• Restorative Dentistry and Endodontics
• /
• 제25권4호
• /
• pp.587-598
• /
• 2000

Urea in the oral cavity is hydrolyzed mainly by bacterial ureases to ammonia, which in turn, raises pH of the oral environment, maintaining oral pH homeostasis, thereby inhibiting dental caries. Streptococcus salivarius has been shown to be a major contribution to oral ureolysis. Synthesis of urease by S. salivarius appears to be constitutive, but can be greatly enhanced in the acidic environment. It has been presumed that ureolytic activity of S. salivarius strains isolated from caries-active site is greater than that of strains from caries-free site. However, no in vivo study has supported the presumption. The present study was performed to observe the ureolytic activity of S. salivarius strains isolated from different environments in the same individual, finding out whether the ureolytic activity is related to dental caries. For the purpose, S. salivarius strains were isolated from caries-active site (>C2), a caries-free site of the tooth, and the dorsum of the tongue of each of 50 patients having decayed teeth. The strains isolated from the patients who harbored S. salivarius in more than two sites were selected and then their ureolytic activities were measured. In order to examine clonal diversity of the strains, their ureC genes were amplified by polymerase chain reaction (PCR) and then restricted with EcoRV, and the protein profiles of the strains were compared by SDS-PAGE. The results were as follows: 1. Of 50 patients, 13 patients harbored S. salivarius in more than two sites; a total of 61 S. salivarius strain were isolated from the patients and selected for the study. 2. Of 17 isolates from the caries-active site of 9 patients harboring S. salivarius in more than two sites including carious lesion, 10 (58.8%) showed a high ureolytic activity (> 200 ${\mu}mol/min/mg$). While, 19 out of 44 isolates (43.2%) from the caries-free site of the teeth and the dorsum of the tongues of 13 patients were the strains with a high ureolytic activity. 3. Of 9 patients harboring S. salivarius in more than two sites including caries-active site. 6 patients were found to have the strains in the caries-active site showing a lower ureolytic activity than the strains in the other sites. 4. Of 34 isolates with ureolytic activity higher than 40 ${\mu}mol/min/mg$, 32 isolates produced 0.54-Kbp PCR products regardless of the sites of bacterial collection. In contrast, of 27 isolates with ureolytic activity lower than 40${\mu}mol/min/mg$, 26 isolates yielded 1.3-Kbp PCR products or none regardless of the sites. 5. Different clonal types of S. salivarius with relatively higher and lower ureolytic activities were found in the same individuals and even in the same sites. 6. None of strains showing different ureolytic activity appeared to be the same clonal type. The overall results suggest that ureolytic activity of the isolates does not appear to be related to differences of the environments but related to their own genetic traits.

• 생태와환경
• /
• 제46권2호
• /
• pp.276-288
• /
• 2013

본 연구는 질소 시비에 의해 증가된 토양 질소가 식물의 성장 및 식물체의 화학적 조성에 미치는 영향과 이로 인한 분해에서의 변화를 확인하고자 야외성장실험과 분해실험을 진행하였다. 온실에서 질소 시비구와 비시구 토양에 각각 벼를 재배하였으며 식물이 성숙한 뒤 수확하여 C, N, lignin, cellulose 함량을 측정하였다. 대조구와 질소 처리구 토양에서 재배된 식물의 개체 당 평균 건중량은 각각 0.70 g, 1.32 g로 질소 시비에 의해 1.9배 증가하였다. 식물체의 N 및 C 함량은 질소 시비에 의해 증가하였고 lignin, C/N, lignin/N, cellulose/N은 감소하였다. 이후, 수확된 식물의 지상부는 microcosm 분해실험에 이용되었으며, 분해 식물체에서 건중량의 변화, microbial biomass C와 microbial biomass N, 그리고 dehydrogenase와 urease 활성을 측정하고, 분해과정 중 발생하는 $CO_2$의 양을 정량하였다. 대조구 토양에서 분해시킨 대조구 식물체와 질소 처리구 식물체, 그리고 질소를 처리한 토양에서 분해시킨 질소 처리구 식물체의 잔존량은 각각 초기 건중량의 53.0%, 47.1%, 53.6%를 나타내었다. 질소 시비는 식물체에서 N 함량을 높이고 C/N 및 lignin/N을 낮추어 식물체의 분해를 촉진하였으나, 분해 과정에서의 토양 질소처리는 분해를 억제하였다. 질소 시비에 의해 토양에서 microbial biomass C와 dehydrogenase 활성은 감소하였고, 반면에 microbial biomass N과 urease 활성은 증가하였다. 분해 중 발생한 $CO_2$의 양은 30일 이후부터 질소 시비에 의해 감소하였다. 분해 식물체에서 측정된 microbial biomass C는 질소 처리에 의해 초기에 증가하였으나 이후 저해되는 양상을 나타냈으며 microbial biomass N은 유의한 차이를 보이지 않았다. 질소 시비에 의해 분해 식물체에서 dehydrogenase 활성은 저해되었으며 urease는 분해 초기에 가장 높은 활성을 보였으나 분해 후기에 현저한 감소를 나타냈다. 본 실험에서 질소 시비는 식물의 성장을 증가시키고 식물체의 N 함량을 높여 화학적 조성의 변화를 일으키며 분해율을 증가시키나 분해 단계에서 질소의 시비는 미생물의 활성을 억제시켜 분해를 저해하는 결과를 나타내었다.

• Mycobiology
• /
• 제39권2호
• /
• pp.125-128
• /
• 2011

Enzyme activities of Cenococcum geophilum isolates were examined on enzyme- specific solid media. Deoxyribonuclease, phosphatase, and urease were detected in all isolates, whereas cellulase was not detected in any of the isolates. Variations in enzyme activities of amylase, caseinolysis, gelatinase, lipase, and ribonuclease were observed among isolates.

• Journal of Applied Biological Chemistry
• /
• 제48권4호
• /
• pp.187-192
• /
• 2005

Influence of herbicide oxadiazon on soil microbial activity and nitrogen dynamics was evaluated. Soil samples were treated with oxadiazon at field and tenfold field rates and incubated. Organic amendment was added as an additional substrate for soil microorganisms. Tenfold field rate oxadiazon stimulated substrate-induced respiration (SIR) and dehydrogenase activity (DHA) in amended soil as compared to unamended soil and control treatment. Soil urease activity was not affected by oxadiazon treatment. In both amended and unamended soils, treatment of the herbicide at higher rate had not significant influence on $NH_4$-N and $NO_3$-N concentrations. Higher dose of oxadiazon was degraded in both soils, but dissipation rate in amended soil was higher than unamended soil, with half-lives ($t_{1/2}$) of 23.1 and 138.6 days, respectively. Recommended field rate did not affect microbial activity and nitrogen dynamics in soil ecosystem. Results showed influence of oxadiazon on cycling processes of nitrogen in soil was not significant however its effect on microbial activity was a tendency depending on addition of organic amendment to soil.

• 한국균학회지
• /
• 제41권3호
• /
• pp.181-184
• /
• 2013

충남 금산군과 전남 완도군, 제주도 송악산 등지에서 서식하고 있는 야생화들로부터 Rhodosporidium fluviale 201-C-1과 Kluyveromyces thermotolerans 150-JE-2(1), Rodosporidium paludigenum과 Candida sp. 80-J-3등의 국내 미기록 효모들을 분리, 선발하여 이들의 미생물학적 특성들을 조사하였다. Rhodosporidium fluviale 201-C-1은 내염성의 무포자 효모로 의균사를 형성하였고 urease 활성을 갖고 있었다. Kluyveromyces thermotolerans 150-JE-2(1)는 내당성과 내염성을 가진 무포자효모로서 $30^{\circ}C$, pH 4.0~6.0에서 잘 생육하였다. Candida sp. 80-J-3과 Rhodosporidium paludigenum 86-J-1 균주들은 모두 무성생식을 하는 무포자 효모들이었고 YPD 배지, Vitamin-free 배지와 5% NaCl을 함유한 YPD 배지 등에서 잘 생육하였다. 또한 Candida sp. 80-J-3 균주의 urease 활성은 음성이었으나 Rhodosporidium paludigenum 86-J-1 균주는 urease 활성이 양성이면서 pH 7.0~8.0에서 잘 생육하였다.

• 한국토양비료학회지
• /
• 제42권3호
• /
• pp.222-229
• /
• 2009

화산회토 감귤원 토양의 시비관리에 따른 토양효소 활성과 인지질 지방산함량을 분석하여 토양미생물활성과 미생물군집구조에 미치는 영향을 평가하고자 수행하였다. 토양은 13년간 시비량을 달리하여 관리되고 있는 무비료구, 퇴비구, 1/2NPK+퇴비구, NPK+퇴비구, NPK구, 3NPK구에서 2007년 3, 5, 7, 9월초에 채취하여 분석하였다. Urease 활성은 3, 5, 9월에 NPK+ 퇴비구에서 가장 높게 나타났으며, 화학비료+퇴비구가 화학비료구보다 높았고, 3월과 5월은 NPK구>퇴비구>무비료구, 7월과 9월은 퇴비구>NPK구>무비료구 순이었다. Dehydrogenase활성은 5월에 1/2NPK+퇴비구가 $4.3ug\;TPF\;g^{-1}\;24h^{-1}$로 무비료구 $2.4ug\;TPF\;g^{-1}\;24h^{-1}$ 보다 높았고 처리간에 통계적 유의성을 나타냈다. $\beta$-glucosidase 활성은 5월에 NPK구와 1/2NPK+퇴비구가 무비료구 보다 높았으며 처리간에 유의성을 나타내었다. 3월에 인지질 지방산 총함량은 NPK+퇴비구가 $349.2n\;mol\;g^{-1}$로 3NPK구 $228.5n\;mol\;g^{-1}$보다 높게 나타났다. 5월은 1/2NPK+퇴비구가 $237.8n\;mol\;g^{-1}$로 3NPK구 $133.1n\;mol\;g^{-1}$보다 높았다. PLFA의 Biomaker에 의한 미생물군들의 분포비율은 조사시기와 처리간에 통계적으로 유의성 있는 변화를 나타내지 않았다. 시기별로 인지질 지방산 함량을 이용하여 처리구별 미생물군집의 변화에 대한 주성분 분석결과 3월의 경우 퇴비구와 3NPK구가 다른 처리구와 다르게 군집구조를 나타냈으나 5월에는 퇴비구와 3NPK구간에 군집구조의 차이가 나타나지 않았으며, 7월과 9월에는 처리구간에 군집구조의 차이가 없었다. 화학비료 시비와 시간적 변이가 미생물 군집구조 변화에 영향을 준 것으로 판단되었다.

• 한국토양비료학회지
• /
• 제27권1호
• /
• pp.40-47
• /
• 1994

담수(湛水)된 고유기물(高有機物) 논토양에서의 ammonium thiosulfate(ATS)의 urease 활성(活性) 억제(抑制) 효과(效果)와 토양의 생물학적 활성 및 화학적 성질에 미치는 영향을 조사하고, ATS의 효과를 sodium thiosulfate(STS)와 비교하고 유기물 처리의 영향을 검토한 결과를 요약하면 다음과 같다. 1. Thiosulfate의 urease 활성 저해 효과는 3~5일후부터 나타났다. glucose 첨가구에서는 STS 처리가 ATS보다 효과가 다소 컸고, glucose를 첨가하지 않았을 때에는 처리 효과가 비슷하였다. 2. Thiosulfate 처리구의 pH는 초기에 높아지다가 glucose 무첨가시에는 10일 이후 낮아졌고, glucose 첨가시에는 15일 이후 낮아졌다. Eh는 thiosulfate 처리에 의하여 대체로 낮아졌다. 3. Thiosulfate 처리구에서 acet 산(酸)과 butyr 산(酸)은 소량($10{\mu}g/g$ 이하) 검출되었으므로, thiosulfate 처리에 의해 수도(水稻)의 생육이 저해되지는 않을 것이라 추정된다. 4. Glucose를 첨가하지 않았을 때에는 thiosulfate 처리에 의해 $CO_2$ 발생량이 증가하여 토양 생물의 활성을 높였다고 해석된다.

• Asian-Australasian Journal of Animal Sciences
• /
• 제6권3호
• /
• pp.441-445
• /
• 1993

Ten bacteriocin-producing Enterococcus faecium strains with urease activity ($1.10-6.2nkat.mL^{-1}$) were isolated from the rumen of 2-8 weeks old calves. All strains were resistant aginst disodium arsenate at a minimal inhibition concentration - MIC $5g.L^{-1}$ and mercury chloride ($MIC=10-20mg.L^{-1}$). Eight strains were resistant against silver nitrate ($MIC=40-50mg.L^{-1}$) and three against antibiotics used. The resistance against six antibiotics was found in A23 strain. Values of adherence index ranged from 5.02 to 20.4 enterococci adhered per one epithelial cell of rumen wall. All isolates produced bacteriocins which inhibited the growth at least of one of five indicator organisms. The EF1 strain with a good affinity to the epithelial cell ($15.2{\pm}1.2$) produced bacteriocin substance with antimicrobial activity against grampositive and gramnegative indicator bacteria.

• Journal of Microbiology and Biotechnology
• /
• 제10권4호
• /
• pp.532-534
• /
• 2000

The inhibitory effects of different Bifidobacterium spp. on the growth of Helicobacter pylori (HP) were investigated. A significant suppression of HP growth occurred only when HP was inoculated onto a petri dish containing 0.1 mg/ml of Bifidobacterium spp. When HP was separately cultured with B. breve K-110, B. catenulatum K-309, B magnum K-311, B. magnum K-321, and B. cuniculi K-513, the urease activity was also inhibited by these Bifidobacterium spp. Therefore, it appears that these Bifidobacterium spp. excrete a heat-labile inhibitory component for HP growth into the culture medium. Although most organic acids produced by the Bifidobacterium spp. inhibited the growth of HP, the HP growth was not inhibited by the physiological concentrations of organic acids produced in bifidobacteria-cultured media. Accordingly, these results suggest that some Bifidobacterium spp. may produce antibiotic-like compounds (bacteriocins).

• Asian-Australasian Journal of Animal Sciences
• /
• 제10권4호
• /
• pp.398-401
• /
• 1997

A caecal fermentation study was conducted in 30 Angora rabbits equally placed under five whole diets (75 concentrate : 25 roughage) supplemented with processed Neem (Azadirachta indica) kernel meal (NKM ; 2% urea or 1.5% NaOH, W/W), replacing isonitrogenously either at 50 or 100% level of deoiled peanut (Arachis hypogea) meal, for 18 wk period. The total volatile fatty acids level was depressed (p < 0.05) in all the experimental groups (0.02 to 0.04 mEq/g) and ammonia-nitrogen was lowest (p < 0.05; $24.9{\mu}mol/g$) in rabbits fed NaOH treated NKM supplemented diet. Enzyme activity (unit/g) of carboxy methyl-cellulase, ${\alpha}$-amylase, protease and urease exhibited much variation and did not differ significantly. Hence, the results could not confirm a possible adverse effect of feeding NKM on caecal fermentation.