• Parasites, Hosts and Diseases
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• 제52권4호
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• pp.435-438
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• 2014

The disinfectant effects (DEs) of 10 types of chemicals, defined by their ability to destroy or inhibit oocysts and consequently prevent sporulation of Eimeria tenella field isolate, were evaluated in vitro. Correct species assignments and sample purities were confirmed by the singular internal transcribed spacer (ITS)-PCR analysis. A total of 18 treatments were performed, and the disinfection suppression levels were 75.9% for 39% benzene + 22% xylene (1:10 dilution), 85.5% for 30% cresol soup (1:1 dilution), and 91.7% for 99.9% acetic acid (1:2 dilution) group. The results indicate that acetic acid, cresol soup, and benzene+xylene are good candidates for suppression of E. tenella oocyst sporulation.

• Journal of Microbiology
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• 제37권1호
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• pp.27-34
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• 1999

Two fractions with unusual antifungal activity that suppress asexual sporulation of several fungi were obtained from culture filtrate of Pseudomonas aeruginosa and were partially purified through the repeated silicagel flash column chromatographies. The sporulation-suppressive actions of these fractions in Aspergillus nidulans, Rhizopus stolonifer, and Coprinus cinereus, were analyzed by light and electron microscopes. The germination ability of the spores produced in the presence of these fractions were also checked to determine the persistent effects of these antifungal substances on the next generation. Light microscopic observation of developing sporangia of R. stolonifer grown in the presence of both fractions revealed that the significant number of sporangia failed to reach maturity, and frequently, uncontrolled growths of hyphae and rhizoids from the sporangiophores were found. In A. nidulans addition of these fractions appeared to cause different classes of morphological abnormality in conidia development, which included aborted formation of conidiogenous cells from the apex of conidiophores and enhanced hyphal growths either at the tip or middle of the conidiophores. Germination abilities of spores obtained from the cultures grown in the presence of antifungal fractions were 40∼60% in Aspergillus, 50∼80% in Coprinus (thallic spores), and 30∼40% in Rhizopus compared to those of normal spores.

• 식물병연구
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• 제12권3호
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• pp.240-248
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• 2006

Control of white rot which is one of the most serious apple diseases in Korea has mainly relied on periodical spray of protective fungicides. As the main inoculum source of the disease is pycnidiospores produced in the warts formed on affected stems of apple tree, it can be conceivable that inhibition of spore production might be an effective means for controlling the disease. Inhibitory efficacy of eight selected fungicides against sporulation of the fungus was assessed by counting the number of spores produced at detached warts treated with the fungicides of recommended dilution. They showed diverse effect on sporulation. Carbendazim and azoxystrobin suppressed sporulation almost completely, the former irreversively. Thiram and folpet promoted sporulation as producing much more number of spores than untreated control. Others showed almost no effect on sporulation. Effects of suppression and promotion in the sporulation shown by the fungicides on the control of white rot were examined by incidences of disease and infection at the plots adopted the spray programs of which the fungicide at late May was substituted by carbendazim, azoxystrobin, folpet and thiram, respectively. Disease incidence and infection frequency at the plots sprayed former two chemicals which suppressed sporulation were much lower than those of the plots adopted latter two chemicals and untreated plot at which the fungicide spray was skipped at that time. These facts were reconfirmed in the experiments conducted with carbendazim and thiram, in which 100 fruits were bagged just prior to each spray from late May to late July for elucidating the effect of the two fungicides on the action of subsequent ones. Disease incidence and infection frequency on the fruit bagged just prior to each spray were gradually increased as the seasons going on. The increase rate at the carbendazim plot was much lower than that of thiram. Especially, the fruit infected till late July at the carbendazim plot were almost completely cured by the three fungicides, iminoctadine-triacetate, tebuconazole and samzinwang, a combined formular of iminoctadine-triacetate and difenoconazole, sprayed at late July and hence. In thiram plot, infected fruit were also cured by the 3 fungicides but not remarkable. From these results, it can be concluded that control efficiency of white rot can be greatly enhanced by selecting the fungicide capable of suppress the sporulation of white rot fungus at the season when the mass dispersal of spores is not initiated.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 1994년도 Proceedings of International Symposium on BIOLOGICAL CONTROL OF PLANT DISEASES Korean Society of Plant Pathology
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• pp.27-49
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• 1994

Root colonization of biocontrol agents via seed treatment was investigated and a compatible combination, Gliocladium virens G872B and Pseudomonas putida Pf3, in colonizing cucumber rhizosphere was confirmed through the study. Much higher number of fungal and bacterial propagules were detected when two isolates were inoculated together. The presence of Pf3 in root system was greatly helpful to G872B to colonize at root tip. The mechanism of this phenomenon is partially elucidated through the results of in vitro experiments and the observations of scanning electron and fluorescence microscope. Addition of Pf3 cells resulted earlier germination of G872B conidia and increased mycelial growth. And the more number of germinated conidia on seed coat, the more vigorous hypal streching and sporulation on the root surface were observed in coinoculated treatment. The propagules of G872B on the cucumber root when they were challenged against the pathogenic Fusarium oxysporum, were even higher than that of G872B treated alone, and the magnitude of such a difference was getting grater toward the root ip and the population of F. oxysporum on the root was reduced by seed inoculation of G872B. The rhizosphere competence was obviously reflected to disease suppression and plant growth promotion that induced by the given isolate. Green house experiments revealed that the combined treatment provided long-term disease suppression with greater rate and the larger amount of fruit yield than single treatments. Through this study the low temperature growing Pseudomonas fluorescens M45 and MC07 were evaluated to apply them to the winter crops in field or plastic film house. In vitro tests reveal that M45 and MC07 inhibited the mycelial growth of Pythium ultimum, Rhizoctona solani and Phytophthora capsici and enhanced growth of cucumber cotyledon in MS agar. This effect was more pronounced when the bacteria were incubated at 14$^{\circ}C$ than at 27$^{\circ}C$. And disease suppression and plant growth promotion in green house were also superior at low temperature condition. Seed treatment of M45 or soil treatment of MC07 brought successful control of damping-off and enhanced seedling growth of cucumber. The combined treatment of two isolates was more effective than any single treatment.

• Mycobiology
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• 제36권4호
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• pp.242-248
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• 2008

The present study was undertaken to explore the inhibitory effect of cyanobacterial extracts of Nostoc commune FA-103 against the tomato-wilt pathogen, Fusarium oxysporum f. sp. lycopersici. In an optimal medium, cell growth, antifungal activity, and antifungal compound production could be increased 2.7-fold, 4.1-fold, and 13.4-fold, respectively. A crude algal extract had a similar effect as mancozeb at the recommended dose, both in laboratory and pot tests. In vitro and in vivo fungal growth, spore sporulation and fungal infection of wilt pathogen in tomato seeds were significantly inhibited by cyanobacterial extracts. Nostoc commune FA-103 extracts have potential for the suppression of Fusarium oxysporum f. sp. lycopersici.

• 한국미생물·생명공학회지
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• 제23권2호
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• pp.236-242
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• 1995

Biological control of soilborne plant pathogens by the addition of antagonistic microorganisms to the soil may offer a practical supplement or alternative to existing disease management strategies that depend heavily on chemical pesticides. Soil amendment with antagonistic microbes was non-effective because of high cost, low efficacy, and inconvenient usage on the treatment course. Therefore, seed coating formulation for the application of biological seed treatments has been being to apply successful disease suppression for many important crops. The objectives of this study were to investigate the optimal condition for the spore production of biocontrol agent Bacillus subtilis YBL-7 and the liquid coating formulation that contained a suspension of a proper aqueous binder, as well as a ground fine solid particulate material. The maximum yield has been obtained from 60 hrs-old culture at 30$\circ$C in spore forming (SF) medium containing 0.8% nutrient broth, 0.05% yeast extract, 10$^{-1}$ M MgCl$^{2}$, 10$^{-4}$ M MnCl$^{2}$, 10$^{-5}$ M dipicolinic acid, and pH 6.5. The optimal condition of dried spore preparation was achieved when cells of B. subtilis YBL-7 was heat-dried with 50$\circ$C for 2 hrs.

• Mycobiology
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• 제45권3호
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• pp.213-219
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• 2017

In our previous study, three bacterial strains, Bacillus megaterium KU143, Microbacterium testaceum KU313, and Pseudomonas protegens AS15, were selected as effective biocontrol agents against Aspergillus flavus on stored rice grains. In this study, we evaluated the inhibitory effects of the volatiles produced by the strains on A. flavus growth and aflatoxin production on stored rice grains. The three strains significantly reduced mycelial growth of A. flavus in dual-culture assays compared with the negative control strain, Sphingomonas aquatilis KU408, and an untreated control. Of these tested strains, volatiles produced by B. megaterium KU143 and P. protegens AS15 markedly inhibited mycelial growth, sporulation, and conidial germination of A. flavus on agar medium and suppressed the fungal populations in rice grains. Moreover, volatiles produced by these two strains significantly reduced aflatoxin production in the rice grains by A. flavus. To our knowledge, this is the first report of the suppression of A. flavus aflatoxin production in rice grains using B. megaterium and P. protegens volatiles.

• Journal of Microbiology
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• 제43권6호
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• pp.523-528
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• 2005

Using the genomic library constructed at the downstream of the niiA promoter, which induces the over-expression of an inserted DNA fragment, we have attempted to screen the genes affecting growth or development by over-expression. The wild-type strain was transformed using the AMA-niiA(p) library and cultured on 1.2 M sorbitol media, in which asexual sporulation is induced, but sexual development is repressed. Over 100,000 strains transformed to $pyrG^+$ were analyzed with regard to any changes in phenotype. Consequently, seven strains were isolated for further analyses. These strains were designated NOT [niiA(p) over-expression transformants] stains. Four of the strains were of the inducible type, and the remaining strains were of the multi-copy suppression type. Two of the inducible-type strains, NOT 1 and NOT40, harbored genes which had been inserted in reverse direction, suggesting that the mutant phenotypes had been derived from an excess amount of anti-sense mRNA. Domain analyses of the deduced polypeptides from the DNA fragments rescued from the transformants revealed that NOT1, NOT40 and NOT6 harbored a LisH motif, a forkhead domain, and a $Zn(II)_2Cys_6$ binuclear zinc cluster, respectively.

• 식물병연구
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• 제10권4호
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• pp.319-323
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• 2004

본 연구는 부생성 균류인 Ulocladium atrum을 이용하여 Botrytis spp.에 의한 백합 잎마름병 및 오이 잿빛곰팡이병의 방제효과를 조사하고 그 작용특성을 규명함으로서 U. atrum의 생물학적 방제제로서의 이용 가능성을 평가하기 위해 실시하였다. 토마토 잎의 표면과 조직 속에서 분리한 Ulocladium sp. CNU 9037과 CNU 9054 균주는 형태적 특징에 의하여 U. atrum로 동정되었으며 이것이 U. atrum의 국내 최초의 보고이다. 토마토 및 오이의 고사된 잎을 이용하여 U. atrum의 Botrytis spp. 포자형성억제력을 실내검정으로 조사하였던 바, U. atrum은 고사된 잎 절편에서 Botrytis의 포자형성을 효과적으로 억제하였다. Botrytis의 포자형성억제력은 U. atrum을 Botrytis보다 먼저 처리했을 경우 효과가 높았다. 백합 잎마름병 방제를 위한 포장(온실)실험 결과 U. atrum CNU 9037 균주의 포자현탁액 처리는 백합 잎마름병을 효과적으로 억제하였으며 방제가는 70%, 77%로 procymidone 약제 처리구의 방제가(58%)보다 우수하였다. U. atrum(CNU 9037, CNU 9054) 포자현탁액처리는 오이 잿빛곰팡이병도 효과적으로 억제하였으며, 그 방제가는 66${\sim}$71%였다. 본 연구의 결과는 U. atrum 균주가 오이, 백합의 Botrytis병의 생물학적 방제제로서 개발 가능성이 있음을 나타낸다

• 식물병연구
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• 제25권4호
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• pp.220-225
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• 2019

2018년 경북 김천 지역 포도 하우스 재배 농가에서 포도송이가 무르고 마른 포도 과실이 낙과되는 피해가 발생하였다. 병반 표면에는 검갈색의 곰팡이 포자가 형성된 것을 확인할 수 있었으며, 이병과실에서 병원균을 분리하여 균학적 특징 및 염기서열 분석결과 병원균은 Aspergillus tubingensis로 동정하였다. 이 증상의 원인균을 증명하기 위해 이병과실에서 병원균을 분리하여 병원성 검정을 수행한 결과, 고온으로 갈수록 급격히 병이 진전되고 하우스에서 발생한 병징과 일치하였다. 또한, 포도송이 썩음 병원균에 대하여 화학농약 약제의 선발을 통해 병원균의 확산을 막고 예방을 하고자 단제 7종 균사생장 억제 효과 검정을 실시하였다. Dipenoconazole, tebuconazole, metconazole, iminoctadine, captan 5가지의 약제에서 균사생장 억제 효과가 확인되었다. A. tubingensis에 의한 포도송이썩음병(가칭)은 2018년도부터 국내 샤인머스켓 포도에 처음 발생되고 있음을 보고하고, 효과적으로 포도송이썩음병의 발생을 예방할 수 있는 5종의 약제를 보고한다.