• Journal of Microbiology
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• 제42권4호
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• pp.267-277
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• 2004

Effects of elevated $CO_2$ on soil microorganisms are known to be mediated by various interactions with plants, for which such effects are relatively poorly documented. In this review, we summarize and syn­thesize results from studies assessing impacts of elevated $CO_2$ on soil ecosystems, focusing primarily on plants and a variety the of microbial processes. The processes considered include changes in microbial biomass of C and N, microbial number, respiration rates, organic matter decomposition, soil enzyme activities, microbial community composition, and functional groups of bacteria mediating trace gas emission such as methane and nitrous oxide. Elevated $CO_2$ in atmosphere may enhance certain micro­bial processes such as $CH_4$ emission from wetlands due to enhanced carbon supply from plants. How­ever, responses of extracellular enzyme activities and microbial community structure are still controversy, because interferences with other factors such as the types of plants, nutrient availabilitial in soil, soil types, analysis methods, and types of $CO_2$ fumigation systems are not fully understood.

• 한국환경보건학회지
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• 제34권5호
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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.

• Environmental Engineering Research
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• 제25권1호
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• pp.29-35
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• 2020

The aim of this study was to estimate the microbial metabolic activity of indigenous soil microbes under the radon exposure with different intensity and times in the secured laboratory radon chamber. For this purpose, the soil microbes were collected from radon-contaminated site located in the G county, Korea. Thereafter, their metabolic activity was determined after the radon exposure of varying radon concentrations of 185, 1,400 and 14,000 Bq/㎥. The average depth variable concentrations of soil radon in the radon-contaminated site were 707, 860 and 1,185 Bq/㎥ from 0, 15, and 30 cm in deep, respectively. Simultaneously, the soil microbial culture was mainly composed of Bacillus sp., Brevibacillus sp., Lysinibacillus sp., and Paenibacillus sp. From the radon exposure test, higher or lower radiation intensities compared to the threshold level attributed the metabolic activity of mixed microbial consortium to be reduced, whereas the moderate radiation intensity (i.e. threshold level) induced it to the pinnacle point. It was decided that radon radiation could instigate the microbial metabolic activity depending on the radon levels while they were exposed, which could consequently address that the certain extent of threshold concentration present in the ecosystem relevant to microbial diversity and population density to be more proliferated.

• 지질공학
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• 제33권1호
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• pp.15-25
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• 2023

화성암과 퇴적암으로 이루어진 국내 산림토양 중 표토와 심토에서 채취된 시료의 미생물군집 활성도에 미치는 산불의 영향을 알아보았다. 베타글루코시다아제의 분석결과, 화성암보다 퇴적암의 미생물군집에서 높게 나타났다. 산불 발생 초기에 효소 활성이 관찰되지 않았으나, 시간이 경과됨에 따라 활성이 회복되었다. 또한, 토양의 훼손여부와 상관없이 심토는 표토에 비해 활성이 33~46% 저해되었다. EcoPlate를 이용하여 산불이 미생물 기질이용성에 미친 영향을 알아보았다. 정상토와 훼손토의 평균반응구발색도 값 백분율은 표토에서 각각 52.7~56.8% 및 62.3~83.6%로 나타났다. 산불 발생은 토양 유기물의 분해를 촉진함으로 심토미생물군집의 다양성 및 기질이용성에 영향을 준 것으로 보여진다. 미생물군집의 종다양성지수인 샤논 인덱스(Shanon index, H)는 모든 시료의 표토에서 높게 나타났다. 샤논 풍부도는 퇴적암 토양미생물이 화성암에 비하여 높게 나타났으며, 표토가 심토보다 높게 나타났다.

• 대한환경공학회지
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• 제31권12호
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• pp.1069-1074
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• 2009

본 연구에서는 CuO와 ZnO의 입자 크기가 옥수수의 성장과 토양 미생물 군집에 미치는 독성을 microcosm 실험을 통하여 살펴보았다. 나노 입자는 micro 입자에 비해 옥수수의 biomass를 약 30% 감소시켜 나노 입자가 옥수수의 성장을 저해하는 것으로 나타났다. 토양 미생물 활성 지표인 Dehydrogenase activity는 CuO 나노 입자에서는 낮게 나타났으나 ZnO 나노 입자에서는 높게 나타났다. Biolog test 결과, CuO 나노 입자와 ZnO micro 입자에서 토양 미생물 다양성이 감소하는 것으로 나타났다. 그러므로, metal oxide의 나노 입자가 micro 입자보다 항상 토양 미생물의 활성 및 다양성에 더 유해한 영향을 나타내는 것은 아니라고 판단된다.

• Journal of Ecology and Environment
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• 제41권9호
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• pp.271-280
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• 2017

Background: Soil microorganisms play key roles in nutrient cycling and are distributed throughout the soil profile. Currently, there is little information about the characteristics of the microbial communities along the soil depth because most studies focus on microorganisms inhabiting the soil surface. To better understand the functions and composition of microbial communities and the biogeochemical factors that shape them at different soil depths, we analyzed microbial activities and bacterial and fungal community composition in soils up to a 120 cm depth at a fallow field located in central Korea. To examine the vertical difference of microbial activities and community composition, ${\beta}$-1,4-glucosidase, cellobiohydrolase, ${\beta}$-1,4-xylosidase, ${\beta}$-1,4-N-acetylglucosaminidase, and acid phosphatase activities were analyzed and barcoded pyrosequencing of 16S rRNA genes (bacteria) and internal transcribed spacer region (fungi) was conducted. Results: The activity of all the soil enzymes analyzed, along with soil C concentration, declined with soil depth. For example, acid phosphatase activity was $125.9({\pm}5.7({\pm}1SE))$, $30.9({\pm}0.9)$, $15.7({\pm}0.6)$, $6.7({\pm}0.9)$, and $3.3({\pm}0.3)nmol\;g^{-1}\;h^{-1}$ at 0-15, 15-30, 30-60, 60-90, and 90-120 cm soil depths, respectively. Among the bacterial groups, the abundance of Proteobacteria (38.5, 23.2, 23.3, 26.1, and 17.5% at 0-15, 15-30, 30-60, 60-90, and 90-120 cm soil depths, respectively) and Firmicutes (12.8, 11.3, 8.6, 4.3, and 0.4% at 0-15, 15-30, 30-60, 60-90, and 90-120 cm soil depths, respectively) decreased with soil depth. On the other hand, the abundance of Ascomycota (51.2, 48.6, 65.7, 46.1, and 45.7% at 15, 30, 60, 90, and 120 cm depths, respectively), a dominant fungal group at this site, showed no clear trend along the soil profile. Conclusions: Our results show that soil C availability can determine soil enzyme activity at different soil depths and that bacterial communities have a clear trend along the soil depth at this study site. These metagenomics studies, along with other studies on microbial functions, are expected to enhance our understanding on the complexity of soil microbial communities and their relationship with biogeochemical factors.

• 한국지하수토양환경학회지:지하수토양환경
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• 제25권2호
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• pp.16-23
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• 2020

In this work, ²²²Rn activity, major dissolved ions, and microbial community in ground- and surface waters were investigated to characterize groundwater inflow to the stream located in an urban area, Daejeon, Korea. The measured ²²²Rn activities in groundwater and stream water ranged from 136 to 231 Bq L^-1 and 0.3 to 48.8 Bq L^-1, respectively. The spatial distributions of ²²²Rn activity in the stream strongly suggested groundwater inflow to the stream. The change of geochemical composition of the stream water indicated the effect of groundwater discharge became more pronounced as the stream flows downstream. Furthermore, microbial community composition of the stream water had good similarity to that of groundwater, which is another evidence of groundwater discharge. Although groundwater inflow could not be estimated quantitatively in this study, the results can provide useful information to understand interactions between groundwater and surface water, and determine hydrological processes governing groundwater recharge and hydrogeological cycles of dissolved substances such as nutrients and trace metals.

• 한국토양비료학회지
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• 제48권2호
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• pp.81-86
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• 2015

Soil management for orchard depends on the effects of soil microbial activities. The present study evaluated the soil microbial community of 25 orchard (5 sites for sandy loam, 7 sites for silt loam, and 13 sites for loam) in Gyeongnam Province by fatty acid methyl ester (FAME) method. The average values for 25 orchard soil samples were $270nmol\;g^{-1}$ of total FAMEs, $72nmol\;g^{-1}$ of total bacteria, $34nmol\;g^{-1}$ of Gram-negative bacteria, $34nmol\;g^{-1}$ of Gram-positive bacteria, $6nmol\;g^{-1}$ of actinomycetes, $49nmol\;g^{-1}$ of fungi, and $7nmol\;g^{-1}$ of arbuscular mycorrhizal fungi. In addition, silt loam soils had significantly low ratio of cy17:0 to $16:1{\omega}7c$ and cy19:0 to $18:1{\omega}7c$ compared with those of loam soils (p < 0.05), indicating that microbial activity increased. The average soil microbial communities in the orchard soils were 26.7% of bacteria, 17.9% of fungi, 12.6% of Gram-negative bacteria, 12.5% of Gram-positive bacteria, 2.5% of arbuscular mycorrhizal fungi, and 2.2% of actinomycetes. The soil microbial community of Gram-negative bacteria in silt loam soils was significantly higher than those of sandy loam and loam soils (p < 0.05).

• 한국토양비료학회지
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• 제43권6호
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• pp.1012-1017
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• 2010

본 연구는 고추 연작의 작부체계가 토양 미생물의 변화에 미치는 효과를 분석하고자 10년 동안 무농약 및 화학적 무비료의 시용방법으로 수행되었다. 지표 PLFAs 분석을 통해 토양미생물상과 활성도를 평가하였다. 고추와 마늘의 단작, 마늘과 고추의 간작의 작부체계에 따른 토양의 화학학성은 큰 차이를 보이지 않았으나 토양 미생물의 PLFAs의 다양성은 PC2에서 다른 작부체계와 상이한 미생물상으로 구분되었으며, 토양 미생물의 PLFAs의 총량은 마늘 단작구와 비교하여 고추 단작구에서 유의적인 감소를 보였으며, 미생물군집의 구조는 내생균근균의 비율에서 유의성있는 감소를 보였다. 이는 마늘과 고추의 근계에 따라 내생균근균의 미생물체량의 감소하였으며, 이것이 토양미생물상과 활성도를 다른 작부체계와 구분한 것으로 판단된다.

• Journal of Microbiology and Biotechnology
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• 제26권12호
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• pp.2127-2137
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• 2016

A mangrove microbial community was analyzed at the gene and protein levels using metagenomic and proteomic methods with the green macroalgae Enteromorpha prolifera as the substrate. Total DNA was sequenced on the Illumina HiSeq 2000 PE-100 platform. Two-dimensional gel electrophoresis in combination with liquid chromatography tandem mass spectrometry was used for proteomic analysis. The metagenomic data revealed that the orders Pseudomonadales, Rhizobiales, and Sphingomonadales were the most prevalent in the mangrove microbial community. By monitoring changes at the functional level, proteomic analyses detected ATP synthase and transporter proteins, which were expressed mainly by members of the phyla Proteobacteria and Bacteroidetes. Members of the phylum Proteobacteria expressed a high number of sugar transporters and demonstrated specialized and efficient digestion of various glycans. A few glycoside hydrolases were detected in members of the phylum Firmicutes, which appeared to be the main cellulose-degrading bacteria. This is the first report of multiple "omics" analysis of E. prolifera degradation. These results support the fact that key enzymes of glycoside hydrolase family were expressed in large quantities, indicating the high metabolic activity of the community.