• Animal cells and systems
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• v.14 no.3
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• pp.225-236
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• 2010

We compared the composition of phospholipid fatty acids (PLFA) to assess the microbial community structure in the soil and rhizosphere community of non-transgenic watermelons and transgenic watermelons in Miryang farmlands in Korea during the spring and summer of 2005. The PLFA data were seasonally examined for the number of PLFA to determine whether there is any difference in the microbial community in soils from two types of watermelons, non-transgenic and transgenic. We identified 78 PLFAs from the rhizosphere samples of the two types of watermelons. We found eight different PLFAs for the type of plants and sixteen PLFAs for the interaction of plant type and season. The PLFA data were analyzed by analysis of variance separated by plant type (P<0.0085), season (P<0.0154), and the plant type${\times}$season interaction (P<0.1595). Non-parametric multidimensional scaling (NMS showed a small apparent difference but multi-response permutation procedures (MRPP) confirmed that there was no difference in microbial community structure for soils of both plant types. Conclusively, there was no significant adverse effect of transgenic watermelon on bacterial and fungal relative abundance as measured by PLFA. We could reject our hypothesis that there might be an adverse effect from transgenic watermelon with our statistical results. Therefore, we can suggest the use of this PLFA methodology to examine the adverse effects of transgenic plants on the soil microbial community.

• The Plant Pathology Journal
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• v.38 no.6
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• pp.692-699
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• 2022

Bacterial wilt caused by Ralstonia solanacearum is considered one of the most harmful diseases of pepper plants. Recently, research on plant disease control through the rhizosphere microbiome has been actively conducted. In this study, the relationship with disease occurrence between the neighboring plant confirmed by analyzing the physicochemical properties of the rhizosphere soil and changes in the microbial community. The results confirmed that the microbial community changes significantly depending on the organic matters, P₂O₅, and clay in the soil. Despite significant differences in microbial communities according to soil composition, Actinobacteriota at the phylum level was higher in healthy plant rhizosphere (mean of relative abundance, D: 8.05 ± 1.13; H: 10.06 ± 1.59). These results suggest that Actinobacteriota may be associated with bacterial wilt disease. In this study, we present basic information for constructing of healthy soil in the future by presenting the major microbial groups that can suppress bacterial wilt.

• Journal of Microbiology and Biotechnology
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• v.16 no.9
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• pp.1481-1484
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• 2006

In this study, glucose and glutamate (copiotrophic conditions) were used to enrich electrochemically active bacteria (EAB) in a microbial fuel cell (MFC). The enriched population consisted primarily of ${\gamma}$-Proteobacteria (36.5%), followed by Firmicutes (27%) and O-Proteobacteria (15%). Accordingly, we compared our own enrichments done under many different conditions with those reported from the literature, all of which support the notion that electrochemically active bacteria are taxonomically very diverse. Enrichments with different types and levels of energy sources (fuels) have clearly yielded many different groups of bacteria.

• Journal of Environmental Health Sciences
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• v.34 no.4
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• pp.327-332
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• 2008

To determine structure and activities of microbial communities in a food wastewater treatment system, biofilm of RABC (rotating activated Bacillus contactor) and samples of aeration tanks were analyzed. Heterotrophic bacterial concentrations were similar between biofilm and stage 1 aeration tank and decreased 2-log at stage 3 aeration tank as dissolved oxygen decreased, however portions of Bacillus groups were increased at stage 3 aeration tank. It was revealed by quantitative and qualitative analysis of metabolic fingerprinting patterns of Biolog GN2 plate that RABC represented much higher activities and a different microbial community structure compared to aeration tanks. Metabolic fingerprinting showed the carbon sources that isolated Bacillus groups could or could not use, were used similarly meaning that not only Bacillus groups but also other microbial groups would contribute to the treatment of wastewater.

• Korean Journal of Microbiology
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• v.48 no.4
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• pp.254-261
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• 2012

The purpose of this research was to optimize electric current production of sediment microbial fuel cells by injecting glucose and to investigate its impact on microbial communities involved. It was shown that injection of proper concentration of glucose could increase electric current generated from sediment microbial fuel cells. When 1,000 mg/L of glucose, as opposed to higher concentrations, was injected, electric current increased up to 3 times. This increase is mainly attributed to the mutual relationship between fermenting bacteria and exoelectrogenic bacteria. Here the organic acids generated by fermenting bacteria could be utilized by exoelectrogenic bacteria, removing feedback inhibition caused by the organic acids. When glucose was injected, the population of Clostridium increased as to ferment injected glucose. Glucose fermentation can have either a positive or negative effect on electric current generation. When exoelectrogenic bacteria may readily utilize the end-product, electric current could increase. However, when the end-product was not readily removed, then detrimental chemical reactions (pH decrease, methane generation, organic acids accumulation) occurred: exoelctrogenic bacteria population declined and non-microbial fuel cell related microorganisms prospered. By injecting a proper concentration of glucose, a mutual relationship between fermenting bacteria, such as Clostridium, and exoelectrogenic bacteria, such as Geobacter, should be fulfilled in order to increase electricity production in mixed cultures of microorganisms collected from the aquatic sediments.

• Korean Journal of Microbiology
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• v.39 no.1
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• pp.45-50
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• 2003

The diversity and change of microbial communities during kimchi fermentation at $4^{\circ}C$ were analyzed by denaturing gradient gel electrophoresis (DGGE). Kimchi samples were taken every 5 days over the fermentation periods (for 60 days) to extract total DNA for DGGE analysis. Touchdown polymerase chain reaction was performed to amplify the V3 region of 16S rRNA gene. Sequencing results of partial 16S rDNA amplicons from DGGE profiles revealed that lactic acid bacteria (LAB), especially Weissella koreensis, Lactobacillus sakei and Leuconostoc gelidum were dominants in kimchi fermentation at $4^{\circ}C$. And we knew that W. koreensis steadily existed throughout the whole fermentation period, also Lb. sakei and Leuc. gelidum appeared from 10th day and 30th day of fermentation time, respectively and then these species were to be dominant microorganisms.

• Journal of Microbiology and Biotechnology
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• v.13 no.1
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• pp.15-21
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• 2003

Two microbial communities of activated sludge in the same municipal wastewater, but treated with different systems, were studied and compared using molecular microbiological approaches. The bacterial 16S rDNA sequences from 124 clones were analyzed, however, the majority of them were not closely related to any known species, and found to belong to 8 different phylogenetic groups and 3 different unidentified groups. The relative frequencies of each group were similar between the two microbial communities. Fingerprinting using terminal restriction fragment length polymorphism (T-RFLP) showed that the putative Nitrospira-related populations were more diverse and quantitatively higher in the KNR process system than in the other system using a conventional activated sludge process. The relationship between the bacterial community composition and the higher removal efficiency of nitrogen and phosphorus in the KNR process is discussed.

• Mycobiology
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• v.48 no.5
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• pp.392-398
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• 2020

This study was conducted to understand the dynamics of microbial communities of soil microorganisms, and their distribution and abundance in the indigenous microorganisms (IMOs) manipulated from humus collected from the forest near the crop field. The soil microorganisms originated from humus and artificially cultured microbial-based soil amendments were characterized by molecular and biochemical analyses. The bacterial population (2 × 10⁶~13 × 10⁶ CFU/g sample) was approximately 100-fold abundant than the fungal population (2 × 10⁴~8 × 10⁴ CFU/g sample). The 16S rDNA and ITS sequence analyses showed that the bacterial and fungal communities in humus and IMOs were mainly composed of Bacillus and Pseudomonas, and Trichoderma and Aspergillus species, respectively. Some of the bacterial isolates from the humus and IMOs showed strong inhibitory activity against soil-borne pathogenic fungi Fusarium oxysporum and Sclerotinia sclerotiorum. These bacteria also showed the siderophore production activity as well as phosphate solubilizing activity, which are requisite traits for biological control of plant pathogenic fungi. These results suggest that humus and IMOs could be a useful resource for sustainable agriculture.

• Microbiology and Biotechnology Letters
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• v.44 no.2
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• pp.171-179
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• 2016

Recent succession of soil microorganisms and vegetation has occurred in the glacier foreland, because of glacier thawing. In this study, whole microbial communities, including bacteria, archaea, and eukaryotes, from the glacier foreland of Midtre Lovénbreen in Svalbard were analyzed by metagenome sequencing, using the Ion Torrent Personal Genome Machine (PGM) platform. Soil samples were collected from two research sites (ML4 and ML7), with different exposure times, from the ice. A total of 2,798,108 and 1,691,859 reads were utilized for microbial community analysis based on the metagenomic sequences of ML4 and ML7, respectively. The relative abundance of microbial communities at the domain level showed a high proportion of bacteria (about 86−87%), whereas archaeal and eukaryotic communities were poorly represented by less than 1%. The remaining 12% of the sequences were found to be unclassified. Predominant bacterial groups included Proteobacteria (40.3% from ML4 and 43.3% from ML7) and Actinobacteria (22.9% and 24.9%). Major groups of Archaea included Euryarchaeota (84.4% and 81.1%), followed by Crenarchaeota (10.6% and 13.1%). In the case of eukaryotes, both ML4 and ML7 samples showed Ascomycota (33.8% and 45.0%) as the major group. These findings suggest that metagenome analysis using the Ion Torrent PGM platform could be suitably applied to analyze whole microbial community structures, providing a basis for assessing the relative importance of predominant groups of bacterial, archaeal, and eukaryotic microbial communities in the Arctic glacier foreland of Midtre Lovénbreen, with high resolution.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.7
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• pp.503-508
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• 2013

The aim of this study was to investigate the microbial communities in animal carcass disposal soils to examine the possible threat of pathogens from leachate. DNA extraction was performed for the soils in three carcass disposal sites located in Gyeonggi-do, Korea, and then 16S rRNA pyrosequencing was conducted to identify the microbial communities. Results indicate that, according to phylum classification, Proteobacteria (100%) was identified in soil A, Actinobacteria (66.4%) > Proteobacteria (31.1%) > Bacteriodetes (2.1%) > Acidobacteria (0.3%) in soil B, and Actinobacteria (63.1%) > Proteobacteria (36.9%) in soil C. According to genus classification, Pseudomonas was dominant in soil A (98%), Arthrobacter in soil B (68%) and C (61%). There were no detections of pathogens such as Salmonella, Campylobacter and Clostridium perfringens. However, high concentration of Ralstonia pickettii causing bacteremia was observed. Although carcass disposal soils examined in this study were not highly contaminated with pathogens, further monitoring is still needed to examine the potential threat of pathogens in leachate derived from carcass disposal sites.