• 한국응용곤충학회지
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• 제32권3호
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• pp.330-337
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• 1993

벼멸구에 강한 병원성이 있는 Serratia marcescens, biotype A2a를 분리, 동정하였다. 벼 유묘에 분무한 후 성충-계절풍을 따라 비래하는 형태-을 공시하고 병원성을 조사하여 3~5일 만에 강한 살충력을 발견하였다. 따라서, 본 세균의 곤충병원성 관련 형질 탐색을 하기 위하여 Tn5로써 돌연변이를 시도한 후, Chitinase, Protease, DNase indicator media에서 돌연변이 계통을 분리하였다. 이들을 공시충에 병원성을 검정한 결과 Pro-Strain중에서 병원력이 현저히 떨어지는 현상을 관찰하였다. 공시충을 전자현미경(SEM, TEM)으로 관찰하여, abdomen의 전장부위와 표피사이에 다수의 세균이 증식하였음을 발견하였다. 곤충복부표피조직 중 cuticle층은 intact한 상태였다. 따라서, 이에 관련된 유전자를 분리하기 위해 genomic library 실험을 진행하고 있다.

• Journal of Microbiology and Biotechnology
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• 제24권1호
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• pp.1-7
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• 2014

The possibility of using hyphomycete fungi as suitable biocontrol agents against greenhouse whitefly has led to the isolation of various insect pathogenic fungi. Among them is Beauveria bassiana, one of the most studied entomopathogenic fungi. The objective of this study was to use B. bassiana M130 as an insecticidal agent against the greenhouse whitefly. M130 isolated from infected insects is known to be a biocontrol agent against greenhouse whitefly. Phylogenetic classification of M130 was determined according to its morphological features and 18S rRNA sequence analysis. M130 was identified as B. bassiana M130 and showed chitinase (342.28 units/ml) and protease (461.70 units/ml) activities, which were involved in the invasion of the host through the outer cuticle layer, thus killing them. The insecticidal activity was 55.2% in petri-dish test, 84.6% in pot test, and 45.3% in field test. The results of this study indicate that B. bassiana has potential as a biological agent for the control of greenhouse whitefly to replace chemical pesticides.

• 한국유기농업학회지
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• 제30권3호
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• pp.393-407
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• 2022

본 논문에서는 Neobacillus sp. JC05의 추출물을 처리한 오이 식물체에서 고구마뿌리혹선충 감염에 대한 식물의 방어 반응을 조사하였다. Neobacillus sp. JC05의 추출물을 처리한 오이 식물체에서는 고구마뿌리혹선충에 의한 감염이 감소하여 control에 비하여 병 발생이 감소하였으며, 식물이 받는 피해도 줄어들었다. 이때 Neobacillus sp. JC05 추출물을 처리한 오이 식물체의 병 저항성 유전자의 발현량을 관찰한 결과, chitinase와 lipoxygenase 유전자의 발현량이 상대적으로 증가하였으며, 식물체 내 산화 스트레스를 감소시키는 항산화효소 중 peroxidase의 활성이 현저히 증가하는 것을 관찰하였다. 또한, Neobacillus sp. JC05 추출물을 처리한 오이 식물체의 토양 FDase 활성이 증가하였으며, 반면 인산가용화효소와 유레아제 활성은 control에 비해 유의하지 않았다. 그러므로, 이전의 연구 결과와 종합하면, Neobacillus sp. JC05의 추출물은 직접적으로 고구마뿌리혹선충의 알 부화율을 억제하고 유충의 사멸률을 높여 토양 내 고구마뿌리혹선충의 밀도를 감소시키기도 하지만 본 연구의 결과에 따르면, 오이 식물체의 고구마뿌리혹선충에 대한 방어 반응을 증가시켜 저항성을 유도하며, 이를 통해 고구마뿌리혹선충병 발생을 감소시키는데 기여하는 것으로 사료된다.

• 한국해양생명과학회지
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• 제8권1호
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• pp.56-67
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• 2023

Marine macroalgae are important in coastal ecosystems and interact with marine microorganisms. In this study, we isolated fungi from seven types of marine macroalgae including Cladophora sp., Gloiopeltis furcate, Gracilariopsis chorda, Hydroclathrus clathratus, Prionitis crispata, Sargassum micracanthum, and Ulva lactuca collected in Korea. Morphological and phylogenetic analyses identified the isolates as four Aspergillus spp. (A. fumigatus, A. sydowii, A. tamarii, and A. terreus), three Penicillium spp. (P. crustosum, P. jejuense, and P. rubens), and Cladosporium tenuissimum. Among them, A. fumigatus TOP-U2, A. tamarii SH-Sw5, and A. terreus GJ-Gf2 strains showed the activities of all enzymes examined (amylase, chitinase, lipase, and protease). Based on the enzymatic index (EI) values in solid media, A. terreus GJ-Gf2 and C. tenuissimum UL-Pr1 exhibited the highest amylase and lipase activities, respectively. Chitinolytic activity was only observed in A. terreus GJ-Gf2, A. tamarii SH-Sw5, and A. fumigatus TOP-U2. Penicillium crustosum UL-Cl2 and C. tenuissimum UL-Pr1 showed the highest protease activities. To the best of our knowledge, this is the first report of lipolytic and proteolytic activities in a marine-derived C. tenuissimum strain. Overall, the fungal strains isolated from the marine macroalgae in this study actively produced industrially important enzymes.

• 대한약침학회지
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• 제26권4호
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• pp.307-318
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• 2023

Objectives: Bacterial biofilm is regarded as a significant threat to the production of safe food and the arise of antibiotic-resistant bacteria. The objective of this investigation is to evaluate the quorum sensing inhibitory effect of Nepeta curviflora methanolic extract. Methods: The effectiveness of the leaves at sub-inhibitory concentrations of 2.5, 1.25, and 0.6 mg/mL on the virulence factors and biofilm formation of P. aeruginosa was evaluated. The effect of N. curviflora methanolic extract on the virulence factors of P. aeruginosa, including pyocyanin, rhamnolipid, protease, and chitinase, was evaluated. Other tests including the crystal violet assay, scanning electron microscopy (SEM), swarming motility, aggregation ability, hydrophobicity and exopolysaccharide production were conducted to assess the effect of the extract on the formation of biofilm. Insight into the mode of antiquorum sensing action was evaluated by examining the effect of the extract on the activity of N-Acyl homoserine lactone (AHL) and the expression of pslA and pelA genes. Results: The results showed a significant attenuation in the production of pyocyanin and rhamnolipid and in the activities of protease and chitinase enzymes at 2.5 and 1.25 mg/mL. In addition, N. curviflora methanolic extract significantly inhibited the formation of P. aeruginosa biofilm by decreasing aggregation, hydrophobicity, and swarming motility as well as the production of exopolysaccharide (EPS). A significant reduction in AHL secretion and pslA gene expression was observed, indicating that the extract inhibited quorum sensing by disrupting the quorum-sensing systems. The quorum-sensing inhibitory effect of N. curviflora extract appears to be attributed to the presence of kaempferol, quercetin, salicylic acid, rutin, and rosmarinic acid, as indicated by LCMS analysis. Conclusion: The results of the present study provide insight into the potential of developing anti-quorum sensing agents using the extract and the identified compounds to treat infections resulting from quorum sensing-mediated bacterial pathogenesis.

• IMMUNE NETWORK
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• 제21권3호
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• pp.22.1-22.17
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• 2021

Chitinase-3-like-1 (CHI3L1) is known to induce inflammation in the progression of allergic diseases. Previous our studies revealed that 2-({3-[2-(1-cyclohexen-1-yl)ethyl]-6,7-dimethoxy-4-oxo-3,4-dihydro-2-quinazolinyl}sulfanyl)-N-(4-ethylphenyl)butanamide (K284-6111; K284), the CHI3L1 inhibiting compound, has the anti-inflammatory effect on neuroinflammation. In this study, we investigated that K284 treatment could inhibit the development of atopic dermatitis (AD). To identify the effect of K284, we used phthalic anhydride (5% PA)-induced AD animal model and in vitro reconstructed human skin model. We analyzed the expression of AD-related cytokine mediators and NF-κB signaling by Western blotting, ELISA and quantitative real-time PCR. Histological analysis showed that K284 treatment suppressed PA-induced epidermal thickening and infiltration of mast cells. K284 treatment also reduced PA-induced release of inflammatory cytokines. In addition, K284 treatment inhibited the expression of NF-κB activity in PA-treated skin tissues and TNF-α and IFN-γ-treated HaCaT cells. Protein-association network analysis indicated that CHI3L1 is associated with lactoferrin (LTF). LTF was elevated in PA-treated skin tissues and TNF-α and IFN-γ-induced HaCaT cells. However, this expression was reduced by K284 treatment. Knockdown of LTF decreased the expression of inflammatory cytokines in TNF-α and IFN-γ-induced HaCaT cells. Moreover, anti-LTF antibody treatment alleviated AD development in PA-induced AD model. Our data demonstrate that CHI3L1 targeting K284 reduces AD-like skin inflammation and K284 could be a promising therapeutic agent for AD by inhibition of LTF expression.

• The Plant Pathology Journal
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• 제28권3호
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• pp.282-289
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• 2012

The root rot of pepper (Capsicum annuum L.) caused by Phytophthora capsici is one of the most important diseases affecting this crop worldwide. This work presents the evaluation of the capacity of Streptomyces griseus H7602 to protect pepper plants against Phytophthora capsici and establishes its role as a biocontrol agent. In this study, we isolated an actinomycete strain H7602 from rhizosphere soil, identified it as Streptomyces griseus by 16S rRNA analysis and demonstrated its antifungal activity against various plant pathogens including P. capsici. H7602 produced lytic emzymes such as chitinase, ${\beta}$-1,3-glucanase, lipase and protease. In addition, crude extract from H7602 also exhibited destructive activity toward P. capsici hyphae. In the pot trial, results showed the protective effect of H7602 against pepper from P. capsici. Application of H7602 culture suspension reduced 47.35% of root mortality and enhanced growth of pepper plants for 56.37% in fresh root and 17.56% g in fresh shoot as compared to control, resulting in greater protection to pepper plants against P. capsici infestation. Additionally, the enzymatic activities, chitinase and ${\beta}$-1,3-glucanase, were higher in rhizosphere soil and roots of pepper plants treated with H7602 than other treated plants. Therefore, our results indicated a clear potential of S. griseus H7602 to be used for biocontrol of root rot disease caused by P. capsici in pepper.

• 미생물학회지
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• 제52권4호
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• pp.437-443
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• 2016

여러 토양에서 분리한 400여 개의 방선균 균주에 대해 4가지 식물병원성 진균에 대한 항진균 활성을 조사하였으며 그 중 Streptomyces costaricanus HR391 균주는 PDB 배지에서 식물병원성 진균인 Fusarium oxysporum f. sp. raphani, F. oxysporum f. sp. niveum, F. oxysporum f. sp. lycopersici와 Rhizoctonia solani의 균사 생장을대조군과 비교하여 각각 26.5, 26.2, 21.2와 23.8% 저해하였다. S. costaricanus HR391은 항진균물질인 siderophore를 $98{\mu}M$을 생성할 뿐만 아니라 유화활성을 나타내며 막지질을 파괴할 수 있는 생물계면활성제인 rhamnolipid와 lipopeptide인 iturin A와 surfactin를 생성하였다. 또한 진균 세포막을 분해할 수 있는 chitinase와 glucanase 활성도 나타내었으며 병원균의 막을 파괴하는 AMP와 항생물질 phenazine도 분비하였다. 이외에도 식물생장 촉진활성을 갖는 zeatin, gibberellin과 indole acetic acid 같은 식물호르몬도 생성하였다. 이와 같이 항진균 활성을 나타내는 S. costaricanus HR391 균주는 다양한 종류의 항진균 물질의 상승작용과 더불어 높은 생물계면활성이 본 균주의 항진균 활성에 큰 역할을 하는 것으로 보이며 친환경적인 생물학적 항진균제로서 활용이 가능할 것으로 기대된다.

• Journal of Microbiology and Biotechnology
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• 제18권4호
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• pp.784-787
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• 2008

Antifungal activity of ChiCW and synergistic interactions between ChiCW with fungicides were investigated. Conidial germinations of phytopathogenic fungi, Alternaria brassicicola, Botrytis elliptica, and Colletotrichum gloeosporioides, were inhibited by ChiCW but A. longipes was not. In addition, ChiCW showed synergistic effect with fungicides Switch (cyprodinil+fludioxonil) and tebuconazole to inhibit fungal conidial germinations. The level of synergism of ChiCW with tebuconazole was higher than that with Switch. The results indicate that ChiCW may exhibit a higher level of synergism with fungicides that have a primary effect upon membranes.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
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• pp.64.1-64
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• 2003

Inoculation of primary pepper leaves with an avirulent strain of Xanthomonas campestris pv. vesicatoria induced systemic acquired resistance (SAR) in secondary leaves. This SAR response was accompanied by the systemic expression of defense-related genes, a systemic microoxidative burst generating H2O2, and the systemic induction of ion-leakage and callose deposition in the non-inoculated, secondary leaves. Some defense-related genes encoding PR-1, chitinase, peroxidase, PR10, thionin, defensin and zinc-finger protein were distiilctly induced in the systemic leaves. The systemically striking accumulation of H$_2$O$_2$and strong increase in peroxidase activity in pepper was suggested to contribute to the triggering of cell death In the systemic micro-HRs, leading to the induction of SAR. Treatment of non-inoculated, secondary leaves with diphenylene iodinium (DPI), an inhibitor of the oxidative burst, substantially reduced the induction of some defense-related genes and subsequently SAR.