• 식물병연구
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• 제17권1호
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• pp.82-85
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• 2011

2009년 전남 해남 지역의 논에서 벼 키다리병과 유사한 병징을 나타내는 피를 채집하여 병원균을 분리하였다. 이병 식물체는 줄기가 고사하여 하얗게 말라 죽고, 줄기 표면에 흰가루 모양의 포자가 형성되었다. 분리균은 균학적 특성과 분자생물학적 특성에 따라 Fusarium fujikuroi로 동정되었다. Translation elongation factor 1-alpha 유전자의 염기서열 분석 결과, GenBank에 등록된 F. fujikuroi와 상동성을 나타내었다. 벼와 피를 대상으로 침지접종에 의해 병원성을 확인하였으며, 이는 피가 벼 키다리병의 전염원으로서의 역할을 할 수 있음을 의미한다. 따라서 벼 키다리병의 방제와 건전종자의 채종을 위해서는 논에 발생한 이병식물체뿐 아니라 전염원으로 작용할 수 있는 피를 제거해야 할 것으로 생각된다.

• The Plant Pathology Journal
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• 제29권1호
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• pp.42-51
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• 2013

One of the most important limiting factors for the production of the grafted cactus in Korea is the qualitative and quantitative yield loss derived from stem rots especially caused by Bipolaris cactivora. This study is aimed to develop microbial control agents useful for the control of the bipolaris stem rot. Two bacteria (GA1-23 and GA4-4) selected out of 943 microbial isolates because of their strong antibiotic activity against B. cactivora were identified as Bacillus subtilis and B. amyloliquefaciens, respectively, by the cultural characteristics, Biolog program and 16S rRNA sequencing analyses. Both bacterial isolates significantly inhibited the conidial germination and mycelial growth of the pathogen with no significant difference between the two, of which the inhibitory efficacies varied depending on the cultural conditions such as temperature, nutritional compositions and concentrations. Light and electron microscopy of the pathogen treated with the bacterial isolates showed the inhibition of spore germination with initial malformation of germ tubes and later formation of circle-like vesicles with no hyphal growth and hyphal disruption sometimes accompanied by hyphal swellings and shrinkages adjacent to the bacteria, suggesting their antibiotic mode of antagonistic activity. Control efficacy of B. subtilis GA1-23 and B. amyloliquefaciens GA4-4 on the cactus stem rot were not as high as but comparable to that of fungicide difenoconazole when they were treated simultaneously at the time of pathogen inoculation. All of these results suggest the two bacterial isolates have a good potential to be developed as biocontrol agents for the bipolaris stem rot of the grafted cactus.

• The Plant Pathology Journal
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• 제29권1호
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• pp.52-58
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• 2013

Fusarium head blight (FHB) caused by the filamentous fungus Fusarium graminearum is one of the most severe diseases threatening the production of small grains. Infected grains are often contaminated with mycotoxins such as zearalenone and trichothecences. During survey of contamination by FHB in rice grains, we found a bacterial isolate, designated as BN1, antagonistic to F. graminearum. The strain BN1 had branching vegetative hyphae and spores, and its aerial hyphae often had long, straight filaments bearing spores. The 16S rRNA gene of BN1 had 100% sequence identity with those found in several Streptomyces species. Phylogenetic analysis of ITS regions showed that BN1 grouped with S. sampsonii with 77% bootstrap value, suggesting that BN1 was not a known Streptomyces species. In addition, the efficacy of the BN1 strain against F. graminearum strains was tested both in vitro and in vivo. Wheat seedling length was significantly decreased by F. graminearum infection. However, this effect was mitigated when wheat seeds were treated with BN1 spore suspension prior to F. graminearum infection. BN1 also significantly decreased FHB severity when it was sprayed onto wheat heads, whereas BN1 was not effective when wheat heads were point inoculated. These results suggest that spraying of BN1 spores onto wheat heads during the wheat flowering season can be efficient for plant protection. Mechanistic studies on the antagonistic effect of BN1 against F. graminearum remain to be analyzed.

• Applied Biological Chemistry
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• 제41권2호
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• pp.119-124
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• 1998

체내혈액의 응고기작에 의해 생성된 단백질인 fibrin을 분해할 수 있는 효소를 분비하는 균을 청국장으로부터 분리하여 동정하였다. 청국장으로부터 protein 분해능이 있는 균주를 분리하고 분리한 균주들 중에서 혈전용해능이 가장 우수한 균주인 KCK-7를 선발하였다. 이 균주는 호기성으로 포자를 형성 하는 Gram(+)균이었으며 Gas chromatography에 의한 세포의 지방산 분석은 $C_{150}\;anteiso$형이 40.85%, $C_{150}\;iso$형이 19.47% 이었다. 이 균주는 생리, 생화학적 특성 및 세포지방산 분석을 통하여 Bacillus subtilis로 동정되었다. Bacillus subtilis KCK-7의 fibrinolytic enzyme 생성을 위한 최적 배양 온도와 pH는 각각 $37^{\circ}C$, 8.0이었다.

• Applied Biological Chemistry
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• 제42권1호
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• pp.6-11
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• 1999

fibrin 단백질을 분해할 수 있는 효소를 분비하는 균을 된장으로부터 분리하여 동정하였다. 된장으로부터 protein 분해능이 있는 균주를 분리하고 분리한 균주들 중에서 혈전용해능이 가장 우수한 균주인 KDO-13을 선발하였다. 이 균주는 호기성으로 포자를 형성하는 Gram(+)균 이었으며 gas chromatography에 의한 세포의 지방산 분석은 $C_{15:0}$ anteiso fatty acid가 47.7%, $C_{15:0}$ iso fatty acid가 13.5% 이었다. 이 균주는 생리, 생화학적 특성 및 세포지방산 분석을 통하여 57.7%의 similarity를 갖는 Bacillus atrophaeus로 잠정 동정되었다. Bacillus atrophaeus KDO-13의 fibrinolytic enzyme 생성을 위한 최적 배양 온도와 pH는 각각 $37^{\circ}$와 6.0 이었다.

• 한국미생물·생명공학회지
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• 제13권3호
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• pp.273-278
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• 1985

새로운 페니실린 발효방법으로서, Penicillin chrysogenum의 포자를 담체의 미세구멍 조직에 흡착시킨 후 배양하여 얻은 균사증식담체를 이용하여 페니실린 발효를 시도하였다. 고정화 담체로써는 Celite가 가장 효율적이었으며, 이때 균사는 담체의 내부에서부터 포자가 발아하여 담체의 표면에서 증식하기 때문에 매우 안정된 biofilm growth를 얻을 수 있었다. 프라스크 배양에서 담체의 양을 5-10% 첨가하였을 때 세포의 증식과 페니실린의 생산이 전통적인 dispersed filamentous growth 에 의한 발효방법보다 현저히 증가되었다. 그러나 두 경우 모두 세포의 활성은 1900 unit/mg-cellㆍhr로 일정하였다. 균사증식 담체를 이용하여 유동층 발효조에서 반연속식으로 발효를 진행시킨 결과 페니실린의 연속생산이 가능함을 발견하였다. 그러나 발효조내에서 biofilm growth시 film두께의 조절과 페니실린 생산성을 일정수준으로 오랫동안 유지시킬 수 있는 방법이 앞으로 연구되어야 할 것으로 판단되었다.

• 한국환경과학회지
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• 제28권3호
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• pp.385-392
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• 2019

This study investigated the relationship among seven species of trichoderma through the identification of strains collected in Korea. The phylogenetic tree among the collected strains was classified into four groups. The trichoderma strains isolated in this way showed inhibitory effect on the fusarium wilt which is parasitic to cotyledon stem..The invisibility of J9, J10, J13 and J16 strains were higher in comparison with other strains in vitro test stand, and their spore production level was also higher. In the aluminum ring tests, it showed that the yield of the spores in J9, J10 and J13 were more than any other strain. As a result conducting the port test for cucumbers, the plant lengths of J13 were larger than the control plot, and the root lengths of all strains, except for J2 were longer than the control plot, and the root weights of J1, J9, J10, J13 and J16 were larger than the control plot. The disease severity for the fusarium wilt showed the smallest values at J13 and J16 in comparison with the control plot, and the control values of J13 and J16 were higher than other strains.

• The Plant Pathology Journal
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• 제37권6호
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• pp.533-542
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• 2021

Chitosan has been considered an environmental-friendly polymer. However, its use in agriculture has not been extended yet due to its relatively low solubility in water. N-Methylene phosphonic chitosan (NMPC) is a water-soluble derivative prepared by adding a phosphonic group to chitosan. This study demonstrates that NMPC has a fungicidal effect on the phytopathogenic fungus Fusarium solani f. sp. eumartii (F. eumartii) judged by the inhibition of F. eumartti mycelial growth and spore germination. NMPC affected fungal membrane permeability, reactive oxygen species production, and cell death. Also, this chitosan-derivative exerted antifungal effects against two other phytopathogens, Botrytis cinerea, and Phytophthora infestans. NMPC did not affect tomato cell viability at the same doses applied to these phytopathogens to exert fungicide action. In addition to water solubility, the selective biological cytotoxicity of NMPC adds value in its application as an antimicrobial agent in agriculture.

• Journal of Microbiology and Biotechnology
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• 제33권5호
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• pp.607-620
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• 2023

The biocontrol approach using beneficial microorganisms to control crop diseases is becoming an essential alternative to chemical fungicides. Therefore, new and efficient biocontrol agents (BCA) are needed. In this study, a rhizospheric actinomycete isolate showed unique and promising antagonistic activity against three of the most common phytopathogenic fungi, Fusarium oxysporum MH105, Rhizoctonia solani To18, and Alternaria brassicicola CBS107. Identification of the antagonistic strain, which was performed according to spore morphology and cell wall chemotype, suggested that it belongs to the Nocardiopsaceae. Furthermore, cultural, physiological, and biochemical characteristics, together with phylogenetic analysis of the 16S rRNA gene (OP869859.1), indicated the identity of this strain to Nocardiopsis alba. The cell-free filtrate (CFF) of the strain was evaluated for its antifungal potency, and the resultant inhibition zone diameters ranged from 17.0 ± 0.92 to 19.5 ± 0.28 mm for the tested fungal species. Additionally, the CFF was evaluated in vitro to control Fusarium wilt disease in Vicia faba using the spraying method under greenhouse conditions, and the results showed marked differences in virulence between the control and treatment plants, indicating the biocontrol efficacy of this actinomycete. A promising plant-growth promoting (PGP) ability in seed germination and seedling growth of V. faba was also recorded in vitro for the CFF, which displayed PGP traits of phosphate solubilization (48 mg/100 ml) as well as production of indole acetic acid (34 ㎍/ml) and ammonia (20 ㎍/ml). This study provided scientific validation that the new rhizobacterium Nocardiopsis alba strain BH35 could be further utilized in bioformulation and possesses biocontrol and plant growth-promoting capabilities.

• 식물병연구
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• 제22권2호
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• pp.72-80
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• 2016

D. bryoniae에 의해 발생되는 덩굴마름병은 세계적으로 수박 재배에 주요한 병으로 알려져 있으며, 본 실험은 D. bryoniae에 대한 수박의 효율적인 저항성 검정법을 확립하기 위해 수행하였다. 함안 지역에서 전형적인 덩굴마름병 병징을 보이는 수박으로부터 GBS3 균주를 분리하였고 ITS 영역의 염기서열 분석을 통해 GBS3 균주는 D. bryoniae로 동정되었다. 다양한 조건에서의 포자 형성량과 형성된 포자의 5가지 생육 시기의 수박 유묘에 대해 병원력 차이를 조사하고, 이로부터 저항성 검정을 위한 간편한 접종원 대량 생산 방법을 확립하였다. 시판 중인 수박 22개 품종의 GSB3 균주에 대한 저항성 정도를 확인하고, 그 결과로부터 저항성 정도가 다른 수박 4개 품종을 선발하였다. 그리고 접종원 농도, 습실 처리 기간, 접종 후 재배온도 등의 발병 조건에 따른 이들 품종의 덩굴마름병 발생을 조사하였다. 이들 결과로부터 덩굴마름병에 대한 효율적인 수박 저항성 검정 방법으로 본엽 2엽이 충분히 전개된 수박 유묘에 $5.0{\times}10^5spores/ml$ 농도의 D. bryoniae 포자현탁액을 분무접종하고, $25^{\circ}C$ 습실에서 48시간 동안 배양 후에 항온항습실($25^{\circ}C$, 상대습도 80%)로 이동하여 하루 12시간씩 광을 처리하면서 재배하고, 접종 3-4일 후에 접종한 잎의 병반면적률을 조사하는 것을 제안하고자 한다.