• Journal of Microbiology and Biotechnology
• /
• 제15권6호
• /
• pp.1164-1169
• /
• 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.

• 한국유기농업학회지
• /
• 제24권2호
• /
• pp.253-262
• /
• 2016

친환경농자재 11종을 대상으로 황색참다래 과실무름병에 대한 항균활성 검정결과 SS (B. subtilis 10%), WS (Microbial extract 70%), DS (Sulfur 78%) 3종을 선발하였다. SS, WS, DS를 PDA 배지에 10일 동안 처리 시 B. dothidea의 균사 생장 저해 정도는 각각 94.2%, 65.2%, 58.9%였다. 선발 친환경농자재를 이용한 저장시험에서 WS와 SS가 병 방제 효과가 좋았다. 포장시험에서는 SS와 WS 단독 처리, DS-WS와 WS-SS 교호처리가 효과적이었다.

• Plant Biotechnology Reports
• /
• 제5권4호
• /
• pp.301-308
• /
• 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.

• 한국유기농업학회지
• /
• 제19권spc호
• /
• pp.251-254
• /
• 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
• /
• 제18권9호
• /
• pp.1578-1583
• /
• 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
• /
• 제37권4호
• /
• pp.277-285
• /
• 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
• /
• 제44권4호
• /
• pp.491-498
• /
• 2002

본 실험에서는 lactobacilli와 bifidobacteria에 의한 E. coli와 S. typhimurium에 대한 생육 억제능을 조사 하였다. 생육억제활성은 well disc assay와 turbidimetry method로 측정하여 비교하였다. 시험균주 10종 중에서 두 가지 방법 모두 평균적으로 높은 항균 활성을 나타낸 균주는 L. acidophilus La-5, L. acidophilus NCFM와 L. casei Lc-01인 것으로 나타났다. 선택된 3가지 유산균과 대표적 enteropathogen인 E. coli와 S. typhimurium을 각각의 혼합 배양하여 생균수를 측정한 결과 병원성균 생육억제는 생균수가 급격히 감소하는 배양 9시간 이후부터 나타났으며 30시간 혼합배양 후에는 병원성균의 생균수는 거의 존재하지 않았다. 실험결과 유산균의 항균활성은 pH 저하 만에 의한 것이 아니었고 유산균의 종류에 따라 생육억제활성에 차이가 있었다.

• The Plant Pathology Journal
• /
• 제36권2호
• /
• pp.133-147
• /
• 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.

• 농약과학회지
• /
• 제19권2호
• /
• pp.119-124
• /
• 2015

공주와 논산 육묘장에서 Pseudomonas syringae pv. syringae에 의한 세균점무늬병이 애호박에 심각한 피해를 주고 있지만, 점무늬병을 방제하기 위한 방제법이 개발되어 있지 않다. 종자처리와 방제약제를 선발하기 위하여 살균제 6종을 선택하여 병원균의 생장억제효과, 유묘에서 병 방제효과, 종자처리에 의한 병원균 및 병 방제효과를 각각 조사하였다. King's B배지에서 병원균 생장억제효과는 oxytetracycline 170 ppm, oxytetracycline 15 ppm + Streptomycin sulfate 188 ppm, oxolinic acid 200 ppm, streptomycin 200 ppm 처리 순으로 효과가 높게 확인되었다. Oxytetracycline 1.5% + streptomycin sulfate 18.8% WP와 oxytetracycline 17% WP의 유묘처리 시 방제가는 각각 71.4%, 49.4%이었다. Oxytetracycline 1.5% + streptomycin sulfate 18.8% WP를 인위적으로 감염된 종자에 처리하였을 때, 병원균의 생장을 완전히 억제하였으며, 유묘 발아실험에서 96% 방제효과를 나타내었다. Oxytetracycline 17% WP 2,000배 처리구에서 인위 감염 종자로부터 80 cfu/g의 병원균이 검출되었으며, 유묘발아실험에서 90%의 방제효과를 보였다. Streptomycin 20% WP의 2,000배액을 종자 처리하였을 때 병원균이 280 cfu/g으로 검출되었으며, 유묘발아실험에서 60% 방제효과를 나타내었다. 이러한 결과 oxytetracycline 1.5% + streptomycin sulfate 18.8% WP가 Pseudomonas syringae pv. syringae 에 의한 세균점무늬병의 방제와 종자처리를 위한 최적의 살균제로 판단된다.

• 한국식품과학회지
• /
• 제44권5호
• /
• pp.634-637
• /
• 2012

딸기병해는 생육기 동안 과실의 생산량감소 및 품질저하를 가져오고 있으며, 약제방제의 어려움 등으로 인해 친환경적인 병해 방제법의 개발이 요구된다. 실내에서 자외선(UV-C, 264 nm)조사에 의한 딸기병원균의 균사생장 억제효과를 구명하기 위하여 5종의 딸기병원균을 자외선을 조사하면서 $25^{\circ}C$ 항온실에서 배양한 후 균총의 직경을 측정하였다. 5종의 딸기병원균을 PDA 상에서 배양하면서 자외선을 조사하면, 하루 1시간 조사에 의해서도 생장이 억제되었고 9-12시간을 조사한 균의 생육은 현저하게 억제되었으며 역병균은 생육이 완전하게 억제되었다. 자외선광원과 병원균의 거리에서는 40-50 cm의 거리에서 자외선을 조사한 배양기에서 병원균생장의 억제효과가 크게 나타났다. 배지에 접종한 후 바로 자외선을 처리한 병원균은 모두 2일간 배양한 후 자외선을 접종한 배양기에서보다 생육이 억제되었다. 딸기 탄저병균(C. gloeosprioides)과 시들음병균(F. oxysporum)은 V8A에서 자외선에 의한 균의 생장억제효과가 큰 것으로 나타났다.