• Journal of Microbiology
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• 제43권3호
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• pp.219-227
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• 2005

Little is known about the bacterial communities associated with the plants inhabiting sand dune ecosystems. In this study, the bacterial populations associated with two major sand dune plant species, Calystegia soldanella (beach morning glory) and Elymus mollis (wild rye), growing along the costal areas in Tae-An, Chungnam Province, were analyzed using a culture-dependent approach. A total of 212 bacteria were isolated from the root and rhizosphere samples of the two plants, and subjected to further analysis. Based on the analysis of the 16S rDNA sequences, all the bacterial isolates were classified into six major phyla of the domain Bacteria. Significant differences were observed between the two plant species, and also between the rhizospheric and root endophytic communities. The isolates from the rhizosphere of the two plant species were assigned to 27 different established genera, and the root endophytic bacteria were assigned to 21. Members of the phylum Gammaproteobacteria, notably the Pseudomonas species, comprised the majority of both the rhizospheric and endophytic bacteria, followed by members of Bacteroidetes and Firmicutes in the rhizosphere and Alphaproteobacteria and Bacteroidetes in the root. A number of isolates were recognized as potentially novel bacterial taxa. Fifteen out of 27 bacterial genera were commonly found in the rhizosphere of both plants, which was comparable to 3 out of 21 common genera in the root, implying the host specificity for endophytic populations. This study of the diversity of culturable rhizospheric and endophytic bacteria has provided the basis for further investigation aimed at the selection of microbes for the facilitation of plant growth.

• Journal of Ginseng Research
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• 제43권1호
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• pp.77-85
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• 2019

Background: Glomus intraradices is a species of arbuscular mycorrhizal fungi that, as an obligate endomycorrhiza, can form mutually beneficial associations with plants. Panax ginseng is a popular traditional Chinese medicine; however, problems associated with ginseng planting, such as pesticide residues, reduce the ginseng quality. Methods: In this experiment, we studied the effect of inoculating G. intraradices on several physiological properties and microbial communities of ginseng. UV-Visible Spectrum method was used to detect physical properties. Denaturing gradient gel electrophoresis method was used to analyze microbial communities. Results: The results indicated that inoculation with G. intraradices can improve the colonization rate of lateral ginseng roots, increase the levels of monomeric and total ginsenosides, and improve root activity as well as polyphenol oxidase and catalase activities. We also studied the bacterial and fungal communities in ginseng rhizospheric soil. In our study, G. intraradices inoculation improved the abundance and Shannon diversity of bacteria, whereas fungi showed a reciprocal effect. Furthermore, we found that G. intraradices inoculation might increase some beneficial bacterial species and decreased pathogenic fungi in rhizospheric soil of ginseng. Conclusion: Our results showed that G. intraradices can benefit ginseng planting which may have some instructive and practical significance for planting ginseng in farmland.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2018년도 추계학술대회
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• pp.121-121
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• 2018

• Journal of Microbiology and Biotechnology
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• 제17권6호
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• pp.919-927
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• 2007

Antagonistic fluorescent pseudomonads isolated from rhizospheric soil of rice were characterized by 16S rRNA amplicon and fatty acid methyl ester (FAME) analyses. Antagonistic isolates were grown in the fermentation media, and production of antibiotics was confirmed by thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). Production of fungal cell-wall-degrading enzymes such as protease, cellulase, pectinase, and chitinase was determined. Dendrogram based on the major and differentiating fatty acids resulted into 5 clusters, viz., cluster I (P. pseudoalcaligenes group), cluster II (P. plecoglossicida group), cluster III (P. fluorescens group), cluster IV (P. aeruginosa group), and cluster V (P. putida group). Characteristic presence of high relative proportions of cyclopropane (17:0 CYCLO w7c) was observed in antagonistic bacteria. Data revealed biodiversity among antagonistic fluorescent pseudomonads associated with the rice rhizosphere. Results presented in this study will help to identify the antagonistic isolates and to determine their mechanisms that mediate antagonism against fungal pathogens of rice.

• 미생물학회지
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• 제55권2호
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• pp.171-173
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• 2019

Paenibacillaceae계의 Cohnella 속은 다양한 환경 속에서 서식한다. 여기에 우리는 한국 한라산 꼭대기의 구상나무(Abies koreana) 근권 토양으로부터 분리된 Cohnella sp. HS21의 전체 게놈 서열을 보고한다. 균주 HS21은 원형 염색체 7,059,027 bp와 44.8%의 GC 함량을 가지고 있다. 5,939개의 단백질 코딩 유전자와 78개의 트랜스퍼 (tRNA) 유전자, 27개의 리보솜 RNA (rRNA) 유전자, 4개의 비 코딩 RNA 유전자(ncRNA), 90개의 위 유전자가 존재했다. 박테리아는 항생제 관련 유전자 클러스터와 식물 세포벽 분해 효소를 코딩하는 유전자를 포함하고 있다.

• Journal of Microbiology and Biotechnology
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• 제30권8호
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• pp.1169-1179
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• 2020

In this study, two soybean genotypes, i.e., aluminum-tolerant Baxi 10 (BX10) and aluminumsensitive Bendi 2 (BD2), were used as plant materials and acidic red soil was used as growth medium. The soil layers from the inside to the outside of the root are: rhizospheric soil after washing (WRH), rhizospheric soil after brushing (BRH) and rhizospheric soil at two sides (SRH), respectively. The rhizosphere bacterial communities were analyzed by high-throughput sequencing of V4 hypervariable regions of 16S rRNA gene amplicons via Illumina MiSeq. The results of alpha diversity analysis showed that the BRH and SRH of BX10 were significantly lower in community richness than that of BD2, while the WRH exhibited no significant difference between BX10 and BD2. Among the three sampling compartments of the same soybean genotype, WRH had the lowest community richness and diversity while showing the highest coverage. Beta diversity analysis results displayed no significant difference for any compartment between the two genotypes, or among the three different sampling compartments for any same soybean genotype. However, the relative abundance of major bacterial taxa, specifically nitrogen-fixing and/or aluminum-tolerant bacteria, was significantly different in the compartments of the BRH and/or SRH at phylum and genus levels, indicating genotype-dependent variations in rhizosphere bacterial communities. Strikingly, as compared with BRH and SRH, the WRH within the same genotype (BX10 or BD2) always had an enrichment effect on rhizosphere bacteria associated with nitrogen fixation.

• The Plant Pathology Journal
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• 제34권3호
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• pp.218-235
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• 2018

Plant growth promoting rhizobacteria and endophytic bacteria were isolated from different varieties of turmeric (Curcuma longa L.) from South India. Totally 50 strains representing, 30 PGPR and 20 endophytic bacteria were identified based on biochemical assays and 16S rDNA sequence analysis. The isolates were screened for antagonistic activity against Pythium aphanidermatum (Edson) Fitzp., and Rhizoctonia solani Kuhn., causing rhizome rot and leaf blight diseases in turmeric, by dual culture and liquid culture assays. Results revealed that only five isolates of PGPR and four endophytic bacteria showed more than 70% suppression of test pathogens in both assays. The SEM studies of interaction zone showed significant ultrastructural changes of the hyphae like shriveling, breakage and desication of the pathogens by PGPR B. cereus (RBacDOB-S24) and endophyte P. aeruginosa (BacDOB-E19). Selected isolates showed multiple Plant growth promoting traits. The rhizome bacterization followed by soil application of B. cereus (RBacDOB-S24) showed lowest Percent Disease Incidence (PDI) of rhizome rot and leaf blight, 16.4% and 15.5% respectively. Similarly, P. aeruginosa (BacDOB-E19) recorded PDI of rhizome rot (17.5%) and leaf blight (17.7%). The treatment of these promising isolates exhibited significant increase in plant height and fresh rhizome yield/plant in comparison with untreated control under greenhouse condition. Thereby, these isolates can be exploited as a potential biocontrol agent for suppressing rhizome rot and leaf blight diseases in turmeric.

• 한국유기농업학회지
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• 제19권spc호
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• pp.251-254
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• 2011

Botrytis cinerea infects stems and leaves of greenhouse tomatoes and can cause serious economic losses. This study was conducted to develop environment-friendly control method against tomato gray mold. Antagonistic microorganisms (bacteria) were screened for control activity against Botrytis cinerea, both in vitro and in vivo, using stem sections. One hundred bacterial strains were isolated from the rhizospheric soil of various plants including tomato. These strains were screened for growth inhibition of Botrytis cinerea on agar plate by the dual culture and thirty strains showing strongly inhibitory effect against the pathogen were selected first. Among thirty strains, JB 5-12, JB 22-2, JB 22-3, U 4-8 and U46-6 reduced significantly disease incidence, when applied simultaneously with the pathogen. These results suggested that five antagonistic bacteria strains selected have the potential to control tomato gray mold in organic farming.

• 한국환경농학회지
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• 제25권3호
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• pp.262-267
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• 2006

Increased application of glyphosate (Gly) in glyphosate-resistant (GR) soybean cropping systems may affect rhizospheric microorganisms including IAA-producing rhizobacteria (IPR) and their effect on the growth of soybean. This field experiment was conducted to assess IPR populations in the rhizosphere of GR soybean ('Roundup-Ready' DeKalb DKB38-52) treated with glyphosate and foliar amendment treatments such as $PT21^{(R)}$ (urea solution with N 21 %) and $Grozyme^{(R)}$ (Biostimulant: mixtures of micro nutrients and enzymes). Effects of herbicide, sampling date, and their interaction on total bacterial numbers were significant (P < 0.001, 0.001, 0.013, respectively). Total bacteria (TB) numbers were increased with glyphosate treatment at 20 d after application and highest TB populations were associated with $Grozyme^{(R)}$ application, possibly due to the additional substrate from this product. The IPR of the soybean rhizosphere was significantly affected by herbicide, sampling date, and the herbicide*foliar amendment interaction. The ratios of numbers of IPR to TB ranged from 0.79 to 0.99 across the sampling dates irrespective of treatments. IPR numbers were slightly hindered by glyphosate application regardless of foliar amendment.

• 미생물학회지
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• 제51권1호
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• pp.86-95
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• 2015

독도의 해안에 군락을 이룬 해안식물 근권에서 호염성 및 염내성을 가지는 세균의 분리를 위해 3종의 해안식물의 군락을 선정한 후 각 식물의 군집 하부에서 토양시료를 채취하였다. 시료는 marine broth 한천배지를 이용하여 형태학적인 구분을 통해 순수분리 되었다. 분리된 161개 세균들을 NaCl 9.0% 농도로 조정된 배지에서 생존하는 26개 균주를 선발하여 genomic DNA를 얻은 후, 16S rRNA gene sequence를 증폭하여 부분동정 하였다. 이들의 유연관계 확인을 위해 계통수를 작성한 결과, 이들은 각각 Firmicutes (30.8%), Gamma proteobacteria (53.8%), Bacteroidetes (7.7%), Alpha proteobacteria (7.7%), Actinobacteria (7.7%)에 속하였으며, 이는 기존의 독도 토양 및 해수 미생물상 연구와 특징적 차이를 보인다. 또한, 분리된 세균의 종 조성도 기존 독도 토양 및 해양연구와 유의적으로 상이함을 보였다. 이에 더하여 선발된 26개 균주들 중에서 4균주가 12.0% 이상의 염농도에서 생장하였으며, 이들 중에서 3개 균주가 15.0% 이상의 염농도에서 생장하여 극호염성의 특성을 나타내었으며, 광범위한 염분농도에서도 생장하는 특성을 보였다. 이들은 해안식물 근권에서 독도 특유의 고염분 및 염분변화라는 환경적 스트레스를 극복하며 해안식물과 어떠한 상호작용을 하는 것으로 생각된다.