• Microbiology and Biotechnology Letters
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• v.29 no.1
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• pp.37-42
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• 2001

An antifungal substance was purified from culture broth of Pseudomonas flulorescens 2112 that showed a broad-spectrum antagonistic activity against various phytopathogenic fungi including capsici. The substance was identified as 2,4-diacetylphloro-glucinol basd on NMR analysis. The 2,4-diacetylphloroglcinol showed antibiotic activity in broad acidic range from pH 1.0 to pH 9.0. About 83% of initial activity was remained after incubation for 30min ar $60^{\circ}C$, however, the activity was dropped up to 50% after 30 min incubation in $80^{\circ}C$. When the nucleotides of P. capsici treated with 2,4-diacetylphloroglucinol were labeled with[$^{3}$ H]-Adenin, the newly synthesized and radioactive-labeled RNA was significantly reduced than those of untreated P. capsici. indicating that the 2,4-diacetylphloroglucinol inhibits RNA synthesis.

• Journal of Life Science
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• v.31 no.7
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• pp.641-653
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• 2021

The purpose of this study was to confirm the antifungal activity, plant growth-promoting activity, and mineral solubilizing activity of 18 types of bacteria isolated purely from rhizosphere soil. The potential of isolates of the genus Bacillus and Pseudomonas as biocontrol agents was confirmed through the antifungal activity of these isolates. This activity has been determined to be due to various hydrolytic enzymes on the cell wall of plant pathogenic fungi and the production of siderophores in isolates. In addition, most of the isolates have been found to have aminocyclopropane-1-carboxylate deaminase production activity, indole-3-acetic acid production activity, and nitrogen fixation activity. These characteristics are believed to have a positive effect on root development, growth, and the productivity of crops via a reduction in the concentration of ethylene under conditions of environmental stress, to which plants are commonly exposed. In addition, on testing for the solubilizing activity of the isolates for phosphoric acid, silicon, calcium carbonate, and zinc, some isolates were found to have mineral solubilizing activities. Inoculation of these isolates during plant growth is expected to assist plant growth by converting nutrients necessary for growth into usable forms that can be absorbed by plants. The 18 isolated strains can be used as biocontrol agents due to their antifungal activity, plant growthpromoting activity, and mineral solubilizing activity.

• Korean journal of applied entomology
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• v.22 no.3 s.56
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• pp.186-192
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• 1983

The growth of germ tube of Fusarium oxysporum f. sp. cucumerinum was remarkably inhibited on the water agar treated with 100ppm of Fe-EDDHA, a synthetic iron chelating agent, whereas germination rate of microconidia did not show much differences compare with that of non treated water agar. Both of the germination and the germ tube elongation of microconidia were suppressed significantly in King's B agar by the bacterial siderophores produced by Pseudomonas putida. The highest germination of the chlamydospores was obtained in the soil added with $0.25\%$ of glucose plus $0.05\%$ of asparagine. The chlamydospores of cucumber wil fungus germinated about $14\%$ in rhizosphere soil of 2 day-old cucumber seedlings within 48 hours, and the germination was enhanced notably in rhizosphere soil of 10 day-old seedling. But the rates of germination was not increased according to cucumber growth age after 10 day-old seedling. The effect of P. putida and Fe-EDDHA on the germination on chlamydospores in conducive soil was not pronounced in the non-rhizosphere soil added with nutrient. However, the germination was suppressed significantly both in rhizosphere soil and in rhizosphere soil added with nutrient. The suppression of chlamydospore germination was greater in the bacteria inoculated soil than that in Fe-EDDHA treated soil.

• Research in Plant Disease
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• v.28 no.2
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• pp.69-81
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• 2022

This study was performed to screen the efficacy of antagonistic bacterial isolates from various sources against the bacterial fruit blotch (BFB) causing pathogen (Acidovorax citrulli) in cucurbit crops. In addition, plant growth promoting traits of these antagonistic bacterial isolates were characterized. Two thousand seven hundred ninety-four microorganisms were isolated from the collected samples. Molecular identification revealed two A. citrulli out of 2,794 isolates. In vitro antagonistic results showed that, among the 28 antagonistic bacterial isolates, 24 and 14 bacterial isolates exhibited antagonism against HPP-3-3B and HPP-9-4B, respectively. Antagonistic and growth promotion characterization of the antagonistic bacterial isolates were further studied. Results suggested that, 4 antagonistic bacteria commonly showed both antagonism and growth promotion phenotypes. Moreover, 3 isolates possessed growth promoting activities. Overall results from this study suggests that BFB causing bacterial pathogen (A. citrulli) was suppressed in in vitro antagonism assay by antagonistic bacterial isolates. Furthermore, these antagonistic bacterial isolates possessed growth promotion and antagonistic enzyme production ability. Therefore, data from this study can provide useful basic data for the in vivo experiments which ultimately helps to develop the eco-friendly agricultural materials to control fruit rot disease in cucurbit crops in near future.

• Journal of Life Science
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• v.34 no.5
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• pp.304-312
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• 2024

This study was conducted to characterize strain Y10, isolated from discarded chicken feathers. Strain Y10 was identified as Bacillus amyloliquefaciens through phenotypic and 16S rRNA gene analysis. B. amyloliquefaciens Y10 exhibited plant growth-promoting activities, including the production of fungal cell-degrading enzymes (cellulase, lipase, protease, and pectinase), siderophores, ammonia, and indoleacetic acid. Furthermore, strain Y10 was able to inhibit the mycelial growth of several phytopathogenic fungi. When 0.1% sucrose as a carbon source and 0.05% casein as a nitrogen source were added to the basal medium, adjusted to pH 10, and cultured at 35℃, the degradation rate of chicken feathers by strain Y10 was about two times higher than that of the basal medium, with the feathers almost completely degraded in four days. Strain Y10 also degraded various keratin substrates, including duck feathers, wool, and human nails. It was confirmed that the feather hydrolyzates prepared using strain Y10 exhibited antioxidant activities, such as 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity (EC₅₀ = 0.38 mg/ml) and superoxide dismutase-like activity (EC₅₀ = 183.7 mg/ml). These results suggest that B. amyloliquefaciens Y10 is a potential candidate for the development of bioinoculants and feed additives applicable to the agricultural and livestock industries, as well as the microbiological treatment of keratin waste.