• 한국수산과학회지
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• 제46권5호
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• pp.552-558
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• 2013

This study was performed to determine effects of the supplementation of Kimchi lactic acid bacterial culture in extruded pellets (EP) on the growth, body composition, blood chemistry and immune response of olive flounder Paralichthys olivaceus. Four hundred eighty individuals averaging 16.1 g were randomly distributed into 12, 180 L flow-through tanks (forty fish per tank). Four concentrations of Kimchi lactic acid bacterial culture (KL) were prepared: Control (0%), 0.1%, 0.2% and 0.5%. Three concentrations (0.1%, 0.2% and 0.5%) of Kimchi lactic acid bacterial culture were each diluted to 10% of EP weight and then fully absorbed by EP for 10 minutes. Each diet was fed to triplicate groups of fish. Fish were hand-fed to apparent satiation twice a day for 8 weeks. At the end of the 8-week feeding trial, the plasma lysozyme and bacterial activities of fish were determined. In addition, the cumulative mortality of fish was monitored for 8 days after their artificial infection with Edwardsiella tarda. The weight gain, specific growth rate, feed efficiency ratio, protein efficiency ratio, protein retention, hepatosomatic index and condition factor of fish were not affected by dietary supplementation with KL. None of the proximate composition, plasma parameters, lysozyme or bactericidal activities of fish was affected by dietary supplementation with KL. However, the cumulative mortalities of fish fed EP containing 0.1% and 0.5% Kimchi lactic acid bacterial culture were relatively low compared to that of fish fed the control diet. In conclusion, dietary supplementation with KL did not effectively improve growth, feed utilization, body composition, plasma chemistry, lysozyme, bactericidal activities or immune response of olive flounder after E. tarda infection under these experimental conditions.

• Applied Biological Chemistry
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• 제48권3호
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• pp.296-300
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• 2005

Among the root colonizing and plant growth promoting bacteria isolated from the bacterial wilt suppressive soil, five strains were detected to produce siderophores by CAS agar assay. The most effective isolate, TS3-7 strain induced significant suppression of bacterial wilt disease in tomato and pepper plants. Seed treatment followed by soil drench application with this strain resulted in over 80% reduction of bacterial wilt disease compared with the control. Significant disease suppression by TS3-7 strain was related to the production of siderophore. Besides iron competition, induction of resistance of the host plant with siderophore was suggested to be another mode of action that suppress bacterial wilt, based on the lack of direct antibiosis against pathogen in vitro. According to Bergey's Manual of Systemic Bacteriology and 16S rDNA sequence data, TS3-7 stain was identified as Pseudomonas sp. TS3-7.

• Journal of Species Research
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• 제6권3호
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• pp.207-213
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• 2017

In order to investigate the indigenous prokaryotic species diversity of the Nakdong River system in Korea, fresh water samples from Hapcheonho Lake and Jinyangho Lake were analyzed for bacterial taxonomic diversity. The isolated bacterial strains were identified based on 16S rRNA gene sequences, and those exhibiting at least 98.7% sequence similarity with known bacterial species, but never reported in Korea, were selected as unrecorded species. Eleven unrecorded bacterial species were discovered in this study. The isolates were identified as Aquabacterium citratiphilum, Clostridium ghonii, Curvibacter delicates, Deinococcus depolymerans, Eubacterium moniliforme, Flavobacterium nitrogenifigens, Kineosporia mesophila, Luteibacter jiangsuensis, Microbacterium terricola, Rhizobium larrymoorei, and Sediminicoccus rosea belonging to the phyla Actinobacteria, Bacteroidetes, Firmicutes, Proteobacteria and Deinococcus-Thermus. The selected isolates were further characterized for cellular and colonial morphologies, growth conditions, physiological properties, and enzymatic activities. Descriptive information of these previously unrecorded species is also provided.

• 한국응용곤충학회지
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• 제14권1호
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• pp.7-12
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• 1975

벼 흰빛잎마름병의 병원균(Xanthomonas oryzae)을 이용하여 항생제의 일종인 Agrepto에 대한 약제저항성형성을 조사하기 위하여 세대 경과에 따른 약제처리효과를 Optical Density로 간접 측정하여 다음과 같은 결과를 얻었다. 1. Agrepto는 액체배양기에 첨가되었을 때 처리 제1세대 30ppm까지의 낮은 농도 처리에서도 세균증식에 현저한 저지 효과를 나타내었다. 2. 동일농도의 4세대간 처리에서 세대의 경과에 따라 세균 증식량이 현저히 증가하였고 증식율은 10ppm 처리구에서 보다 30ppm 처리구에서 더욱 뚜렷하였다. 3. 전세대 20ppm 처리구의 선발집단의 경우 세대가 경과할수록 더욱 내성의 증가 현상을 나타내었다. 4. 고농도 처리구에서 선발된 세균이 저농도처리구에서 선발된 세균의 경우보다 저항성 형성이 현저히 증가되는 경향을 보였다.

• The Plant Pathology Journal
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• 제29권3호
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• pp.350-355
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• 2013

Plants protect themselves from diverse potential pathogens by induction of the immune systems such as systemic acquired resistance (SAR). Most bacterial plant pathogens thrive in the intercellular space (apoplast) of plant tissues and cause symptoms. The apoplastic leaf exudate (LE) is believed to contain nutrients to provide food resource for phytopathogenic bacteria to survive and to bring harmful phytocompounds to protect plants against bacterial pathogens. In this study, we employed the pepper-Xanthomonas axonopodis system to assess whether apoplastic fluid from LE in pepper affects the fitness of X. axonopodis during the induction of SAR. The LE was extracted from pepper leaves 7 days after soil drench-application of a chemical trigger, benzothiadiazole (BTH). Elicitation of plant immunity was confirmed by significant up-regulation of four genes, CaPR1, CaPR4, CaPR9, and CaCHI2, by BTH treatment. Bacterial fitness was evaluated by measuring growth rate during cultivation with LE from BTH- or water-treated leaves. LE from BTH-treatment significantly inhibited bacterial growth when compared to that from the water-treated control. The antibacterial activity of LE from BTH-treated samples was not affected by heating at $100^{\circ}C$ for 30 min. Although the antibacterial molecules were not precisely identified, the data suggest that small (less than 5 kDa), heat-stable compound(s) that are present in BTH-induced LE directly attenuate bacterial growth during the elicitation of plant immunity.

• 한국양식학회지
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• 제10권1호
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• pp.69-76
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• 1997

카이이케 호수에서 년중 농밀한 개체군을 형성하고 있는 Chromatium sp.는 질소고정능을 가지고 있으며, 질소고정과정에서 수소를 생산한다. 이 균의 질소고정과 수소생산은 광합성 조건에서 활발히 이루어지며, 생장 중 대수생장기(exponential growth phase)에서 활성도가 가장 높았다. 1994년 7월 27일 채집한 카이이케 호수의 bacterial plate 식과를 이용하여 실험실에서 질소고정과 수소생산에 끼치는 빛과 황화수소의 영향을 조사하였다. 저조도 (250 lux) 에서는 실험개시후 약 18시간이 지나고나서 질소고정과 수소생산이 측정되었으나, 고조도(1000 lux)에서는 조사와 동시에 높은 속도의 질소고정과 수소생산이 관측되었다. 황화수소를 전혀 투입하지 않은 경우에는 극히 낮은 질소고정이 나타났으나, 황화수소의 농도의 증가에 따라 질소고정속도가 높아졌으며, 20 mg H sub(2)S-S/l에서 가장 높았다.

• 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.

• 농약과학회지
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• 제15권3호
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• pp.298-302
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• 2011

국내에서 Ralstonia solanacearum에 의한 풋마름병은 토마토 재배에 심각한 피해를 주고 있다. R. solanacearum에 의한 풋마름병을 방제하기 위한 약제를 선발하기 위하여 5종 항생제를 이용하여 균에 대한 생장 억제 효과와 포장에서의 토마토 풋마름병 방제효과를 조사하였다 R. solanacearum에 대한 생장억제효과를 조사한 결과, streptomycin 수화제, oxytetracyclin streptomycin sulfate 수화제, oxolinic acid 수화제는 병원균에 대한 생육억제 효과가 우수하였다. 포장에서 토마토 풋마름병에 대한 방제효과 시험을 실시한 결과, copper hydroxide 수화제가 62.5%의 가장 높은 방제효과를 나타내었다. Copper hydroxide 수화제는 친환경유기농자재에 등록된 약제로서 관행 재배뿐만 아니라 토마토 친환경 재배시에도 풋마름병 방제에 사용할 수 있을 것이다.

• Journal of Microbiology and Biotechnology
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• 제22권3호
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• pp.301-310
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• 2012

Prosopis juliflora and Parthenium hysterophorus are the two arid, exotic weeds of India that are characterized by distinct, profuse growth even in nutritionally poor soils and environmentally stressed conditions. Owing to the exceptional growth nature of these two plants, they are believed to harbor some novel bacterial communities with wide adaptability in their rhizosphere. Hence, in the present study, the bacterial communities associated with the rhizosphere of Prosopis and Parthenium were characterized by clonal 16S rRNA gene sequence analysis. The culturable microbial counts in the rhizosphere of these two plants were higher than bulk soils, possibly influenced by the root exudates of these two plants. The phylogenetic analysis of V1_V2 domains of the 16S rRNA gene indicated a wider range of bacterial communities present in the rhizosphere of these two plants than in bulk soils and the predominant genera included Acidobacteria, Gammaproteobacteria, and Bacteriodetes in the rhizosphere of Prosopis, and Acidobacteria, Betaproteobacteria, and Nitrospirae in the Parthenium rhizosphere. The diversity of bacterial communities was more pronounced in the Parthenium rhizosphere than in the Prosopis rhizosphere. This culture-independent bacterial analysis offered extensive possibilities of unraveling novel microbes in the rhizospheres of Prosopis and Parthenium with genes for diverse functions, which could be exploited for nutrient transformation and stress tolerance in cultivated crops.

• Journal of Microbiology and Biotechnology
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• 제23권11호
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• pp.1560-1568
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• 2013

Salmonella, a main cause of foodborne diseases, encounters a variety of environmental stresses and overcomes the stresses by multiple resistance strategies. One of the general responses to hyperosmotic stress is to import or produce compatible solutes so that cells maintain fluid balance and protect proteins and lipids from denaturation. The ProP and ProU systems are the main transport systems for compatible solutes. The OsmU system, recently identified as a third osmoprotectant transport system, debilitates excessive growth as well by reducing production of trehalose. We studied a fourth putative osmoprotectant transport system, YehZYXW, with high sequence similarity with the OsmU system. A Salmonella strain lacking YehZ, a predicted substrate-binding protein, did not suffer from hyperosmolarity but rather grew more rapidly than the wild type regardless of glycine betaine, an osmoprotectant, suggesting that the YehZYXW system controls bacterial growth irrespective of transporting glycine betaine. However, the growth advantage of ${\Delta}yehZ$ was not attributable to an increase in OtsBA-mediated trehalose production, which is responsible for the outcompetition of the ${\Delta}osmU$ strain. Overexpressed YehZ in trans was capable of deaccelerating bacterial growth vice versa, supporting a role of YehZ in dampening growth. The expression of yehZ was increased in response to nutrient starvation, acidic pH, and the presence of glycine betaine under hyperosmotic stress. Identifying substrates for YehZ will help decipher the role of the YehZYXW system in regulating bacterial growth in response to environmental cues.