• Korean Journal of Microbiology
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• v.15 no.1
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• pp.20-30
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• 1977

Relationship of soil properties and seasonal variation on microbilogical population to-continuous culture and first-time culture of ginseng was investigated by bimonthly from May 1976 to January 1977. pH and P contents of 2 years continuous culture of soil were higher than other culture plot of soil, and contraty to the above, 2 years first-time culture of ginseng soil was conplot of soil, and contraty to the above, 2 years first-time culture of ginseng soil was contained more potassium contents than other culture plot of soil. In microbiological fluctuation with seasonr in various soil conditions, the population, trends of Fusarium spp., Erwiniaspp., and flourescent Psedudomonas spp. were increased in May and July in general, but decreased in the other month. It was observed that in all type of soil, Fusarium spp. was distributed in abundance in and on rihizosphere, and decreased the propagules numbers as soil depth increase. The numbers of Erwinia spp. and fluorescent Pseudo-monas spp. were distributed greater in numbers on the surface zone of soil depth decreasing the numbers along the soil layer increase, and also in 2years continuous culture of soil especially, a great numbers of Erwinia spp. and fluorescent Pseudomonas were evenly distributed in surface zone and rhizosphere. Ginseng disease with a high incidence of bacterial disease in continuous culture of 2 and 4 years was seemed to be associated with soil bacteria that was high in numbers of Erwinia spp. and fluorescent Pseudomonas spp. in May and July.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.3
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• pp.269-274
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• 1987

A laboratory experiment was conducted to find out the effect of inoculation with plant growth of associative $N_2$-fixing bacteria on the combination of eight different rice seedling with seven different associative $N_2$-fixing bacteria in which were isolated and identified from grasses and rice in saline and reclaimed saline paddy soil. Those were examined in N-free axenic culture medium. The result of this experiment exemplified the contribution of associative $N_2$-fixing bacteria to their host plant were varied much by the combination of rice cultivars and bacterial strains. Acetylene reduction ($N_2$-fixation) activity seems to be more variable with respect to the combination of rice cultivars and bacterial strains. The relationship between acetylene reduction activity and rice performance such as dry matter weight, plant height, root length, and number of root were statistically insignificant. However, in comparision with the control, the dry matter yield of Annapuruna was increased by inoculation of all the seven bacteria strains. Among the seven rice cultivars, the average acetylene reducing activity was the highest in Annapuruna, and Shingwang, and the lowest in IR-8 inoculated with Pseudomonas sp H8. Among the seven bacterial strains the highest acetylene reducing activity was obtained by the combination of Shingwang with Pseudomonas sp H8.

• Research in Plant Disease
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• v.12 no.3
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• pp.267-271
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• 2006

Botrytis cinerea Pers. was found to be highly virulent to the grapevine plant, especially in greenhouse condition. Pseudomonas species play key roles for the biocontrol of many plant diseases especially in soil. Of the 83 isolates of Pseudomonas spp., a bacterial strain P84, isolated from tomato rhizosphere, was shown to suppress a wide range of phytopathogenic fungi in vitro. The isolate was identified as Pseudomonas putida on the basis of its bacteriological and genetic characteristics. The P. putida P84 strain carry the phlD gene for 2,4-diacetylphloroglucinol biosynthesis and may produce the antibiotics as an antagonistic mechanism involved in biocontrol. The antagonistic activity of the bacterium has a promising implication for its use as a biocontrol agent to control grapevine gray mold.

• Microbiology and Biotechnology Letters
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• v.20 no.3
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• pp.263-270
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• 1992

For the selection of powerful antagonistic bacterium for biological control of soil borne Eminia carotovora subsp. carotovora causing rot of vegetable, excellent strains (S4, S14, 565) were selected from 1,196 strains of bacteria which were isolated from rhizosphere in vegetable root rot-suppresive soil. Strains were identified to be Pseudomonas species with Api 20NE kit. Antagonistic substance was produced in 523 synthetic broth medium at pH 7~8 and $30^{\circ}C$ during 3 days culture. The substance was stable in the pH range of 6 to 9. When the basal medium was supplemented with mannitol and sorbitol as carbon source and calcium chloride as metal salt, the production of the inhibitory substance was increased. The inhibitory acitivity was increased by the addition of fertilizer in soil. The isolated strains were resistant to the agricultural chemical such as benomyl and fosethyl-Al-folpet, and the antibiotics such as penicillin and lincomycin. We had found that Pseudomonas sp. S14 strain had a single plasmid. After treated with acridin orange for curing, we confirmed the existence of antagonistic gene in the chromosomal DNA.

• Microbiology and Biotechnology Letters
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• v.34 no.2
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• pp.180-184
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• 2006

Nineteen nitrogen-fixing bacteria were isolated from rice roots cultivated in the southern part of the Korean peninsula. Among them, three isolates - Stenotrophomonas sp. KNUC89, Pseudomonas sp. KNUC116, and Delftia sp. KNUC133 - showed antifungal activities against phytopathogenic fungi Rhizoctonia solani and Fusarium oxysporum. Besides they could produce auxin and siderophores.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2003.10b
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• pp.14-14
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• 2003

The aim of the present study isto assess the importance of siderophore producing rhizosphere bacteria on the growth of Brassica junceaunder chromium stress. Pseudomonassp. (A4) produced an iron chelating substance siderophores in iron deficient medium. Under chromium stress condition Pseudomonassp. (A4) markedly increased the root and shoot length and also biomass of Brassica juncea as compared to Pseudomonas sp. (A3). This plant growth promotion has been related to the microbial production of siderophore.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2003.10a
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• pp.20-29
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• 2003

The aim of the present study isto assess the importance of siderophore producing rhizosphere bacteria on the growth of Brassica junceaunder chromium stress. Pseudomonassp. (A4) produced an iron chelating substance siderophores in iron deficient medium. under chromium stress condition Pseudomonassp. (A4) markedly increased the root and shoot length and also biomass of Brassica juncea as compared to Pseudomonas sp. (A3). This plant growth promotion has been related to the microbial production of siderophore.

• Journal of Life Science
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• v.24 no.7
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• pp.757-761
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• 2014

Olive flounder (Paralichthys olivaceus) is an important aquaculture fish species in Jeju Island, South Korea. Due to the intensification of flounder fish farming, huge amounts of chemical antibiotics are used against several fish diseases. This has many harmful side effects on fish, as well as human consumers. Hence, an alternative to chemical antibiotic agents is needed for disease control. In this study, three strains of rhizobacteria (BRH433-2, TRH415-2, and THJ609-3) were isolated from the rhizosphere of plants. Assays of their antibacterial activity against fish pathogens, such as S. iniae, S. parauberis, V. anguillarum, and E. tarda, were performed with untreated broth culture (without cell separation), supernatant, and precipitated pellets separated by centrifugation. Among these, the cell suspension prepared from the precipitated pellet showed significant antimicrobial activity when compared with that of the untreated broth culture and centrifugal supernatant. These results indicate that the three isolated rhizobacterial strains exhibit antibacterial activity. Analysis of the 16S rDNA sequences of the BRH-433-2, THJ609-3, and TRH415-2 strains showed the highest similarity to Burkholderia gladioli (99.5%), Pseudomonas baetica (97.7%), and P. koreensis and P. baetica (98.4%), respectively. We suggest that the strains hold promise in disease management of fish.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.6
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• pp.442-446
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• 2007

From the rhizoplane and rhizosphere of pepper, tomato, lettuce, pasture, and grass, unsoluble inorganic phosphate solubilizing bacterial strains were isolated using plate base assay on Pikovskaya's medium. Two strains, CL-1 and CL-2, which produced largest halo on plates (indicative of phosphate solubilization)were selected for further studies. Based on these biochemical and 16S rRNA analysis strains CL-1, CL-2 were found to be as species of Pseudomonas sp. and Kluyvera sp., respectively. In broth assay Pseudomonas sp. CL-1 and Kluyvera sp. CL-2 solubilized insoluble phosphate by 193.4 mg and $493.6P\;mg\;L^{-1}$, respectively after $3^{rd}$ day inoculation. These effecient phosphate solubilizing bacteria have a potential to be developed as microbial based fertilizer in future.

• Journal of Microbiology and Biotechnology
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• v.21 no.8
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• pp.777-790
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• 2011

To elucidate the biodiversity of plant growth-promoting rhizobacteria (PGPR) in Korea, 7,638 bacteria isolated from the rhizosphere of plant species growing in many different regions were screened. A large number of PGPR were identified by testing the ability of each isolate to promote the growth of cucumber seedlings. After redundant rhizobacteria were removed via amplified rDNA restriction analysis, 90 strains were finally selected as PGPR. On the basis of 16S ribosomal RNA sequences, 68 Gram-positive (76%) and 22 Gram-negative (24%) isolates were assigned to 21 genera and 47 species. Of these genera, Bacillus (32 species) made up the largest complement, followed by Paenibacillus (19) and Pseudomonas (11). Phylogenetic analysis showed that most of the Grampositive PGPR fell into two categories: low- and high- G+C (Actinobacteria) strains. The Gram-negative PGPR were distributed in three categories: ${\alpha}$-proteobacteria, ${\beta}$- proteobacteria, and ${\gamma}$-proteobacteria. To our knowledge, this is the largest screening study designed to isolate diverse PGPR. The enlarged understanding of PGPR genetic diversity provided herein will expand the knowledge base regarding beneficial plant-microbe interactions. The outcome of this research may have a practical effect on crop production methodologies.