• 한국유기농업학회지
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• 제26권3호
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• pp.427-437
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• 2018

In this study, microorganism community characteristics of organic managed soil which applied rye (Secale cereal L.) as green manure for 25 years, were determined. The chemical properties of organic soil showed high level of organic matter and available $P_2O_5$, while the level of exchangeable cation was low. The analysis of dehydrogenase activity and carbon source utilization indicated that the values in on organic soil were significantly higher than those of the control. It suggested that the microorganism community of organic soil had high microorganism activity, compared to the control. In addition, when the 16S rRNA gene-targeted NGS (Next generation sequencing) analysis was conducted to estimate the class of bacterial community, the class level of bacterial taxon composition on organic soil showed higher portion of Sphingobacteriia, Acidobacteriia, Gammaproteobacteria, Solibacteres and Planctomycetia. By base on the results of various reports in which organic managed soil had high portion of Acidobacteriia and Planctomycetia, the characteristic of taxon composition in organic soil, which showed the high percentages of Ktedonobacteria, Sphingobacteriia, Acidobacteriia and Gammaproteobacteria, was resulted from the application of rye as a green manure for the long term. However, further researches were needed because the crop effect was not considered in this study.

• Journal of Forest and Environmental Science
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• 제34권3호
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• pp.258-261
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• 2018

Drought alters soil microorganisms; however, it is still not clear how soil microbes respond to severe drought conditions. In this study, the responses of soil bacterial community to experimental drought in a coniferous stand were examined. Six $6m{\times}6m$ plots with three replicates of control and drought treatments were delimited. PCR amplification and Illumina sequencing were conducted for cluster analysis of soil bacterial community and species richness and species diversity was analyzed. Along the 393 days of simulated drought from July 2016 to October 2017, soil bacterial species diversity slightly increased whereas species richness decreased in both control and roof plots. Moreover, soil bacterial species richness more decreased in roof plots than in controls. Combining these results, soil bacterial activity might have been altered by simulated drought.

• 한국환경농학회지
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• 제38권3호
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• pp.197-204
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• 2019

BACKGROUND: Living modified microorganisms (LMMs) have been focused in two very different aspects of positive and negative effects on ecology and human health. As a model experiment, wild type and a foreign origin gene-harboring modified E. coli strains were subjected to comparison of their metabolomes and potential effects on soil microbiota in the laboratory sets. This study assumes the unintentional release of LMMs and tries to suggest potential effects on the soil microbiota even at minimal settings. METHODS AND RESULTS: Metabolomes from the wild type and LM E. coli were analyzed by NMR and the profiles were compared. In the laboratory soil experiments, the two types of E. coli were added to the soils and monitored for the bacterial community compositions. Those metabolomic profiles did not show significant differences. The microbial community structures from the time series soil DNAs for both the sets using wild type and LMO also did not indicate significant changes, but minor by the addition of foreign organisms regardless of wild or LMO. CONCLUSION: Even if the recombinant microorganism (LMO) is released into the soil environment, the survival of microorganisms in the environment would be one of the major factors for the transfers of foreign genes to other organisms and diffusion into the soil environment.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2021년도 학술발표회
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• pp.128-128
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• 2021

Most of the studies about stormwater low impact development technologies used generalized observations without fully understanding the mechanisms affecting the whole performance of the systems from catchment to the facility itself. At present, these LID technologies have been treated as black box due to fluctuating flow and environmental conditions affecting its operation and treatment performance. As such, the implications of microbial community to the overall performance of the tree-box filter were investigated in this study. Summer season was found to be the most suitable season for microorganism growth since more microorganism were found during this season. Least microorganism count was found in spring because of the plant growth during this season since plant penology influences the seasonal dynamics of soil microorganisms. Litterfall during fall season might have affected the microorganism count during winter since, during this season, the compositional variety of soil organic matter changes affecting growth of soil microbial communities. Microbial analyses of sediment samples collected in the system revealed that the most dominant microorganism phylum is Proteobacteria in all the seasons in both inlet and outlet comprising 37% to 47% of the total microorganism count. Proteobacteria was followed by Acidobacteria, Actinobacteria and Chloroflexi which comprises 6% to 20%, 9% to 20% and 2% to 27%, respectively of the total microorganism count for each season. These findings were useful in optimizing the design and performance of tree box filters considering physical, chemical and biological pollutant removal mechanisms.

• Journal of Microbiology and Biotechnology
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• 제30권11호
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• pp.1688-1696
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• 2020

Soil physical and chemical characteristics, soil potential denitrification rates (PDR), community composition and nirK-, nirS- and nosZ-encoding denitrifiers were studied by using MiSeq sequencing, quantitative polymerase chain reaction (qPCR), and terminal restriction fragment polymorphism (T-RFLP) technologies base on short-term (5-year) tillage field experiment. The experiment included four tillage treatments: conventional tillage with crop residue incorporation (CT), rotary tillage with crop residue incorporation (RT), no-tillage with crop residue retention (NT), and rotary tillage with crop residue removed as control (RTO). The results indicated that soil organic carbon, total nitrogen and NH₄⁺-N contents were increased with CT, RT and NT treatments. Compared with RTO treatment, the copies number of nirK, nirS and nosZ in paddy soil with CT, RT and NT treatments were significantly increased. The principal coordinate analysis indicated that tillage management and crop residue returning management were the most and the second important factors for the change of denitrifying bacteria community, respectively. Meanwhile, this study indicated that activity and community composition of denitrifiers with CT, RT and NT treatments were increased, compared with RTO treatment. This result showed that nirK, nirS and nosZ-type denitrifiers communities in crop residue applied soil had higher species diversity compared with crop residue removed soil, and denitrifying bacteria community composition were dominated by Gammaproteobacteria, Deltaproteobacteria, and Betaproteobacteria. Therefore, it is a beneficial practice to increase soil PDR level, abundance and community composition of nitrogen-functional soil microorganism by combined application of tillage with crop residue management.

• 한국환경과학회지
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• 제14권4호
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• pp.367-371
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• 2005

Soil samples were collected from new-developed wetland soil ecosystem of Tamarix chinesis plantation in Chinese Yellow River Delta in different months of 2003. Soil characteristics, temporal change and spatial distribution of microbial community composition and their relationship with nitrogen turnover and circling were investigated in order to analyze and characterize the role of microbial diversity and functioning in the specific soil ecosystem. The result showed that the total population of microbial community in the studied soil was considerably low, compared with common natural ecosystem. The amount of microorganism followed as the order: bacteria> actinomycetes>fungi. Amount of actinomycetes were higher by far than that of fungi. Microbial population remarkably varied in different months. Microbial population of three species in top horizon was corrected to that in deep horizon. Obvious rhizosphere effect was observed and microbial population was significantly higher in rhizosphere than other soils due to vegetation growth, root exudation, and cumulative dead fine roots. Our results demonstrate that microbial diversity is low, while is dominated by specific community in the wetland ecosystem of Tamarix chinesi.

• 한국유기농업학회지
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• 제19권spc호
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• pp.190-193
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• 2011

Organic and chemical fertilizer amendments are an important agricultural practice for increasing crop yields. In order to maintain the soil sustainability, it is important to monitor the effects of fertilizer applications on the shift of soil microorganism, which control the cycling of many nutrients in the soils. Here, culture-dependent and culture-independent approaches were used to analyze the soil microorganism and community structure under six fertilization treatments, including green manure, rice straw compost, rapeseed cake, pig mature compost, NPK +pig mature compost, NPK and control. Both organic and chemical fertilizers caused a shift of the cultural microorganism CFUs after treatments. Bacterial CFUs of the organic fertilization treatments were significantly higher than that of chemical fertilization treatments. The DGGE profiles of the bacterial communities of the samples showed that the green manure treatment was a distinct difference in bacterial community, with a greater complexity of the band pattern than other treatments. Cluster analyses based on the DGGE profile showed that rice straw compost and pig mature compost had a similar banding pattern and clustered together firstly. Rapeseed cake, NPK, NPK +pig manure compost and control clustered together in other sub-cluster and clearly distinguished from green manure.

• 한국환경과학회지
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• 제30권5호
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• pp.379-389
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• 2021

Soil microorganism activity in an agricultural field is affected by various factors including climate conditions, soil chemical properties, and crop cultivation. In this study, we elucidate the correlation between microorganism activity and agricultural environment factors using the dehydrogenase activity (DHA) value, which is one of the indicators of soil microbial activity. As a result, the various factors noted above were related to the DHA value. Annual rainfall, soil Mg2+, bacterial and fungal diversities, types of crops, developmental stages, seasons, and cultivation status were highly correlated with the DHA value. Furthermore, next-generation sequencing (NGS) analysis was used to identify that the type of crop affected soil microbial compositions of both bacteria and fungi. Soil used for soybean cultivation showed the highest relative abundance for Verrucomicrobia, Planctomycetes, and Acidobacteria but Actinobacteria and Firmicutes had the lowest relative abundance. In the case of soil used for potato cultivation, Actinobacteria had the highest relative abundance but Proteobacteria had the lowest relative abundance. Armatimonadetes showed the highest relative abundance in soil used for cabbage cultivation. Among the fungal communities, Mortierellomycota had the highest relative abundance for soybean cultivation but the lowest relative abundance for cabbage cultivation; further, Rozellomycota, Chytridiomycota, and Cercozoa had the highest relative abundance for cabbage cultivation. Basidiomycota had the highest relative abundance for potato cultivation but the lowest relative abundance for soybean cultivation.

• 한국환경농학회지
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• 제38권2호
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• pp.76-82
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• 2019

저투입생산환경에서 콩 재배가 토양미생물군집활성도에 미치는 영향에 대한 결과는 다음과 같다. 초기 비료 및 퇴비 투입 후 유기물은 재배기간 내내 콩을 재배한 화분이 감자를 재배한 화분보다 높게 나타났으며, 토양 중 인산은 콩을 재배한 토양에 비해 감자를 재배한 토양에서 다소 높은 경향을 보였다. DHA 값은 콩을 재배한 토양이 생육기간 전반에 걸쳐 감자를 재배한 토양보다 유의하게 높게 나타나 토양미생물 활성도가 콩을 재배한 토양에서 증가됨을 알 수 있었고, 이러한 결과는 콩을 재배한 토양의 유기물함량 증가에도 영향을 미친것으로 판단된다. DGGE로 토양미생물군집을 분석한 결과 Proteobacteria 문(phylum)에 속하는 미생물들이 공통적으로 확인되었으며, 감자를 재배한 토양이 콩을 재배한 토양보다 다양한 미생물이 동정되었다. 또한, 콩 재배 토양의 높은 토양미생물활성도는 콩 재배 시 형성되는 소수의 특정한 미생물들에 의한 영향으로 판단된다.

• Journal of Microbiology and Biotechnology
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• 제22권4호
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• pp.563-566
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• 2012

To investigate the possibility of horizontal gene transfer between agricultural microorganisms and soil microorganisms in the environment, Bacillus subtilis KB producing iturin and the PGPR recombinant strain Pseudomonas fluorescens MX1 were used as model microorganisms. The soil samples of cucumber or tomato plants cultivated in pots and the greenhouse for a six month period were investigated by PCR, real-time PCR, Southern hybridization, and terminal restriction fragment length polymorphism (T-RFLP) fingerprinting. Our data from Southern blotting and T-RFLP patterns suggest that the model bacteria do not give significant impacts on the other bacteria in the pots and greenhouse during cultivation.