• Research in Plant Disease
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• v.10 no.3
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• pp.159-166
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• 2004

This study were carried out to identify pathogens and determine the seasonal occurrence and chemical control of safflower (Carthamus tinctorius) diseases from 2000 to 2002 in Gyengbuk province, Korea. Major diseases of safflower were, anthracnose caused by Colletotricum acutatum in open field, and gray mold by Botrytis cinerea in rain sheltered plastic house. Other diseases occurred were powdery mildew caused by Sphaerotheca fuliginea, collar rot by Sclerotium rolfsii, leaf spot by Alternaria carthami and A. alternata, rust by Puccinia carthami, root-rot and stem-rot by Phytophthora cactorum, root-rot and wilt by Fusarium oxysporum and damping-off by Pythium ultimum. Seasonal occurrence of anthracnose on safflower has begun from late April, and increased until harvesting, especially rapid increased after rainfall during stem elongation season that is from May to June. In open fields, maximum incidence of anthracnose was 67 ％ in late July. But in rain-sheltered plastic house, it was very low, about 5％ in July. Gray mold caused by Botrytis cinerea was most important disease in rain-sheltered plastic house cultivation. Maximum incidence of gray mold on floral head was 27.4％, whereas other diseases occurred below 1 ％. In the test of the chemical control of the safflower anthracnose, metiram WP, carbendazim$.$kasugamycin WP and iminoctadintris$.$thiram WP were the highest controlling chemicals. In chemical control of gray mold, iminoctadintris$.$thiram WP, fluazinam WP and iprodion WP showed highest controlling effects.

• The Korean Journal of Mycology
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• v.41 no.2
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• pp.112-117
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• 2013

Phytophthora capsici is one of major limiting factors in production of pepper and other important crops worldwide by causing foliage blight and rot on fruit and root. Increased demand for the replacement of fungicides has led to searching a promising strategy to control the fungal diseases. To meet eco-friendly agriculture practice, we isolated microorganisms and assessed their beneficial effects on plant health and disease control efficacy. A total of 360 bacterial strains were isolated from rhizosphere soil of healthy pepper plants, and categorized to 5 representative isolates based on colony morphology. Among the 5 bacterial strains (GJ-1, GJ-4, GJ-5, GJ-11, GJ-12), three bacterial strains (GJ-1, GJ-11, GJ-12) presented antifungal activity against P. capsici in an fungal inhibition assay. In phosphate solubilization and siderophore production, the strain GJ-1 was more effective than others. The strain GJ-1 was identified as Bacillus sp. using 16S rDNA analysis. Bacillus sp. GJ-1 was also found to be effective in inhibiting other plant pathogenic fungi, including Rhizoctonia solani, Pythium ultimum and Fusarium solani. Therefore, the Bacillus sp. GJ-1 can serve as a biological control agent against fungal plant pathogens.

• Korean Journal of Microbiology
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• v.44 no.1
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• pp.56-62
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• 2008

Two hundred and sixty-eight bacterial strains were isolated from pine mushroom (Tricholoma matsutake) basal soil. In the course of screening for antifungal activity against seven plant pathogenic fungi (Alternaria panax, Botrytis cinerea, Colletotrichum gloeosprioides, Fusarium oxysporum, Phytopthora capsici, Pythium ultimum, Rizoctonia solani) of isolates, strain KM1-15 showed strong antibiotic activity against Alternaria panax and Colletotrichum gloeosprioides. In determining its relationship on the basis of 16S rDNA sequence, KM1-15 strain was most closely related to Bacillus $koguryoae^T$ (AY904033) (99.62%). When assayed with the API 50CHE Kit, unlike Bacillus koguryoae, it is positive for utilization of L-arabinose, cellobiose, inulin, and D-turanose. Results of cellular fatty acid analysis showed that major cellular fatty acids were 15:0 anteiso (35.78%) and 17:0 anteiso (17.97%). In particular, hydroxyl fatty acids such as 13:0 iso 3-OH, 14:0 iso 3-OH, 15:0 iso 3-OH, and 17:0 iso 3-OH were only restricted to strain KM1-15. DNA G+C content was 43.7 mol% and quinone system was MK-7 (100%) in strain KM1-15.

• Journal of Life Science
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• v.33 no.10
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• pp.842-850
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• 2023

Pyrrolnitrin, pyrrolomycin, and pyoluteorin are functional halogenated phenylpyrrole derivatives (HPDs) derived from microorganisms with diverse antimicrobial activities. Pyrrolnitrin is a secondary metabolite produced from L-tryptophan through four-step reactions in Pseudomonas fluorescens, Burkholderia cepacia, Serratia plymuthica, etc. It is currently used for the treatment of superficial dermatophytic fungal infections, has high antagonistic activities against soil-borne and foliar fungal infections, and has many industrial applications. Since pyrrolnitrin is easily decomposed by light, it is difficult to widely use it outdoors. As an alternative, fludioxonil, a synthetically produced non-systemic surface fungicide that is structurally similar and has excellent light stability, has been commercialized for seed and foliar treatment of plants. However, due to its high toxicity to aquatic organisms and adverse effects in human cell lines, many countries have established maximum residue levels and strictly control its levels. Pyrrolomycin and pyoluteorin, which have antibiotic/antibiofilm activity against Gram-positive bacteria and high anti-oomycete activity against the plant pathogen Pythium ultimum, respectively, were isolated and identified from microorganisms. This review summarizes the biosynthesis and production of natural pyrrolnitrin derived from bacteria and the characteristics of synthetic fludioxonil and other natural phenylpyrrole derivatives among the HPDs. We expect that a plethora of highly effective, novel HPDs that are safe for humans and environments will be developed through the generation of an HPD library by microbial biosynthesis and chemical synthesis.

• Journal of Life Science
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• v.34 no.6
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• pp.393-398
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• 2024

The purpose of this study was to verify the antifungal properties of various herbal medicines belonging to the Ranunculaceae family and to find an extraction method effective in inhibiting fungal growth. When antifungal activity was measured in a liquid medium with extracts obtained by either hot water extraction or organic solvent extraction of the herbal medicines Clematis apiifolia, Coptis chinensis, and Pusatilla chinensis, effective results were obtained from the chloroform extract. In addition, fungal growth inhibition experiments were performed on unicellular fungi, Candida albicans, Candida tropicalis, and Candida lusitaniae, and on filamentous fungi, such as Pythium ultimum, Aspergillus fumigatus, and Fusarium oxysporum, using disk diffusion experiments on solid media. It was confirmed that P. chinensis extract has excellent antifungal properties against Candida spp. and C. apiifolia extract against filamentous mold. Finally, GC-MS analysis was performed to explore the useful antifungal substances present in the extract. As a result of the study, thurbergenone from C. apiifolia and 16-hydroxycleroda-3, 13(14)-dien-15, 16-olide (16-HCDO) from C. chinensis were confirmed as antifungal candidates. In conclusion, it was confirmed that C. apiifolia, C. chinensis, and P. chinensis have antifungal activity against various fungi, and in GC-MS analysis, all herbal medicines were confirmed to have different antifungal candidates. These results indicate that the Ranunculaceae family has evolved in several directions for fungal resistance traits.

• The Plant Pathology Journal
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• v.28 no.1
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• pp.20-31
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• 2012

Endophytic bacterial communities of tidal flat plants antagonistic to oomycete plant pathogens were studied by the isolation of 256 root colonizing endophytic bacteria from surface-disinfected root tissues of six plants ($Rosa$ $rugosa$, $Suaeda$ $maritima$, $Vitex$ $rotundifolia$, $Carex$ $scabrifolia$, $Glehnia$ $littoralis$ and $Elymus$ $mollis$) growing in a tidal flat area of Namhae Island, Korea. To understand the antagonistic potential, an $in$ $vitro$ antagonistic assay was performed to characterize and identify strains that were antagonistic to the oomycete plant pathogens $Phytophthora$ $capsici$ and $Pythium$ $ultimum$ from the total population. Nine percent of the total number of isolated bacteria exhibited in vitro inhibitory activity against target plant pathogenic oomycetes. Taxonomic and phylogenetic placement of the antagonistic bacteria was investigated by analysis of the 16S rRNA gene sequences. The sequence analysis classified the antagonistic strains into four major classes of the domain bacteria ($Firmicutes$, ${\alpha}-Proteobacteria$, ${\gamma}-Proteobacteria$ and $Actinomycetes$) and 10 different genera. Further production of secondary metabolites, hydrolytic enzymes and plant growth promoting traits were determined for the putative new species of antagonistic endophytic bacteria. These new strains could not be identified as known species of ${\alpha}-Proteobacteria$, and so may represent novel bacterial taxa. The unexpected high antagonistic bacterial diversity associated with the tidal flat plants may be indicative of their importance in tidal flat plants as a promising source of novel antimicrobial compounds and biocontrol agents.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.102.1-102
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• 2003

A bacterial strain YC4963 with antifungal activity against Colletotrichum orbiculare, a causal organism of cucumber anthracnose was isolated from the rhizosphere soil of Siegesbeckia pubescens (Siegesbeckia pubescens Makino；Family：Compositae) in Korea. Based on physiological and biochemical characteristics and 16S ribosomal DNA sequence analysis, the bacterial strain was identified as Pseudomonu aureofaciens. The bacteria also inhibited mycelial growth of several plant fungal pathogens such as Botrytis cinerea, Fusarium oxysporum and Rhizoctonia solani on PDA and 0.1 TSA media. The antibiotic activity was found from the culture filtrate of TSB(tryptic soy broth) and its active compounds were quantitatively bound to XAD adsorber resin. The antibiotic spectrum was broad and growth of C. orbiculare and F. oxysporum, B. cinerea were inhibited at very low concentration. The chemical data from various chromatographic procedures showed that active fraction consisted of at least two phenazine derivatives. However, the metabolites had no inhibitory effect on Pythium ultimum which was reported to be sensitive to phenazine antibiotics. The compounds responsible for the activity are now under investigation.

• International Journal of Industrial Entomology and Biomaterials
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• v.39 no.2
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• pp.82-85
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• 2019

We investigated the anti-microbial activity of propolis against the pathogenic bacteria and fungi on ginseng. We selected six microbials that caused postharvest root rots in ginseng. Propolis extracts were prepared by using the ethanol extraction method. We seeded the bacteria and fungi related to ginseng disease on a specific culture medium, and treated it with propolis extracts by using the paper disc method. Propolis extracts indicate the anti-microbial activity against Paenibacillus polymyxa, Fusarium solani, Rhizoctonia solani AG-1 and Pythium ultimum. However, the anti-fungal activity of propolis is weak on Pseudomonas fluorescens subsp. Cellulosa and Colletotrichum gloeosporioides. As a result, the antimicrobial effects of propolis against microbial that prevent ginseng growth were confirmed. The antimicrobial effects are shown according to the concentration of propolis against root rot. The fungi also showed antibacterial effects in a dose-dependent manner.

• Journal of Microbiology and Biotechnology
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• v.14 no.3
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• pp.599-606
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• 2004

Gram-positive antagonistic bacilli were isolated from agricultural soils for possible use in biocontrol of plant pathogenic fungi, Fusarium oxysporum, Rhizoctonia solani, and/or Pythium ultimum. Among the 65 antagonistic Gram-positive soil isolates, 22 strains were identified as Bacillus species by 16S rDNA sequence analyses. Four strains, including DF14, especially exhibited multiple antagonistic properties against the three damping-off fungi. Genotypic properties of the Bacillus isolates were characterized by rapid molecular fingerprinting methods using repetitive extragenic palindromic-PCR (REP-PCR), ribosomal intergenic spacer-length polymorphisms (RIS-LP), 16S rDNA PCR-restriction fragment length polymorphisms (PCR-RFLP), and strain-specific PCR assays. The results indicated that the REP-PCR method was more valuable than the RIS-LP and 16S rDNA PCR-RFLP analyses as a rapid and reliable approach for bacilli typing and identification. The use of strain-specific primers designed based on 16S rDNA sequence comparisons enabled it to be possible to selectively detect a strain, DF14, which is being used as a biocontrol agent against damping-off fungi.

• Korean Journal Plant Pathology
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• v.11 no.2
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• pp.158-164
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• 1995

토마토의 엽권에서 분리한 Fusariym graminearum이 분비하는 물질은 벼 도열병균(Pyricularia oryzae)의 여러 종의 식물병원 진균에 대한 항균활성을 나타내었으며, 이러한 활성물질을 PDA에서 본 균을 배양 한 후 chloroform으로 추출하여 분리정제 하였다. HPLC에 의하여 5종류의 활성 물질을 분획하였으며, 그중 1번(F402) 화합물을 벼 도열병균(P. oryzae)을 포함한 22개 식물 병원 진균에 대하여 살균 활성범위를 조사한 결과, 이 화합물은 50$\mu\textrm{g}$/ml 농도에서 Pythium ultimum, Rhizoctonia solani, Sclerotinia sclerotiorum은 전혀 억제하지 못하였으며, Phytophthora spp., Cladosporium fulvum, Fusarium spp., Corynespora cassicola에는 어느 정도의 활성이 있었지만 낮게 나타났고, P. oryzae, Cochliobolus miyabeanus, Alternaria solani는 100% 억제하여 활성이 높게 나타났다. 또한 장내 세균에 대한 활성을 MIC로 비교할 때 Streptococcus pyogenes, Streptococcus faecium에 대하여는 각각 12.5, 25 $\mu\textrm{g}$/ml였고 Staphylococcus aureus는 25-50$\mu\textrm{g}$/ml으로 나타났으며, Pseudomonas aeruginosa, Salmonella typhimurium, Klebsiella aerogenes, Enterobacter cloacae에서는 100$\mu\textrm{g}$/ml 이상으로 활성이 나타나지 않았다. F402를 200$\mu\textrm{g}$/ml의 농도로 직접 살포한 식물체에서의 방제효과는 벼도열병, 벼 깨씨무늬병, 보리 흰 가루병에 대하여는 80%이상이었으나, 벼 잎집무늬마름병, 오이 잿빛곰팡이병, 토마토 역병, 밀 녹병에서는 낮았다.