• The Plant Pathology Journal
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• 제20권3호
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• pp.177-183
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• 2004

Phenylacetic acid (PAA) was evaluated for in vitro anti-oomycete activity and in vivo control efficacy against Phytophthora capsici. Microscopic observation revealed that the high level of anti-oomycete activity of PAA (10 $\mu\textrm{g}$/ml) against P. capsici is mainly due to the lytic effect on zoospores. Zoospore lysis began in the presence of 5 u$\mu\textrm{g}$/ml of PAA and most of the zoospores were collapsed at 10 $\mu\textrm{g}$/ml. PAA showed inhibitory activity against the zoospore germination and hyphal growth of P. capsici at the concentration of 50 $\mu\textrm{g}$/ml. In the glasshouse, the protective effect of PAA against Phytophthora blight was high on pepper plants when treated just before inoculation with P. capsici. In the artificially infested field, protection of pepper plants against the Phyto-phthora epidemic was achieved at a considerable level by PAA treatment.

• Mycobiology
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• 제29권4호
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• pp.218-223
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• 2001

A rapid radicle assay for prescreening antagonistic bacteria to Phytophthora capsic4 causal agent of Phytophthora blight of pepper was developed. Sixty-four bacterial strains with in vitro antifungal activity selected out of 1,400 strains isolated from soils of Ansung, Chunan, Koyang, and Paju, Korea in 1998 were used for development of the bioassay. Uniformly germinated pepper seeds dipped in bacterial cells for 3 hours were placed near the edges of growing mycelia of P. capsici on water agar containing 0.02% glucose. Five-week-old pepper plants(cv. Nockwang) were inoculated to compare with results of the radicle assay developed in this study. For plant inoculation, pepper seeds were sown in potting mixtures incorporated with the bacterial strains, then transplanted into steam-sterilized soils 3 weeks later. Plants were hole-inoculated with zoospores of P. capsici 2 weeks after transplanting. Disease incidence and severity were determined in radicle and plant assessments, respectively. In radicle assay, six strains, GK-B15, GK-B25, OA-B26, OA-B36, PK-B09, and VK-B14 consistently showed the significant(P=0.05) disease reduction against radicle infection by the fungus, four of which also did in plant assessments. Strains OA-B36 and GK-B15 consistently reduced the fungal infection in both the radicle assay and the plant assessment. Therefore, prescreening strains using the radicle assay developed in this study followed by plant assay could reduce time and labor, and improved the possibility of selecting antagonistic bacteria for control of Phytophthora blight of peppers.

• 한국미생물·생명공학회지
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• 제31권3호
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• pp.235-241
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• 2003

항진균성 항생물질에 의한 고추역병의 생물방제에 관한 연구를 위하여 지역 경작지에서 고추역병균 P. capsici 생육을 저해는 다기능의 강력한 길항세균을 선발하였다 선발된 균주는 배양학적, 생리학적, 생화학적 실험과 AEI(CHB50) 및 Biolog(Microlog 4.01C) 시스템을 이용하여 동정한 결과 B. megaterium와 97%이상 일치하여 최종적으로 선발된 길항세균을 B. megaterium KL 39로 명명하였다. B.megaterium KL 39의 P. capsic에 대한 길항은 열에 안정하고 n-BuOH에 추출이 되는 저분자성 항생물질과 용매에 추출되지 않은 열에 약한 고분자성의 식물병원균 세포벽 가수분해효소인 cellulase에 의한 것으로 확인되었다. 길항균주 B.megaterium KL 39가 생산하는 항진균성 항생물질은 P.capsici의 포자발아와 균사성장에 큰 영향을 미쳤으며 0.4% fructose, 0.3% yeast extract, 5 mM KCI (pH 8.0)을 포함한 배지에서 3$0^{\circ}C$, 40시간 배양하였을 때 그 생산성이 최대치를 나타내었다. Diaion HP-20 column, silica gel column, Sephadex LH-20 column과 HPLC에 의해 항생물질을 정제하였으며 정제된 항생물질은 TLC plate상에서 Ethanol:Ammonia:Wate.(8:1:1)로 전개한 결과 RF value가 0.32를 나타내었으며, 단일물질로 정제된 항생물질을 KL39로 명명하였다. 선발된 길항미생물 E. megaterium KL 39와 정제된 항생물질 KL39를 가지고 고추를 기주식물로 하여 in vivo pot시험 결과 고추역병균 P.capsic게 의해 유발되는 고추역병에 대한 길항력으로 두 가지 모두 고추역병 방제력이 있음을 식물실험에서 확인할 수 있었다.