• Journal of Microbiology and Biotechnology
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• 제25권7호
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• pp.978-987
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• 2015

Aluminum (Al) toxicity is one of the greatest limitations to agriculture in acid soils, particularly in tropical regions. Arbuscular mycorrhizal fungi (AMF) can supply plants with nutrients and give protection against Al toxicity. The aim of this work was to evaluate the effects of soil liming (i.e., reducing Al saturation) on the AMF community composition and structure in the roots of maize lines contrasting for Al tolerance. To this end, we constructed four 18S rDNA cloning libraries from L3 (Al tolerant) and L22 (Al sensitive) maize lines grown in limed and non-limed soils. A total of 790 clones were sequenced, 69% belonging to the Glomeromycota phylum. The remaining sequences were from Ascomycota, which were more prominent in the limed soil, mainly in the L3 line. The most abundant AM fungal clones were related to the family Glomeraceae represented by the genera uncultured Glomus followed by Rhizophagus and Funneliformis. However, the most abundant operational taxonomic units with 27% of the Glomeromycota clones was affiliated to genus Racocetra. This genus was present in all the four libraries, but it was predominant in the non-limed soils, suggesting that Racocetra is tolerant to Al toxicity. Similarly, Acaulospora and Rhizophagus were also present mostly in both lines in non-limed soils. The community richness of AMF in the non-limed soils was higher than the limed soil for both lines. The results suggest that the soil Al saturation was the parameter that mostly influences the AMF species composition in the soils in this study.

• 한국균학회지
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• 제42권2호
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• pp.133-137
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• 2014

본 연구에서는 간벌 처리에 따른 외생균근균의 군집 구조의 변화를 확인하기 위해 간벌지와 비간벌지에서 정량적으로 토양을 채취하여 간벌에 따른 외생균근균의 종 다양성, 종 수, 외생균근 수, 군집 내 종 구성을 비교하였다. 분석 결과 간벌지와 비간벌지는 공통적으로 Russula 속이 우점하고 있으나, 간벌 처리 후 산림 토양의 외생균근균 군집의 종 구성이 달라지고 종 수가 증가되는 것을 확인하였다. 본 연구결과는 간벌이 산림 생태계의 지상부 뿐만 아니라 외생균근균과 같은 토양속의 미생물의 군집 구조에도 유의미한 영향을 미치는 중요한 요인이라는 것을 보여주고 있다.

• Mycobiology
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• 제50권2호
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• pp.142-149
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• 2022

Orchids live with mycorrhizal fungi in mutualism. This symbiotic relationship plays an essential role in the overall life cycle of orchids from germination, growth, settlement, and reproduction. Among the 1000 species of the orchid, the Korean lady's slipper, Cypripedium japonicum, is known as an endangered species. Currently, only five natural habitats of the Korean lady's slipper remain in South Korea, and the population of Korean lady's slipper in their natural habitat is not increasing. To prevent extinction, this study was designed to understand the fungal community interacting in the rhizosphere of the Korean lady's slipper living in the native and artificial habitats. In-depth analyses were performed to discover the vital mycorrhizal fungi contributing to habitat expansion and cultivation of the endangered orchid species. Our results suggested that Lycoperdon nigrescens contributed most to the increase in natural habitats and Russula violeipes as a characteristic of successful cultivation. And the fungi that helped L. nigrescens and R. violeipes to fit into the rhizosphere community in Korean lady's slipper native place were Paraboeremia selaginellae and Metarhizium anisopliae, respectively. The findings will contribute to restoring and maintaining the endangered orchid population in natural habitats.

• The Plant Pathology Journal
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• 제32권2호
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• pp.136-144
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• 2016

Pseudomonas fluorescens pc78 is an effective biocontrol agent for soil-borne fungal diseases. We previously constructed a P43-gfp tagged biocontrol bacteria P. fluorescens pc78-48 to investigate bacterial traits in natural ecosystem and the environmental risk of genetically modified biocontrol bacteria in tomato rhizosphere. Fluctuation of culturable bacteria profile, microbial community structure, and potential horizontal gene transfer was investigated over time after the bacteria treatment to the tomato rhizosphere. Tagged gene transfer to other organisms such as tomato plants and bacteria cultured on various media was examined by polymerase chain reaction, using gene specific primers. Transfer of chromosomally integrated P43-gfp from pc78 to other organisms was not apparent. Population and colony types of culturable bacteria were not significantly affected by the introduction of P. fluorescens pc78 or pc78-48 into tomato rhizosphere. Additionally, terminal restriction fragment length polymorphism profiles were investigated to estimate the influence on the microbial community structure in tomato rhizosphere between non-treated and pc78-48-treated samples. Interestingly, rhizosphere soil treated with strain pc78-48 exhibited a significantly different bacterial community structure compared to that of non-treated rhizosphere soil. Our results suggest that biocontrol bacteria treatment influences microbial community in tomato rhizosphere, while the chromosomally modified biocontrol bacteria may not pose any specific environmental risk in terms of gene transfer.

• 한국환경농학회지
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• 제38권3호
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• pp.185-196
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• 2019

BACKGROUND: This study investigated the effects of rice genetically modified to be resistant against rice blast and rice bacterial blight on the soil microbial community. A comparative analysis of the effects of rice genetically modified rice choline kinase (OsCK1) gene for disease resistance (GM rice) and the Nakdong parental cultivar (non-GM rice) on the soil microbial community at each stage was conducted using rhizosphere soil of the OsCK1 and Nakdong rice. METHODS AND RESULTS: The soil chemistry at each growth stage and the bacterial and fungal population densities were analyzed. Soil DNA was extracted from the samples, and the microbial community structures of the two soils were analyzed by pyrosequencing. No significant differences were observed in the soil chemistry and microbial population density between the two soils. The taxonomic analysis showed that Chloroflexi, Proteobacteria, Firmicutes, Actinobacteria, and Acidobacteria were present in all soils as the major phyla. Although the source tracking analysis per phylogenetic rank revealed that there were differences in the bacteria between the GM and non-GM soil as well as among the cultivation stages, the GM and non-GM soil were grouped according to the growth stages in the UPGMA dendrogram analysis. CONCLUSION: The difference in bacterial distributions between Nakdong and OsCK1 rice soils at each phylogenetic level detected in microbial community analysis by pyrosequencing may be due to the genetic modification done on GM rice or due to heterogeneity of the soil environment. In order to clarify this, it is necessary to analyze changes in root exudates along with the expression of transgene. A more detailed study involving additional multilateral soil analyses is required.

• Mycobiology
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• 제43권3호
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• pp.203-209
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• 2015

Three new fungal species of the genus Mortierella, Mortierella zychae, Mortierella ambigua, and Mortierella indohii, have been reported in Korea. The fungi were encountered during a study on the fungal community of soil samples collected from different locations in Korea. The species were identified based on molecular and morphological analyses. This study presents detailed descriptions of the morphological observations and molecular phylogenetic analysis of these three fungi. All three species were found to be sensitive to triphenyltetrazolium chloride staining. M. zychae demonstrated the highest intensity of mycelial staining, indicating that this species has the highest potential to produce arachidonic acid of the three species. The staining results indicated that the newly recorded species could potentially be useful for arachidonic acid production.

• 한국균학회지
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• 제46권4호
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• pp.427-435
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• 2018

본 연구에서는 충남, 제주, 경남, 충북 등에서 새우난초(Calanthe discolor)와 은대난초(Cephalanthera longibracteata)의 뿌리를 채취하여 표면살균한 후 내생균을 순수분리 하였다. 분리된 내생균의 형태학 특징을 관찰하고 internaltranscribed spacer (ITS) rDNA영역의 염기서열을 ITS1F와 ITS4프라이머를 이용하여 분석하였다. 서로 다른 지역에서 채집한 새우난초와 은대난초이지만, 공통적으로 Leptodontidium orchidcola가 높은 상대수도와 빈도를 나타냈으며, 내생균류의 군집차이를 분석할 결과, 지역적 차이보다는 숙주에 의한 차이가 더 큰 영향을 미치는 것으로 나타났다.

• Journal of Microbiology and Biotechnology
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• 제32권12호
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• pp.1561-1572
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• 2022

Plastic pollution has been recognized as a serious environmental problem, and microbial degradation of plastics is a potential, environmentally friendly solution to this. Here, we analyzed and compared microbial communities on waste plastic films (WPFs) buried for long periods at four landfill sites with those in nearby soils to identify microbes with the potential to degrade plastics. Fourier-transform infrared spectroscopy spectra of these WPFs showed that most were polyethylene and had signs of oxidation, such as carbon-carbon double bonds, carbon-oxygen single bonds, or hydrogen-oxygen single bonds, but the presence of carbonyl groups was rare. The species richness and diversity of the bacterial and fungal communities on the films were generally lower than those in nearby soils. Principal coordinate analysis of the bacterial and fungal communities showed that their overall structures were determined by their geographical locations; however, the microbial communities on the films were generally different from those in the soils. For the pulled data from the four landfill sites, the relative abundances of Bradyrhizobiaceae, Pseudarthrobacter, Myxococcales, Sphingomonas, and Spartobacteria were higher on films than in soils at the bacterial genus level. At the species level, operational taxonomic units classified as Bradyrhizobiaceae and Pseudarthrobacter in bacteria and Mortierella in fungi were enriched on the films. PICRUSt analysis showed that the predicted functions related to amino acid and carbohydrate metabolism and xenobiotic degradation were more abundant on films than in soils. These results suggest that specific microbial groups were enriched on the WPFs and may be involved in plastic degradation.

• 한국균학회지
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• 제42권1호
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• pp.34-39
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• 2014

완도의 동백나무 자생지역에서 동백나무의 근권과 주변 일반 식물의 근권 토양을 수집하여 토양 내 수지상균근균(AMF)의 다양성 및 군집 구조를 확인하였다. 분석 결과 두 근권은 모두 Acaulospora mellea 포자로 우점되어 있지만 동백나무 근권에 비해 일반 기주식물의 근권에서 AMF종 다양성 지수와 종 수 및 포자 수가 더 높게 나타나는 경향을 확인하였다. 기주식물의 종류에 상관없이 A. mellea가 높은 빈도로 출현하는 것으로 보아 A. mellea가 다른 AMF종에 비해 산림 토양 및 목본 식물에 특이적으로 적응된 것으로 생각된다. 두 근권에서 발견된 AMF 군집간의 유사도를 분석한 결과 동백나무의 근권에서 발견된 AMF 군집간의 유사도가 동백나무 근권 AMF 군집 일반 기주식물 근권 AMF 군집 간의 유사도나 일반 기주식물 근권 AMF 군집간의 유사도에 비해 더 높은 것으로 나타났다. 이는 동백나무 근권이 다른 일반 기주식물의 근권과는 다른 독특한 AMF 군집 구조를 형성하고 있으며, 식물의 근권 주변의 AMF 군집은 기주식물에 의해 유의미한 수준으로 달라질 수 있음을 보여준다.

• Journal of Ecology and Environment
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• 제44권2호
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• pp.72-80
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• 2020

Background: Antibiotics are widely used to treat animals from infections. After fertilizing, antibacterials can remain in the soil while adversely affecting the soil microorganisms. The concentration of oxytetracycline (OTC) in the soil and its effect on the soil microbial community was assessed. To assess the impact of OTC on the soil microbial community, it was added to the soil at concentrations of 50, 150, and 300 mg kg^-1 and incubated for 35 days. Results: The concentration of OTC added to the soil decreased from 150 to 7.6 mg kg^-1 during 30 days of incubation, as revealed by LC-MS. The deviations from the control values in the level of substrate-induced respiration on the 5th day of the experiment were, on average, 26, 68, and 90%, with OTC concentrations at 50, 150, and 300 mg kg^-1, respectively. In samples with 150 and 300 mg kg^-1 of OTC, the number of bacteria from the 3rd to 14th day was 2-3 orders of magnitude lower than in the control. The addition of OTC did not affect the fungal counts in samples except on the 7th and 14th days for the 150 and 300 mg kg^-1 contaminated samples. Genes tet(M) and tet(X) were found in samples containing 50, 150, and 300 mg kg^-1 OTC, with no significant differences in the number of copies of tet(M) and tet(X) genes from the OTC concentration. Conclusions: Our results showed that even after a decrease in antibiotic availability, its influence on the soil microbial community remains.