• The Plant Pathology Journal
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• v.29 no.1
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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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• v.32 no.3
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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).

• Korean Journal of Environmental Agriculture
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• v.31 no.1
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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.

• Korean Journal of Food Science and Technology
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• v.35 no.6
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• pp.1169-1173
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• 2003

Growth of a newly emerging pathogen, Arcobacter butzleri, in domestic raw meat was evaluated by various sanitizing agents. One percent of acetic acid, citric acid, lactic acid, and trisodium phosphate (TSP) added to the cell suspension of six A. butzleri strains inhibited their growth within ten minutes, and especially the lactic acid inhibited growth within five minutes. One percent of all the acids at the culture broth inhibited growth completely within one hr. 0.1% of the acids inhibited growth within 72 hr, whereas two percent of TSP had the same effect in one hr. Among the acids, lactic acid had the strongest inhibition activity. Hydrogen peroxide, sodium hypochlorite, and ethanol showed lower inhibiting activities than the above agents. While garlic extract and lactic acid bacteria culture also inhibited A. butzleri, onion extract did not. Therefore, food-borne poisoning of A. butzleri in raw meat could be prevented by organic acid and trisodium phosphate treatments.

• Microbiology and Biotechnology Letters
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• v.49 no.3
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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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• v.37 no.2
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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.

• Research in Plant Disease
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• v.14 no.3
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• pp.187-192
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• 2008

Five environment-friendly farm materials including $Chitomate^{(R)}$, $Diegyun^{(R)}$, IC-$66D^{(R)}$, Gold $Bordo^{(R)}$, and $Biospot^{(R)}$ were examined for their growth inhibition effect of the 7 fungal pathogens of grape in vitro. $Diegyun^{(R)}$, being composed of natural ingredients which are extracted from a plant, was the most effective in suppression of mycelial growth of the fungi. $Diegyun^{(R)}$ inhibited the mycelial growth of all of fungi over 75% at $2,500{\mu}g{\cdot}mL^{-1}$ on potato dextrose agar(PDA) except Colletotrichum gloeosporioides 04-159. Growth inhibition effect of $Chitomate^{(R)}$, being composed of the chitosan, varied depending on the fungal pathogens on PDA. It inhibited the mycelial growth of the Botrytis cinerea 06-063 at the rate of 75.8% at $40,000{\mu}g{\cdot}mL^{-1}$ on PDA while it inhibited the mycelial growth of the C. gloeosporioides 04-159 at the rate of 6.5%. IC-$66D^{(R)}$ and Gold $Bordo^{(R)}$ are two different formula of the Bordeaux mixture, showed different control effects on mycelial growth inhibition. Except of Acremonium sp. the growth inhibition of IC-$66D^{(R)}$ was a little higher than Gold $Bordo^{(R)}$. $Biospot^{(R)}$, a chlorine formula, showed the strongest growth inhibition on C. gloeosporioides 04-159 among the farm materials used. Inhibition of spore germination of $Chitomate^{(R)}$, $Biospot^{(R)}$ and Gold $Bordo^{(R)}$ was higher than mycelial growth inhibition for Pseudocercospora vitis 04-152. The results suggest that the different types of environment-friendly farm materials are needed for different disease control in organic grape farm.

• Microbiology and Biotechnology Letters
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• v.46 no.4
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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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• v.11 no.6
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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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• 2003.10a
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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.