• Microbiology and Biotechnology Letters
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• v.40 no.2
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• pp.83-91
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• 2012

Quorum sensing (QS) is a cell-to-cell communication system, which is used by many bacteria to regulate diverse gene expression in response to changes in population density. Bacteria recognize the differences in cell density by sensing the concentration of signal molecules such as N-acyl-homoserine lactones (AHL) and autoinducer-2 (AI-2). In particular, QS plays a key role in biofilm formation, which is a specific bacterial group behavior. Biofilms are dense aggregates of packed microbial communities that grow on surfaces, and are embedded in a self-produced matrix of extracellular polymeric substances (EPS). QS regulates biofilm dispersal as well as the production of EPS. In some bacteria, biofilm formations are regulated by c-di-GMP-mediated signaling as well as QS, thus the two signaling systems are mutually connected. Biofilms are one of the major virulence factors in pathogenic bacteria. In addition, they cause numerous problems in industrial fields, such as the biofouling of pipes, tanks and membrane bioreactors (MBR). Therefore, the interference of QS, referred to as quorum quenching (QQ) has received a great deal of attention. To inhibit biofilm formation, several strategies to disrupt bacterial QS have been reported, and many enzymes which can degrade or modify the signal molecule AHL have been studied. QQ enzymes, such as AHL-lactonase, AHL-acylase, and oxidoreductases may offer great potential for the effective control of biofilm formation and membrane biofouling in the future. This review describes the process of bacterial QS, biofilm formation, and the close relationship between them. Finally, QQ enzymes and their applications for the reduction of biofouling are also discussed.

• KSBB Journal
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• v.4 no.1
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• pp.18-20
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• 1989

Solid gelatin microcarrier with the size distribution between $100{\mu}{\textrm}{m}$ and $400{\mu}{\textrm}{m}$ was prepared for the attachment and growth experiment for anchorage-dependent animal cell lines, i.e., L 929 and BHK 21. The growth and the maximum cell densities on this gelatin based and polyacrylamide (PAA) microcarriers were compared with those on the commercial dextran based Cytodex 3 microcarrier. Both cell lines showed good comparable attachment and growth patterns on the above three microcarriers. The mouse fibroblast, L 929 showed about the same maximum cell density on PAA, gelatin and Cytodex 3 MC'S BUT BHK 21, the baby hamster kidney cell line, showed the best result on Cytodex 3, which was about $4\times10^6$ cells/ml with the microcarrier concentration of 10 g/1.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.6
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• pp.29-36
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• 2015

In this study, to examine the use of sulfur polymer as a coating agent for concrete, durability and hazard evaluations were performed. The result of the evaluation indicated that the chemical resistance of the coating agent for concrete was outstanding against acidic, base, and alkaline solutions. The evaluation of the bond strength after an accelerated weathering test depending on the mixing condition indicated that the most outstanding strength characteristic was obtained when silica powder and fly ash were mixed at the same time. The bond strength exceeded 1 MPa in every mixing condition even after the repeated hot and cold treatment of the coating agent specimen for concrete, and the SFS mix proportion showed the highest bond strength. The examination of the accelerated carbonation and chloride ion penetration resistance of the concrete coated with the coating agent indicated that the specimen coated with the coating agent using silica powder as a filler showed the most outstanding durability. When a fish toxicity test was performed to examine the hazard of the use of the functional polymer as a coating agent for concrete, the functional polymer was found to have no effect on the organisms. When the chemical resistance, freezing and thawing resistance, carbonation, and chloride ion penetration resistance of the coating agent were considered, substituting silica powder and fly ash as the fillers of the functional polymer by 20%, respectively, was the optimal level in the range of this study.

• Korean Journal of Environmental Biology
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• v.27 no.1
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• pp.88-94
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• 2009

The process of atherosclerosis begins through secretion of inflammatory cytokine or adhesion of leukocyte from damage in blood vessels and transmigration. This study was conducted to investigate the effects of delphinidin chloride (DC) in the initial process of atherosclerosis on the expression of ICAM-1 (Intracellular Adhesion Molecule-1) and VCAM-1 (Vascular Adhesion Molecule-1) related to adhesion of leukocyte at the HUVEC (human umbilical vein endothelial cell line. As a result, cell growth inhibition rate at 50 ${\mu}M$ was respectively 4, 3 and 5% without cell toxicity. As a result of morphological observation monocyte-endothelial cell adhesion assay and optical microscope carried out to measure attachment of mononuclear cells to endothelial cells induced by Tumor necrosis factor-alpha (TNF-$\alpha$) at concentrations without cell toxicity, DC concentration-dependently suppressed attachment. When effects on the expression of VCAM-1 and ICAM-1, cell adhesion molecules induced from endothelial cells by TNF-$\alpha$, were comparatively analyzed using western blot analysis and RT-PCR methods, protein of VCAM-1 and ICAM-1 and expression at the level of mRNA were concentration-dependently reduced. Taken together, the results of this studies provide evidence that DC possess an anti-metastatic activity.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.2
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• pp.184-191
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• 2007

Coal-, coconut- and wood-based activated carbons and anthracite were tested for an adsorption and biodegradation performances of nitrogenous chlorinated by-products such as chloropicrin, DCAN, DBAN and TCAN. In early stage of operations, an adsorption performance was a main mechanism for removal of nitrogenous chlorinated by-products, however as increasing populations of attached bacteria, the bacteria played a major role in removing nitrogenous chlorinated by-products in the activated carbon and anthracite biofilter. It was also investigated that the compounds were readily subjected to biodegrade. Whilst the coal- and coconut-based activated carbons were found most effective in adsorption of the compounds, the anthracite was worst in adsorption of the compounds. Highest populations and activity of attached bacteria were shown in the coal-based activated carbon. The populations and activity of attached bacteria decreased in the order: coconut-based activated carbon > wood-based activated carbon > anthracite. The attached bacteria were inhibited for removal of the compounds at temperatures below $10^{\circ}C$. The attached bacteria were more active at higher water temperatures$(20^{\circ}C\;<)$ but less active at love. water temperature$(10^{\circ}C\;>)$. The removal efficiencies of the compounds obtained using coal-, coconut- and wood-based activated carbons and anthracite were directly related to the water temperatures. In particular, water temperature was the most important factor for removal of the compounds in the anthracite biofilter because the removal of the compounds depended mainly on biodegradation. Therefore, the main removal mechanism of the compounds the main mechanism on the removal of the compounds using activated carbon was both adsorption and biodegradation by the attached bacteria. The observation suggests that using coal-based activated carbon is the best for removal of nitrogenous chlorinated by-products in the water treatment.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2022.09a
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• pp.50-50
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• 2022

비짜루과 둥굴레속(Asparagaceae: Polygonatum)은 전 세계적으로 약 90여 종이 알려져 있으며, 유럽, 북아메리카, 아시아 등 북반구 온대 지역에 집중적으로 분포한다. 국내 둥굴레속 분류군은 총 16분류군이며, 이중 잎이 호생하고, 난형에서 타원형 모양의 엽질성 포를 가지며, 화피통 내부에 털이 없고, 수술대 표면에 돌기가 나있는 분류군들은 용둥굴레열(series. Bracteata)에 속한다. 그러나 이들은 종간 교잡 또는 주요 기관의 형질 변이가 다양하여 중간형질을 보이는 개체군들에 대한 종 식별에 많은 어려움이 있었다. 경남 창원시에서 채집된 목포용둥굴레(P. cryptanthum) 변이 개체집단는 기존의 목포용둥굴레와 달리 식물체 높이와 화경·소화경이 길며, 포 부착위치의 변이 폭이 넓으며, 포가 타원형이고 밖으로 말리는 습성으로 형태적 차이가 나타났다. 따라서 본 연구에서는 명확한 분류학적 실체를 구명하고자 분자생물학적 계통분석(nrDNA ITS + cpDNA matK, trnK-rps16, rps16, rbcL) 연구를 진행중에 있다.

• Journal of Ocean Engineering and Technology
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• v.23 no.6
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• pp.39-43
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• 2009

A flow and low temperature of deep seawater the biofouling properties in a seawater environment of different materials, such as a steel pipe, polyethylene pipe, and nylon net, used for ocean industries. Experiments in a real sea environment were performed to grasp the quantitative and qualitative biofouling from diatoms attached to materials by measuring the Chlorophyll-a density. Experimental samples were placed under five types of ocean environmental conditions and analyzed every month for five months. It is shown that the biofouling by diatoms was strongly affected by the seawater temperature for all of the experimental samples. It was found that diatoms mainly adhered to the nylon net, while crustaceans prefer polyethylene, under a high temperature condition. It is believed that the biofouling properties are strongly related to the surface roughness of a material. The biofouling under the low temperature condition of deep seawater was rare and stable for the experimental periods. The inside of a pipe conveying deep seawater can be presumed to remain clear without biofouling on the condition of a flow and low temperature of deep seawater.

• Environmental Analysis Health and Toxicology
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• v.23 no.4
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• pp.337-343
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• 2008

따개비류는 암반기질에 무리를 이루어 비교적 단단히 부착생활을 하며 전 세계적으로 분포하는 생물이다. 본 생물은 형태가 다른 두 단계의 플랑크톤 유생시기를 거쳐 기질에 부착하여 생활한다. 따개비류에 관한 국내연구는 순수 분류학적으로 몇 편의 연구가 이루어졌을 뿐이며 실험실 내 사육조건 및 유생의 민감도 등에 관한 연구는 제대로 수행되어 있지 않은 실정이다. 본 연구에서는 첫 번째 단계 유생을 대상으로 몇몇 중금속(Cd, Cr, Cu 그리고 Zn)에 대한 민감도를 조사하였고 타 연구결과와의 비교로 생태 독성학적 적용을 시도하였다. 네 가지 금속물질, 카드뮴, 크롬, 구리 그리고 아연에 대한 따개비 유생의 반수사망농도는 각각 0.43, 24.4, 0.22 그리고 1.74mg/L로 산정되었다. 외국의 생물검정용 따개비와 본 연구에 사용된 고랑따개비의 민감도는 아주 유사하게 나타났다. 따라서 국내산 고랑따개비의 유생은 해양 환경 평가에 일반적으로 이용되는 해양생물과 동반 검정의 수행에 자격을 갖추었다고 할 수 있다. 본 연구의 결과는 해양환경의 평가는 물론 방오물질개발 등에의 기초자료를 제공할 수 있을 것으로 사료된다.

• Journal of Applied Biological Chemistry
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• v.64 no.4
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• pp.357-362
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• 2021

In this study, to investigate the anticariogenic effect of red ginseng, the antibacterial effect, cell adherence and biofilm formation inhibitory effect of n-hexane extract of red ginseng marc (HERGM) against Streptococcus mutans, the causative bacteria of caries, were measured. The growth of S. mutans was inhibited in proportion to the concentration of HERGM, and was hardly observed at a concentration above 125 ㎍/mL (MIC =125 ㎍/mL). It was found that HERGM acts on the cell membrane and the nucleic acid component of the cell was leaked. In addition, HERGM inhibited the adherence and biofilm formation of S. mutans by more than 90% at a concentration of 125 ㎍/mL. GTase activity was completely inhibited at a concentration of 50 ㎍/mL of HERGM. In conclusion, it was found that HERGM commonly inhibited the growth and biofilm formation of S. mutans.

• Development and Reproduction
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• v.2 no.1
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• pp.81-87
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• 1998

A scanning electron microscopic study on the glochidial encystment and excystment during the development of Anodonta arcaeformis flavotincta on Carassius auratus, a common natural host fish, was carried out. The glochidia were attached to the fins, buccal cavity and gills of the host fish within 30 minutes. In this study, the fins of host fish infected with the glochidia were examined in a time series. The attachment rates of the glochidia on the pectoral fins, caudal fin and pelvic fins of the host fish were 30%, 22%, and 17%, respectively. The glochidia which attached to the fish became encysted within 27 hrs. The process of encystment progressed slowly. Ti took 24 to 27 hours in the formation of the primary cyst, and after 5 to 6 days, the larvae was covered completely with the epithelial cels of the host tissues. The process of detachment of juvenile clam was observed on the 8th day after host infection. Most of the juvenile clams have sloughed from the cyst of the host within 15 days. No significant size difference was observed in the glochidia and the juvenile which were found before attachment and after detachment from the cyst of the host fish.