• Mycobiology
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• v.46 no.1
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• pp.52-63
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• 2018

In our previous studies, Bacillus megaterium KU143, Microbacterium testaceum KU313, and Pseudomonas protegens AS15 have been shown to be antagonistic to Aspergillus flavus in stored rice grains. In this study, the biocontrol activities of these strains were evaluated against Aspergillus candidus, Aspergillus fumigatus, Penicillium fellutanum, and Penicillium islandicum, which are predominant in stored rice grains. In vitro and in vivo antifungal activities of the bacterial strains were evaluated against the fungi on media and rice grains, respectively. The antifungal activities of the volatiles produced by the strains against fungal development and population were also tested using I-plates. In in vitro tests, the strains produced secondary metabolites capable of reducing conidial germination, germ-tube elongation, and mycelial growth of all the tested fungi. In in vivo tests, the strains significantly inhibited the fungal growth in rice grains. Additionally, in I-plate tests, strains KU143 and AS15 produced volatiles that significantly inhibited not only mycelial growth, sporulation, and conidial germination of the fungi on media but also fungal populations on rice grains. GC-MS analysis of the volatiles by strains KU143 and AS15 identified 12 and 17 compounds, respectively. Among these, the antifungal compound, 5-methyl-2-phenyl-1H-indole, was produced by strain KU143 and the antimicrobial compounds, 2-butyl 1-octanal, dimethyl disulfide, 2-isopropyl-5-methyl-1-heptanol, and 4-trifluoroacetoxyhexadecane, were produced by strain AS15. These results suggest that the tested strains producing extracellular metabolites and/or volatiles may have a broad spectrum of antifungal activities against the grain fungi. In particular, B. megaterium KU143 and P. protegens AS15 may be potential biocontrol agents against Aspergillus and Penicillium spp. during rice grain storage.

• Restorative Dentistry and Endodontics
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• v.40 no.1
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• pp.50-57
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• 2015

Objectives: The usage of medicinal plants as natural antimicrobial agents has grown in many fields including dental medicine. The aim of this in vitro study was three-fold: (i) to determine the chemical compositions of the Ferula gummosa essential oil (FGEO), (ii) to compare the antimicrobial efficacy of the oil with sodium hypochlorite (NaOCl) and chlorhexidine (CHX), (iii) to assess the toxic behavior of FGEO in different concentrations compared to 5% NaOCl and 0.2% CHX. Materials and Methods: Gas chromatography/mass spectrometry (GC/MS) was used to determine the chemical compositions of the oil. The disk diffusion method and a broth micro-dilution susceptibility assay were exploited to assess the antimicrobial efficacy against Enterococcus faecalis, Staphylococcus aureus, Streptococcus mitis, and Candida albicans. The cytocompatibility of the FGEO was assessed on L929 fibroblasts, and compared to that of NaOCl and CHX. Results: Twenty-seven constituents were recognized in FGEO. The major component of the oil was ${\beta}$-pinene (51.83%). All three irrigants significantly inhibited the growth of all examined microorganisms compared to the negative control group. FGEO at $50{\mu}g/mL$ was effective in lower concentration against Enterococcus faecalis than 5% NaOCl and 0.2% CHX, and was also more potent than 0.2% CHX against Candida albicans and Staphylococcus aureus. FGEO was a cytocompatible solution, and had significantly lower toxicity compared to 5% NaOCl and 0.2% CHX. Conclusions: FGEO showed a promising biological potency as a root canal disinfectant. More investigations are required on the effectiveness of this oil on intracanal bacterial biofilms.

• Nutrition Research and Practice
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• v.9 no.5
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• pp.466-471
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• 2015

BACKGROUND: Currently, natural products have been shown to exhibit interesting biological and pharmacological activities and are used as chemotherapeutic agents. The purpose of this study, conducted on Wistar rats, was to evaluate the beneficial effects of Artemisia arborescens oil on oestroprogestative treatment induced damage on liver. MATERIALS/METHODS: A total of 36 Wistar rats were divided into 4 groups; a control group (n = 9), a group of rats who received oestroprogestative treatment by intraperitoneal injection (n = 9), a group pre-treated with Artemisia arborescens then injected with oestroprogestative treatment (n = 9), and a group pre-treated with Artemisia arborescens (n = 9). To minimize the handling stress, animals from each group were sacrificed rapidly by decapitation. Blood serum was obtained by centrifugation and the livers were removed, cleaned of fat, and stored at $-80^{\circ}C$ until use. RESULTS: In the current study, oestroprogestative poisoning resulted in oxidative stress, which was demonstrated by 1) a significant increase of lipid peroxidation level in hepatic tissue 2) increased levels of serum transaminases (aspartate amino transferase and serum alanine amino transferase), alkaline phosphatase, glycemia and triglycerides and a decrease in the level of cholesterol 3) alteration of hepatic architecture. Pre-administration of Artemisia arborescens oil was found to alleviate oestroprogestative treatment induced damage by lowering lipid peroxidation level and by increasing activity of catalase, superoxide-dismutase, and glutathione-peroxidase in liver and by reducing disruption of biochemical parameters. CONCLUSION: Therefore, the results obtained in this study confirmed that Artemisia essential oil protects against oestroprogestative administration induced hepatotoxicity by restoration of liver activities.

• Microbiology and Biotechnology Letters
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• v.48 no.4
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• pp.471-479
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• 2020

The aim of this study was to investigate the anti-oxidant and anti-inflammatory activities of the Rhododendron weyrichii flower extract fermented using Shindari, a traditional Jeju barley Nuruk-based fermentation. In this study, we examined the antioxidant potential of R. weyrichii flower extracts (RF) and R. weyrichii flower extracts fermented with Nuruk or Shindari (RFFN or RFFS, respectively) using various in vitro antioxidant assays including DPPH and ABTS radical scavenging assays, total phenol content and FRAP assays. We also evaluated the anti-inflammatory activity of the RF and RFFS on murine RAW 264.7 cells. The anti-inflammatory activity was evaluated by treating the RAW 264.7 cells with various concentrations (6.25, 12.5, 25, and 50 ㎍/ml) of RF or RFFS. As a result, we observed that the ABTS radical scavenging activity and total phenol content of RFFS was higher than that of RF and RFFN. Additionally, lipopolysaccharide-induced nitric oxide (NO) production was significantly lower in RFFS-treated cells when compared to the LPS-treated control. In addition, RFFS-treated cells exhibited decreased expression of inducible NO synthase (iNOS) proteins and high-performance liquid chromatography (HPLC) fingerprinting showed that both the quercetin and quercetin glucoside (quercitrin and isoquercitrin) levels were affected by the fermentation process. In conclusion, our data suggests that traditional fermentation could be an important strategy in improving the biological properties of raw materials including their antioxidant and anti-inflammatory activities. Finally, RFFS may be a candidate for developing topical antioxidant and anti-inflammatory agents.

• The Plant Pathology Journal
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• v.39 no.4
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• pp.397-408
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• 2023

Fire blight disease, caused by Erwinia amylovora, is a devastating affliction in apple cultivation worldwide. Chemical pesticides have exhibited limited effectiveness in controlling the disease, and biological control options for treating fruit trees are limited. Therefore, a relatively large-scale survey is necessary to develop microbial agents for apple trees. Here we collected healthy apple trees from across the country to identify common and core bacterial taxa. We analyzed the endophytic bacterial communities in leaves and twigs and discovered that the twig bacterial communities were more conserved than those in the leaves, regardless of the origin of the sample. This finding indicates that specific endophytic taxa are consistently present in healthy apple trees and may be involved in vital functions such as disease prevention and growth. Furthermore, we compared the community metabolite pathway expression rates of these endophyte communities with those of E. amylovora infected apple trees and discovered that the endophyte communities in healthy apple trees not only had similar community structures but also similar metabolite pathway expression rates. Additionally, Pseudomonas and Methylobacterium-Methylorobrum were the dominant taxa in all healthy apple trees. Our findings provide valuable insights into the potential roles of endophytes in healthy apple trees and inform the development of strategies for enhancing apple growth and resilience. Moreover, the similarity in cluster structure and pathway analysis between healthy orchards was mutually reinforcing, demonstrating the power of microbiome analysis as a tool for identifying factors that contribute to plant health.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.88-88
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• 2022

Detection of stress responses in crops is important to diagnose crop growth and evaluate yield. Also, the multi-spectral sensor is effectively known to evaluate stress caused by nutrient and moisture in crops or biological agents such as weeds or diseases. Therefore, in this experiment, multispectral images were taken by an unmanned aerial vehicle(UAV) under field condition. The experiment was conducted in the long-term fertilizer field in the National Institute of Crop Science, and experiment area was divided into different status of NPK(Control, N-deficiency, P-deficiency, K-deficiency, Non-fertilizer). Total 11 vegetation indices were created with RGB and NIR reflectance values using python. Variations in nutrient content in plants affect the amount of light reflected or absorbed for each wavelength band. Therefore, the objective of this experiment was to evaluate vegetation indices derived from multispectral reflectance data as input into machine learning algorithm for the classification of nutritional deficiency in rice. RandomForest model was used as a representative ensemble model, and parameters were adjusted through hyperparameter tuning such as RandomSearchCV. As a result, training accuracy was 0.95 and test accuracy was 0.80, and IPCA, NDRE, and EVI were included in the top three indices for feature importance. Also, precision, recall, and f1-score, which are indicators for evaluating the performance of the classification model, showed a distribution of 0.7-0.9 for each class.

• Journal of the Korean Electrochemical Society
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• v.27 no.3
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• pp.81-87
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• 2024

Nanomaterial electrodes are used to improve the analytical performances of electrochemical measurements in biological and chemical field. Frequently used methods for fabricating metal nanostructures are solution processing and electrodeposition. In the solution process, it is possible to control the characteristics (e.g., direction) of metal growth by using capping agents, thereby fabricating nanoparticles of specific structures. In the electrodeposition, the electrode surface and the deposited metal atoms are in direct contact. Each process has its own limitation as well, and many studies are conducted to overcome such limitation. In this paper, we report an integration of the two fabrication methods and the characteristics, such as structural and electrochemical properties, of the fabricated electrodes. Lastly, we discuss the possibility of using the fabricated nanostructured electrode as a sensor.

• Korean journal of applied entomology
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• v.48 no.2
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• pp.253-261
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• 2009

For the environment-friendly control of beet armyworm, Spodoptera exigua, in spring onion fields, we have examined an alternative application method. Twenty-five insecticides registered for spring onion were tested for control effect against the beet armyworm in the laboratory, then the best 9 chemical and a single biological insecticides were selected and compared with 2 new isolates of Bacillus thuringiensis in a polyvinyl house. After that, 4 chemical and 3 B. thuringiensis treatments were used in the field for the control of beet armyworm in the spring onion. Two application methods are used: one is triple treatments with the same chemical and the other is alternative application with different chemicals and B. thuringiensis for 7 days intervals. Indoxacarb WP - chlorfluazuron EC - B.t. var. kurstaki CAB141 and indoxacarb WP - methoxyfenozide + spinosad SC - Chlorfluazuron EC - B.t. var. aizawai CAB109, B.t. var. kurstaki CAB141 showed greater than 78% mortality of beet armyworm larvae and greater than 43% damage decrease in spring onions infested by beet armyworm. These results showed that alternative applications had higher control effect than any other applications. It was suggested that alternative applications with microbial biological agents such as B. thuringiensis might minimize the development of insecticide resistance and might be used as the environment-friendly control of the beet armyworm.

• Journal of Life Science
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• v.28 no.2
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• pp.216-222
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• 2018

Desmodium heterocarpon is one of vines belongs to Fabaceae family, mainly distributed in Asian countries such as Korea and Japan. This study was conducted to explore new nutraceutical resources from the plant kingdom possessing biological activities. To fulfill this purpose, the anti-oxidative and anti-inflammatory activities of D. heterocarpon ethanol extract (DHEE) were evaluated by 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity assay, reactive oxygen species (ROS) scavenging activity assay, nitric oxide (NO) inhibitory activity assay, and the analysis of related protein expressions by Western blot hybridization. DHEE exhibited potent anti-oxidative activity as confirmed by DPPH radical scavenging capacity against DPPH similar with ascorbic acid, a well-known anti-oxidative agent, used as a positive control. DHEE also effectively suppressed hydrogen peroxide ($H_2O_2$)-induced ROS on RAW 264.7 murine macrophage cells. Furthermore, DHEE induced the expression of the anti-oxidative enzyme heme oxygenase 1 (HO-1), and its upstream transcription factor, nuclear factor-E2-related factor 2 (Nrf2) as a dose dependent manner. DHEE inhibited lipopolysaccharide (LPS) induced nitric oxide (NO) formation as a consequence of inducible NO synthase (iNOS) down regulation. Taken together, these results suggest that DHEE has anti-oxidative and anti-inflammatory activities and thus appears to be useful sources as potential anti-oxidant and anti-inflammatory agents. The identification of active compounds that confer biological activities of DHEE might be needed.

• Microbiology and Biotechnology Letters
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• v.48 no.1
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• pp.38-47
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• 2020

This study was conducted to investigate both plant growth-promoting and plant disease- controlling activities of bacterial strains isolated from soil. All the isolated strains were able to grow at various temperatures. All the strains, except ANG40, showed antagonistic effects against various phytopathogenic fungi. This antagonism can be ascribed to the production of siderophores and antibiotic substances. In addition, all the strains showed abilities such as nitrogen fixation, phosphate solubilization, and siderophore production. These results suggest that nitrogen, phosphorus, and iron can be converted into forms that can be easily absorbed by the plants for their growth. Analysis of the growth-promoting properties revealed that ANG51 produced 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase and indole-3-acetic acid (IAA) both of which are related to ethylene production. In contrast, the other strains were found to have only IAA-producing ability. Therefore, this study suggests that Pseudomonas geniculata ANG3, Exiguobacterium acetylicum ANG40, and Burkholderia stabilis ANG51, which were selected through analysis of comparative advantages for both plant growth promotion and disease-controlling activity, may be used as biological agents.