• Journal of Information Processing Systems
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• 제19권1호
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• pp.55-66
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• 2023

Community portraits can deeply explore the characteristics of community structures and describe the personalized knowledge needs of community users, which is of great practical significance for improving community recommendation services, as well as the accuracy of resource push. The current community portraits generally have the problems of weak perception of interest characteristics and low degree of integration of topic information. To resolve this problem, the reader community portrait method based on the thematic and timeliness characteristics of interest labels (UIT) is proposed. First, community opinion leaders are identified based on multi-feature calculations, and then the topic features of their texts are identified based on the LDA topic model. On this basis, a semantic mapping including "reader community-opinion leader-text content" was established. Second, the readers' interest similarity of the labels was dynamically updated, and two kinds of tag parameters were integrated, namely, the intensity of interest labels and the stability of interest labels. Finally, the similarity distance between the opinion leader and the topic of interest was calculated to obtain the dynamic interest set of the opinion leaders. Experimental analysis was conducted on real data from the Douban reading community. The experimental results show that the UIT has the highest average F value (0.551) compared to the state-of-the-art approaches, which indicates that the UIT has better performance in the smooth time dimension.

• The Plant Pathology Journal
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• 제35권6호
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• pp.705-711
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• 2019

Understanding the microbial community and function are crucial knowledge for crop management. In this study, bacterial and fungal community structures both rhizosphere and endosphere in kiwifruit were analyzed to gain our knowledge in kiwifruit microbiome. Microbial community in rhizosphere was less variation than endosphere community. Functional prediction results demonstrated that abundance of saprotrophic fungi was similar in both rhizosphere and endosphere, but potential pathogenic fungi was more abundance in endosphere than in rhizosphere. This finding suggested that maintain healthy soil is the first priority to protect the host plant against biotic stresses.

• Journal of Microbiology and Biotechnology
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• 제26권7호
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• pp.1320-1332
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• 2016

Light hydrocarbons accumulated in subsurface soil by long-term microseepage could favor the anomalous growth of indigenous hydrocarbon-oxidizing microorganisms, which could be crucial indicators of underlying petroleum reservoirs. Here, Illumina MiSeq sequencing of the 16S rRNA gene was conducted to determine the bacterial community structures in soil samples collected from three typical oil and gas fields at different locations in China. Incubation with n-butane at the laboratory scale was performed to confirm the presence of "universal microbes" in light-hydrocarbon microseepage ecosystems. The results indicated significantly higher bacterial diversity in next-to-well samples compared with background samples at two of the three sites, which were notably different to oil-contaminated environments. Variation partitioning analysis showed that the bacterial community structures above the oil and gas fields at the scale of the present study were shaped mainly by environmental parameters, and geographic location was able to explain only 7.05% of the variation independently. The linear discriminant analysis effect size method revealed that the oil and gas fields significantly favored the growth of Mycobacterium, Flavobacterium, and Pseudomonas, as well as other related bacteria. The relative abundance of Mycobacterium and Pseudomonas increased notably after n-butane cultivation, which highlighted their potential as biomarkers of underlying oil deposits. This work contributes to a broader perspective on the bacterial community structures shaped by long-term light-hydrocarbon microseepage and proposes relatively universal indicators, providing an additional resource for the improvement of microbial prospecting of oil and gas.

• ALGAE
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• 제23권2호
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• pp.151-162
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• 2008

Marine algal flora and community structure were seasonally examined at three sites in the vicinity of the Wolseong nuclear power plant in Korea from February to November 2006. A total of 126 seaweeds including 25 green, 31 brown, 70 red algae, and 1 marine plant were identified. The greatest number of species occurred at Jeonchonri (101 species) followed by intake (88 species) and discharge (29 species) during the study period. Of 126 seaweeds, 76 annuals and 13 warm tolerance species were recorded. Dominant species based on important value (IV > 10) were Ulva pertusa and Enteromorpha linza at intake, U. pertusa and Padina arborescens at discharge, and Sargassum horneri and Corallina pilulifera at Jeonchonri shore. Annual average biomass exhibited a wide range of variations, from 40.67g m-2 in dry weight at discharge to 133.69g m-2 at Jeonchonri. Among six functional groups, dominant group was coarsely-branched form at intake and Jeonchonri, but it was different at discharge site as filamentous form. Seaweed community structures of discharge site were distinguishable in decreasing species richness, biomass, species diversity index (H’), richness index (R), and evenness index (J’). Also, the ratios of green algae, warm tolerance species, annual algae, filamentous form and dominance index (DI) remarkably increased. Such phenomenons of discharge site are usually found under environmentally stressful conditions such as high disturbance. Thus, I can conclude that the heated effluents of nuclear power plant act as environmental stress influencing seaweed community structures and it can be detected with various community indices.

• Journal of Microbiology and Biotechnology
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• 제26권4호
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• pp.757-762
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• 2016

The group of Fe(III) oxide-reducing bacteria includes exoelectrogenic bacteria, and they possess similar properties of transferring electrons to extracellular insoluble-electron acceptors. The exoelectrogenic bacteria can use the anode in microbial fuel cells (MFCs) as the terminal electron acceptor in anaerobic acetate oxidation. In the present study, the anodic community was compared with the community using Fe(III) oxide (ferrihydrite) as the electron acceptor coupled with acetate oxidation. To precisely analyze the structures, the community was established by enrichment cultures using the same inoculum used for the MFCs. High-throughput sequencing of the 16S rRNA gene revealed considerable differences between the structure of the anodic communities and that of the Fe(III) oxide-reducing community. Geobacter species were predominantly detected (>46%) in the anodic communities. In contrast, Pseudomonas (70%) and Desulfosporosinus (16%) were predominant in the Fe(III) oxide-reducing community. These results demonstrated that Geobacter species are the most specialized among Fe(III)-reducing bacteria for electron transfer to the anode in MFCs. In addition, the present study indicates the presence of a novel lineage of bacteria in the genus Pseudomonas that highly prefers ferrihydrite as the terminal electron acceptor in acetate oxidation.

• 한국토양비료학회지
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• 제44권1호
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• pp.127-145
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• 2011

Various environmental ecosystems are valuable sources for microbial ecology studies, and their analyses using recently developed molecular ecological approaches have drawn significant attention within the scientific community. Changes in the microbial community structures due to various anthropogenic activities can be evaluated by various culture-independent methods e.g. ARISA, DGGE, SSCP, T-RFLP, clone library, pyrosequencing, etc. Direct amplification of total community DNA and amplification of most conserved region (16S rRNA) are common initial steps, followed by either fingerprinting or sequencing analysis. Fingerprinting methods are relatively quicker than sequencing analysis in evaluating the changes in the microbial community. Being an efficient, sensitive and time- and cost effective method, T-RFLP is regularly used by many researchers to access the microbial diversity. Among various fingerprinting methods T-RFLP became an important tool in studying the microbial community structure because of its sensitivity and reproducibility. In this present review, we will discuss the important developments in T-RFLP methodology to distinguish the total microbial diversity and community composition in the various ecosystems.

• Journal of the korean society of oceanography
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• 제33권1-2호
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• pp.18-27
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• 1998

Based on 53 quantitative samples collected in April (23 stations) and August (30 stations) of 1993, the species composition, distribution and abundance of macrobenthic invertebrates and bottom characteristics in Chonsu Bay were conducted. Bottom sediments consisted of mud at the close to the dyke, sandymud in the central bay, and coarse sand in the mouth of the bay. A total of 273 species (177 species in April and 200 species in August) were identified. Mean density per sampling station was 480 ind./m$^2$ in April and 1126 ind./m$^2$ in August, respectively. Number of species and densities decreased in the northern part of the bay. The macrobenthos showed a temporal difference in species composition, range of distribution, and community delimitation caused by larval settling. Although during the settling period in summer, large numbers of juveniles added in most of regions, unrelated to environmental conditions, but, successful recruitment may has been a rare event locally Theora fragilis (bivalve), Lumbrineris longifolia(polychaete), Neptys oligobranchia (polychaete) were numerically dominant, but their densities varied seasonally. Community structures of macrobenthos in Chonsu Bay were affected by several bottom environmental conditions, related to tidal current speed, regionally.

• 한국발생생물학회지:발생과생식
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• 제26권4호
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• pp.145-153
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• 2022

The gut microbiota is involved in the maintenance of physiological homeostasis and is now recognized as a regulator of many diseases. Although germ-free mouse models are the standard for microbiome studies, mice with antibiotic-induced sterile intestines are often chosen as a fast and inexpensive alternative. Pathophysiological changes in the gut microbiome have been demonstrated, but there are no reports so far on how such alterations affect the bacterial composition of the uterus. Here we examined changes in uterine microbiota as a result of gut microbiome disruption in an antibiotics-based sterile-uterus mouse model. Sterility was induced in 6-week-old female mice by administration of a combination of antibiotics, and amplicons of a bacteria marker gene (16S rRNA) were sequenced to decipher bacterial community structures in the uterus. At the phylum-level, Proteobacteria, Firmicutes, and Actinobacteria were found to be dominant, while Ralstonia, Escherichia, and Prauserella were the major genera. Quantitative comparisons of the microbial contents of an antibiotic-fed and a control group revealed that the treatment resulted in the reduction of bacterial population density. Although there was no significant difference in bacterial community structures between the two animal groups, β-diversity analysis showed a converged profile of uterus microbiotain the germ-free model. These findings suggest that the induction of sterility does not result in changes in the levels of specific taxa but in a reduction of individual variations in the mouse uterus microbiota, accompanied by a decrease in overall bacterial population density.

• Journal of Microbiology and Biotechnology
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• 제33권6호
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• pp.760-770
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• 2023

Continuous cropping obstacles have become a serious factor restricting sustainable development in modern agriculture, while companion planting is one of the most common and effective methods for solving this problem. Here, we monitored the effects of companion planting on soil fertility and the microbial community distribution pattern in pepper monoculture and companion plantings. Soil microbial communities were analyzed using high-throughput sequencing technology. Companion plants included garlic (T1), oat (T2), cabbage (T3), celery (T4), and white clover (T5). The results showed that compared with the monoculture system, companion planting significantly increased the activities of soil urease (except for T5) and sucrase, but decreased catalase activity. In addition, T2 significantly improved microbial diversity (Shannon index) while T1 resulted in a decrease of bacterial OTUs and an increase of fungal OTUs. Companion planting also significantly changed soil microbial community structures and compositions. Correlation analysis showed that soil enzyme activities were closely correlated with bacterial and fungal community structures. Moreover, the companion system weakened the complexity of microbial networks. These findings indicated that companion plants can provide nutrition to microbes and weaken the competition among them, which offers a theoretical basis and data for further research into methods for reducing continuous cropping obstacles in agriculture.

• 한국균학회지
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• 제44권1호
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• pp.16-22
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• 2016

본 연구에서는 충남 서해안에 분포하는 5개의 섬 지역(신진도, 마도, 대난지도, 원산도, 삽시도)과 육지 해안 지역인 무창포의 근권 토양내 수지상균근균 군집 구조의 차이점을 확인해보았다. 그 결과 충남 지역에서 국내 미기록종인 Acaulospora brasiliensis, Redeckera fulvum를 포함하여 14개 속 24종의 수지상균근균을 확인하였다. 또한 대부분의 섬 지역에서 Acaulospora 속이 우점하고 있음을 확인할 수 있었으며, 섬 지역의 근권에서는 육지 지역과는 다른 수지상균근균 군집 구조가 발달함을 보여주었다. 특히 섬 간의 수지상균근균 군집은 섬들 사이의 물리적 거리가 가까울수록 더 유사하게 발달하는 것을 확인하였다.