• 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.

• Mycobiology
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• 제32권3호
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• pp.128-133
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• 2004

Twenty plant extracts were tested against mycelial growth, sclerotium formatiom and dry weight of mycelium with sclerotia of Sclerotium rolfsii Sacc. The highest(90 mm) mycelial growth was measured in Adhatoda vasica, Tegetes erecta, Allium cepa, and Curcuma longa. The lowest(25 mm) was in Azadirachta indica. No mycelial growth was found in any concentration of cow, buffalo, and goat urine. The highest(90 mm) and the lowest(15 mm) mycelial growth were measured in Biomil and Urea, respectively. No mycelial growth was observed in Zinc. The highest(60 mm) and the lowest(2 mm) mycelial growth were recorded in Macuprex(Dodine; 65% WP) and Boron(100% Boric acid and 17% Boron) respectively. Mycelial growth was totally inhibited in Rovral(Iprodione; 50% WP).

• 한국환경농학회지
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• 제31권1호
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• pp.30-36
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• 2012

BACKGROUND: The resistance of rice bakanae disease pathogens against the fungicide prochloraz has been reported. Understanding the resistance mechanisms is an important for better control of the pathogens. In the present study, we investigated the resistance mechanisms of Fusarium fujikuroi CF337 (CF337) against prochloraz. METHODS AND RESULTS: Morphological changes in the cell wall of CF337 grown in potato dextrose broth (PDB) with or without prochloraz was investigated by transmission electron microscopy. Growth inhibition of CF337 was examined in PDB containing prochloraz or an ABC transporter inhibitor or both of them. Cell wall thickness of CF337 grown in PDB with prochloraz was significantly increased from $80.73{\pm}1.99nm$ to $193.11{\pm}7.07nm$. Significant inhibition in the growth of CF337 was observed in the presence of both prochloraz and the inhibitor, but no growth inhibition was observed in the presence of the inhibitor or prochloraz. Sequence analysis of ATP-binding cassette transporter (ABC) gene of CF337 showed 70 to 80% similarities to the genes of the pathogens resistant to other fungicides. CONCLUSION: Efflux transporter system and changes in cell wall thickness were suggested as resistance mechanisms of CF337 against prochloraz.

• 한국식품과학회지
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• 제35권6호
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• pp.1169-1173
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• 2003

새롭게 출현한 식중독 세균으로 국내 유통 계육 등에 많이 오염이 되어 있는 Arcobacter butzleri를 제어하기 위해 여러 위생제 처리에 따른 생육영향을 평가하였다. 이들 균체에 1%농도의 유기산과 trisodium phosphate를 5, 10분간 처리한 결과 대부분이 10분 이내에 사멸한 것을 확인할 수 있었으며, 젖산의 경우는 5분 이내에 모든 균주가 사멸하였다. 배양할 때의 유기산의 농도별 생육영향은 1%의 농도로는 1시간 이내에, 0.1%의 농도에서 72시간 이내에 A. butzleri가 사멸한 것을 볼 수 있었으며, trisodium phosphate의 경우 2% 농도에서는 1 시간이내에 사멸하였다. 유기산 중에는 젖산의 생육저해효과가 가장 우수하게 나타났으며 hydrogen peroxide, sodium hypochlorite와 ethanol에 대한 사멸효과를 보았으나, 이 처리제는 효과가 나쁘거나 풍미에 영향을 주어 좋은 처리제라 할 수 없었다. 그리고 마늘과 양파즙에 대한 항미생물 작용에서 마늘에만 생육저해작용을 확인할 수 있었으며, 젖산균이 생산하는 유기산에 의한 낮은 pH에 의한 저해효과를 확인할 수 있었다. 따라서 계육 등의 육가공 및 취급 시에 유기산 및 TSP 등을 이용하여 주요 Arcobacter에 의한 식중독저해가 가능할 것으로 사료되었다.

• 한국미생물·생명공학회지
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• 제49권3호
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• pp.374-383
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• 2021

Rhizoctonia solani is one of the major pathogens that cause sheath blight disease in rice. Sheath blight is one of the most difficult diseases to control. Biological control (with the use of rhizobacteria) is one of the ways to control this disease. Plant Growth Promoting Rhizobacteria (PGPR) is a rhizosphere bacterium that can be used to enhance plant growth. The composition of the rhizobacteria in organic and nonorganic soil is affected by the chemical characteristics of the soil - which influences plant physiology and root exudation patterns. This study aimed to obtain a species of rhizobacteria which shows PGPR activity, from organic and nonorganic rice fields and test their capability to suppress R. solani growth. Out of 23 isolates screened for PGPR activity, the following isolates showed high PGPR activity and were selected for in vitro antagonistic activity testing against R. solani: ISO6, ISO11, ISO15, ISN2, ISN3, and ISN7, The six isolates produced 43,42-75,23 ppm of IAA, possessed phosphorus solubilization capability, and chitinase-producing activity. ISO6 (54.88%) and ISN7 (83.33%) displayed high inhibition capacities against R. solani, in vitro. ISO6 and ISN7 inhibited the growth of R. solani lesions on rice leaves by 89% and 100% (without lesion), respectively, after 7 days of incubation. Analysis of their 16S rRNA sequences revealed that the ISO6 isolate was Citrobacter freundii and ISN7 isolate was Pseudomonas aeruginosa.

• Mycobiology
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• 제37권2호
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• pp.77-81
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• 2009

This study was conducted to identify the Colletotrichum species causing anthracnose disease of strawberry in Balgladesh and to evaluate in vitro activity of commercial fungicides it. Based on morphological and cultural characteristics, all 22 isolates were identified as Colletotrichum gloeosporioides. They developed white or glittery colonies with grey to dark grey reverse colony colors and they produced cylindrical conidia. The efficacy of five commercial fungicides, Bavistin DF, Dithane M-45, Sulcox 50 WP, Corzim 50 WP and Rovral 50 WP, were tested against the fungus. Bavistin inhibited radial growth completely and was followed in efficacy by Dithane M-45. In Bavistin DF treated media, the fungus did not produce conidia. The percent inhibition of radial growth of the fungus was increased with the increasing concentrations of fungicide.

• 식물병연구
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• 제14권3호
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• pp.187-192
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• 2008

본 연구에서는 키토메이트, 다이균, IC-66D, 골드보르도, 바이오스팟 등 5종의 친환경농자재의 포도 주요 균류병 병원균 7가지에 대한 생장억제 효과를 검정하였다. 병원균의 생장억제 효과는 친환경농자재 별로 차이를 보였는데, 천연 식물추출물성분인 다이균의 생장억제 효과가 가장 우수하였다. 다이균은 $2,500{\mu}g{\cdot}mL^{-1}$을 포함한 PDA 배지에서 C. gloeosporioides 04-159를 제외한 병원균의 균사생장을 75% 이상 억제하였다. 키토메이트의 생장억제 효과는 병원균에 따라 큰 차이가 있었는데 $40,000{\mu}g{\cdot}mL^{-1}$을 함유한 PDA 배지에서 B. cinerea 06-063의 균사생장을 81.1% 억제한 반면에 탄저병균인 C. gloeosporioides 04-159는 6.5% 균사 생장억제율을 보였다. 두 가지 보르도액 제제인 IC-66D와 골드보르도의 생장억제 효과는 흰얼룩 증상의 원인균인 Acremonium sp.을 제외하고 IC-66D가 골드보르도보다 약간 높았다. 바이오스팟은 다이균 다음으로 생장억제 효과가 높았는데 특히 탄저병균인 C. gloeosporioides 04-159에 대해서는 사용한 농자재 중에서 가장 높았다. 키토메이트, 바이오스팟, 골드보르도의 갈색무의병 포자 발아억제율은 같은 농도에서의 균사 생장억제율보다 월등히 높았다. 본 실험은 포도 친환경적병 방제를 위해서는 한 가지 친환경농자재를 사용할 것이 아니라 여러 가지 제제를 다양하게 사용할 것을 제안한다.

• 한국미생물·생명공학회지
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• 제46권4호
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• pp.346-359
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• 2018

Xanthomonas oryzae, a bacterial pathogen causing leaf blight disease (BLB) in rice, can cause widespread disease and has caused epidemics globally, resulting in severe crop losses of 50% in Asia. The pathogen is seed-borne and is transmitted through seeds. Thus, control of BLB requires the elimination of the pathogen from seeds. Concern about environment-friendly organic production has spurred improvements in a variety of biological disease control methods, including the use of bacteriophages, against bacterial plant pathogens. The present study explored the potential of bacteriophages isolated from diseased plant leaves and soil samples in killing the bacterial pathogen in rice seeds. Eight different phages were isolated and evaluated for their bacteriolytic activity against different pathogenic X. oryzae strains. Of these, a phage designated ${\varphi}XOF4$ killed all the pathogenic X. oryzae strains and showed the broadest host range. Transmission electron microscopy of ${\varphi}XOF4$ revealed it to be a tailed phage with an icosahedral head. The virus was assigned to the family Siphoviridae, order Caudovirales. Seedlings raised from the seeds treated with $1{\times}10^8pfu/ml$ of ${\varphi}XOF4$ phage displayed reduced incidence of BLB disease and complete bacterial growth inhibition. The findings indicate the potential of the ${\varphi}XOF4$ phage as a potential biological control agent against BLB disease in rice.

• Journal of Microbiology and Biotechnology
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• 제11권6호
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• pp.1061-1065
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• 2001

The antibacterial effects of water extracts of Scutellariate Radix (a dried root of Scutellaria baicalensis GEORGI) and its major flavonoid components, Baicalin and Baicalein, on Salmonella typhimurium, a representative enteric pathogen, were studied. Through a Kriby-Bauer disc analysis, the growth-inhibition activity of Scutellariae Radix against. S. typhimurium was found to be compatible with commercial antibiotics, such as ampicillin, chloramphenicol, and streptomycin. In contrast, the growth of a nonpathogenic E. coli strain was unaffercted by Scutellariae Radix. To examine the effect of polyphosphate kinase (ppk), a putative virulence factor, on the antibacterial activity of Scutellariae Radix, the growth profile of a ppk mutant of S. typhimurium was investigated in a tryptic soy broth containing different concentrations of water extracts of Scutellariae Radix. The ppk mutant was able to grow in 6 mg/ml of water extracts of Scutellariae Radix, whereas in 6 mg/ml of water extracts of Scutellariae Radix, whereas the wild-type could not, implying that the inactivation of ppk made S. typhimurium more resistant to the antibacterial activity of Scutellariae Radix. No enhanced resistance was observed in a ppk mutant of S. typhimurium complemented with a ppk expression vector. The attenuation of the virulence by ppk inactivation was also observed in a virulence assay using BLAB/c mice. Neither Baicalin nor Baicalein exhibited any growth-inhibition activity against S. typhimurium. The water extracts of Scutellariae Radix stimulated the transcription of ppk, especially in the early growth-stage of S. typhimurium.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XIII)
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• pp.415-419
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• 2003

One strain was isolated from wilted chestnut tree and identified as Helicosporium nizamabadense. Also, the strain was evaluated for biocontrol potentials against phytopathogens. Autoclaved fraction of the isolate also showed complete growth inhibition of the turfgrass large patch pathogen, Rhizoctonia. solani AG2-2 and plant pathogen, Botrytis cinerea. Culture extracts of Helicosporium nizamabadense were purified by Thin Layer Chromatography. The several fractions were analyzed by GC-MS, and NMR etc. Antifungal activities were presumably showed more than 5 fractions against the pathogens. Among them, the most effective antifungal fraction was identified as 2-Methylresocinol using GC-MS, and NMR. These results suggest that the 2-Methylresocinol may be useful for biochemicals.