• Journal of Applied Biological Chemistry
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• v.42 no.3
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• pp.146-150
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• 1999

As a part of the integrated disease system in greenhouse, an antifungal fungus(AF1) was isolated from greenhouse soil. It exhibited strong inhibitory activites against Pythium ultimum, Phytophtora capsici, Rhizoctonia solani, Botrytis cinerea, and Fusarium oxysporum based on dual culture on 1/5 strength of potato dextrose agar between antagonistic fungus and several plant pathogens. The antagonistic fungus was identified as Chaetomium cochliodes, based on morphological characteristics; the body of the perithecium bears straight or slightly wavy, unbranched hairs, whilst the apex bears a group of spirally coiled hairs. To investigate antagonistic principles, antifungal compound was extracted and fractionated by different solvent systems. An antifungal compound was isolated as pure crystal from is culture filtrate using organic solvent extraction and column chromatography, followed by preparative thin layer chromatography. The chemical structure of the purified antifungal compound was identified as chaetoglobosin A based on the data obtained form $^1H-NMR$, $^{13}C-NMR$, DEPT 90, 135, $^1H-^1H$ COSY, $^1H-^{13}C$ COSY and EI/MS. $ED_{50}$ values of the chaetoglobosin A against P. ultimum, P. capsici, R. solani, B. cinerea and F. oxysporum were 1.98, 4.01, 4.16, 2.67 and 35.14 ppm, respectively.

• Journal of Microbiology and Biotechnology
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• v.22 no.3
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• pp.326-330
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• 2012

Antifungal metabolites were isolated from a culture of Pseudomonas aurantiaca IB5-10. Chemical structures of the metabolites were elucidated as phenazine-1-carboxylic acid (PCA; 1), 2-hydroxyphenazine (2-OH-PHZ; 2), and cyclo-(L-Pro-L-Val; 3), respectively, based on spectroscopic methods. Among them, 3 was isolated for the first time from this strain. The antifungal activities of 1-3 were evaluated against a variety of plant pathogens. To the best of our knowledge, the antifungal activities of 3 against plant fungal pathogens have been evaluated for the first time in this work. PCA (1) showed the most potent antifungal activities against Phytophthora capsici, Rhizoctonia solani AG-1(IA), and Pythium ultimum with MICs (${\mu}g/ml$) of less than 1.0, 1.3, and 2.0, respectively. On the other hand, 2-OH-PHZ (2) showed potent antifungal activity against R. solani AG-1(IA) with the MIC (${\mu}g/ml$) of 2.0, whereas it showed moderate antifungal activity against P. ultimum with the MIC (${\mu}g/ml$) of 50.0. In addition, 3 showed antifungal activity against only R. solani AG-1(IA).

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.87.2-87
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• 2003

Long-term repeated culturing of biocontrol agents on a certain medium often results in reduced biocontrol efficacy and altered physiology. Effect of culturing media on biocontrol ability and physiological state of Burkholderia gladioli strain B543 was investigated. Over 20 times repeated cultivation of B. giadioli strain B543 on Kings B medium or nutrient agar medium showed improved biological control of cucumber damping-off caused by Pythium ultimum, while one time cultivation on KB or NA did not. The repeated cultivation also induced the physiological changes of the biocontrol agent such as antifungal activity and the production of protease and siderophore. Our result indicates that adaptation to proper culturing medium can alter biocontrol ability and must consider in optimizing the use of biocontrol agents.

• Korean Journal Plant Pathology
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• v.14 no.4
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• pp.345-349
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• 1998

Fifty isolates of myxobacteria were isolated from soils from several areas in Korea during 1996-1997 and bioactivity against plant pathogenic fungi of these isolates was examined. A myxobacterial isolate KR025 showed good antifungal activities against Pyricularia oryzae, Cryphonectria parasitica, Colletotrichum lagenarium, and C. gloeosporioides but did not against Rhizoctonia solani, Fusarium oxysporum and Pythium ultimum. The bacterium was identified as Myxococcus fulvus based on morphological and physiological characteristics. Antifungal substances were extracted from culture broth and bacterial cell of Myxococcus fulvus KR025 by ethyl acetate. Antifungal substance of Myxothiazole (100 ${\mu}{\textrm}{m}$/ml) produced by Myxococcus fulvus KR 025 controlled 97.0% rice blast, tomato late blight, wheat leaf rust, and barley powdery mildew and showed 45.0 and 82.6% disease control of rice sheath blight and cucumber gray model, respectively.

• Journal of Microbiology and Biotechnology
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• v.10 no.4
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• pp.568-571
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• 2000

Cepacidine A was previously isolated as a novel antifungal antibiotic from the culture broth of Pseudomonas cepacia AF2001. It exhibits a potent in vitro antifungal activity against various plant pathogenic fungi, such as Plasmopora veticola on grapes, Septoria nodorum and Fusarium culmorum on wheat, as well as Colletotrichum lagenarium on cucumbers. Accordingly, this study was conducted to evaluate the potential crop protection activity of strain P. cepacia AF2001. The strain was tested in semi-greenhouse biocontrol assays, and showed an excellent biological activity against Pythium ultimum in cotton and cucumbers; however, only a minor activity against Rhizoctonia aolani in cotton was observed. Furthermore, the nematodes Haemonchus contortus and Trichostrongylus only exhibited a moderated activity in the in vitro larval development assay with no activity in the in vivo animal model.

• Korean Journal Plant Pathology
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• v.11 no.1
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• pp.47-52
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• 1995

One hundred and thirty bacterial isolates with high chitinolytic activity on chitin agar media were isolated and identified. Most of the isolates were Aeromonas hydrophila (110 isolates), and the others were Serratia marcescens (11 isolates), Aeromonas caviae (3 isolates), Chromobacterium violaceum strain C-61 (2 isolates), Chromobacterium violaceum strain C-72 (1 isolate) and unknown species (3 isolates). Among them, C. violaceum strain C-61 had highest chitinolytic activity and fungal growth inhibition on PDA. This bacterium also inhibited the growth of Rhizoctonia solani, Sclerotinia scelrotiorum, Phytophthora capsici and Pythium ultimum, but it didn't inhibit the growth of Fusarium oxysprum and Fusarium solani. C. violaceum strain C-61 suppressed damping-off of eggplant caused by R. solani. Populations of the chitinolytic bacteria such as Aeromonas hydrophila, Serratia marcescens, Aeromonas caviae, Chromobacterium violaceum strain C-61 and Chromobacterium violaceum strain C-72 introduced into R. solani-infested soil were continuously decreased until 20 days after treatment, but their populations except A. caviae were not changed significantly and maintained over 5$\times$104 CFU per g of soil thereafter.

• Journal of Applied Biological Chemistry
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• v.42 no.2
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• pp.97-99
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• 1999

Endophytic fungi from Ginkgo biloba and Taxus cuspidata in Korea were screened for production of taxol. Eighteen and twelve fungal isolates from G. biloba and T. cuspidata, respectively, were shown to produce immunologically detectable amount of taxol. The highest production of taxol at 260 ng/l was achieved by stationary culture of an Alternaria isolate from G. biloba. The strain also produced unidentified antifungal agent(s) against Pythium ultimum. However, the activity gradually decreased when the strain was stored at $4^{\circ}C$ for 6 months.

• The Korean Journal of Pesticide Science
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• v.2 no.3
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• pp.28-35
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• 1998

An antimicrobial peptide producing bacterium, Bacillus subtilis A405, was screened and identified among 700 of antagonistic bacteria. The heat-resistant antimicrobial peptide, AMP-405, was purified from the broth culture of B. subtilis A405 through $20{\sim}40%$ ammonium sulfate precipitation and ultrafiltration. The AMP-405 exhibited strong antimicrobial activities against Botrytis cinerea, Cercospora sp., Fusarium oxysporum, Penicillium digitatum, Celletotrichum gloeosporioides, Rhizoctonia solani, Pythium ultimum, Pyricularia oryzae, Escherichia coli, Pseudomonas spp. and Candida albicans. The molecular weight of the peptide was about 3.0 kDa determined by SDS-PAGE, Native-PAGE and Tris-Tricine gradient electrophoresis, and composed of 9 kinds of amino acid such as aspartic acid, glycine, serine, glutamine, valine, leucine, isoleucine, proline, tyrocine. To determine the efficiency of AMP-405 as a potential maintenance of fruits freshness, cherry tomato was srored at $25^{\circ}C$ for 2 weeks after treatment with $50{\mu}g/ml$ of AMP-405 and $10^{5}$ spores/ml of Botrytis cinerea simultaneously. Treatment with AMP-405 resulted in significantly less infection by Botrytis cinerea, than the treatment with tap water as a control.

• Research in Plant Disease
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• v.10 no.4
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• pp.248-259
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• 2004

A total 115 isolates of Fusarium species from ginseng roots of 'rotted', and soils collected during 1982-1985 in Korea, were identified and classified into 11 species with the Snyder & Hansen System (with reference to Gerlach-Nirenberg's Modified System). The most dominant of these species were F. solani (55 isolates), F. oxysporum (35 isolates), and F. moniliforme (10 isolates) sensu Snyder & Hansen. The other 8 species (15 isolates) were very rarely isolated and previously identified as F. roseum sensu Snyder & Hansen (1945); these were F. equiseti, F. avenaceum, F. graminum, F. arthrosporioides, F. sambucinum, F. reticulatum, F. semitectum and F. poa. Tested for the ability to infect the roots of ginseng (3 yr. old plants) in field condition with the mycelial inoculum, only one isolate of F. solani (34 isolates tested) and one isolate of F. oxysporum (24 isolates tested) were weakly pathogenic to ginseng roots. Any of the isolates (7 isolates tested) of F. moniliforme [Liseola section] were not pathogenic to ginseng. However, all the isolates of tested of the species of Phytophthora cactorum, Pythium ultimum, and Cylindrocarpon destructans were highly pathogenic to ginseng roots. The species of Fusarium solani and Cylindrocarpon destructans were supposed to be a host dominant disease agent in ginseng plant.

• The Korean Journal of Pesticide Science
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• v.14 no.4
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• pp.421-426
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• 2010

Many bacterial strains inhabit strong saline condition, such as tidal mudflat and salted seafoods, were identified and reported for the proposed protease activities and salt resistance; however antifungal activities against plant fungal pathogen have not well been studied until now. In this study, primary screening was performed for the isolation of promising strains against major plant pathogens like Sclerotinia sclerotiorum, Fusarium oxysporum, Phytophthora capsici, Botrytis cineria, Collectotrichum acutatum and Pythium ultimum. Totally 423 bacterial strain were isolated from laboratory media which was based on different morphological characteristics and all the strains were dual cultured against major fungal pathogens on PDA, finally 40 strains were selected as antifungal bacterial strain and identified by fatty acid phylogenic difference analysis from MIDI shorlock gas chromatography system. As a result, antifungal strains from tidal mudflat were 10 species of 6 genus. Paenibacillus macerans was dominant species; 5 strains among the 17 isolates from tidal mudflat. Antifungal strains from salted seafoods were 7 species of 3 genus and Bacillus atrophaeus was dominant species; 12 strains among the 23 isolates from salted fishes.