gamma irradiation can be considered useful for inhibiting urease activity and reducing fishy smell during fish storage.

• KSBB Journal
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• 제29권5호
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• pp.323-327
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• 2014

Microbially induced calcite precipitation is a naturally occurring biological process in which microbes produce calcite on the surface of the microorganisms by urease activity. In order to collect calcite forming bacteria (CFB) in Korea, we isolated 343 putative CFB strains from various environments over three year period (2011~2013) and selected 100 CFB strains. Average of calcite productivity was 10.56 mg/mL. And average of ammonium concentration by urease activity was $8.00{\mu}M$. Two useful CFB strains of the others were analyzed by 16S rRNA and identified as Sporosarcina sp. and Viridibacillus arenosi. The CFB strains presented in this study are indigenous microorganisms in Korea and they are expected to be applicable to a variety of environments in the country.

• Journal of Microbiology and Biotechnology
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• 제20권11호
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• pp.1571-1576
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• 2010

Two bacterial strains designated as CT2 and CT5 were isolated from highly alkaline cement samples using the enrichment culture technique. On the basis of various physiological tests and 16S rRNA sequence analysis, the bacteria were identified as Bacillus species. The urease production was 575.87 U/ml and 670.71 U/ml for CT2 and CT5, respectively. Calcite constituted 27.6% and 31% of the total weight of sand samples plugged by CT2 and CT5, respectively. Scanning electron micrography analysis revealed the direct involvement of these isolates in calcite precipitation. This is the first report of the isolation and identification of Bacillus species from cement. Based on the ability of these bacteria to tolerate the extreme environment of cement, they have potential to be used in remediating the cracks and fissures in various building or concrete structures.

• Archives of Pharmacal Research
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• 제19권6호
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• pp.447-449
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• 1996

Inhibitory effects of the mushrooms on the growth and urease of Helicobacter pylori (HP), which is associated with human gastroduodenal diseases such as gastritis, peptic ulcer and gastric carcinoma, were investigated. Most of the mushroom extracts did not show inhibitory effect on HP urease except Coriolus versicolar, Auricularia auricular Sarcodon aspratus and Flammulina velutipes. The extract of Ganoderma lucidum, Coriolus versicolar, Gyropora esculenta and Agaricus bisporus var. albidus inhibited the growth of HP. When their extracts were fractionated, the ether fraction of Ganoderma lucidum and Agaricus bisporus var. albidus were the most effective. Among seven components separated from the ether fraction of G. lucidum extract by silica gel column chromatography, P3 was the most potent: MIC was $200{\mu}g/ml$. However, P3 did not inhibit the urease.

• Archives of Pharmacal Research
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• 제22권3호
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• pp.274-278
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• 1999

Expression of the active urease of the enterobacterium, Klebsiella aerogens, requires the presence of the accessory genes (ureD, ureE, ureF, and ureG) in addition to the three structural genes (ureA, ureB, and ureC). These accessory genes are involved in functional assembly of the nickel-metallocenter for the enzyme. Characterization of ureF gene has been hindered, however, since the UreF protein is produced in only minute amount compared to other urease gene products. In order to overexpress the ureF gene, a recombinant pMAL-UreF plasmid was constructed from which the UreF was produced as a fusion with maltose-binding protein. The MBP-UreF fusion protein was purified by using an amylose-affinity column chromatography followed by an anion exchange column chromatography. Polyclonal antibodies raised against the fusion protein were purified and shown to specifically recognize both MBP and UreF peptides. The UreF protein was shown to be unstable when separated from MBP by digestion with factor Xa.

• 한국식품과학회지
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• 제35권6호
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• pp.1182-1187
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• 2003

위질환 원인균으로 알려진 H. pylori 생육을 저해하는 물질을 탐색하기 위하여 호장근 메탄을 추출물 및 분획물을 이용하여 H. pylori에 대한 항균실험 및 urease 활성 억제효과를 검토하였다. 호장근 메탄올 추출물의 항균실험을 실시한 결과 5mg/cylinder의 농도일 때 inhibition zone이 17mm 정도로 높은 항균성을 가지는 것으로 나타났으며, 분획물의 경우 1mg/cylinder의 농도일 때 hexane 분획과 chloroform 분획물에서 각각 24mm, 17mm로 높은 항균 활성을 보였다. H. pylori의 crude urease를 분리하여 urea broth에서 흡광도와 pH를 조사한 결과, 반응 2시간 후 pH가 8.35까지 증가하였고 $O.D._{560nm}$에서의 흡광도는 0.859까지 증가하였다. 호장근에 의한 urease 활성억제는 호장근의 메탄올 추출물의 농도가 0.5 mg/mL에서 대조구에 비해 35% 억제효과를 보였고, 2 mg/mL에서는 85% 이상으로 매우 높은 억제활성을 보였다. 또한. 각 분획물의 저해 효과를 10배 농도의 메탄올추출물과 비교하였을 때. $20\;{\mu}g/mL$의 농도에서 water 분획을 제외한 모든 분획물들이 반응 2시간 후 $30{\sim}40%$의 저해를 보여 $200\;{\mu}g/mL$ 농도의 메탄올추출물이 20% 이하의 저해를 보인 것과 비교해 높은 활성을 보였다. 호장근 메탄올 추출물 처리에 의한 H. pylori의 형태변화를 조사하기 위하여 주사 및 투과전자 현미경으로 균의 형태를 관찰하였다. 주사전자 현미경 관찰 시 대조구는 균체 표면이 깨끗하고 완전한 구형을 이루고 있는 반면, 호장근 처리구는 균체 표층 구조가 심하게 허물고 떨어져 나간 것을 볼 수 있었고 또한 세포가 팽대하였고 일부 세포벽은 완전히 파괴되어 균체내 성분이 모두 유출되어 균 형태가 없어져 버린 것도 관찰되었다.

• 미생물학회지
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• 제37권2호
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• pp.151-157
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• 2001

위염 및 위궤양, 심이지장궤양, 위암의 주요한 발병 원인균으로 알려져 있는 Helicobacter pylori의 생육을 특이적으로 억제하는 유산균을 선발하기 위해서, 45종의 유산균에 대하여 paper disk법을 이용한 항균 효과, Caco-2세포에 대한 정착능, urease activity법을 이용한 H. pylori 억제능 등을 파악하고, 유산균 배양액과 H. pylori의 동시배양에 따른 요소 분해효소의 활성 변화와 우유 발효능 등을 실험하였다. H. pylori의 생육을 억제하는 물질의 생성 유무를 확인하기 위하여 paper disk법으로 유산균 배양액에 의한 H. pylori의 생육 억제환을 측정한 결과, 28종의 유산균에서 생육 억제환이 형성되었다. 대부분이 유산 생성에 의한 낮은 pH 때문인 것으로 판단되지만, 일부 균종에서는 항균성 물질에 의한 억제환이 형성되었다. 다른 유산균에 비해서 생육 억제환이 가장 큰 Lactobacillus gasseri MK-03 균주가 H. pylori에 대한 항균 활성이 가장 우수한 것으로 나타났다. 항균 활성을 나타낸 28종의 유산균을 대항으로 Caco-2 세포에 대한 정착능을 실험한 결과, 18종의 유산균에서 정착능이 확인되었으며, Bifidobacterium longum MK-26 균주가 가장 우수한 것으로 나타났다. 특히 반응 2시간 전에 미리 Caco-2 세포에 정착시켰을 때, H. pylori의 정착율은 0.105%에서 0.004%로 감소되었다. 한편 요소 분해효소 활성을 저해하여 H. pylori를 억제하는 유산균을 선발하기 위해서 항균활성이 인정되는 28종의 유산균을 대상으로 실험한 결과, 21종의 유산균에서 요소 분해효소 활성의 저해 효과가 나타났으며, 이중에서 Lb. acidophilus MK-07 균주가 가장 우수한 것으로 판명되었다. 따라서 Lb. gasseri MK-03 균주는 항균 활성에서, Lb. acidophilus MK-07 균주는 요소 분해효소의 활성 억제에 의해서, Bif. longum MK-26 균주는 정착능 저해에 있어서 각각 우수한 H. pylori 생육 억제능을 나타냈다. 한편 최종적으로 선발된 3종의 유산균과 대조균주로서 13종의 유산균에 대해서는 우유 배양실험을 실시한 결과, 3종의 선발균주 모두가 발효유 제품에의 응용 적합성을 나타냈다.

• Archives of Pharmacal Research
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• 제21권1호
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• pp.6-11
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• 1998

The activities of two types of antiulcer agents against 9 strains of Helicobacter pylori (H. pylori) were determined by the agar dilution method. The antiulcer agents were YJA20379, a newly synthesized proton pump inhibitor developed by Yung-jin Pharmaceutical company, and omeprazole. Both compounds were found to have significant activities against this organism. The MIC values of YJA20379 and omeprazole were 11.7 and $31.25{\mu.g/ml}$ respectively. In addition, the inhibitory potency of both compounds was investigated on H. pylori urease which is believed to be an important colonization and virulence factor in the pathogenesis of gastritis and peptic ulcers. These compounds dose-dependently inhibited urease extracted with distilled water and their $IC_50$ values were $16.4{\times}10^{-5} M and 14.3{\times}10^{-5}M,$ respectively. In addition, a pH-dependent study to determine whether inhibitory potency would be activated by acid condition was performed. It was found that unlike omeprazole, YJA20379 was not affected by acid condition. To determine the inhibition pattern and optimal concentration of substrate, kinetics were evaluated at various pH levels (pH 5.0, 7.0, and 8.5). The data show that YJA20379 noncompetitively inhibited H. pylori urease and $K_M/K_i$values were 0.96 $mM/60{\mu}M (pH 5.0), 0.56 mM/141.5 {\mu}M (pH 7.0)$, and $1.94mM/34{\mu}M (pH 8.5)$, respectively. Based on data obtained, it is concluded that YJA20379 is a significant inhibitor of H. pylori growth and urease and therefore, taking these results into consideration, YJA20379 might be a beneficial therapy for gastritis and peptic ulcers induced by H. pylori.

• 한국막학회:학술대회논문집
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• 한국막학회 2004년도 춘계 총회 및 학술발표회
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• pp.49-52
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• 2004

생체 내에서의 요소 형성은 단백질이 아미노산으로 분해되어 인체에 남은 요소는 오줌으로 배출된다. 그러나 고농도의 urea의 경우 단백질을 변형시키게 된다[1-2]. 이러한 고 농도의 urea를 단백질 공정을 통해서 제거시키는 기술이 최근의 투석 과학이다. 그러나 이러한 방법은 urea의 제거와 함께 많은 양의 단백질과 양이온이 유출 및 오염의 문제가 많이 발생하고 있다[3].(중략)