• Korean Journal of Soil Science and Fertilizer
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• v.44 no.2
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• pp.221-227
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• 2011

Applications of green manures generally improve the soil quality in rice paddy in part through restructuring of soil microbial communities. To determine how different green manures affect soil microbial communities during the early stages of rice growth, fatty acid methyl ester (FAME) profiles were used to the effects of different management practices: 1) conventional farming (CF), 2) no-treatment (NT), 3) Chinese milk vetch (CMV), 4) green barley (GB), and 5) triticale in paddy field. With applications of green manures, soil organic matter was significantly higher than CF, while soil Na concentration was significantly lower compared with CF (p<0.05). Total soil microbial biomass of CMV was higher (p<0.05) than NF by approximately 31%. The highest ratio of monounsaturated fatty acid to saturated fatty acid was found in the GB plot, followed by CMV and triticale compared with CF (p<0.05), possibly indicating that microbial stress was less in GB and CMV plots. Populations of Gram-negative bacteria and arbuscular mycorrhizal fungi also were significantly higher green manures than CF (p<0.05). Our findings suggest that GB should be considered as optimum green manure for enhancing soil microbial community at an early growing stage in paddy field.

• Journal of Microbiology
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• v.42 no.1
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• pp.9-13
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• 2004

Culture-independent approaches, based on 16S rDNA sequences, are extensively used in modern microbial ecology. Sequencing of the clone library generated from environmental DNA has advantages over fingerprint-based methods, such as denaturing gradient gel electrophoresis, as it provides precise identification and quantification of the phylotypes present in samples. However, to date, no method exists for comparing multiple bacterial community structures using clone library sequences. In this study, an automated method to achieve this has been developed, by applying pair wise alignment, hierarchical clustering and principle component analysis. The method has been demonstrated to be successful in comparing samples from various environments. The program, named CommCluster, was written in JAVA, and is now freely available, at http://chunlab.snu.ac.kr/commcluster/.

• The Korean Journal of Community Living Science
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• v.25 no.4
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• pp.601-608
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• 2014

This study evaluates changes in yogurt with Ulmus davidiana var. japonica (U. davidiana) in terms of its physicochemical, microbial, and sensory properties during storage. The pH value and mean microbial counts of this yogurt with 0.2 to 0.8% of U. davidiana added ranged from 4.1 to 4.3 and from $1.4{\times}10^8$ to $2.3{\times}10^8cfu/mL$, respectively, during storage at $7^{\circ}C$ for 16 d. In terms of its color, the L value was significantly higher in the control and U. davidiana yogurt 0.2 to 0.4% up to 4 d, than other yogurt samples, and the b value was influenced by the addition of U. davidiana over 0.6% throughout the storage. According to a sensory test, there was a significant difference in the yellowness score between U. davidiana yogurt and the control, but earthy, and bitterness, and viscosity scores were similar. Overall acceptability was not significantly influenced after 8 d of storage in all yogurt samples, including the control. According to these results, concentrations (0.2 and 0.4%) of U. davidiana yogurt had no significantly adverse effects on its physicochemical, microbial, and sensory properties.

• Journal of Environmental Health Sciences
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• v.34 no.5
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• pp.387-394
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• 2008

The toxicity of methyl tert-butyl ether (MTBE), tert-butyl alcohol (TBA) and formaldehyde (FA) on the indigenous microbial community in forest soil was studied. MTBE, TBA and FA with different concentrations were added into microcosms containing forest soil samples. After 10 and 30 days, total viable cell number and dehydrogenase activity in the microcosms were evaluated. Bacterial communities in the microcosms were also analyzed using a denaturing gradient gel electrophoresis (DGGE). Dehydrogenase activity and total viable cell number were decreased according to the increase of MTBE, TBA and FA concentrations (P<0.05). FA toxicity was the highest, but TBA toxicity was the lowest. The results of principal component analysis using DGGE fingerprints showed that the microbial communities contaminated MTBE, TBA and FA were grouped by exposure time not exposure concentration. Dominant species in the microcosms were as follows: Photobacterium damselae sub sp. and Bacillus sp. KAR28 for MTBE; Mycobacterium sp. and Uncultured Clostridium sp. for TBA; and Uncultured Paenibacillaceae bacterium and Anxynobacillus, Flavithermus for FA.

• Advances in environmental research
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• v.7 no.1
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• pp.39-52
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• 2018

Direct membrane filtration (DMF) of wastewater has many advantages over conventional biological wastewater treatment processes. DMF is not only compact, but potentially energy efficient due to the lack of biological aeration. It also produces more biosolids that can be used to produce methane gas through anaerobic digestion. Most of ammoniacal nitrogen in wastewater is preserved in effluent and is used as fertilizer when effluent is recycled for irrigation. In this study, a technical feasibility of DMF was explored. Organic and nitrogen removal efficiencies were compared between DMF and membrane bioreactor (MBR). Despite the extremely high F/V ratio, e.g., $14.4kg\;COD/m^3/d$, DMF provided very high COD removal efficiencies at ~93%. Soluble microbial products (SMP) and extracellular polymeric substances (EPS) were less in DMF sludge, but membrane fouling rate was far greater than in MBR. The diversity of microbial community in DMF appeared very narrow based on the morphological observation using optical microscope. On the contrary, highly diverse microbial community was observed in the MBR. Microorganisms tended to form jelly globs and attach on reactor wall in DMF. FT-IR study revealed that the biological globs were structurally supported by feather-like materials made of secondary amines. Confocal laser scanning microscopy (CLSM) study showed microorganisms mainly resided on the external surface of microbial globs rather than the internal spaces.

• Environmental Engineering Research
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• v.11 no.4
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• pp.173-180
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• 2006

Autotrophic nitrogen removal and its microbial community from a laboratory scale upflow anaerobic sludge bed reactor were characterized with dynamic behavior of nitrogen removal and sequencing result of molecular technique (DNA extraction, PCR and amplification of 16S rDNA), respectively. In the experiment treating inorganic wastewater, the anaerobic granular sludge from a full-scale UASB reactor treating industrial wastewater was inoculated as seed biomass. The operating results revealed that an addition of hydroxylamine would result in lithoautotrophic ammonium oxidation to nitrite/nitrate, and also hydrazine would play an important role for the success of sustainable nitrogen removal process. Total N and ammonium removal of 48% and 92% was observed, corresponding to nitrogen conversion of 0.023 g N/L-d. The reddish brown-colored granular sludge with a diameter of $1{\sim}2\;mm$ was observed at the lower part of sludge bed. The microbial characterization suggests that an anoxic ammonium oxidizer and an anoxic denitrifying autotrophic nitrifier contribute mainly to the nitrogen removal in the reactor. The results revealed the feasibility on development of high performance lithoautotrophic nitrogen removal process with its microbial granulation.

• KSBB Journal
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• v.26 no.5
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• pp.407-411
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• 2011

Microbial fuel cell (MFC) wes enriched using sludge in wastewater treatment. The microbial community of activated sludge and enriched MFC were analyzed by FISH (fluorescent in situ hybridization) and 16S rDNA sequencing. Bacteroidetes group were pre-dominant in activated sludge by FISH. ${\alpha}$ group, ${\gamma}$ group and Acintobacter group were dominant and they were similar to distribution. The average value of 10 peak of MFC is 0.44C. When MFC wase enriched by sludge, ${\gamma}$-Proteobacteria, Plantomycetes group increased 70% and 60%, respectively. In results of 16S rDNA sequencing, Sphiringomonas sp. was comprised in ${\alpha}$ proteobacteria and Enterobacter sp., Klebsiella sp., Acinetobacter sp., Bacillus sp. were comprised in ${\gamma}$ proteobacteria and Chryseobacterium sp. was comprised in Flavobacteria were isolated from sludge.

• Journal of Microbiology and Biotechnology
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• v.27 no.3
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• pp.524-534
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• 2017

The development and utilization of crop straw biogas resources can effectively alleviate the shortage of energy, environmental pollution, and other issues. This study performed a continuous batch test at $35^{\circ}C$ to assess the methane production potential and volatile organic acid contents using the modified Gompertz equation. Illumina MiSeq platform sequencing, which is a sequencing method based on sequencing-by-synthesis, was used to compare the archaeal community diversity, and denaturing gradient gel electrophoresis (DGGE) was used to analyze the bacterial community diversity in rice straw, dry maize straw, silage maize straw, and tobacco straw. The results showed that cumulative gas production values for silage maize straw, rice straw, dry maize straw, and tobacco straw were 4,870, 4,032.5, 3,907.5, and $3,628.3ml/g{\cdot}VS$, respectively, after 24 days. Maximum daily gas production values of silage maize straw and rice straw were 1,025 and $904.17ml/g{\cdot}VS$, respectively, followed by tobacco straw and dry maize straw. The methane content of all four kinds of straws was > 60%, particularly that of silage maize straw, which peaked at 67.3%. Biogas production from the four kinds of straw was in the order silage maize straw > rice straw > dry maize straw > tobacco straw, and the values were 1,166.7, 1,048.4, 890, and $637.4ml/g{\cdot}VS$, respectively. The microbial community analysis showed that metabolism was mainly carried out by acetate-utilizing methanogens, and that Methanosarcina was the dominant archaeal genus in the four kinds of straw, and the DGGE bands belonged to the phyla Firmicutes, Bacteroidetes, and Chloroflexi. Silage maize is useful for biogas production because it contains four kinds of straw.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.245-245
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• 2017

Heavy metal pollution of agricultural soils affects land productivity and has impact on the quality of surrounding ecosystem. Soil microbial community parameters are used as reliable indices for assessing quality of agricultural lands under metal stress. This study investigated bacterial community structure of polluted and undisturbed paddy soils to elucidate soil factors that are related to alteration of bacterial communities under conditions of metal pollution. No obvious differences in the richness or diversity of bacterial communities were observed between samples from polluted and control areas. The bacterial communities of three locations were distinct from one another, and each location possessed distinctive set of bacterial phylotypes. The abundances of several phyla and genera differed significantly between study locations. Variation of bacterial community was mostly related to soil general properties at phylum level while at finer taxonomic levels concentrations of arsenic and lead were significant factors. According to results of bacterial community functional prediction, the soil bacterial communities of metal polluted locations were characterized by more abundant DNA replication and repair, translation, transcription and nucleotide metabolism pathway enzymes while amino acid and lipid metabolism as well as xenobiotic biodegradation potential was reduced.Our results suggest that the soil microbial communities had adapted to the elevated metal concentrations in the polluted soils as evidenced by changes in relative abundances of particular groups of microorganisms at different taxonomic resolution levels, and by altered functional potential of the microbial communities.

• Journal of Microbiology and Biotechnology
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• v.28 no.7
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• pp.1168-1177
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• 2018

The aim of this study was to investigate the microbial community of three tannery wastewater treatment plants (WWTPs) involved in nitrification by Illumina MiSeq sequencing. The results showed that highly diverse communities were present in tannery wastewater. A total of six phyla, including Proteobacteria (37-41%), Bacteroidetes (6.04-16.80), Planctomycetes (3.65-16.55), Chloroflexi (2.51-11.48), Actinobacteria (1.91-9.21), and Acidobacteria (3.04-6.20), were identified as the main phyla, and Proteobacteria dominated in all the samples. Within Proteobacteria, Beta-proteobacteria was the most abundant class, with the sequence percentages ranging from 9.66% to 17.44%. Analysis of the community at the genus level suggested that Thauera, Gp4, Ignavibacterium, Phycisphaera, and Arenimonas were the core genera shared by at least two tannery WWTPs. A detailed analysis of the abundance of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) indicated that Nitrosospira, Nitrosomonas, and Nitrospira were the main AOB and NOB in tannery wastewater, respectively, which exhibited relatively high abundance in all samples. In addition, real-time quantitative PCR was conducted to validate the results by quantifying the abundance of the AOB and total bacteria, and similar results were obtained. Overall, the results presented in this study may provide new insights into our understanding of key microorganisms and the entire community of tannery wastewater and contribute to improving the nitrogen removal efficiency.