• Korean Journal of Soil Science and Fertilizer
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• v.32 no.3
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• pp.319-325
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• 1999

A culture-dependent survey of bacterial community in the soil-root system of red pepper and tomato was conducted by dilution plate count method. The bacterial community within soil was not different from that of rhizoplane. However, the populations of fluorescent, pseudomonads were higher in rhizoplanes than in soils and higher in healthy rhizoplanes than in Phytophthora disease-infested rhizoplanes. The bacterial community of the pepper cropped soil and rhizoplanes was very similar to that of the tomato-cropped soil and rhizoplanes. Among 285 identified bacterial colonies, most colonies were belong to two groups by fatty acid analyses: 52% of the 285 colonies were belong to low G + C gram positive bacteria group. Bacillus spp. and 33% were belong to high G + C gram positive bacteria group. In order to use beneficial microorganisms to agro-ecosystem, these data of field trials should be intensively accumulated.

• Proceedings of the Korea Society of Environmental Biology Conference
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• 2002.05a
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• pp.14-14
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• 2002

• Research in Plant Disease
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• v.30 no.2
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• pp.165-175
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• 2024

The Korean fir tree (Abies koreana), an endemic species of South Korea, is experiencing a severe decline in population due to climate change. Studies on the conservation of Korean fir have been extensive, yet research regarding its correlation with rhizosphere bacterial communities remains scarce, warranting further investigation. In this study, metagenome amplicon sequencing targeting the 16S rRNA V4 region was conducted to examine the presence of specific bacterial communities in Korean fir and to investigate potential differences based on habitat types (rhizosphere of native or cultivated trees, soil of dead trees, and bulk soil) and seasonal variations (April, June, September, November). Here we show that although we could not identify specific taxa highly specifically with Korean fir, the rhizosphere bacterial community in native trees exhibited less variability in response to seasonal changes compared to that in bulk soils. Suggesting the establishment of relatively stable bacterial populations around the Korean fir natural habitat. Further research on other types of rhizosphere and/or microbes is necessary to investigate the distinct relationship of Korean fir with microbial communities.

• Korean Journal of Microbiology
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• v.51 no.1
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• pp.31-38
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• 2015

The bacterial community structures of two marine sponges, Cinachyrella sp. and Plakortis sp., collected from Chuuk in the South Pacific in February 2012 were analyzed by PCR-DGGE (Denaturing Gradient Gel Electrophoresis) fingerprinting. After isolation of the total genomic DNAs from the sponges, the V3 regions of the 16S rRNA genes were amplified and subjected to DGGE profiling. The two species of sponges displayed different DGGE band patterns. The sequences derived from the DGGE bands revealed 85-100% similarities to known bacterial species in the public database. The bacterial community of Cinachyrella sp. was composed of 6 classes: Actinobacteria, Bacteroidetes, Chloroflexi, and Proteobacteria (Alpha-, Gamma-, Delta-). The bacterial community of Plakortis sp. included 7 classes: Actinobacteria, Chloroflexi, Firmicutes, Spirochaetes, and Proteobacteria (Alpha-, Gamma-, Delta-). Though Actinobacteria, Chloroflexi and Proteobacteria were commonly found in both sponges, the predominant bacterial communities differed between the two. Namely, the predominant bacterial groups in Cinachyrella sp. and Plakortis sp. were Proteobacteria and Chloroflexi, respectively. The sponge-associated bacteria are sponge host-specific, as each of the tested sponges from the same geographical location had different predominant bacterial diversity.

• Korean Journal of Microbiology
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• v.52 no.1
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• pp.49-58
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• 2016

Compared to planktonic bacterial populations, biofilms have distinct bacterial community structures and play important ecological roles in various aquatic environments. Despite their ecological importance in nature, bacterial community structure and its succession during biofilm development in the Antarctic marine environment have not been elucidated. In this study, the succession of bacterial community, particularly during the early stage of biofilm development, in the Antarctic marine environment was investigated by pyrosequencing of the 16S rRNA gene. Overall bacterial distribution in biofilms differed considerably from surrounding seawater. Relative abundance of Gammaproteobacteria and Bacteroidetes which accounted for 78.9-88.3% of bacterial community changed drastically during biofilm succession. Gammaproteobacteria became more abundant with proceeding succession (75.7% on day 4) and decreased to 46.1% on day 7. The relative abundance of Bacteroidetes showed opposite trend to Gammaproteobacteria, decreasing from the early days to the intermediate days and becoming more abundant in the later days. There were striking differences in the composition of major OTUs (${\geq}1%$) among samples during the early stages of biofilm formation. Gammaproteobacterial species increased until day 4, while members of Bacteroidetes, the most dominant group on day 1, decreased until day 4 and then increased again. Interestingly, Pseudoalteromonas prydzensis was predominant, accounting for up to 67.4% of the biofilm bacterial community and indicating its important roles in the biofilm development.

• Proceedings of the Zoological Society Korea Conference
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• 2000.10a
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• pp.141.2-141
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• 2000

• Korean Journal of Microbiology
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• v.35 no.3
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• pp.242-247
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• 1999

This sludy was conducted to investigate the change of bacterial co~munities with season and depth in Lake Soyang. Korea, using fluorescence in situ hybridization (FISH). The oligonucleotide probes used in this study were EUB338, ALF I b. GAM42a, and CF, The percentage of h e Proleobacteria a $\alpha$-group ranged from 0.70 to 33% the $\beta$-group from 1.0 to 26% they -group from 2.4 Lo 37% and Cytophagn and Flavobactefin groups from 4.7 to 24% duing the study period (April Lo November, 1998). They $\gamma$-group was dominant in spring when Asterionella was dominant. and a $\alpha$-group was dominant in summer when the organic content was low and Dinobryon was dominant. However, a specific group was not dominant in ？dl when cyanobacteria group was dominant and the ratio of eubacleria to total bacteria was very low. Therefore, the bacterial communities in Lake Soyang changed with season and depth, which seems to be associated with the telnporal succession of phytoplanlaons.

• Korean Journal of Microbiology
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• v.51 no.1
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• pp.21-30
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• 2015

The goal of this study was to identify relationships between the composition of sulfate reducing bacterial assemblages and terminal restriction fragment length polymorphism (T-RFLP) patterns in rice paddy and dry farming soils. Samples of organic farming soils, conventional farming soils, and dry field farming soils were collected in August and November. Analyses of the soil chemical composition revealed similar total nitrogen, total carbon and total inorganic phosphorus levels; however, the moisture content and total carbon were higher than in the other soils in both August and November, respectively. Sulfate reducing bacteria utilizing lactic acid were more widely distributed than those that used acetic acid, and the number of sulfate reducing bacteria in organic farming soil was most abundant. Phylogenetic analysis based on 181 clones revealed that most showed low similarity with cultured sulfate reducing bacteria, but more than 90% similarity with an uncultured sulfate reducing bacteria isolated from the environment. T-RFLP analysis revealed that fragments of 91, 357, 395, and 474 bp were most common, and the community structure of sulfate reducing bacteria changed seasonally.

• Korean Journal of Microbiology
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• v.33 no.1
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• pp.66-71
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• 1997

호수 생태계내의 생물군집은 생산자로서의 식물플랑크톤과 소비자로서의 동물플랑크톤 및 어류가 주된 위치를 차지하고 세균은 분해자로서 기능한다는 것은 일반적으로 알려진 사실이다. 그러나 1970년대에 들어 세균군집이 생태계내에서 먹이사슬을 연계하는 2차 생산자로서도 기능한다는 사실이 제기되어, 오늘날에는 생태계내에서 세균군집의 역할이 보다 강조되고 있다(6,40,41,42,50). 먹이사슬에 대한 관심은 많은 연구결과들을 생산하였지만 복잡한 먹이사슬 구조는 아직까지 부분적인 이해만을 허락하고 있다. 특히, 어류, 동물 플랑크톤, 식물플랑크톤, 미생물의 각 분야가 서로 구분되어 발전해 왔기 때문에 이들간의 상호작용을 정확하게 밝히는 데에는 많은 한계가 있어 왔다. 1970년대 이래로 담수생태계의 부영양화를 해결하기 위한 방안으로서 생태계내의 먹이 사슬을 이용하는 생물조작의 개념이 대두되었으며, 각 분야의 통합적 연관성을 필요로 함으로써 생태계 이해에 많은 지식을 제공하였다. 이 글에서는 담수생태학의 한 분야로서 생물군집간의 상호작용인 먹이사슬의 연구동향을 생물조작 개념을 중심으로 기술하고자 한다.

• Korean Journal of Microbiology
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• v.45 no.2
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• pp.119-125
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• 2009

To understand the ecological function of heterotrophic bacterial community in water column of large freshwater lakes in the permafrost zone, we investigated the structure and function of bacterial community in Lake Khuvsgul, Mongolia. Species composition of overall bacterial community was analyzed by denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments, and bacteria that can be cultured at 10oC were isolated and characterized. Based on the depth profile of environmental parameters, thermocline and chemocline were recognized at the 5~10 m zone of the water column. The stratified DGGE profile indicated that the discontinuity of water properties might influence the structure of bacterial community: band profiles in the 0~5 m zone were diverse with large change by depth, but the profile was relatively stable at the $\geq$10 m zone, with predominance of the band identified as Acidovorax facilis. Bacterial cultures were screened for protease, cellulase, amylase and lipase activity, and 23 isolates were selected for high activity of the hydrolytic enzymes. The isolates were identified based on their 16S rRNA gene sequences. In the surface water (zero meter depth), Acidovorax defluvii and Sphingobacterium faecium with high cellulase activity were present. Flavobacterium succinicans, Mycoplana bullata and A. facilis were stably predominant isolates at 2 m, 5 m, and $\geq$10 m depths, respectively. F. succinicans isolates showed high protease activity while M. bullata isolates showed moderate levels of protease and celluase activity. A. facilis isolates showed either cellulase or lipase activity, exclusively to each other. According to the profile of growth rates of the isolates in the temperature range of $0\sim42^{\circ}C$, the surface-zone (0~5 m) isolates were facultative psychrophiles while isolates from $\geq$10 m depth were typical mesophiles. This stratification is believed to be due to stratified availability of organic materials to the bacterial decomposers. In the water column below the chemoline, the environment is extremely oligotrophic so that the trait of rapid growth in low temperature might not be demanded by deep-lake decomposers. The stratified distribution of community composition and decomposer activity in Lake Khuvsgul implies that ecological functions of bacterial community in lakes of cold region are sharply divided by water column stratification.