• Journal of Microbiology and Biotechnology
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• v.15 no.6
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• pp.1164-1169
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• 2005

Characteristics of sophorolipid and rhamnolipid were evaluated as antifungal agents against plant pathogenic fungi. Eight percent of mycelial growth of plant pathogen (Phytophthora sp. and Pythium sp.) was inhibited by 200 mg/l of rhamnolipid or 500 mg/l of sophorolipid, and zoospore motility of Phytophthora sp. decreased by $90\%$ at 50 mg/l of rhamnolipid and $80\%$ at 100 mg/l of sophorolipid. The effective concentrations for zoospore lysis were two times higher than those of zoospore motility inhibition. The highest zoospore lysis was observed with Phytophthora capsici; $80\%$ lysis at 100 mg/I of di-rhamnolipid or lactonic sophorolipid, showing the dependency of structure on the lysis. In the pot test, the damping-off disease incidence ratio decreased to $42\%\;and\;33\%$ of control value at 2,000 mg/l sophorolipid and rhamnolipid, respectively. These results showed the potential of microbial glycolipid biosurfactants as an effective antifungal agent against damping-off plant pathogens.

• Korean Journal of Organic Agriculture
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• v.24 no.2
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• pp.253-262
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• 2016

The SS (Bacillus subtilis 10%), WS (Microbial extract 70%), and DS (Sulfur 78%) agents were selected by mycelial growth inhibitory effect test against kiwifruit soft rot pathogen (B. dothidea) with 11 kinds of environment-friendly agricultural materials on PDA medium for 10 days. They showed at 94.2%, 65.2%, 58.9%, respectively. The control value of WS and SS agents were better than DS in storage experiment. It was effective SS and WS single application, DS-WS and WS-SS alternate application in the field trial.

• Plant Biotechnology Reports
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• v.5 no.4
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• pp.301-308
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• 2011

This study tested the relative and combined efficacy of ShPx2 and ShPAL transgenes by comparing Nicotiana tabacum hybrids with enhanced levels of $_L$-phenylalanine ammonia lyase (PAL) activity and cationic peroxidase (Prx) activity with transgenic parental lines that overexpress either transgene. The PAL/Prx hybrids expressed both transgenes driven by the 35S CaMV promoter, and leaf PAL and Prx enzyme activities were similar to those of the relevant transgenic parent and seven- to tenfold higher than nontransgenic controls. Lignin levels in the PAL/Prx hybrids were higher than the PAL parent and nontransgenic controls, but not significantly higher than the Prx parent. All transgenic plants showed increased resistance to the necrotrophs Phytophthora parasitica pv. nicotianae and Cercospora nicotianae compared to nontransgenic controls, with a preponderance of smaller lesion categories produced in Prx-expressing lines. However, the PAL/Prx hybrids showed no significant increase in resistance to either pathogen relative to the Prx parental line. These data indicate that, in tobacco, the PAL and Prx transgenes do not act additively in disease resistance. Stacking with Prx did not prevent a visible growth inhibition from PAL overexpression. Practical use of ShPAL will likely require more sophisticated developmental control, and we conclude that ShPx2 is a preferred candidate for development as a resistance transgene.

• Korean Journal of Organic Agriculture
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• v.19 no.spc
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• pp.251-254
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• 2011

Botrytis cinerea infects stems and leaves of greenhouse tomatoes and can cause serious economic losses. This study was conducted to develop environment-friendly control method against tomato gray mold. Antagonistic microorganisms (bacteria) were screened for control activity against Botrytis cinerea, both in vitro and in vivo, using stem sections. One hundred bacterial strains were isolated from the rhizospheric soil of various plants including tomato. These strains were screened for growth inhibition of Botrytis cinerea on agar plate by the dual culture and thirty strains showing strongly inhibitory effect against the pathogen were selected first. Among thirty strains, JB 5-12, JB 22-2, JB 22-3, U 4-8 and U46-6 reduced significantly disease incidence, when applied simultaneously with the pathogen. These results suggested that five antagonistic bacteria strains selected have the potential to control tomato gray mold in organic farming.

• Journal of Microbiology and Biotechnology
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• v.18 no.9
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• pp.1578-1583
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• 2008

Rhizobacteria are used as inoculants to enhance crop yield and for biological control of fungal pathogens. Fluorescent pseudomonads isolated from the rhizosphere of groundnut showed suppression of the phytopathogen Macrophomina phaseolina that causes charcoal rot of groundnut, an economically important agroproduct. Two strains of fluorescent pseudomonads, designated as PS1 and PS2, were selected as a result of in vitro antifungal activity. After 5 days of incubation at $28{\pm}1^{\circ}C$, both PS1 and PS2 caused clear inhibition zones in dual cultures, restricting the growth of M. phaseolina by 71 % and 74%, respectively. Both the strains were capable of producing siderophores, indole acetic acid, and hydrocyanic acid, and causing phosphate solubilization under normal growth conditions. These strains, when used as inoculants in groundnut, enhanced germination up to 15% and 30% with subsequent increase in grain yield by 66% and 77%, respectively. Conversely, when the pathogen alone was tested 57% decrease in yield was recorded. Thus the studies revealed the potential of the two pseudomonads not only as biocontrol agents against M. phaseolina, but also as a good growth promoter for groundnut.

• Mycobiology
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• v.37 no.4
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• pp.277-285
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• 2009

In this study, dual culture, poison agar, and direct methods were used to assess the ability of Trichoderma virens IMI-392430, T. pseudokoningii IMI-392431, T. harzianum IMI-392432, T. harzianum IMI-392433, and T. harzianum IMI-392434 to control Ceratocystis paradoxa, which causes the pineapple disease of sugarcane. The highest percentage inhibition of radial growth (PIRG) values were observed with T. harzianum IMI-392432 using two dual culture methods, 63.80% in Method I and 80.82% in Method II. The minimum colony overgrowth time was observed with T. harzianum IMI-392432 and the maximum was observed with T. pseudokoningii IMI-392431. Different concentrations of different day-old metabolites of Trichoderma isolates were tested against mycelial growth of C. paradoxa. The highest PIRG (84.685%) exhibited at 80% concentration of 30-day-old metabolites of T. harzianum IMI-392432 using the modified bilayer poison agar method. In the direct assay method the maximum mycelial growth weight (PIGW) was observed at the same concentration and the same day-old metabolites of T. harzianum IMI-392432. This study showed that Trichoderma isolates have a good antagonistic effect on C. paradoxa mycelial growth and T. harzianum IMI-392432 has the most potential to control the pineapple disease pathogen.

• Journal of Animal Science and Technology
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• v.44 no.4
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• pp.491-498
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• 2002

The inhibitory effect of lactobacilli and bifidobacteria on the growth of typical intestinal pathogens, Escherichia coli and Salmonella typhimurium was studied. The degree of inhibition was measured by well disc assay and turbidimetry method. The strains which showed the higher antimicrobial activity were L. acidophilus La-5, L. acidophilus NCFM, L. casei Lc-01 on the average by using two different methods. The associative cultures were performed with selected 3 lactobacilli and 2 enteropathogens E. coli and S. typhimurium, respectively. Inhibition of pathogen began at 9hr after culturing so that viable counts was decreased rapidly. After 30hr incubation, there were no viable pathogens from the mixed culture. Under this experimental condition, the antimicrobial activity of lactic acid bacteria was not due to pH alone and supposed to different to the strains.

• The Plant Pathology Journal
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• v.36 no.2
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• pp.133-147
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• 2020

Hexanal, a C-6 aldehyde has been implicated to have antimicrobial properties. Hence, this study was conducted to determine the antifungal activities of hexanal vapor against major postharvest pathogens of banana viz., Colletotrichum gloeosporioides and Lasiodiplodia theobromae. The pathogens were cultured in vitro and exposed to hexanal vapor at 600, 800, 1,000 and 1,200 ppm. Mycelial growth of both fungal pathogens were inhibited completely at 800 ppm and the incidence of anthracnose and stem-end rot diseases reduced by 75.2% and 80.2%, respectively. The activities of peroxidase, polyphenol oxidase, phenylalanine ammonia-lyase and glucanase had transiently increased in hexanal vapor treated banana by 5 to 7 days and declined thereafter. Postharvest treatment of banana with hexanal vapor resulted in phospholipase D inhibition and also resulted in cell wall thickening of the treated fruit, which impeded the penetration of the pathogenic spores. This was further confirmed by scanning electron micrographs. The defense-related protein intermediaries had increased in hexanal vapor treated banana fruit, which suggests induced resistance against C. gloeosporioides and L. theobromae, via., the phenylpropanoid pathway which plays a significant role in hindering the pathogen quiescence. Delayed ripening due to inhibition of phospholipase D enzyme, inhibition of mycelial growth and induced systemic resistance by defense enzymes collectively contributed to the postharvest disease reduction and extended shelf life of fruit.

• The Korean Journal of Pesticide Science
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• v.19 no.2
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• pp.119-124
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• 2015

Bacterial leaf spot, caused by Pseudomonas syringae pv. syrinage, is a very damaging disease to green pumpkin in Gong-ju and Non-san nursery. However, there is no good method to control the disease in Korea. Growth inhibition of pathogen on medium, control efficacy on seedling stage, and seed treatment effect of 6 anti-bacterial pesticides were investigated for selection of the best pesticide for seed treatment and control of the disease. Growth inhibition zone on King's B medium were the largest by oxytetracycline 170 ppm and oxytetracycline 15 ppm + streptomycin sulfate 188 ppm, oxolinic acid 200 ppm, streptomycin 200 ppm were next respectively. Control efficacy of oxytetracycline 1.5% + streptomycin sulfate 18.8% WP and oxytetracycline 17% WP on seedling stage were 71.4% and 49.4%, respectively. Seed treatment of oxytetracycline 15 ppm + streptomycin sulfate 188 ppm on the artificially inoculated seeds inhibits pathogen growth completely from the treated seeds and 96% control efficacy on grow-out test of the treated seeds. Seed treatment of streptomycin 100 ppm (2,000 dilution of streptomycin 20%) on the artificially inoculated seeds allow 280 cfu/g of pathogen growth from the treated seeds and 60% control efficacy on grow-out test of the treated seeds. Seed treatment of oxytetracycline 85 ppm (2000 dilution of oxytetracycline 17% WP) on the artificially inoculated seeds allow 80 cfu/g of pathogen growth from the treated seeds and 90% control efficacy on grow-out test of the treated seeds. These results suggested that oxytetracycline 1.5% + streptomycin sulfate 18.8% WP was the best pesticide for seed treatment to control of the bacterial spot disease by Pseudomonas syringae pv. syringae.

• Korean Journal of Food Science and Technology
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• v.44 no.5
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• pp.634-637
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• 2012

In strawberry production, among others, the high incidence of diseases by pathogenic fungi resulting in the reduction of fruit yield and quality requires the development of eco-friendly management systems rather than chemical sprays to control them. The diameter of colonies grown in media at $25^{\circ}C$ for 5 days was measured to evaluate the in vitro inhibition of mycelial growth of 5 pathogenic fungi by irradiation with ultraviolet (UV-C, 264 nm). The mycelial growth of 5 pathogenic fungi was inhibited in potato dextrose agar (PDA) by the irradiation of UV-C for 1 hour a day, and was dramatically inhibited by the irradiation of UV-C for 9-12 h a day. The irradiation of UV-C for 9-12 h a day inhibited completely the growth of the late blight pathogen, Phytophthora cactorum. The irradiation distance of 40 to 50 cm was effective for the inhibition of mycelial growth of fungi. The mycelial growth of fungi without pre-incubation was inhibited strongly by UV-C irradiation compared to fungi pre-incubated for 2 days without light. The mycelia growth of Colletotrichum gloeosprioides and Fusarium oxysporum was inhibited strongly by UV-C irradiation in vegetable 8 juice agar compared to PDA.