• 식물병연구
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• 제27권3호
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• pp.99-106
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• 2021

The fungal isolate Isaria javanica pf185 has potential as a mycopesticide because it demonstrates insecticidal activity against the green peach aphid and antifungal activity against Colletotrichum gloeosporioides. For commercialization of this isolate, determination of the optimal and least expensive culture conditions is required; however, these data are not currently available. This study describes the conditions for optimal development of conidia and production of metabolites for the biocontrol of the fungal pathogen. The optimal culture conditions were examined using cultures on solid agar and liquid media. High growth temperature enhanced spore formation but reduced antifungal activity in both solid and liquid media. The highest spore yield was obtained in a medium containing glucose as a carbon source and yeast extract as a nitrogen source. Soybean powder and wheat bran were effective nitrogen sources that promoted spore production and antifungal activity of the isolate. These results revealed the basic, cost-effective growth media for commercial production of a biopesticide with insecticidal and antifungal properties for use in integrated pest management.

• 한국환경농학회지
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• 제34권3호
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• pp.217-222
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• 2015

BACKGROUND: Garlic (Allium sativum) contains polyphenols and sulfur compounds that are recognized as antioxidant, antithrombotic, anticancer, antibacterial, antimicrobial, nematicidal, and insecticidal activity. For this reason, the Environmentally-friendly Agriculture Promotion Act allowed the garlic extract as commercial biopesticide material for crop protection, nine commercial biopesticides containing A. sativum extract have been marketed in Korea. METHODS AND RESULTS: The determination of allylmethyl sulfide (AMS), dimethyl disulfide (DMDS), and dipropyl sulfide (DPS) in biopesticides containing A. sativum extract was developed and validated by gas chromatography (GC) mass spectrometry (MS) with head-space sampler. The developed method was validated, and the limit of quantification (LOQ) and recovery rates of AMS, DMDS, and DPS were 0.08, 0.32, and 0.09 mg/L and 90.3-91.3, 86.2-88.3, and 87.6-89.5%, respectively. From the nine commercial biopesticide samples, contents of AMS, DMDS, and DPS were analyzed using the developed method and results showed

• 한국약용작물학회지
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• 제28권1호
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• pp.38-46
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• 2020

Background: Although Sancho (Zanthoxylum schinifolium Siebold & Zucc) oil has traditionally been used for its antibiotics properties, there is currently a lack of scientific evidence regarding its biological activities. In this study, we investigated the antimicrobial and antioxidant activities of Sancho oil against food-hazardous microorganisms, phytopathogens, and dermatophytes. Methods and Results: We investiated the antimicrobial activity of Sancho oil against 11 food-hazardous microorganisms, nine phytopathogens, and six dermatophytes. The Sancho oil was found to show the strongest antibacterial activity against Shigella flexneri and Listeria spp. Sancho oil also showed high antifungal activity against plant pathogens, particularly Fusarium oxysporum, and showed antimicrobial activity against dermatophytes such as Trichophyton rubrum, Microsporum canis and Candida albicans. The antioxidant activity of Sancho oil was measured using the DPPH method, and was found to be stronger than that of unrefined oil. Moreover, this activity increased with increasing oil concentration. Conclusions: We found that Sancho oil showed differing antimicrobial activities against food-hazardous microorganisms, dermatophytes, and plant pathogens. The antimicrobial activity spectrum of Sancho oil was not broad and varied among microbial strains. On the basis of our findings, we consider that Sancho oil could be used an antibacterial material for food-borne S. flexneri and Listeria spp., a biopesticide for Fusarium spp., and a treatment for dermatophytes such as T. rubrum.

• Journal of Microbiology and Biotechnology
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• 제27권4호
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• pp.731-738
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• 2017

A novel approach to synthesize silver nanoparticles (AgNPs) using leaf extract of Canna edulis Ker-Gawl. (CELE) under ambient conditions is reported here. The as-prepared AgNPs were analyzed by UV-visible spectroscopy, transmission emission microscopy, X-ray diffraction, Fourier transform-infrared spectroscopy, energy-dispersive analysis of X-ray spectroscopy, zeta potential, and dynamic light scattering. The AgNPs showed excellent antimicrobial activity against various pathogens, including bacteria and various fungi. The biocompatibility of the AgNPs was analyzed in the L929 cell line using NRU and MTT assays. Acridine orange/ethidium bromide staining was used to determine whether the AgNPs had necrotic or apoptotic effects on L929 cells. The concentration of AgNPs required for 50% inhibition of growth of mammalian cells is far more than that required for inhibition of pathogenic microorganisms. Thus, CELE is a candidate for the eco-friendly, clean, cost-effective, and nontoxic synthesis of AgNPs.

• 한국환경농학회지
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• 제37권2호
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• pp.125-134
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• 2018

BACKGROUND: Green peach aphid (Myzus persicae) is an insect pest that significantly affects crop production. A number of pesticides have been used for aphid control, but their concerns on insect resistance and food safety have required alternative methods for pest management. In an effort to find for an alternative approach to aphid control, we screened plants extracts and examined their potentiality as insecticidal bio-resources. METHODS AND RESULTS: Two hundred and ninety eight plant extracts were examined for insecticidal activity against the aphid, and the best candidate among them was chosen for further study. The extracts from Cinnamomum camphora was determined to be the best candidate exhibiting insecticidal activity more than 60% at a level of $1,000{\mu}g/mL$. GC/MS analyses detected camphor, borneol, 4-terpineol, ${\alpha}$-terpineol and caryophyllene oxide as major compositions from the extracts obtained by hydrodistillation. Caryophyllene oxide exhibited the highest insecticidal activity with a $LC_{50}$ value of $237{\mu}g/mL$. Camphor lowered significantly the $LC_{50}$ value of caryophyllene oxide and increased largely its concentration in aphid, suggesting that camphor played a role in enhancing the insecticidal activity of caryophyllene oxide. CONCLUSION: This study suggested that camphor and caryophyllene oxide may be used as an insecticidal bio-resource for insect control against green peach aphid.

• Journal of Microbiology and Biotechnology
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• 제22권1호
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• pp.69-79
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• 2012

In an ongoing survey of the bioactive potential of microorganisms from Ladakh, India, the culture medium of a bacterial strain of a new Pseudomonas sp., strain ICTB-745, isolated from an alkaline soil sample collected from Leh, Ladakh, India, was found to contain metabolites that exhibited broad-spectrum antimicrobial and biosurfactant activities. Bioactivity-guided purification resulted in the isolation of four bioactive compounds. Their chemical structures were elucidated by $^1H$ and $^{13}C$ NMR, 2D-NMR (HMBC, HSQC, $^1H$,$^1H$-COSY, and DEPT-135), FT-IR, and mass spectroscopic methods, and were identified as 1-hydroxyphenazine, phenazine-1-carboxylic acid (PCA), rhamnolipid-1 (RL-1), and rhamnolipid-2 (RL-2). These metabolites exhibited various biological activities like antimicrobial and efficient cytotoxic potencies against different human tumor cell lines such as HeLa, HepG2, A549, and MDA MB 231. RL-1 and RL-2 exhibited a dose-dependent antifeedant activity against Spodoptera litura, producing about 82.06% and 73.66% antifeedant activity, whereas PCA showed a moderate antifeedant activity (63.67%) at 60 ${\mu}g/cm^2$ area of castor leaf. Furthermore, PCA, RL-1, and RL-2 exhibited about 65%, 52%, and 47% mortality, respectively, against Rhyzopertha dominica at 20 ${\mu}g/ml$. This is the first report of rhamnolipids as antifeedant metabolites against Spodoptera litura and as insecticidal metabolites against Rhyzopertha dominica. The metabolites from Pseudomonas sp. strain ICTB-745 have interesting potential for use as a biopesticide in pest control programs.

• 농약과학회지
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• 제5권3호
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• pp.50-53
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• 2001

최근 우리나라의 여러 작물에서 뿌리혹병(근두암수병(根頭癌睡病), crown gall)의 발생이 증가하고 있음이 보고되고 있으며, 특히 중요한 화훼작물인 장미를 재배하는 시설하우스에서 뿌리혹병의 발생은 매우 심한 피해를 가져오고 있다. 그럼에도 불구하고 이 병에 대한 방제는 거의 이루어지지 않고 있는 실정이다. 본 연구에서는 전 세계적으로 매우 성공적으로 뿌리혹병의 생물농약으로 개발된 Agrobacterium radiobacter K84의 장미 뿌리혹병 방제효과를 검정하여 국내에서 장미 뿌리혹병의 방제에 그 사용가능성을 확인하고자 하였다. 장마의 지상부에 인위적인 상처를 주고 병원균을 접종하기 전에 그리고 접종 후 A. radiobacter K84 균주 현탁액의 살포는 뿌리흑병의 발병률과 혹의 크기를 크게 감소시켰다. K84 균주를 처리한 장미에서 뿌리혹병의 발병률은 $5.0{\sim}6.7%$로서 병원균을 단독 접종한 대조구에서의 발병률 85%에 비하여 크게 낮았다. K84 균주를 처리한 장미에서 형성된 혹의 크기와 생체중도 병원균만을 접종한 대조구 장미에 형성된 혹의 $4{\sim}5%$로서 K84 균주의 처리에 의해 크게 감소하였다. 장미의 뿌리에 인위적인 상처를 주고 병원균의 접종 전 및 후에 K84 현탁액에 침지 처리한 경우에도 혹의 크기, 생체중 그리고 병 발생률이 크게 감소하였다. 전체적으로 K84 균주 치리에 의한 지상부 혹의 생물적방제가는 $92{\sim}94%$이었고, 뿌리에서의 뿌리혹병 생물적방제가는 $51{\sim}59%$이었다. 이상의 결과는 A. radiobacter K84 균주의 처리가 매우 효과적으로 장미 뿌리혹병을 방제할 수 있음을 보여주고 있다.

• 생명과학회지
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• 제17권5호
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• pp.658-663
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• 2007

B. thuringiensis는 많은 해로운 곤충들을 박멸시키는데 널리 사용되는 생물학적 살충제로 잘 알려져 있다. 그것은 측포자 형태의 결정체($\delta$-내독소)를 생산하고 내생포자들을 형성한다. 본 논문에서는 B. thuringiensis BT-1과 BT-2에 의해 생산되는 내독소의 특성을 주사전자현미경(SEM), 투과전자현미경(TEM), SDS-PACE, 알칼리 용액에서의 용해 활성을 통하여 규명하였다. BT-1, BT-2 균주는 GBY 배지에서 배양되었고, 두 균주의 내독소는 당밀도구배법을 이용하여 정제되어, 주사전자현미경(SEM), 투과전자현미경(TEM)으로 관찰하였다. 형태학적으로, BT-1의 내독소는 사각형 및 납작형이고 크기는 $1.73{\mu}m{\times}0.7{\mu}m$, 그리고 BT-2 내독소는 구형이며 $1.1{\mu}m$, 폭이 $0.9{\mu}m$인 것으로 밝혀졌다. SDS-PACE 방법으로 분석한 결과, BT-1의 분자량은 28 kDa, 21 kDa, 반면에 BT-2의 분자량은 50 kDa, 35 kDa, 22 kDal으로 밴드가 형성되었다. 이들의 결정체는 알칼리 완충용액 내에서 시간에 지나감에 따라서 점차로 용해되었으며 3시간 후에는 거의 완전하게 용해되었다. 이 결과들을 통하여 BT1과 BT-2 결정체의 내독소가 곤충의 중장 내에서 시간이 흐름에 따라 비활성 상태에서 활성상태로 전환되는 것으로 보여진다.

• Journal of Microbiology and Biotechnology
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• 제13권1호
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• pp.50-56
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• 2003

A freshwater bloom-forming cyanobacterium, Microcystis aeruginosa, and local soil isolate Scytonema sp. strain BT 23 were demonstrated to contain biotoxic secondary metabolites with pesticidal and mosquito larvicidal activities. A purified toxic constituent from M aeruginosa showed an absorption maximum at 230 nm and its toxicity symptoms, Rf value on TLC, and retention time observed ill an HPLC analysis were similar to those of the hepatotoxic heptapeptide microcystin-LR. The bioactive constituent of the Scytonema sp. was less polar in nature and exhibited two peaks at 240 and 285 m. When applied to two cruciffrous pests, Pieris brassicae and Plutella flostella, the crude extracts and toxic principles from the two cyanobacteria showed significant antifeedant activity in a no-choice bioassay, and at higher concenuations exhibited contact toxicity to the insect larvae. The purified toxin from M. aeruginosa was found to be more effective and produced 97.5 and $92.8\%$ larval mortality in the two pests, fo11owing 2 h of toxin treatment at a concentration of $25{\mu}g$ Per leaf disc (2.5 cm dia.). Meanwhile, similar treatment with the purified toxin from Sytonema sp. stain BT 23 only produced 73 and $78\%$ mortality in the two pests. The cyanobacterial constituents also showed significant activity against Culex and Anopheles larvae. The M. aeruginosa toxin ($20{\mu}g\;ml^-1$) caused 98.2 and $88.1\%$ mortality in the Culex and Anopheles larvae, respectively, while the purified toxin from the Sytonema sp. was less toxic and only produced a 96.3 and $91.2\%$ mortality, respectively, at a much higher concentration ($40{\mu}g\;ml^-1$). Accordingly, the current results point to certain hitherto unknown biological properties of cyanobacterial biotoxins.

• 한국환경농학회지
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• 제36권1호
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• pp.36-42
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• 2017

BACKGROUND: Yuza seed by-product has been produced in a large amount from the agricultural farms in the southern area of Korea. It has been mostly abandoned after commercial process for the production of juice, jam and tea. The study on the reuse of the yuza seed by-product has received much attention as a bio-resource material for the production of active compound in agriculture. METHODS AND RESULTS: Insecticidal rhamnolipid-producing Pseudomonas sp. EP-3 was grown in mineral salt media with the yuza seed by-product at 2, 20, 50 and 100 g/L. The growth of EP-3 was accompanied by a increase in insecticidal activity against green peach aphid. The highest insecticidal activity was observed when EP-3 was grown in the medium containing 50 g/L of the seed sample, producing approximately 996 mg/L of rhamnolipid at 96 h. Palmitic acid, stearic acid, oleic acid and linoleic acid were determined as the major fatty acids of the seed sample. The EP-3 cultures grown on the fatty acid mixture extracted from the seed sample showed a aphid mortality similar to that of cultures grown on the seed sample. The EP-3 cultures grown on 50 g/L of the seed sample showed aphid mortality more than 90% under greenhouse conditions. CONCLUSION: This study suggested that the yuza seed by-product may be used as a renewable material for microbial production of rhamnolipid against green peach aphid.