• Journal of Microbiology
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• 제42권4호
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• pp.357-360
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• 2004

For determining the process of bacterial aggregation, glucose was added into water from Lake Baikal which had been stored for seven months. In the presence of a higher concentration of glucose, the abun­dance of single bacteria and aggregates were higher, but the biovolumes of both bacteria were similar. Theses results mean that both free-living and aggregated bacteria have similar maximum sizes and that aggregates are forming with available organic materials. With available organic materials, the biovol­ume of aggregates becomes larger.

• 미생물학회지
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• 제36권4호
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• pp.292-298
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• 2000

팔당호에서 fluorescent in situ hybridization(FISH) 방법을 이용하여 aggregates에 부착한 세균군집의 변화를 조사하였다. 조사대상은 Eubacteria에 속하는 세균과 Class Proteobacteria에 속하는 세균중 $\alpha$-, $\beta$-, $\gamma$ -group과 Cytophaga-Flavobacterium group이었고, 환경요인의 변화를 파악하고자 영양염류와 엽록소 a를 측정하였다. Aggregate와 물시료의 조사항목을 비교하면, TN의 경우 5~15배, TP는 81~140배, 엽록소 a는 49~66배로 aggregate가 높게 나타났으며, 총 세균수 역시 물시료에서 전체적으로 1.0~$2.0{\times}10^6$cells.$ml^{-1}$이었고, aggregates 부착세균에서 0.2~~$3.6{\times}10^8$cells.$ml^{-1}$의 범위로 물시료보다는 aggregates에 부착한 세균의 밀도가 200배 높았다. 또 수심별로는 5m trap 보다 20m trap에서 더 많은 수가 측정되었다. 총 세균수에 대한 세균군집구조의 비율은 부유세균의 경우 $\alpha$-group이 4.5~8.3%, $\beta$-group이 2.2~8.0%, ${\gamma}$-group이 2.1~7.4%, Cytophaga-Flavobacterium group이 2.1~6.1% 'Other'group은 0.1~2.5로 매우 낮았으나 aggregate에 부착한 세균의 군집구조는 $\alpha$-, $\beta$-, $\gamma$-group과 Cytophaga-Flavobacterium group이 아닌 'Other'group이 약 10.2~32.1%로 우점하는 경향을 보였다. 이처럼 팔당호에서 aggregates에 부착한 세균의 군집구조는 부유세균과 비교해볼 때 독특한 군집구조를 나타내었다.

• Geosystem Engineering
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• 제21권5호
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• pp.291-296
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• 2018

The aim of this work is to study the effect of aggregate type on the physico-mechanical properties and microstructure of bio-mortar (BM). Three different aggregates such as sand, dolomite and basalt were used. BM was prepared by mixing aggregates with bacterial cells (Sporosarcina Pasteurii) and one equimolar (1 M) of $urea/CaCl_2.2H_2O$. The results proved that the chemical composition and physical properties of aggregates play an important role in the microbial precipitation rate as well as size, morphology and crystallinity of the precipitated calcite, which strongly reflects on the properties of the prepared BM. The BM containing dolomite gave the highest compressive strength and lowest water absorption.

• 한국결정성장학회지
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• 제25권5호
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• pp.212-217
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• 2015

본 연구는 해상 양식장 내에 유해 조류로 인해 발생하는 수산 동, 식물의 폐사를 막고, 양식장을 주기적으로 정화하는 폰툰 시스템 내의 멤브레인 층(Membrane Layer)의 생물오손(Biofouling)을 막고자, ML에 적용되는 인공경량골재 및 골재의 구조에 따른 미생물 흡착을 비교하고자 지오폴리머에 은 나노 입자를 코팅하여 생물오손 정도를 확인하고 그 능력을 평가하였다. 이후 코팅에 따른 미생물 기능 억제 능력을 확인하고자 항균 테스트를 실시하였으며, 한국해양과학기술원 남해연구소 앞바다에 설치하여 생물오손 정도와 무게변화율을 관찰하였다. 항균 테스트 결과 은 나노 입자를 코팅한 인공경량골재에서 99.99 %의 세균 감소율을 확인하였으며, 생물오손 정도를 관찰한 결과 2개월부터 은 나노 입자의 효과에 의해 생물오손 정도가 억제되는 것을 확인하였다. 은 나노 입자 코팅에 의한 생물오손 억제기간은 인공경량골재에서 5개월, 지오폴리머에서 3개월 미만으로 나타났으며, 따라서 은 나노 입자가 코팅된 인공경량골재가 효과적으로 생물오손을 감소시킬 수 있는 친환경적이며 효과적인 방법임을 알 수 있었다.

• The Plant Pathology Journal
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• 제26권3호
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• pp.238-244
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• 2010

Spatial and temporal distribution of Bacillus licheniformis N1 was investigated over time on the leaves, petioles and crowns of the strawberry plants. Bacterial population on the strawberry plants was quantified over time by selective plating. Bacterial population of N1 containing a plasmid pWH43G carrying green fluorescent protein (GFP) declined relatively faster on the plant surface as compared to the Strain N1 itself. However, this result was found to be enough to utilize the strain to visualize bacterial colonization on the plant surface. When B. licheniformis N1 was treated together with Silwet L-77 at 0.03%, the bacterial population on plant surface persisted for up to 7 days. B. licheniformis N1 (pWH43G) containing Silwet L-77 was applied on the strawberry plants and the GFP expressing bacteria were visualized by confocal laser scanning microscopy. Bacterial persistence was also investigated in a growth chamber and in a plastic house after N1 bioformulation treatment on the strawberry plant. The Strain N1 colonized three different tissues well and persisted over 3 to 5 days on the strawberry plants. They formed bacterial aggregates on plant surfaces for at least 3 days, resulting in a biofilm to resist fluctuating plant surface environment. However, the bacterial persistence dramatically declined after 7 days in all tested tissues in a plastic house. This study suggest that B. licheniformis N1 colonizes the strawberry plant surface and persists for a long time in a controlled growth chamber, while it can not persist over 7 days on the plant surface in a plastic house.

• 한국광물학회지
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• 제12권1호
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• pp.32-42
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• 1999

Microbial mats, the yellow and reddish brown deposits formed from the mine drainage, occur on the bottom of drain and mine tailing pond of the Ilkwang mine in Pusan, Korea. The constituents of microbial mats and their biomineralization were studied by using XRD, IR, and SEM-EDX. The upper part of the microbial mat is yellow-colored and composed of tube-shaped and small spheroid bacterial materials, which are mainly made up of amorphous and poor-crystalline iron-oxide minerals. The shape and composition of bacterial materials suggest that they are probably belong to iron-oxide mineral aggregates. The iron-oxide minerals of the yellow microbial mats are mainly goethite, but those of the reddish brown microbial mats contain abundant hematite along with goethite. This implies that with the evolution of biomats, goethite may be transformed to hematite.

• Journal of Periodontal and Implant Science
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• 제36권1호
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• pp.265-272
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• 2006

Dental plaque, a biofilm consisting of more than 500 different bacterial species, is an etiological agent of human periodontal disease, It is therefore important to characterize interactions among periodontopathic microorganisms in order to understand the microbial pathogenesis of periodontal disease. Previous data have suggested a synergistic effect of tow major periodontal pathogens Porphyromonas gingivalis and Tannerella forsythia in the periodontal lesion. In the present study, to better understand interaction between P. gingivalis and T. forsythia, the coaggregation activity between these bacteria was characterized. The coaggregation activity was observed by a direct visual assay by mixing equal amount (1 ${\times}$ $10^9$)of T. forsythia and P. gingivaJis cells. It was found that the first aggregates began to appear after 5-10 min, and that the large aggregates completely settled within 1 h. Electron and epifluorescence microscopic studies confirmed cell-cell contact between two bacteria. The heat treatment of P. gingivalis completely blocked the activity, suggesting an involvement of a heat-labile component of P. gingivalis in the interaction. On the other hand, heat treatment of T. forsythia significantly increased the coaggregation activity; the aggregates began to appear immediately. The coaggregation activity was inhibited by addition of protease, however carbohydrates did not inhibit the activity, suggesting that coaggregation is a protein-protein interaction. The results of this study suggest that coaggregation between P. gingivalis and T. forsythia is a result of cell-cell physical contact, and that coaggregation is mediated by a heat-labile component of P. gingivalis and T. forsythia component that can be activated on heat treatment.

• Journal of Microbiology and Biotechnology
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• 제18권11호
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• pp.1762-1767
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• 2008

Image contrast of whole bacteria was compared in Staphylococcus aureus and Escherichia coli depending on pre-stain suspension liquids by energy-filtering transmission electron microscopy. The two bacterial strains were suspended in three most commonly used liquids for negative staining (triple distilled water [DW], phosphate-buffered saline [PBS], and nutrient broth [NB]) and directly observed without staining or stained with neutralized potassium phosphotungstate (PTA), respectively. Even though in low contrast, unstained bacteria were observed owing to their inherent electron density and cell shape in zero-loss (elastic scattering) images. After being suspended in PBS, unstained bacteria appeared to have higher contrast and more refined periphery than DW-suspended ones, and extracellular appendage structures such as fimbriae and flagella could be discerned. The unstained bacteria appeared to be invariably surrounded with electron-lucent precipitates, possibly from PBS. As far as delineation of the structures, the combination of DW or PBS suspension with subsequent staining provided the most satisfactory results, as evidenced by the high contrast of bacterial morphology and appendage structures. However, after being suspended in NB and stained with PTA, bacteria often had too high contrast or poor staining, with electron-dense aggregates around the bacteria. These results suggest that suspension with concentrated organic aliquots including broth media before PTA staining could deteriorate image contrast, and should be used only in dilute form for visualizing bacterial morphology and appendage structures. Moreover the contrast enhancement of unstained bacteria by salt granules would be advantageous in demonstrating bacterial sorption of environmental particles like heavy metals, maintaining minimal contrast for cell imaging.

• Journal of Microbiology and Biotechnology
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• 제20권4호
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• pp.782-788
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• 2010

Microbiological calcium carbonate precipitation (MCP) has been investigated for its ability to improve the compressive strength of mortar. However, very few studies have been conducted on the use of calcite-forming bacteria (CFB) to improve compressive strength. In this study, we discovered new bacterial genera that are capable of improving the compressive strength of mortar. We isolated 4 CFB from 7 environmental concrete structures. Using sequence analysis of the 16S rRNA genes, the CFB could be partially identified as Sporosarcina soli KNUC401, Bacillus massiliensis KNUC402, Arthrobacter crystallopoietes KNUC403, and Lysinibacillus fusiformis KNUC404. Crystal aggregates were apparent in the bacterial colonies grown on an agar medium. Stereomicroscopy, scanning electron microscopy, and X-ray diffraction analyses illustrated both the crystal growth and the crystalline structure of the $CaCO_3$ crystals. We used the isolates to improve the compressive strength of cement-sand mortar cubes and found that KNUC403 offered the best improvement in compressive strength.

• 한국어병학회지
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• 제21권2호
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• pp.93-105
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• 2008

Goldfish, Carassius auratus (wt 13 g) was intramuscularly infected with Aeromonas hydrophila (4.3x106 cfu / ml). Infected gills showed edematous lamellae with bacterial invasion into the capillaries and gill congestion on 12th day. By 24th day post-infection, histological analysis revealed irregular aggregates of macrophages in gill lamellae, large amount of mucus cells, gill lamellae edematous with bacterial invasion into capillaries, gill congestion and damaged gill epithelium with hyperplasia. Inflammation of the gill filament and hemorrhage globe was associated with the development of severe necrosis on the 36th day in the infected fishes. In infected and herbal treated fish the regenerative responses like fibrosis and infiltration of the leucocytes (neutrophils and monocytes) occurred on 12th day; moderate hypertrophy in the gills was noticed on the 36th day. These results suggest that phytotherapy ensures better protection and regenerative response against A. hydrophila infection in goldfish, C. auratus.