• Korean Journal of Soil Science and Fertilizer
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• v.41 no.5
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• pp.362-368
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• 2008

In order to isolate novel oligotrophic bacteria exhibiting antifungal activities, soils were collected from pepper-cultivated fields of Yeongyang, Jecheon, Nonsan, Eumsong and Goesan area in Korea. From soils in pepper cultivated area, a total of 9,354 strains were isolated as oligotrophic bacteria by the R2A dilution method. Among 9,354 oligotrohic bacteria candidates, 1A strain was selected by screening against Phytophthora capsici causing phytophthora blight of hot pepper in the greenhouse and field. The strain was identified as Bacillus vallismortis based on its 16S rDNA sequence and key characteristics as compared with those of authentic cultures of B. vallismortis(KACC 12149) and B. mojavensis(KACC 12096). The strain showed broad spectrum of antibiotic activity in vitro test, as revealed in its strong inhibitory activity to the genera Phytophthora, Collectotrichum, Botrytis and Fusarium, but not to Rhizoctonia and Magnaporthe. In pot experiments, infection rate of hot pepper in the non-treated pots was about 89%, while it was only 29% in the pots treated with 1A strain. The result indicated B. vallismortis 1A is a potential biocontrol agent for phytophthora blight of hot pepper

• Journal of Life Science
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• v.12 no.3
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• pp.264-273
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• 2002

We have isolated and artificially expressed three cDNA clones of Capsicum annuum PR5 genes for elucidating the antifungal activity against Phytophthora capsici which contracted a hot pepper root rot in field condition. Three divergent PR5 proteins from hot pepper were designated as CAPR5-1 and CAPR5-2 from susceptible cultivar (Subicho) as well as CAPR5-3 from resistant cultivar (CM331) in response to P. capsici. The cDNA similarity was found over 80% of identity among the three CAPR5s, and deduced amino acid sequence was characterized that all of CAPR5s contained 16 cysteine residues which possibly had a significant role in the structural formation. The result of genomic DNA blot showed that CAPR5-1 and CAPR5-2 existed as single copy in the Subicho genome. Three recombinant CPARs in E. coli were identified by SDS-PACE, and each expressed protein was treated on the PDA medium which contained cultured pathogens. Although three CAPR5 proteins did not affected the hyphal growth of Glomerella glycines and Colletotrichum fagenarium, CAPR5-1, CAPR5-2, and CAPR5-3 showed a specific antifungal activities against P. capsici.

• The Korean Journal of Mycology
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• v.19 no.3
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• pp.231-237
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• 1991

This study was conducted in order to find out biological control of sesame wilt and blight caused by Fusarium of oxysporum f. sp. vasinfectum and Phytophthora nicotianae var. parasitica by using Streptomyces spp. Two sesame pathogens, Fusarium oxysporum f. sp. vasinfectum and Phytophthora nicotianae var. parasitica were purely isolated from diseased sesame plants of the field. Streptomyces species were isolated from 72 soil samples collected from red pepper and sesame uplands in Chungbuk and selected as antagonists according to the results of dual culture. The selected Streptomyces isolates such as St-11 and St-20 were confirmed their antagonistic effect through mycelial inhibition zone and inhibitory effects on the mycelial growth of the pathogens by culture filterate of the antagonists. Inhibitory effects on the conidial germination of Fusarium oxysporum vasinfectum and Phytophthora nicotianae parasitica by the antagonists were also tested in addition to mycelial Iysis. The antagonists St-11 and St-20 showed inhibitory effect on growth of sesame seedlings after seeds soaked in the suspension. Effect of soil inoculation with antagonist St-11 showed 40 to 78 percent of control effect for two diseases in comparison with control under greenhouse.

• Journal of Applied Biological Chemistry
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• v.52 no.3
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• pp.121-125
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• 2009

We measured the influence of antifungal antagonists Bacillus subtilis AH18 and Bacillus licheniformis K11 on soil microbial community in microcosms. Both antifungal antagonists were confirmed to suppress hot pepper phytophthora blight. Phospholipid fatty acids (PLFA) were analyzed to investigate the soil microbial community. B. subtilis AH18 changed the total PLFA composition and bio-indicators of PLFA, compared with other treatments. B. subtilis AH18 decreased the proportion of bacteria and gram negative/gram positive bacteria, and increased the fungi/bacteria and anaerobic/aerobic microorganisms. In addition cy19:0/18:$1{\omega}7c$, which means adaptation to unfavorable environmental conditions, was increased by the application of B. subtilis AH18. On the other hand the inoculation of B. licheniformis K11 or combined inoculation of both antifungal strains did not affect soil microbial community. The suppression of phytophthora blight and preservation of indigenous soil microbial community may be achieved by the combined application of B. subtilis AH18 and B. licheniformis K11.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.2
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• pp.123-131
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• 2009

This study was carried out to investigate the feasibility for the use of environmental-friendly materials and the effective recycling of spent mushroom compost(SMC) after cultivation of Button Mushroom, Agaricus bisporus. SMC of white button mushroom contained diverse microorganisms including fluorescent Pseudomonas sp., Bacillus sp., Tricoderma sp. and Actinomycetes. These isolates showed the extensive antifungal spectrum against plant pathogen. Among of the isolates, fungal pathogen such as Alternaria brassicicola, Phytophtora melonis, Phytophthora capsici and Colletotichum gloeosporioides strong showed strong antagonistic activity. 45.8% of the isolates were actively colonized on the pepper root and 5.8% showed rhizosphere competent of >$5{\times}10^2cfu\;root^{-1}$. The plant growth promotion ability of the collected isolates were tested in pot experiments using red pepper seedling. Among them, 62.7% showed pepper growth promoting ability and growth of pepper root showed superior to the control. The germination of pepper treated with aqueous extracts of non-harvest SMC completely inhibited at concentration of more than 33%. The sterilization of SMC resulted in higher inhibition of germination and early growth of pepper. These results suggest that spent mushroom compost(SMC) of Button Mushroom may have adequately the feasibility for the use with environmental-friendly materials.

• Microbiology and Biotechnology Letters
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• v.37 no.3
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• pp.280-286
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• 2009

To investigate anti-phytopathogenic fungal activity of Coptis chinensis, the methanol extract and its organic solvent fractions were prepared. Using the extract and the fractions, in-vitro spore-germination inhibition and mycelial-growth inhibition activities were evaluated against Colletotrichum gloeosporioides, Phytohpthora capsici, Pyricularia grisea, Rhizoctonia solani, Botryosphaeri dothidea, Glomerella cingulata, respectively. Treatment of the methanol extract (500 mg/mL) into the spore of phytopathogenic fungi completely inhibited germinations for 5 days, except B. dothidea, and showed strong antifungal activities against P. grisea and B. cinerea, and antioomycetes activity against P. capsici. The minimal growth inhibition concentrations of the methanol extract against P. grisea, B. cinerea and P. capsici were 300, 300, and 500 mg/mL, respectively. For practical application of C. chinensis in red-pepper field, the hot-water extract (1,000 mg/mL) was prepared in commercial facility, after evaluation of heat stability and solvent-extraction yields of antifungal substances. The 3-times leaf-spray of the extract from June to August, 2008 did not show any deleterious effect to red-pepper. In fact, the leaf-spray promoted plant growth including leaf, root and fruit. The average weight and rind of each fruit were increased to 119% and 117% comparison to those of without treatments. Our results suggest that C. chinensis is a useful source for control of red-pepper diseases and plant growth.

• The Korean Journal of Mycology
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• v.37 no.1
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• pp.114-116
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• 2009

In this study, we selected suitable broth media for mass production of Phytophthora capsici oospore, investigated oospore germination and secured $F_1$ progeny. Carrot broth and V8C broth were determined most effective for oospore formation by calculating and comparing oospore concentration produced from 8 different liquid media. Eleven strains were selected from P. capsici (CapA)/P. tropicalis (CapB) and 9 crosses were formed. Oospore progeny were produced, isolated and germinated from A1 and A2 combinations of P. capsici (CapA) with P tropicalis (CapB). This resulted in a total number of 129 $F_1$ isolates of P. capsici/P. tropicalis with a 0.64-4.0% (mean 1.85%) oospore germination.

• Korean Journal of Weed Science
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• v.14 no.1
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• pp.16-22
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• 1994

Ninty three species of domestic weeds were collected and screened for antimicrobial, antitumor, antioxidant and herbicidal activities. Among them, few showed antifungal activities. Cuscuta japonica showed inhibitory activity against Alternaria mali, Ambrosia artemisiifolia and Geranium sibiricum against Phytophthora capsici, Aster yomema and Aster pilosus against Phytophthora parasitica. Ambrosia artemisiifolia, Artemisia princeps, Artemisia capillaris, Ludwigia prostrata, Chrysanthemum zawadskii, Bidens frondosa, and Geranium sibiricum showed broad antibacterial activities. Carex chordorhiza, Artemisia capillaris, Persicaria nodosa, Senecio koreanus, Pariicum bisulcatum, Geranium sibiricum showed antiblebbing activity on human chronic leukemia K562 cell, among them, Persicaria nodosa was the strongist. Angelica decursiva, Equisetum arvense, Cimicifuga heracleifolia, Persicaria nodosa, Geranium sibiricum, Oenothera odorata, Cyperus sanguinolentus showed antioxidant activities. Ludwigia prostrata and Peucedanum terebinthaceum showed strong herbicidal activities.

• Microbiology and Biotechnology Letters
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• v.34 no.1
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• pp.63-69
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• 2006

We isolated a bacterium which produces antifungal substances from the Lake of Saimaa soils in Fin-land. The isolated strain was identified as Bacillus sp. and shown a strong antifungal activity on plant pathogenic fungi. Bacillus sp. KMU-1011 produced maximum level of antifungal substances under incubation aerobically at $24^{\circ}C$ for 48 hours in nutrient broth containing 1.0% glucose and 1.0% polypeptone at 180 rpm and initiated pH adjusted to 6.0. Precipitate of culture broth by $30{\sim}60%$ ammonium sulfate precipitation exhibited strong antifungal activity against Botrytis cinerea KACC 40573 by dry cell weight. Chloroform extract of cultured broth also shown fungal growth inhibitory activity against C. gloeosporioides KACC 40804, D. bryoniae KACC 40669, F. oxysporum KACC 40037, F. oxysporum KACC 40052, F. oxysporum f. sp. radicis-lycopersici KACC 40537, F. oxysporum KACC 40902, M. cannonballus KACC 40940, P. cambivora KACC 40160, R. solani AG-1 KACC 40101, R. solani AG-4 KACC 40142, and S. scleotiorum KACC by agar diffusion method.

• Research in Plant Disease
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• v.15 no.3
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• pp.222-229
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• 2009

A Pseudomonas strain SG3 producing biosurfactant and showing antifungal and insecticidal activities was isolated from agricultural soil severely contaminated with machine oils. The antagonistic bacterium inhibited mycelial growth of all of the tested fungal pathogens. The fermentation broth of SG3 also effectively suppressed the development of various plant diseases including rice blast, tomato gray mold, tomato late blight, wheat leaf rust, barley powdery mildew and red pepper anthracnose. An antifungal substance was isolated from the fermentation broth of SG3 by ethyl acetate partitioning, silica gel column chromatography and preparative HPLC under the guide of bioassay. The chemical structure of the antifungal substance was determined to be rhamnolipid B by mass and NMR spectral analyses. The antifungal biosurfactant showed a potent in vivo antifungal activity against gray mold and late blight on tomato plants. In addition, rhamnolipid B inhibited mycelial growth of B. cinerea causing tomato gray mold and zoospore germination and mycelial growth of P. infestans causing tomato late blight. Pseudomonas sp. SG3 producing rhamnolipid B could be used as a new biocontrol agent for the control of plant diseases occurring on tomato plants.