• 약학회지
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• 제35권3호
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• pp.245-251
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• 1991

Selective culture of actinomycetes from soil microbes and their antibiotic producing characters by agar-disk method were examined. Some of the organisms which produced antibiotics on agar disk did not produce antibiotics in liquid culture. Further examination indicated that production of antibiotic was dependent on the composition of medium. Many streptomycestes produced antibacterial substances in tryptic soy broth but others produced antifungal antibiotics in V-8 broth. Production of antibacterial substances by Streptomyces sp. was also dependent on the medium composition.

• Mycobiology
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• 제34권3호
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• pp.138-142
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• 2006

Soil cyanobacteria isolated from the rice paddy fields of 10 different locations across Korea were evaluated by agar plate diffusion test for antifungal activity. Aqueous, petroleum ether, and methanol extracts from one hundred and forty two cyanobacterial strains belonging to the 14 genera were examined for antifungal properties against seven phytopathogenic fungi causing diseases in hot pepper (Capsicum annuum L). Of total cyanobacteria, nine cyanobacteria (6.34%) exhibited antifungal effects. The nine cyanobacteria selected with positive antifungal activities were two species of Oscillatoria, two of Anabaena, three of Nostoc, one of Nodularia, and one of Calothrix. Alternaria alternata and Botrytis cinerea were inhibited by nine and eight species of cyanobacteria, respectively. Rhizopus stolonifer was suppressed by only methanol extract of Nostoc commune FK-103. In particular, Nostoc commune FK-103 and Oscillatoria tenuis FK-109 showed strong antifungal activities against Phytophthora capsici. Their antifungal activity at the late exponential growth phase is related to the growth temperature and not associated with the growth parameters such as cell biomass and $chlorophyll-{\alpha}$ concentration. The high inhibition levels of antibiotics were 22.5 and 31.8 mm for N. commune FK-103 and O. tenuis FK-109, respectively. The optimal temperature for antibiotic productivity was $35^{\circ}C$.

• 한국미생물·생명공학회지
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• 제25권4호
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• pp.396-402
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• 1997

Biocontrol of plant pathogens provides an alternative means of reducing the incidence of plant diseases without the negative aspects of chemical pesticides. Nowdays, as the resistant fungi about the chemical fungicides have revealed and the concern of environment has increased, the biological control of phytopathogenic fungi by the antagonistic microorganisms is very much indispensable. For the selection of strong antagonistic bacterium for biological control agent of rice leafblast and cucumber gray mold rot, the antifungal strain KL-3 strain was selected among 120 strains isolated from the rhizosphere soils. And the strain was identified to be a species of Bacillus subtilis or closely related strain. In several biochemical and in vitro antibiosis tests, antifungal substances of Bacillus sp. KL-3 were presumed heat stable, micromolecular antibiotic substances. In vivo test and vinyl house field test, the antifungal substances of Bacillus sp. KL-3 represented excellent biocontrol ability aganist Alternaria mali, Phyricularia oryzae, and Alternaria kikuchiana as well as broad spectrum of other fungi. In particular, Bacillus sp. KL-3 strain showed more predominant activity than some chemical fungicides against fungi shown to resist chemcal fungicides.

• 한국미생물·생명공학회지
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• 제29권3호
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• pp.186-193
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• 2001

경북 경주지역의 저병해 고추경착지역의 토양으로부터 생물학적 방제기작중의 하나인 항생물질을 생산하는 길항미생물을 분히하기 위하여 70여종의 세균을 분리하였으며 이들을 대상으로 고추역병균 Phytophthora capsici를 가장 강력하게 길항하는 균주를 최종 선발하였다. 선발균주는 Chryseomonas luteola로 동정되었고 방제 기작은 약한 siderophore 생산성과 cellulase 생산성도 기인되었으나 항생물질 생산성이 주요 기작임을 확인하였다. 항진균성 항생물질의 대량생산의 기초자료로 활용하고자 항생물질 생산의 최적배지 조건 및 배양조건을 조사하였는데 길항균주의 항생물질 생산에 미치는 탄소원의 영향은 0.45% N-acetyl-D-glucosamine과 0.15% D(+) cellobiose에서 81%와 89%의 P. capsicivh자의 성장 억제율을 나타냈다. 질소원의 경우는 0.55% $NH_4$CI 첨가시 69%의 억제율을 나타냈고 무기염의 영향에 있어서는 0.01% KCI을 사용했을 때 63%의 억제율을 나타냈다. 또한 배양 조건에 있어서는 pH 7.0m $30^{\circ}C$에서 84시간 배양시 가장 높은 항진균성 항생물질 생산성을 나타내었다. 토양내에서 실제로 생물방제력을 발휘하는지를 확인하기 위하여 고추를 이용한 in vivo pot test를 실시한 결과 P capsici 만 처리한 것은 고추역병 현상을 나타냈고, P capsici 와 길항균 C luteola 5042를 함께 처리한 것은 역병 현상이 나타나지 않았다. 이것으로 길항균주는 C luteola 5042 P capsici 의 성장을 저해하여 고추 역병의 발병을 억제한다는 사실을 확인할수 있었다.

• 생명과학회지
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• 제14권1호
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• pp.193-197
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• 2004

A continuous enrichment culture procedure was used to isolate bacteria from various soil sources capable of suppressing large patch disease of turfgrass. Six isolates consistently suppressed large patch in turfgrass, and ranged in the spectrum of extracellular enzymes that they expressed. The best disease- suppressing isolate, TBM912, expressed protease, CMCase, and pectinase activity and inhibited the growth of Rhizectonin solani and Betrytis cinerea in vitro. Here we show that this strain also produces an antibiotic that was identified by TLC, SDS-PACE and HPLC analysis as lipopeptide.

• 한국균학회지
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• 18권2호
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• pp.96-101
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• 1990

양송이 주요병해인 마이코곤병(M. perniciosa)의 생물적방제를 위한 항균성 미생물을 선발하기 위하여 실시한 시험 결과를 요약하면 다음과 같다. 1. 미생물의 분리는 Starch casein, Soybean meal, Oat meal 배지에서 균집락 형성과 균집락의 특성이 다른 배지 보다 빠르며, 다양한 미생물의 분리가 용이하였다. 2. 실내시험에서 사상균 91, 세균 342, 방사선균 556균주의 미생물을 분리 선발한 후 Oat meal 배지에서 대치배양하여 항균력이 높은 세균 12, 방사선균 71균주를 선발하였다. 3.실내에서 항균력이 있는 균주에 대해 실시한 1차 포장시험에서 5개 균주가 수량 및 항균력이 우수하였으며, 확인시험에서는 AJ-117, AJ-136, AK-139의3균주가 뚜렷한 항균력이 있었다.

• Applied Biological Chemistry
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• 제36권6호
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• pp.428-433
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• 1993

Pellicularia sasakii의 생육을 저해하는 한 균주를 토양으로부터 분리하였으며 Pseudomonas aeruginosa 3120으로 동정하였다. P. aeruginosa 3120의 배양액으로부터 분리 정제된 암갈색의 MRL3120 항생물질은 ethylacetate, chloroform 및 methanol에 용해되었으며 곰팡이뿐만 아니라 gram 양성 및 음성세균에도 활성을 나타내었다. UV, IR, EI-MS spectra 및 다른 물리화학적 특성의 분석결과로부터 MRL3120은 2개의 N-methyl-N-thioformylhydroxylamine과 1개의 Cu 이온으로 구성된 chelate 화합물로서 fluopsin C와 유사한 구조를 가진 것으로 추정되었다. Soybean meal을 포함하는 발효배지에 $CuSO_4$의 첨가는 항진균 활성을 증가시켰으나 EDTA(0.1%)의 존재하에서는 활성이 없었다. Soybean meal 대신 soytone을 포함하는 발효배지에서 MRL3120은 생산되지 않았지만 $CuSO_4$의 첨가에 의해 빠르게 생산되었다.

• 한국미생물·생명공학회지
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• 제25권1호
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• pp.62-67
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• 1997

A potential biocontrol bacterium, YB-70 was isolated from a rhizosphere in suppressive soil and identified as a strain of Bacillus subtilis. In several biochemical and in vitro antibiosis tests on Fusarium solani with the culture filterates from B. subtilis YB-70, we found that antifungal mechanism of B. subtilis YB-70 was mediated by antibiotic substances produced from the bacterium. These antifungal substances were appeared to be hear-resistant, micromolecular, and ethy alcohol soluble. Antifungal agents produced by B. subtilis YB-70 showed strong inhibified against root-rotting fungi F. solani in in vivo pot test. An antifungal substance. YBS-1s, was purified from the culture broth of B. subtilis YB-70 by isoelectronic precipitation, silica gel column chromatography and Sephadex LH-20 column chromatography analysis by Fab-MASS, $^{1}$H-NMR, $^{13}$C-NMR, DEPT, and amino acid analyzer revealed that the YBS-1A was a peptide antibiotics of iturin class containing seven amino acids from five different groups, and the other(YBS-1B) was an analogue of iturin group composed of 11 amino acids with larher molecular weight of about 1, 500 dalton, which was lager than that of iturin A.

• Journal of Microbiology and Biotechnology
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• 제28권6호
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• pp.1030-1036
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• 2018

Bacillus strains produce various types of antibiotics, and random mutagenesis has traditionally been used to overproduce these natural metabolites. However, this method leads to the accumulation of unwanted mutations in the genome. Here, we rationally designed a single nucleotide substitution in the degU gene to generate a B. subtilis strain displaying increased plipastatin production in a foreign DNA-free manner. The mutant strain (BS1028u) showed improved antifungal activity against Pythium ultimum. Notably, pps operon deletion in BS1028u resulted in complete loss of antifungal activity, suggesting that the antifungal activity strongly depends on the expression of the pps operon. Quantitative real-time PCR and lacZ assays showed that the point mutation resulted in 2-fold increased pps operon expression, which caused the increase in antifungal activity. Likewise, commercial Bacillus strains can be improved to display higher antifungal activity by rationally designed simple modifications of their genome, rendering them more efficient biocontrol agents.

• 한국미생물·생명공학회지
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• 제23권1호
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• pp.98-103
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• 1995

During the screening of antifungal antibiotics from microbial metabolites, we selected Pseudomonas aeruginosa KGM-100 showing powerful antagonistic activity against various phytopathogenic fungi. Antibiotics KGM-100A and KGM-100B were purified from the culture broth of Pseudomonas aeruginosa KGM-100 by diaion HP-20 column chromatography, ethyl acetate extraction, silica gel column chromatography, preparative TLC and recrystallization. KGM-100A which was recrystallized in MeOH showed antimicrobial activities against a broad spectrum of fungi and bacteria. Physico-chemical properties of KGM-100A were determined and identified to be phenazine-l-carboxylic acid by UV, IR, $^{1}$H-NMR, $^{13}$C-NMR, mass spectrum, and elemental analyses.