• 식물병연구
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• 제17권2호
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• pp.121-128
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• 2011

점액세균은 토양에서 식물 병원균의 활성을 억제하는 2차 대사산물들을 분비하는데, 이들은 기존의 길항균들의 항생물질과는 전혀 다른 생리활성물질이므로 생물방제에 활용이 기대되는 미생물이다. 고추 역병 생물학적 방제를 위해 토양 미생물인 점액세균의 길항능력을 기내에서 검정한 후, 자실체 및 액체배양 여액을 엽권과 근권에 처리하여 온실에서 생물 검정하였다. 점액세균 생리활성 물질이 남아있는 PDCY 배지에 역병균을 접종한 결과 점액 세균 Myxococcus spp. 세 균주 중 KYC 1126과 KYC 1136은 균사생장을 완벽히 저해하였다. 토양 내 점액세균 생리활성물질 분비를 극대화하기 위해 기내에서 다량의 자실체 형성을 위해 먹이인 E. coli를 먼저 배양 후 점액세균 KYC 1126을 치상하는 방법을 확립하였다. 이 방법으로 토양에 자실체를 먼저 투입하고 역병을 관주접종한 결과 방제 효과가 없었다. 한편 시험관에서 역병균 유주포자 현탁액과 점액세균 CYE 액체배양여액을 혼합한 후 고추 뿌리에 침지 접종한 결과 역병 발병을 지연시켜 배양여액의 길항능력을 확인하였다. 점액세균 배양여액을 엽권에 살포하거나 근권에 침지한 방제가는 각각 88%와 40%로서 dimethomorph+propineb의 100%와 propamocarb의 44%에 버금가는 결과였다. 배양여액을 기존 처리의 약 2배인 24시간 이상 뿌리에 침지하면 약해가 발생하였는데, 그 증상은 고추 묘에서 줄기가 잘록해지고 잎이 말려 들어가며 점액성의 물질이 뿌리를 덮어 썩는 것이었다. 선발된 점액세균 KYC 1126의 대량 생산 방안이 확보되면, 배양여액을 엽권에 예방적으로 정기 살포함으로써 고추 역병의 생물학적 방제를 달성할 수 있을 것으로 기대된다.

• Journal of Microbiology and Biotechnology
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• 제26권11호
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• pp.2006-2011
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• 2016

The marine sponges Hyrtios and Haliclona species, both of which are known to produce secondary bioactive metabolites, were used to extract 1304KO-327 and 1304KO-328. Such secondary metabolites are potentially antibacterial, antiviral, anti-inflammatory, antitumoral, antifungal, and antiplasmodial. In the present study, the effects of 1304KO-327 and 1304KO-328 were studied for their clinical and pathological importance. The cytotoxicity of 1304KO-327 and 1304KO-328 was assessed via MTT(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay on HT-29, Caco-2, and Raw 264.7 cells. Rotavirus-infected Caco-2 cells were used to prove the antiviral effects of the marine sponge extracts. The test results cogently proved that the virus-inhibiting effects of the sponge extracts improved with extract concentration. Anti-inflammatory effects of the marine sponge extracts were tested on Lipopolysaccharide-treated Raw 264.7 cells. Nitric oxide and cytokine were produced by treatment of the cells with LPS and the inhibiting effects of the sponge extracts on $IL-1{\beta}$ formation were investigated. This study found that the NO production was decreased dose dependently, and $IL-1{\beta}$ formation was significantly reduced by the marine sponge extracts.

• The Plant Pathology Journal
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• 제28권3호
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• pp.317-321
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• 2012

Plants are the promising reservoirs for natural products with their diverse secondary metabolites. Many invasive plants have been introduced in Korea, which adversely affect on the native ecosystem but holds difficulty removing them due to their proliferation. In this study, we evaluated disease control efficacy of methanol extracts from four invasive plant species against 7 representative crop pathogens. Methanol extract of Phytolacca americana effectively suppressed rice blast, tomato gray mold, and tomato late blight in a dose dependent manner. The methanol extract of Amorpha fruticosa also exhibited potent antifungal activity against pepper anthracnose in a concentration dependent way. These data suggest that the extracts of P. americana and A. fruticosa can be developed as plant disease protection agents against rice blast, tomato gray mold, tomato late blight, and pepper anthracnose. Furthermore, more extensive research will be required to identify and isolate active compounds from problematic invasive plant species to develop valuable agrochemicals.

• Mycobiology
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• 제47권1호
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• pp.87-96
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• 2019

Fungi produce various secondary metabolites that have beneficial and harmful effects on other organisms. Those bioactive metabolites have been explored as potential medicinal and antimicrobial resources. However, the activities of the culture filtrate (CF) and metabolites of whiterot fungus (Schizophyllum commune) have been underexplored. In this study, we assayed the antimicrobial activities of CF obtained from white-rot fungus against various plant pathogens and evaluated its efficacy for controlling anthracnose and gray mold in pepper plants. The CF inhibited the mycelial growth of various fungal plant pathogens, but not of bacterial pathogens. Diluted concentrations of CF significantly suppressed the severity of anthracnose and gray mold in pepper fruits. Furthermore, the incidence of anthracnose in field conditions was reduced by treatment with a 12.5% dilution of CF. The active compound responsible for the antifungal and disease control activity was identified and verified as schizostatin. Our results indicate that the CF of white-rot fungus can be used as an eco-friendly natural product against fungal plant pathogens. Moreover, the compound, schizostatin could be used as a biochemical resource or precursor for development as a pesticide. To the best of our knowledge, this is the first report on the control of plant diseases using CF and active compound from white-rot fungus. We discussed the controversial antagonistic activity of schizostatin and believe that the CF of white-rot fungus or its active compound, schizostatin, could be used as a biochemical pesticide against fungal diseases such as anthracnose and gray mold in many vegetables.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2023년도 임시총회 및 춘계학술대회
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• pp.62-62
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• 2023

Zanthoxylum piperitum ("chopi" in Korean) has been used as traditional medicinal plants with high anti-inflammatory, antioxidant, and antifungal activities. The aims of the study were to identify marker compounds and to investigate metabolites variation of chopi according to different parts and harvest times. Every month from June to September, chopi were harvested with three different parts: leaves, leaf-twig mixtures, twigs. Using liquid chromatography-tandem mass spectrometry (LC-MS/MS), two main marker compounds (quercitrin and quercetin-3-O-glucoside) were characterized in 70% ethanol extracts of chopi. Quantification of the two marker compounds were subsequently conducted by high performance liquid chromatography (HPLC), representing that contents of these compounds were higher in leaves and leaf-twig mixtures rather than twigs. For the comprehensive analysis of metabolites associated with production of marker compounds, 35 primary metabolites were identified using gas chromatography-mass spectrometry (GC-MS). Multivariate analysis results represented that plant parts were main contributors to the separation of chopi. However, significant differences were not observed between leaves and leaf-twig mixtures samples. The partial least square (PLS) predictive model revealed that monosaccharides (fructose, galactose, glucose, mannose, xylose) and branched-chain amino acids (isoleucine, valine, leucine) were important determinants for the production of marker compounds together with alanine, inositol, GABA, and theronic acid. This study could be extended to stabilize and utilize chopi as an industrial material, as well as to find good candidates with various nutritional traits.

• The Plant Pathology Journal
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• 제33권5호
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• pp.488-498
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• 2017

The aim of this study was to identify volatile and agardiffusible antifungal metabolites produced by Bacillus sp. G341 with strong antifungal activity against various phytopathogenic fungi. Strain G341 isolated from four-year-old roots of Korean ginseng with rot symptoms was identified as Bacillus velezensis based on 16S rDNA and gyrA sequences. Strain G341 inhibited mycelial growth of all phytopathogenic fungi tested. In vivo experiment results revealed that n-butanol extract of fermentation broth effectively controlled the development of rice sheath blight, tomato gray mold, tomato late blight, wheat leaf rust, barley powdery mildew, and red pepper anthracnose. Two antifungal compounds were isolated from strain G341 and identified as bacillomycin L and fengycin A by MS/MS analysis. Moreover, volatile compounds emitted from strain G341 were found to be able to inhibit mycelial growth of various phytopathogenic fungi. Based on volatile compound profiles of strain G341 obtained through headspace collection and analysis on GC-MS, dimethylsulfoxide, 1-butanol, and 3-hydroxy-2-butanone (acetoin) were identified. Taken together, these results suggest that B. valezensis G341 can be used as a biocontrol agent for various plant diseases caused by phytopathogenic fungi.

• Journal of Microbiology and Biotechnology
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• 제30권5호
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• pp.668-680
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• 2020

Bacillus velezensis is an important plant growth-promoting rhizobacterium with immense potential in agriculture development. In the present study, Bacillus velezensis Lle-9 was isolated from the bulbs of Lilium leucanthum. The isolated strain showed antifungal activities against plant pathogens like Botryosphaeria dothidea, Fusarium oxysporum, Botrytis cinerea and Fusarium fujikuroi. The highest percentage of growth inhibition i.e., 68.56±2.35% was observed against Fusarium oxysporum followed by 63.12 ± 2.83%, 61.67 ± 3.39% and 55.82 ± 2.76% against Botrytis cinerea, Botryosphaeria dothidea, and Fusarium fujikuroi, respectively. The ethyl acetate fraction revealed a number of bioactive compounds and several were identified as antimicrobial agents such as diketopiperazines, cyclo-peptides, linear peptides, latrunculin A, 5α-hydroxy-6-ketocholesterol, (R)-S-lactoylglutathione, triamterene, rubiadin, moxifloxacin, 9-hydroxy-5Z,7E,11Z,14Z-eicosatetraenoic acid, D-erythro-C18-Sphingosine, citrinin, and 2-arachidonoyllysophosphatidylcholine. The presence of these antimicrobial compounds in the bacterial culture might have contributed to the antifungal activities of the isolated B. velezensis Lle-9. The strain showed plant growth-promoting traits such as production of organic acids, ACC deaminase, indole-3-acetic acid (IAA), siderophores, and nitrogen fixation and phosphate solubilization. IAA production was accelerated with application of exogenous tryptophan concentrations in the medium. Further, the lily plants upon inoculation with Lle-9 exhibited improved vegetative growth, more flowering shoots and longer roots than control plants under greenhouse condition. The isolated B. velezensis strain Lle-9 possessed broad-spectrum antifungal activities and multiple plant growth-promoting traits and thus may play an important role in promoting sustainable agriculture. This strain could be developed and applied in field experiments in order to promote plant growth and control disease pathogens.

• 생명과학회지
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• 제12권5호
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• pp.632-648
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• 2002

The term polyketide defines a class of natural products synthesized through the successive condensation of small arboxylic acids, which results in products containing multiple carbonyl or hydroxyl groups, each separated by one arbon atom, as in the structural element CH$_2$C(=0)CH$_2$CH(OE)CH$_2$C(=0)-. Plant flavonoids, fungal aflatoxins, as well as undreds of compounds of different structures that can inhibit the growth of bacteria, viruses, fungi, parasites or human umor cells are included in this diverse group. Some of antifungal polyketides also have immunosuppresive activity. olyketides can vary widely in structure, and the diversity of polyketide structures reflects the wide variety of their iological properties. This review focuses on the biosynthesis of polyketides and recent progress in combinatorial iosynthesis of new hybrid polyketide compounds.

• 식물병연구
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• 제23권2호
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• pp.177-185
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• 2017

장수풍뎅이 유충의 장내세포에서 분리한 Bacillus amyloliquefaciens LM11은 surfactin, iturin, fengycin 같은 biosurfactants lipopeptide를 생산하여 식물병원성 곰팡이의 성장을 강하게 억제하였다. LM11균주 성장단계에 따라 biosurfactant 생산과 surface tension은 상당히 유의한 차이가 있었다. 항균 물질인 surfactin, iturin, fengycin의 생합성 유전자는 정지기에 도달하면서 집중적으로 발현되었고 그 생산량도 높았다. 또한 LM11균주를 제거한 배양 상등액 함량의 농도에 따라 고추 탄저병원균의 포자발아와 높은 부의 상관관계가 있었다(R=0.761, P<0.001). 식물병원성 곰팡이의 균사 생장억제를 위한 최소 surface tension 수준은 38.5 mN/m였다(R=0.951-0.977, P<0.001). 본 연구 결과는 B. amyloliquefaciens LM11의 biosurfactant가 식물병에 대한 생물학적 방제에 중요한 항진균 대사물질로 작용하며, 배양액의 surface tension 측정은 생물학적 방제제의 최적 사용을 위한 기초 지표로 사용될 수 있음을 보여 주었다.

• Journal of Ginseng Research
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• 제44권6호
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• pp.770-774
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• 2020

Background: Fermentation has been shown to improve the biological properties of plants and herbs. Specifically, fermentation causes decomposition and/or biotransformation of active metabolites into high-value products. Polyacetylenes are a class of polyketides with a pleiotropic profile of bioactivity. Methods: Column chromatography was used to isolate compounds, and extensive NMR experiments were used to determine their structures. The transformation of polyacetylene in red ginseng (RG) and the production of cazaldehyde B induced by the extract of RG were identified by TLC and HPLC analyses. Results: A new metabolite was isolated from RG fermented by Chaetomium globosum, and this new metabolite can be obtained by the biotransformation of polyacetylene in RG. Panaxytriol was found to exhibit the highest antifungal activity against C. globosum compared with other major ingredients in RG. The fungus C. globosum cultured in RG extract can metabolize panaxytriol to Metabolite A to survive, with no antifungal activity against itself. Metabolites A and B showed obvious inhibition against NO production, with ratios of 42.75 ± 1.60 and 63.95 ± 1.45% at 50 µM, respectively. A higher inhibitory rate on NO production was observed for Metabolite B than for a positive drug. Conclusion: Metabolite A is a rare example of natural polyacetylene biotransformation by microbial fermentation. This biotransformation only occurred in fermented RG. The extract of RG also stimulated the production of a new natural product, cazaldehyde B, from C. globosum. The lactone in Metabolite A can decrease the cytotoxicity, which was deemed to be the intrinsic activity of polyacetylene in ginseng.