• Journal of Korean Society of Water and Wastewater
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• v.20 no.3
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• pp.461-467
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• 2006

The seasonal change in attached algae and microbial community structure at sedimentation basin of water treatment plant was investigated by using quinone profiles and denaturing gel gradient electrophoresis (DGGE). The photosynthetic bacteria and algae contains PQ-9 and VK-1 as major quinone are major component of the total quinone fraction in attached algae and microorganisms on sedimentation basin trough. The microorganisms containing menaquinones appear to be sensitivity to the change in temperature than those containing ubiquinones. The plot of the mole fraction of dominant quinone species ($f_d$) to the DQ values showed higher sensitivity to the seasonal change in the microbial community structure. The results indicated that quinone and DGGE are useful tool for the evaluation of the changes in the microbial community structure.

• Microbiology and Biotechnology Letters
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• v.42 no.4
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• pp.377-385
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• 2014

In this study, a wastewater treatment system for hypersaline wastewater utilizing the Hypersaline Wastewater Treatment Community (HWTC) has been developed. The hypersaline wastewater treatment efficiency and microbial community of the HWTC were investigated. The average removal efficiencies of chemical oxygen demand were 84% in an HRT of 2.5 days. Microbial community analysis, by denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S rRNA gene fragments and 16S rRNA gene clone library, revealed community diversity. The 16S rRNA gene analysis of dominant microbial bacteria in 4% hypersaline wastewater confirmed the presence of Halomonas sp. and Paenibacillus sp. Phylogenetic analysis suggested that the taxonomic affiliation of the dominant species in the HWTC was ${\gamma}$-proteobacteria and firmicutes. These results indicate the possibility that an appropriate hypersaline wastewater treatment system can be designed using acclimated sludge with a halophilic community.

• Journal of Applied Biological Chemistry
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• v.59 no.4
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• pp.299-304
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• 2016

When used for amplicon sequencing, Illumina platforms produce more than hundreds of sequence artefacts, which affects operational taxonomic units based analyses such as differential abundance and network analyses. Nevertheless it has become a major tool for fecal microbial community analysis. In addition, results from sequence-based fecal microbial community analysis vary depending on conditions of samples (i.e., freshness, time of storage and quantity). We investigated if freeze-drying samples could improve quality of sequence data. Our results showed reduced number of possible artefacts while maintaining overall microbial community structure. Therefore, freeze-drying feces prior to DNA extraction is recommended for Illumina-based microbial community analysis.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.2
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• pp.139-143
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• 2009

We examined the vertical distribution of specific microbial groups and the patterns of microbial community structure within the soil profile using phospholipid fatty acid (PLFA). Samples were collected from the soil surface down to 15 cm in depth from paddy and upland fields located in Daegu, Korea. The two fields have been fertilized with only chemical fertilizers N, P, K for 33 years. Principal component analysis of the PLFA signatures indicated that the composition of the soil microbial communities changed significantly with the cultivation practices and soil depth, suggesting that cultivation practices of paddy and upland fields had more significant influence on soil microbial community than the soil depth did. The soil microbial communities changed more drastically with soil depth in upland field than in paddy field, with making thicker soil surface in paddy field in terms of soil microbial community. The ratios of cyclopropyl/monoenoic precursors and total saturated/total monounsaturated fatty acids increased with soil depth, suggesting that the deeper soil horizons are more carbon-limited and anaerobic than surface soil. The community analysis using PLFAs as biomarkers revealed that Gram-positive bacteria and actinomycetes tended to increase in proportional abundance with increasing soil depth, while the abundance of Gram-negative bacteria and fungi were highest at the soil surface and substantially lower in the subsurface.

• Ocean Science Journal
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• v.40 no.3
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• pp.145-153
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• 2005

Variation in the microbial biomass and community structure found in sediment of heavily polluted bays and the adjacent unpolluted areas were examined using phospholipid fatty acid analysis. Total microbial biomass and microbial community structure were responding to environmental determinants, sediment grain size, depth of sediment, and pollution due to petroleum hydrocarbons. The marker fatty acids of microeukaryotes and prokaryotes - aerobic, anaerobic, and sulfate-reducing bacteria - were detected in sediments of the areas studied. Analysis of the fatty acid profiles revealed wide variations in the community structure in sediments, depending on the extent of pollution, sediment depth, and sediment grain size. The abundance of specific bacterial fatty acids points to the dominance of prokaryotic organisms, whose composition differed among the stations. Fatty acid distributions in sediments suggest the high contribution of aerobic bacteria. Sediments of polluted sites were significantly enriched with anaerobic bacteria in comparison with clean areas. The contribution of this bacterial group increased with the depth of sediments. Anaerobic bacteria were predominantly present in muddy sediments, as evidenced from the fatty acid profiles. Relatively high concentrations of marker fatty acids of sulfate-reducing bacteria were associated with organic pollution in this site. Specific fatty acids of microeukaryotes were more abundant in surface sediments than in deeper sediment layers. Among the microeukaryotes, diatoms were an important component. Significant amounts of bacterial biomass, the predominance of bacterial biomarker fatty acids with abundance of anaerobic and sulfate-reducing bacteria are indicative of a prokaryotic consortium responsive to organic pollution.

• Journal of Korean Society of Water and Wastewater
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• v.37 no.6
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• pp.325-334
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• 2023

Membrane bioreactor (MBR) provides the benefits on high effluent quality and construction cost without the secondary clarification. Despite of these advantages, fouling, which clogs the pore in membrane modules, affects the membrane life span and effluent quality. Studies on the laboratory scale MBR were focused on the control of particulate fouling, organic fouling and inorganic fouling. However, less studies were focused on the control of biofouling and microbial aspect of membrane. In the full scale operation, most MBR produces high effluent quality to meet the national permit of discharge regulation. In this study, the performance and microbial community analysis were investigated in two MBRs. As the results, the performance of organic removal, nitrogen removal, and phosphorus removal was similar both MBRs. Microbial community analysis, however, showed that Azonexus sp. and Propionivibrio sp. contributed to indirect fouling to cause the chemical cleaning in the DX MBR.

• Journal of Microbiology and Biotechnology
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• v.31 no.7
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• pp.978-989
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• 2021

Allyl isothiocyanate (AITC), as a fumigant, plays an important role in soil control of nematodes, soil-borne pathogens, and weeds, but its effects on soil microorganisms are unclear. In this study, the effects of AITC on microbial diversity and community composition of Capsicum annuum L. soil were investigated through Illumina high-throughput sequencing. The results showed that microbial diversity and community structure were significantly influenced by AITC. AITC reduced the diversity of soil bacteria, stimulated the diversity of the soil fungal community, and significantly changed the structure of fungal community. AITC decreased the relative abundance of dominant bacteria Planctomycetes, Acinetobacter, Pseudodeganella, and RB41, but increased that of Lysobacter, Sphingomonas, Pseudomonas, Luteimonas, Pseudoxanthomonas, and Bacillus at the genera level, while for fungi, Trichoderma, Neurospora, and Lasiodiplodia decreased significantly and Aspergillus, Cladosporium, Fusarium, Penicillium, and Saccharomyces were higher than the control. The correlation analysis suggested cellulase had a significant correlation with fungal operational taxonomic units and there was a significant correlation between cellulase and fungal diversity, while catalase, cellulose, sucrase, and urease were the major contributors in the shift of the community structure. Our results will provide useful information for the use of AITC in the assessment of environmental and ecological security.

• Korean Journal of Microbiology
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• v.49 no.2
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• pp.150-155
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• 2013

We have conducted pyrosequencing for freshwater microbial community analyses. Fourteen sites along the Yeongsan river were selected for this study, and samples were collected monthly from May to July, 2012. Total 987,380 reads were obtained from 42 samples and used for taxonomic classification and OTU distribution analysis. Our results showed that high geographical and temporal variation in the phylum level bacterial composition, suggesting that microbial community is a very sensitive parameter affected by the surrounding environments including tributaries and land use nearby. In addition, we conducted an OTU-based Microbial Source Tracking to identify sources of fecal pollution in the same region. From this study Firmicutes was found to be the most influential taxa in this region. Here, we report that the use of pyrosequencing based microbial community analysis may give an additional information on freshwater quality monitoring, in addition to the currently used water quality parameters, such as BOD and pH.

• Journal of Life Science
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• v.34 no.7
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• pp.453-464
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• 2024

The fermentation of ganjang is known to be greatly influenced by the microbial communities derived from its primary ingredients, meju and sea salt. This study investigated the effects of changes in meju size on the distribution and correlation of microbial communities in ganjang fermentation, to enhance its fermentation process. Ganjang was prepared using whole meju and meju divided into thirds, and samples were collected at 7-day intervals over a period of 28 days for microbial community analysis based on 16S rRNA gene sequencing. At the genus level, during fermentation, ganjang made with whole meju exhibited a dominance of Chromohalobacter (day 7), Pediococcus (day 14), Bacillus (day 21), and Pediococcus (day 28), whereas ganjang made with meju divided into thirds consistently showed a Pediococcus predominance over the 28 days. Beta-diversity analysis of microbial communities in ganjang with different meju sizes revealed significant separation of microbial communities at fermentation days 7 and 14 but not at days 21 and 28 across all experimental groups. The linear discriminant analysis effect size (LEfSe) was determined to identify biomarkers contributing to microbial community differences at days 7 and 14, showing that on day 7, potentially halophilic microbes such as Gammaproteobacteria, Firmicutes, Oceanospirillales, Halomonadaceae, Bacilli, and Chromohalobacter were prominent, whereas on day 14, lactic acid bacteria such as Pediococcus acidilactici, Lactobacillaceae, Pediococcus, Bacilli, Leuconostocaceae, and Weissella were predominant. Furthermore, correlation analysis of microbial communities at the genus and species levels revealed differences in correlation patterns between meju sizes, suggesting that meju size may influence microbial interactions within ganjang.

• Journal of Korean Society on Water Environment
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• v.26 no.4
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• pp.608-613
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• 2010

Electricity generation of microbial fuel cells (MFC) is greatly affected by the kind of feed substrates because substrates would change microbial community of electrochemically active bacteria (EAB) able to transfer electrons to electrode. The effect of different substrates on electricity generation and microbial community of MFC was investigated. Two-chamber MFCs fed with acetate (A-MFC), butyrate (B-MFC), propionate (P-MFC), glucose (G-MFC) and a mixture (M-MFC) of the 4 substrates (acetate : butyrate : propionate : glucose = 1 : 1 : 1 : 1 as $COD_{Cr}$ base) were operated under continuous mode. The maximum power density was found from the M-MFC ($190W/m^3$) which showed the lowest internal resistance ($89{\Omega}$). The maximum power densities of the pure substrates feed MFCs were in order of A-MFC ($25W/m^3$), P-MFC ($21W/m^3$), B-MFC ($20W/m^3$) and G-MFC ($9W/m^3$). In DGGE analysis, the microbial community structure in suspension was quite different from each others depending on feed substrates, while the community structure in the biofilm was relatively similar regardless of the substrates. This result suggests that the feed substrates would affect the microbial community of suspended growth bacteria than attached growth bacteria resulting in difference of electricity generation in MFCs.