• Research in Plant Disease
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• v.18 no.4
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• pp.331-337
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• 2012

Citrus melanose is one of important disease in citrus cultivation, reducing quality of citrus fruits and resulting in economic loss. Like other diseases in citrus, melanose was mainly protected by chemical fungicide in the field. Recently, alternative method of disease control is highly required due to the side effect of the chemicals. In this study four rhizobacterial strains TRH423-3, MRL408-3, THJ609-3, and TRH415-2 are selected by dual-culture testing its antifungal activity against Diaporthe citri causing citrus melanose. To investigate the protection efficacy of the selected rhizobacterial strains to citrus melanose, the bacteria were pre-treated on citrus leaves following inoculation with melanose pathogen. Pre-treatment with all selected rhizobacterial strains showed disease suppression in which the levels of protection rates were different by the rhizobacterial strains. Additional treatment with the rhizobacterial strains after the pathogen inoculation enhanced protection rates in all cases. The strain MRL408-3 and TRH423-3 were identified as Burkholderia gladioli, TRH415-2 as Pseudomons fluorescens and THJ609-3 as Pseudomonas pudia as a result of analyzing the internal transcript spaces of the rhizobacterial strains rDNA. The selected rhizobacterial strains may be valuable as biological control agents in the environment-friendly citrus farm in which chemical application is limited.

• Microbiology and Biotechnology Letters
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• v.37 no.2
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• pp.133-139
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• 2009

Yam (Dioscorea batatas Decne) has been recognized as healthy food due to its various biological activities, such as anti-obesity, anti-constipation, anti-proliferation, anti-mutagenic activity, and decrease of blood glucose and cholesterol level. In this study, the methanol extract and its organic solvent fractions were prepared from dried Dioscorea batatas Decne, and their antimicrobial, antithrombin, and antioxidant activity were evaluated, respectively. The 66.7% of methanol extract was fractioned into water residue, and most of total-polyphenol/total-flavonoids were found in ethylacetate fraction. This ethylacetate fraction at $500\;{\mu}g/disc$ concentration showed strong antibacterial activity against gram-negative and gram-positive bacteria, except Staphylococcus aureus. Antifungal activity was not observed in methanol extract and its fractions. But, strong antithrombin activity was found in methanol extract. At 4.8 mg/mL concentration, thrombin time was 99.5 sec, which is coincides with 30% activity of aspirin, a commercial available antithrombosis agent. The ethylacetate fraction showed strong DPPH scavenging activity ($IC_{50}$ of $80.5\;{\mu}g/mL$), compared to vitamin C ($IC_{50}$ of $15.2\;{\mu}g/mL$). Also, the ethylacetate fraction showed strong SOD-like activity and reducing power, which are coincide with 43% of vitamin C and 82.7% of butylated hydroxytoluene activity, respectively.

• Journal of Life Science
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• v.18 no.2
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• pp.255-263
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• 2008

Bacteria that antagonize plant pathogenic fungi were isolated from the sediment soil at the Ansan industrial estate. One isolate of them showed growth inhibition of Rhizoctonia solani, Botrytis cenerea, and Fusarium oxysporum. This strain was identified as Pandoraea sp. based on phenotypic and phylogenetic characteristics and termed Pandoraea sp. BCNU 315. Tryptone as nitrogen source and sucrose as carbon source were found to be most effective for the microbial growth. In addition, the optimum temperature and pH for microbial growth were $30^{\circ}C$ and pH 7.0, respectively. The substances generated from Pandoraea sp. BCNU 315 were purified and analyzed by column chromatography, HPLC, GC-MS and NMR. As a result, one compound was determined to be indole, another compound was predicted as cyclopentadecaheptene. Detailed structural clarification of the all of the rest six compounds from Pandoraea sp. BCNU 315 has to be accompanied in the further studies.

• Microbiology and Biotechnology Letters
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• v.37 no.3
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• pp.266-272
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• 2009

The annual productions of yam and its aerial bulbils are estimated to 5,000 and 2,500 ton, respectively. But the majority of bulbils had been discarded without specific use. In this study, methanol extract and its organic solvent fractions were prepared from bulbils of Dioscorea batatas Decne, and their antimicrobial, antithrombin, and antioxidant activities were evaluated, respectively. The methanol extract contained 58.98% of water-soluble materials as like yam's extract. But the bulbils's extract contained 12-folds of total polyphenol and 3.4-folds of total flavonoids compared than yam's extract, respectively. For antimicrobial activity the hexane and ethyl acetate fraction showed strong antibacterial activity at $500{\mu}g/disc$ concentration against gram-negative and gram-positive bacteria. Antifungal activity was not observed in any fractions. Strong antithrombin activity was found in the hexane fractions. At 4.8 mg/mL concentration thrombin time (TT) was over 300 sec, which is 4-folds extended than the TT of yam. In a while, the ethyl acetate fraction showed strong DPPH scavenging activity ($IC_{50}$ of $38.1{\mu}g/mL$), SOD-like activity and reducing power, which are comparable to vitamin C or BHT. Our results suggest that the bulbils of yam as yam tuber have useful bio-activities, such as antibacterial, antithrombosis, and antioxidant activity.

• The Korean Journal of Pesticide Science
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• v.13 no.4
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• pp.275-282
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• 2009

The effect of two plant growth-promoting rhizobacteria (PGPR) on plant growth and systemic protection against soft rot disease and stem rot disease of canola (Brassica napus), caused by Erwinia carotovora and Sclerotinia sclerotiorum was investigated in a laboratory and a greenhouse. Selected PGPR strains C4 and D8 were treated to canola seeds by soaking. Strains C4 and D8 significantly not only increased plant height and root length about 74% and 40.3% and also reduced disease severity of soft rot disease by 80% by C4 and D8 respectively, compared to the control. Especially strain C4 showed antifungal activity against 6 fungal pathogens, S. sclerotiorum, Rhizoctonia solani, Botrytis cinerea, Fusarium oxysporum, Phytophthora capsici and Colletotrichum acutatum. In greenhouse experiment, the seed treatment of both of them increased plant height, leaf width and leaf length of canola plant to 19.5% and 24.9%, 11.3% and 15.3%, and 14.1% and 20.7% by C4 and D8, respectively, and reduced disease severity of S. sclerotiorium. These results indicate that these two PGPR strains can decrease disease severity and increased plant growth under greenhouse condition. Therefore, these two bacteria have a potential in controlling Sclerotinia stem rot of canola. These strains have to investigate under field condition to determine their role of antibiosis, induced systemic resistance and plant growth promotion on canola.

• Microbiology and Biotechnology Letters
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• v.39 no.2
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• pp.104-110
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• 2011

Actinomycetes, Gram positive soil bacteria, are valuable microorganisms which produce useful secondary metabolites including antibiotics, antiparasitic substances, anti-cancer drugs, and immunosuppressants. Although a major family of actinomycetes, known as streptomycetes, has been intensively investigated at the molecular level for several decades, a potentially valuable and only recently isolated non-streptomycetes rare actinomycetes (NSRA) family has been poorly characterized due to lack of proper genetic manipulation systems. Here we report that a PCR-based genome screening strategy was performed with approximately 180 independently isolated actinomycetes strains to isolate potentially valuable NSRA strains. Thanks to this simple PCR-based genome screening strategy we were able to identify only seven NSRA strains, followed by 16S rRNA sequencing for confirmation. Through further bioassays, one potentially valuable NSRA strain (tentatively named Nocardiopsis species MMBL010) was identified which possessed both antifungal and antibacterial activities, along with the presence of polyketide synthase and non-ribosomal peptide synthase genes. Moreover, Nocardiopsis species MMBL010, which was intrinsically recalcitrant to genetic manipulation, was successfully transformed via E. coli-driven conjugation. These results suggest that PCR-based genome screening, followed by the establishment of an E. coli-driven conjugation system, is an efficient strategy to maximize potentially valuable compounds and their biosynthetic genes from NSRA strains isolated from various environments.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.34 no.4
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• pp.325-331
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• 2008

This study was carried to investigate the efficiency of antimicrobial plant extracts as natural preservative in the cosmetic formulations. Ethanol extracts of different plants were tested using the disc diffusion (paper disc) method and the minimum inhibitory concentration (MIC) method for their antimicrobial activity against the common poultry pathogens. Terminalia chebula and Rhus japonica (gallut) extracts exhibited antibacterial activity against Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. Cinnmomum cassia extract exhibited antifungal activity against Candida albicans and Aspergillus niger while the remaining plant extracts showed no activity. A study of the preservative efficacy of the cosmetic formular containing the T. chebula, R. japonica and C. cassia extracts demonstrated sufficient preservative efficacy against bacteria and eukaryotic test microbes. Also, the cosmetic formulations containing antimicrobial plant extracts more effectively inhibited the microoranisms than the mixture of traditional chemical preservatives. These results suggest that the mixture of antimicrobial plant extracts, T. chebula, R. japonica and C. cassia is incorporated as preservative in the cosmetic formulation and the mixture have considerable effect on its efficacy.

• Journal of Life Science
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• v.19 no.9
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• pp.1245-1250
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• 2009

Beimu (Fritillaria thunbergii Miquel), a bulbous plant of Liliaceae found in Korea, Japan and China, has been used as an antitussive and expectorant agent, and is also useful in alleviating stonsillitis and bronchiolitis. Most researches have been focused on micro-propagation and plant regeneration, component analysis, and dormancy relieving of beimu. Reports regarding the biological activity of beimu, such as anti-Helicobacter pyroli or platelet aggregation inhibition activity, are few and not widely available. In this study, methanol extract and its organic solvent fractions were prepared from Fritillaria thunbergii Miquel and their antimicrobial, antithrombin, and antioxidant activities were evaluated, respectively. The methanol extract contained lots of water-soluble materials (58.98%) and hexane-soluble oils (14.85%). The ethylacetate and butanol fraction at $500{\mu}g$/disc concentration showed strong antibacterial activity against tested bacteria, except Escherichia coli. Antifungal activity was not observed in methanol extract and its fractions. The hexane, ethylacetate and butanol fractions showed strong antithrombin activity at 4.8 mg/ml concentration. Especially, the ethylacetate fraction showed 95.4 sec of thrombin time at a concentration of 1.2 mg/ml, which is comparable to aspirin, a widely used antithrombosis agent. For antioxidation activity, the ethylacetate and butanol fraction showed good 1,1-diphenyl-2-picryl hydrazyl scavenging activity ($IC_{50}$ of $344{\sim}368{\mu}g$/ml). In superoxide dismutase-like activity and reducing power, the fractions showed $20{\sim}25%$ of vitamin C, and $51{\sim}54%$ of butyl hydroxytoluene, respectively.

• Research in Plant Disease
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• v.17 no.2
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• pp.142-147
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• 2011

In order to develop a environmentally friendly control protocol for managing tomato leaf mold disease in the field, we employed bacteria- and fungi-based commercially available microbial preparations. The field experiment was conducted from April to July in 2010. Average incidence rates tomato leaf mold caused by Fulvia fulva were 13.1% at the two plastic houses located in Jangsung, Jeonnam area. Initially 11 microbial preparations were tested for antifungal activity against F. fulva in vitro. Among them, 7 selected preparations showed to be inhibited the mycelial growth of the fungal pathogen over 50%. Four microbes suppressed disease incidence as much 50% under greenhouse condition. Eventually in the field two microbial products including Bacillus subtilis GB-0365 and B. subtilis KB-401 respectively were showed control value up to 71.8% for four times sprays from 20 days to 70 days after transplanting. Furthermore, the control value of three times spray program demonstrated 79.3%. Efficacy of the three and four spray programs was more effective than that of non-spray control treatment. Our results indicated that adjustment of application method of commercially available microbial preparation could be used to control a target plant disease as an effective and efficient crop protection system for organic farming.

• Journal of Marine Bioscience and Biotechnology
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• v.2 no.1
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• pp.48-54
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• 2007

Bacillus polyfermenticus SCD (B. polyfermenticus SCD) has been appropriately used for the therapy of long-term intestinal disorders, because live strains in the form of active endospores can successfully reach the target intestine in humans. B. polyfermenticus SCD produces the most antibiotic-related materials. In the present study, B. polyfermenticus SCD was fermented with soybeans (BPFS) and its probiotic properties were investigated. B. polyfermenticus SCD and BPFS showed a broad spectrum of antimicrobial activity against pathogenic Gram-positive (Streptococcus parauberis, Streptococcus iniae, Lactococcus garviae) and Gram-negative (Flexibacter tractuosus, Vibrio harveyi, Vibrio vulnificus, Vibrio ordalii) bacteria and moulds (Aspergillus niger, Aspergillus oryzae). Sebastes schlegeli were used to examine survival rate and cleanup action by BPFS. Bacterial infection resulted in a mortality of up to 99% in the commercial fodder fed groups. BPFS both enhanced the growth rate of fry by improving their appetite and had cleaned by decreased eutrophication. Therefore, it seems appropriate that BPFS should be developed as an antibiotic replacement, favorable fodder additive, and antifungal material in fish farming systems.