• Journal of Microbiology
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• v.43 no.3
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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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• v.43 no.1
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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.

• Proceedings of the Korean Society of Crop Science Conference
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• 2018.10a
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• pp.121-121
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• 2018

• Journal of Microbiology and Biotechnology
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• v.17 no.6
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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.

• Korean Journal of Microbiology
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• v.55 no.2
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• pp.171-173
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• 2019

The genus Cohnella, which belongs to the family Paenibacillaceae, inhabits a wide range of environmental niches. Here, we report the complete genome sequence of Cohnella sp. HS21, which was isolated from the rhizospheric soil of Korean fir (Abies koreana) on the top of Halla Mountain in the Republic of Korea. Strain HS21 features a 7,059,027 bp circular chromosome with 44.8% GC-content. Its genome contains 5,939 protein-coding genes, 78 transfer RNA (tRNA) genes, 27 ribosomal RNA (rRNA) genes, 4 noncoding RNA genes (ncRNA), and 90 pseudogenes. The bacterium contains antibiotic-related gene clusters and genes encoding plant cell wall-degrading enzymes.

• Journal of Microbiology and Biotechnology
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• v.30 no.8
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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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• v.34 no.3
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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.

• Korean Journal of Organic Agriculture
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• v.19 no.spc
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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.

• Korean Journal of Environmental Agriculture
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• v.25 no.3
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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.

• Korean Journal of Microbiology
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• v.51 no.1
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• pp.86-95
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• 2015

To study the halobacterial diversity at the rhizospheric soil of coastal plant native to Dokdo islands, several host plant were selected and its rhizospheric soil was sampled. Soil sample was diluted serially and pure isolation was done by sub-culture using marine agar media. 26 halophilic strains cultivable at the marine medium containig concentration of 9.0% sodium chloride were selected among total 161 isolates. Their partial 16S rRNA gene sequences extracted from genomic DNA were analyzed and partially identified. Furthermore, to identify their genetic relationship, phylogenetic tree was deduced. Total 26 strains were belongs to Firmicutes (30.8%), Gamma proteobacteria (53.8%), Bacteroidetes (7.7%), Alpha proteobacteria (7.7%), and Actinobacteria (7.7%). These results showed the specific difference from previous researches which has been reported the microbial flora of soil or sea water around the Dokdo islands. Furthermore, 4 among 26 halophilic strains grew at above 12.0% NaCl concentrated marine broth, and 2 strains Idiomarina abyssalis LM4H23 and Halomonas huangheensis AS4H13 grew at 15.0% concentration. These halophilic strains thought to overcoming the severe stress like high salt concentration or variation derived from Dokdo-specific climate and might have unknown, specific relationship with their host coastal plant native to Dokdo islands.