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Ginseng (Panax ginseng C. A. Meyer) is an economically valuable pharmaceutical crop in Korea.In order to find promising biocontrol agents for soil-borne fungal pathogens which infect ginseng roots, wehave isolated actinomycete, BK185 from soil. The isolate was investigated for the antifungal activity againstto ginseng rot pathogens prior to testing genetic and chemical properties. The strain was identified asStreptomyces sp. using phylogenetic analysis based on 16S rRNA gene sequence. The most closely relatedspecies was S. sporoclivatus and S. geldanamycininus with high similarities (>99%). The isolate, BK185showed positive reaction for PCR detection targeting biosynthetic gene clusters of PKS (Type-I polyketidesynthase) and NRPS (Non-ribosomal polypeptide synthetase) genes. Major metabolite from the BK185 wasanalyzed by The LC/MS and identified to geldamycin, which was known to contained broad antibacterial,antifungal or anticancer activities. The results provide evidences that the strain, BK185 can be promisingbiocontrol agent for ginseng organic farming.Key words ginseng rot, antifungal activity, Streptomyces, BK185

An isolate of Bacillus amyloliquefaciens subsp. plantarum CC110 was selected as an effectiveantagonist for biological control of cucumber downy mildew caused by Pseudoperonospora cubensis.Temperature range for growth of CC110 isolate was 7.5~55.0 o C, and its optimal temperature at 36.6 o C. pHrange for growth of CC110 isolate was 4.5~9.5, and its optimal pH at 7.0. In this study, the most effectivesources of carbon and nitrogen for growth of CC110 isolate were fructose and yeast extract, respectively. Thevolatile of CC110 isolate was found to be effective to control downy mildew on cucumber showing nodiseased area whereas that of control was 13.2% using the I plate bioassay. The culture broth and cells ofisolate CC110 cultured in TSB media for 48 hours at 28 o C inhibited occurrence of cucumber downy mildew.The cells and culture broth were transformed into sporangia of P. cubensis by in observation under lightmicroscope and scanning electron microscope. Key words Biological control, Cucumber, Cultivation, Downy mildew, Bacillus amyloliquefaciens subsp.plantarum CC110, Volatile compounds

Various microorganisms live in soil, of which those colonizing rhizosphere interact with nearby plants and tend to develop unique microbial communities. In this study, we isolated diverse actinomycetes from rhizosphere of rice (Oryza sativa L.) cultivated in fertilized (APK) and non-fertilized (NF) paddy soils, and investigated the diversity and antimicrobial activity of them. Using four kinds of selective media, 152 isolates were obtained from the soil samples and identified by determining 16S rRNA gene sequence. All of the isolates showed 99.0%~100.0% similarities with type strains and were classified into six genera: Dactylosporangium, Micromonospora, Kitasatospora, Promicromonospora, Streptomyces and Streptosporangium. Most of the isolates, 143 isolates, were classified into the genus Streptomyces. Additionally, many isolates had antimicrobial activity against plant pathogens, especially Magnaporthe oryzae (rice blast pathogen) in fungi. These findings demonstrated that rice rhizosphere can be a rich source of antagonistic actinomycetes producing diverse bioactive compounds.

Bacillus amyloliquefaciens M27 was selected as a control agent for the biological control ofcucumber powdery mildew. The new mixture of B.amyloliquefaciens M27 and plant (Eucalytus) extract wasdeveloped to improve the control activity of B.amyloliquefaciens M27 against cucumber powdery mildew. Themixed formulation showed the high preventive and curative control effect against cucumber powdery mildewwhen it was diluted at 500 times and foliar-sprayed. Its control effect was higher in preventive spraying thancurative spraying. When 500-fold diluted solution of the formulation was sprayed preventively four times atfive-day intervals, three times at seven-day intervals and twice at ten-day intervals, the diseased leaf area wasshown to be 4.4%, 8.0%, 27.9%, respectively; Whereas the diseased leaf area in the control plot was 45.4%.When the 500-fold diluted formulation was sprayed curatively four times at five-day intervals, three times atseven-day intervals and twice at ten-day intervals after occurred cucumber powdery mildew, the diseases leafarea was 11.5%, 25.2%, 51.8%, respectively; whereas in the control plot, the diseases leaf area was 64.3%.When the 500-fold diluted formulation was treated four times at five-day intervals in the plastic house, itscontrol effect was higher than that treated three times at seven-day intervals and twice at ten-day intervals. Asthe results, the mixed formulation of B.amyloliquefaciens M27 and plant extract could be a promisingcandidate of bio-fungicides for the environment-friendly control of powdery mildew of cucumber.Key words Bacillus amyloliquefaciens M27, Cucumber Powdery mildew, Plant Extract

Ginseng (Panax ginseng C. A. Meyer) is an economically important crop in Korea. While the consumption of the crop is gradually increasing, the yield is decreasing due to the injury of continuous cultivation or infection of soil-borne fungal pathogens such as Cylindrocarpon destructans, Fusarium solani, Rhizoctonia solani and Sclerotinia nivalis. In order to find promising biocontrol agents, we have isolated 439 soil bacteria from ginseng cultivated soil and tested their antifungal activities against ginseng rot pathogens. Among them, 3 strains were finally selected and tested for the elucidation of their genetic and biochemical properties. They were identified as Bacillus amyloliquefaciens using phylogenetic analysis based on 16S rRNA gene sequences. Moreover, all selected strains showed positive reaction for PCR detection targeting biosynthetic gene sequences of iturin A and surfactin. The results provided promising evidences that the bacterial strains isolated from ginseng cultivated soil can be novel biocontrol agents for ginseng cultivaion.