• Journal of Microbiology and Biotechnology
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• 제12권2호
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• pp.204-208
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• 2002

A Streptomyces sp. isolated from a soil sample collected in Taejeon, Korea has previously been found to produce two new polyene antibiotics. The two new antibiotics were named "16-methyloxazolomycin (antibacterial)" and "tetrin C (antifungal)", and their chemical structures are presented elsewhere [10, 11]. In the current study, chemotaxonomy, numerical taxonomy, and ISP methods were all employed for the taxonomic study. The spore chains were spirales and the spore surface was smooth. The spore mass was a gray series and no melanin pigment was produced. On the basis of the morphological and physiological properties, the microorganism was identified to be Streptomyces erumpens, belonging to the gray series of category IV, as defined by Bergey′s Manual. Tetrin C at the concentration of 20 ${\mu}g$/ml demonstrated a potent in vivo (pot test) preventive effect against rice blast, rice sheath blight, cucumber gray mold, wheat powdery mildew, and barley leaf rust.

• Journal of Microbiology and Biotechnology
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• 제14권1호
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• pp.212-215
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• 2004

In order to develop a biocontrol agent that can effectively control Fusarium wilt on Cymbidium genus, the effectiveness of antagonistic microbes against the cause pathogen was screened. The selected microbe showed a broad spectrum of antifungal activity, and the culture broth of this microbe had better preventive effect on Fusarium wilt than the commercial chemical agent in the pot assay. This isolated strain, GBA-12, was identified as Streptomyces kasugaensis, and the antifungal substance was purified from a broth culture of GBA-12. This purified substance was identified as a polyene macrolide (YS-822A) that was newly discovered from Streptomyces kasugaensis, and it exhibited antifungal activity against several phytopathogenic fungi.

• Journal of Microbiology and Biotechnology
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• 제22권5호
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• pp.674-683
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• 2012

A new strain, SD12, was isolated from tannery waste polluted soil and identified as Pseudomonas aeruginosa on the basis of phenotypic traits and by comparison of 16S rRNA sequences. This bacterium exhibited broad-spectrum antagonistic activity against phytopathogenic fungi. The strain produced phosphatases, cellulases, proteases, pectinases, and HCN and also retained its ability to produce hydroxamate-type siderophore. A bioactive metabolite was isolated from P. aeruginosa SD12 and was characterized as 1-hydroxyphenazine ((1-OH-PHZ) by nuclear magnetic resonance (NMR) spectral analysis. The strain was used as a biocontrol agent against root rot and wilt disease of pyrethrum caused by Rhizoctonia solani. The stain is also reported to increase the growth and biomass of Plantago ovata. The purified compound, 1-hydroxyphenazine, also showed broad-spectrum antagonistic activity towards a range of phytopathogenic fungi, which is the first report of its kind.

• 한국균학회지
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• 제49권4호
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• pp.441-454
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• 2021

Fungal diseases including anthracnose, stem rot, blight, wilting, and root rot of crops are caused by phytopathogens such as Colletotrichum species, Sclerotinia sclerotiorum, Phytophthora species, and Fusarium oxysporum and F. solani which threaten the production of chili pepper. In this study, to identify biological control agents (BCAs) of phytopathogenic fungi, potentially useful Bacillus species were isolated from the field soils. We screened out five Bacillus strains with antagonistic capacity that are efficiently inhibiting the growth of phytopathogenic fungi. Bacillus species were characterized by the production of extracellular enzymes, siderophores, and indole-3-acetic acid (IAA). Furthermore, the influence of bacterial strains on the plant growth promoting activity and seedling vigor index were assessed using Brassica juncea as a model plant. Inoculation with Bacillus subtilis SRCM 121379 significantly increased the length of B. juncea shoots and roots by 45.6% and 52.0%, respectively. Among the bacterial isolates, Bacillus subtilis SRCM 121379 showed the superior enzyme activities, antagonistic capacity and plant growth promoting effects. Based on the experimental results, Bacillus subtilis SRCM 121379 (GenBank accession no. NR027552) was finally selected as a BCA candidate.

• Journal of Microbiology and Biotechnology
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• 제19권8호
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• pp.792-802
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• 2009

Antimicrobial peptides (AMPs) are considered to be a promising alternative to conventional antibiotics for future generations. We identified four novel hexapeptides with antimicrobial activity: KCM11 (TWWRWW-$NH_2$), KCM12 (KWRWlW-$NH_2$), KCM21 (KWWWRW-$NH_2$), and KRS22 (WRWFIH-$NH_2$), through positional scanning of a synthetic peptide combinatorial library (PS-SCL). The ability of these peptides to inhibit the growth of a variety of bacteria and unicellular fungi was evaluated. KCM11 and KRS22 preferentially inhibited the normal growth of fungal strains, whereas KCM12 and KCM21 were more active against bacterial strains. Bactericidal activity was addressed in a clear zone assay against phytopathogenic bacteria, including Pectobacterium spp., Xanthomonas spp., Pseudomonas spp., etc. KCM21 showed the highest activity and was effective against a wide range of target organisms. Application of KCM21 with inoculation of Pectobacterium carotovorum subsp. carotovorum on detached cabbage leaves resulted in an immune phenotype or a significant reduction in symptom development, depending on the peptide concentration. Cytotoxicity of the four hexapeptides was evaluated in mouse and human epithelial cell lines using an MTT test. The results revealed a lack of cytotoxic effects.

• The Plant Pathology Journal
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• 제23권2호
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• pp.113-115
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• 2007

A kind of naphthoquinone, plumbagin was purified and identified from the leaves of Nepenthes $ventricosa\;{\times}\;maxima$ through solvent extraction, silica gel column chromatography, and recrystallization. The yield (0.51%) was higher than that of the root of Plumbago scandens (0.26%), P. capensis (0.15%), and N. thorelii (0.092%). It exhibited antifungal activity against all plant pathogenic fungi tested, Alternaria alternata, Aspergillus niger, Bipolaris oryzae, Fusarium oxysporum, Phytophthora capsici, Rhizoctonia solani, Rhizopus stolonifer var. stolonifer and Sclerotinia sclerotiorum. The minimum inhibitory concentration values ranged from about 4.8 to $56.6\;{\mu}g/ml$ against the above eight fungi and R. solani was the most sensitive.

• 환경생물
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• 제18권4호
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• pp.441-446
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• 2000

Trichoderma harzianum is an aggressive causal agent of green mold disease on mushroom cultivation. Some bacterial strains isolated, from oyster mushroom compost in Wonju, were found to have in vitro antifungal activity against Trichoderma harzianum ATCC 6385, 6504, and our isolates Trichoderma spp. Y and G. Further in vitro antifungal studies on several strains of phytopathogenic fungi showed that all of 12 phytopathogenic fungal strains were significantly inhibited by the isolated antifungal bacteria in Petri dishes. Of these, KATB 99121 showed the broadest inhibiting effect and displayed as negative coagulase, negative sulfide production and rod shape. KATB 99121 was resistant to ampicillin, chlorampenicol, and kanamycin. Identification of isolates was determined by Biolog GN system, and KATB 99121 was identified as Photobacterium logei because of 96 probability, 0.65 similarity, and 4.97 disturbance. With electron microscopy, thin section of KATB 99121 strain revealed typical rod-like shaped cell (0.6-0.8${\mu}{\textrm}{m}$$\times$1.5-2.0${\mu}{\textrm}{m}$) with prokaryotic structure and organization.

• Applied Biological Chemistry
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• 제42권4호
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• pp.271-276
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• 1999

새로운 천연물 농약 또는 생산군주를 개발하기 위하여 Streptomyces 속의 여러 균주를 대상으로 항진균 물질을 탐색하여 항진균 물질 생산 균주 Streptomyces hygroscopicus MJM1004를 선발하였다. 항진균 물질의 생산을 위한 발효 배지를 선정하기 위하여 여러 탄소원, 질소원과 무기원을 대상으로 균체 생장 정도와 항진균 물질의 생산성을 조사하였으며, 생산 배지는 2% soybean meal, 1% glucose, 2% starch, 0.3% $CaCO_3$, 0.05% $MgSO_4{\cdot}7H_2O$, 0.05% $K_2HPO_4$를 조성으로 하였다. S. hygroscopicus MJM1004 균주의 균체에서 추출된 항진균 물질은 Candida albicans와 여러 식물 병원성 곰팡이들에 대하여 광범위한 저해 효과를 나타내었다. S. hygroscopicus MJM1004 균체로부터 분리된 항진균 물질, SH-1004를 핵자기공명법($^1H,\;^{13}C$, DQF COSY, HMQC 및 HMBC)을 통하여 분석한 결과 azalomycin F complex 임을 확인할 수 있었다. Positive FAB mass spectrum을 통하여 SH-1004는 azalomycin F4a와 F5a가 1.8 : 1의 비율로 혼합된 물질임을 확인하였다.

• 한국식물병리학회지
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• 제2권2호
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• pp.89-95
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• 1986

쇠비름 즙액에서 얻은 5종의 저급지방산인 isobutyric(C-4), butyric(C-4), isovaleric(C-5), valeric (C-5), caproic(C-6) acids등이 그들 사이에 항균력의 차이는 있었지만 공시한 25종의 식물병원균의 포자발아나 균사생장에 대하여 폭넓은 항균스펙트럼을 보여주었다. 각각의 지방산의 항균력은 포자발아검정이나 균사신장검정에 있어서 공시균주에 따라 큰 차이를 보여주었다. 포자발아검정에 공시한 17종의 병원균과 균사신장검정에 공시한 16종의 병원균은 그들의 포자발아나 균사신장을 제각기 완전히 저해하는 각각의 지방산의 최저저해농도(MIC)에 따라 3군으로 나눌 수 있다. 이밖에도 이 연구의 결과에서 다음과 같은 가설을 제시할 수 있었다. 1) Caproic acid는 공시균의 균사신장보다 포자발아에 대하여 더욱 강한 독성을 보였으나 약간의 예외는 있었지만 그 밖의 지방산은 이와같은 독성을 보여주지 않았다. 2) 지방산의 사슬이 길수록 항균력도 강하다. 3) n-Butyric acid와 n-Valeric acid는 그들의 이성체보다 항균력이 강하다. 4) 각각의 지방산은 부생균의 포자발아나 균사신장에 대한 것보다 활물기생균이나 몇가지 조건적 기생균의 그것들에 대하여 더욱 강한 독성을 보여주었다.

• 한국균학회지
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• 제41권4호
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• pp.274-279
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• 2013

미산성 차아염소산수는 다양한 종류의 미생물들에 대해 강력한 살균력을 나타내지만 인간과 자연에 무해한 살균제로 잘 알려져 있다. 4%의 희석된 염산만으로 무격막 전해조에서 전기분해를 통해 만들어졌으며 유효염소 농도가 20~30 ppm(HOCl 97%)이고 pH 5.0~6.5인 미산성 차아염소산수의 식물병원균들에 대한 살균효과를 조사하였다. Botrytis cinerea, Colletotrichum acutatum, Phytophthora capsici 등의 포자들에 대해서는 대략 10초 정도의 처리시간으로도 100% 살균효과가 나타났으나 Penicillium hirsutum의 경우는 3분 이상의 처리시간이 요구되었다. 희석농도에 따른 C. acutatum에 대한 살균효과를 조사한 결과 1:1(미산성 차아염소산수:멸균수)의 비율로 희석한 처리구에서는 포자발아가 100% 억제되었으나 1:2 처리구에서는 63%로 억제율이 낮아졌다. 고추탄저병균 C. acutatum을 고추열매에 접종한 후 24시간이 지나서 처리된 미산성 차아염소산수의 병방제 효과를 조사한 결과 방제가는 70.4%였다. 본 연구를 통해 미산성 차아염소산수의 강하고 광범위한 살균력이 확인되었으며 식물병 방제를 위한 살균제로 유용하게 활용될 수 있을 것으로 예상됐다.