• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.94.2-95
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• 2003

E. intermedium 60-2G possessing a strong ability to solubilize insoluble phosphate, has plant growth-promoting activity, induced systemic resistance activity against scab pathogen in cucumber, and antifungal activity against various phytopathogenic fungi. The phosphate solubilizing activity of 60-2G may be mainly accomplished by production of gluconic acid through a direct extracellular oxidation of glucose by glucose dehydrogenase that required a PQQ cofactor for its activation. A pqq gene cluster conferred Phosphate-solubilizing activity in E. coli DH5${\alpha}$ was cloned and sequenced. The 6,783 bP pqq sequence had six open reading frames (from A to F) and showed 50-95％ homology to pqq genes from other bacteria. The E. coli strain expressing the pqq genes solubilized phosphate from hydroxyapatite after a pH drop to 4.0, which paralleled in time the secretion of gluconic acid. To study the role of PQQ in biocontrol traits of E. intermedium, PQQ mutants of 60-2G were constructed by marker exchangee mutagenesis. The PQQ mutants of E. intermedium were lost activities of solubilizing phosphate, growth inhibition of phytopathogenic fungi, and plant growth promotion. These findings suggest that PQQ plays an important role, possibly activation of certain enzymes, in several beneficial bacterial traits of E. intermedium by as yet an unknown mechanism.

• Journal of Apiculture
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• v.34 no.2
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• pp.125-129
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• 2019

Honey bees are important pollinators in agriculture, but are threatened by the pathogen Ascosphaera apis, which causes chalkbrood. Despite attempts to control this fungus using synthetic fungicides, none of them have been proven to be completely effective. Among 640 natural compounds that we tested, 4-hydroxyderricin (MIC=3.125, 6.25 mg/L after 24 h and 48 h growth, respectively) exhibited the strongest anti- Ascosphaera apis activity, followed by acetylshikonin (MIC=12.5 mg/L for 24 h and 48 h growth). 4-Hydroxyderricin showed selective growth inhibition of Ascosphaera apis and Rhizopus oryzae among tested fungus strains. Treatment 4-hydroxyderricin with miconazole revealed a synergistic effect (FICI=0.65±0.13 at 48 h incubation). These findings suggest that 4-hydroxyderricin, which has antifungal activity against Ascosphaera apis but few other fungal species, can effectively control infectious fungal diseases. Combined treatment of bees with 4-hydroxyderricin and miconazole could reduce cytotoxicity and improve the cost effectiveness of treatment.

• Korean journal of food and cookery science
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• v.31 no.5
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• pp.515-523
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• 2015

In the study reported here, the antimicrobial and antioxidant activities of the ethanol leaf extract of Dendropanax morbiferus Lev. from Jeju Island was investigated. Of the 14 strains of 12 species of microorganisms tested, the extract exhibited antimicrobial activity observed against seven Gram-positive bacteria of four species, but not against six Gram-negative bacteria and a yeast strain. Using the disc diffusion method, the diameter of the inhibition zone increased with application of the extract with every strain and the highest growth inhibition was exhibited with Staphylococcus aureus KCTC 1916 at 5 mg/ml. The minimal inhibitory concentration of the extract (MIC) by turbidity was 2.5 mg/ml against Bacillus cereus KACC 12672 and 15 mg/ml when with Enterococcus faecalis KCTC 3206. The minimum bacterial concentration (MBC) values defined as being $${\geq_-}99.9%$$ reduction in viable cells against the tested strains was higher than the MIC values. Time killing curves using the optimum MIC were performed on seven strains incubated for 48 hr. The growth of B. cereus KACC 12672 was detected after 12 hr and no significant growth was found in the others strains after 48 hr (p<0.05). The 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity of the ethanol leaf extract was similar to that of butylated hydroxyanisole (BHA) at the same concentration. These results indicate that leaf extract of D. morbiferus Lev. can be utilized as a natural preservative and an antioxidant.

• Korean Journal of Organic Agriculture
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• v.13 no.2
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• pp.161-173
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• 2005

This study was carried out to clarify the effects of antifungal bacterial strains isolated from the greenhouse soil grown strawberry plants on the growth inhibition of plant pathogen, gray mold (Botrytis cinerea) infected in strawberry plants in Damyang and Jangheung districts. Antagonistic bacterial strains were isolated and investigated into the antagonistic activity against gray mold. Screened ten bacterial strains which strongly inhibited Botrytis cinerea were isolated from the greenhouse grown strawberry plants, and the best antifungal microorganism designated as SB 143 was finally selected. Antifungal bacterial strain SB 143 was identified to be the genus Bacillus sp. based on the morphological and biochemical characterization. Bacillus sp. SB 143 showed 59.4% of antifungal activity against Botrytis cinerea. By the bacterialization of culture broth and heated filtrates of culture broth, Bacillus sp. SB 143 showed 93.1% and 32.1% of antagonistic activity against Botrytis cinerea.

• International Journal of Oral Biology
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• v.32 no.2
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• pp.75-78
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• 2007

The periodontal diseases and dental caries are major infectious diseases in oral cavity. Many of the preventive and therapeutic dental products contain the antimicrobial and anti-inflammatory components. But some of these antimicrobial have weak points such as coloration, burning sensation and insolubility in water. We have screened the therapeutic herbal extracts of the Plant Extract Bank for the antimicrobial activity on the major dental pathogens by growth inhibition assay. For the Porphyromonas gingivalis, 8 herbal extracts had an antimicrobial activity, 11 herbal extracts for the Prevotella intermedia, 43 herbal extracts for the Haemophilus actinomycetemcomitans and 61 herbal extracts for the Streptococcus mutans. Among these extracts, 6 herbal extracts had an antimicrobial activity for more than 3 species of dental pathogens. These extracts are Araliae Cordatae Radix, Crassirhizomae Rhizoma, Mori Radicis Cortex, Psoraleae Semen, Pini Ramulus and Sieges- beckiae Herba. All of effective extracts were CA group, ethanol extracts. Among these 6 herbal extracts, only Crassirhizomae is known to have a antibacterial effects. Therefore these herbal extracts have a possibility to be a candidate for a major antibacterial components in dental products.

• KSBB Journal
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• v.31 no.4
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• pp.312-314
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• 2016

This study was carried out to determine the antifungal activity of $SeO_2$ against pathogenic fungus, Candida albicans. Concentration-dependent Inhibitory activity of $SeO_2$ against C. albicans was shown. When $400{\mu}g/disc$ of $SeO_2$ was tested, the inhibition size ranged from 20.7 to 26.8 mm (avg. 23.4 mm). MIC values of $SeO_2$ against cell growth of C. albicans ranged from 50 to $100{\mu}g/mL$ (avg. $70{\mu}g/mL$). These results could be applied to antibiotics-resistant C. albicans and other pathogenic fungi.

• Journal of Microbiology and Biotechnology
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• v.15 no.4
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• pp.701-709
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• 2005

An efficient method of selecting an antagonistic strain for use as a biological control agent strain was developed. In this improved method, the surface tension reduction potential of an isolate was included in the 'decision factor,' in addition to two other factors; the growth rate and pathogen inhibition. By using a statistically designed method, an isolate from the soil was selected and identified as Bacillus sp. GB 16. In the pot test, this strain showed the best performance among the isolated strains. The lowest disease incidence rate and fastest seed growth were observed when the Bacillus sp. GB 16 was used. The action of the surface tension reducing component was assumed to enhance the wetting, spreading, and residing of the antagonistic strain in the rhizosphere. This result showed that the improved selection method was quite effective in selecting the best antagonistic strain for the biological control of soilborne infectious plant pathogens.

• Microbiology and Biotechnology Letters
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• v.31 no.1
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• pp.90-93
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• 2003

The antibacterial activity of chitosan-alginate-Fe(II) complex (CAFC) against Escherichia coli and Staphylococcus aureus, and an opportunistic pathogen, Candida albicans, was investigated. A concentration of 1 mg/1 was needed to inhibit the growth of S. aureus and E. coli, while 100 mg/liter was sufficient for the growth inhibition of Candida albicans. The ion leakage of potassium and phosphate from E. coli cell and the penetration of ethidium bromide dye into it indicate that CAFC might be able to increase the cell permeability and consequently cellular leakage, thus leading to cell plasmolysis. Scanning electronmicroscope showed that E. coli cells treated with CAFC became irregular, swelling and expanded. In a field trial, control piglets showed average mortality of up to 60% within 3 days after the onset of diarrhea. In contrast, CAFC-treated groups without mortality was decreased to average 56% on the 1 st day after the treatment, and average 7% on the 3rd day. After then, piglets with diarrhea was not found.

• International Journal of Oral Biology
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• v.43 no.1
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• pp.37-42
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• 2018

It is noted that Streptococcus mutans (S. mutans) triggers dental caries establishment by two major factors: the synthesis of organic acids, which demineralize dental enamel, and the synthesis of glucans, which mediate the attachment of bacteria to the tooth surface. Therefore, it is noted that the development of a more effective, substantial and safe preventive agent that works against dental caries and periodontal disease is required at this time. For this reason, the present study was designed to investigate the effect of croton seed ethanol extracts on the growth, acid production, adhesion, and insoluble glucan synthesis of S. mutans. In this case, the ethanol extract of croton seed showed concentration dependent inhibitory activity against the growth, acid production and adhesion of S. mutans. Especially, it is important to note that it has produced significant inhibition at the concentration of 0.1 and 0.2 mg/ml as compared to the control group. Moreover, these results suggest that the application of croton seed extract may be considered to be a useful method for the prevention of dental caries.

• Journal of Ginseng Research
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• v.19 no.2
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• pp.175-180
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• 1995

The disease development of root-rot [pathogen:Cylindrocarpon destruction (Zinssm.) Scholten] occurred in 2-year old ginseng (Panax ginseng C.A. Meyer) was investigated in the continuous (the first cultivation: 1978∼1982, 2nd cultivation: 1990∼1993 and abolished in 1993 due to replanting problem) and replanted cultivation (period of cultivation: 1980∼1984). In the continuous cultivation, incidences of root-rot were 0.7% on May 3, 48.6% on May 24, and 95.8% on June 14, respectively. In the replanted cultivation, no symptom was observed on May 3 and disease incidence was generally lower compared with the continuous cultivation. On the aerial part of the ginseng infected by C. desiccates, the end and/or margin of leaves were changed to dark reddish color that appeared for behind the root-rot symptom. In this field, the longitudinal growth of lateral root was more inhibited than in the case of the replanted cultivation by C. destmctans. The inhibition rate of rootlet growth was 37.3% in the continuous cultivation as compared with that of replanted cultivation at June 14. Though lesions of root-rot were formed all over the roots, 61.2% of the lesions was positioned within 6 cm under the rhizome. Key words Panax ginseng, Cylindrocarpon destmtan, root-rot of ginseng, replanting problem of ginseng.