• Korean Journal of Ecology and Environment
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• v.46 no.3
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• pp.360-366
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• 2013

This study was it conducted on effluent or river water close to discharge locations from a treatment plant, which were analyzed for the presence, phenotype and antibiotic resistance rates of Vancomycin Resistant Enterococci (VRE). The test results for isolation and identification of Enterococcus spp. showed that they all were VRE positive, with a total of 32 strains detected. Multiplex PCR was conducted for 32 strains, each of which were identified as E. faecium, and the results indicated that they were all confirmed as VRE, corresponding to the Van A phenotype. The results of E. faecium concentrations measured at various locations indicated that they were, on average, higher at the location of sewage treatment plants. The frequency of positive tests as well as the number of colonies was higher downstream of treatment plants. The minimum inhibitory concentration was inspected for 26 strains of discharged water samples from sewage water treatment plants, and 6 strains of river samples. Out of 19 antibiotics, 14 and 5 species showed resistance and sensitivity, respectively.

• Korean Journal of Food Science and Technology
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• v.26 no.3
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• pp.261-265
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• 1994

To detect naturally occurring bioactive compounds in unused marine resources such as marine by-products and algae, the screening test for the antimicrobial compounds containing in Asterina pectinifera, Halocynthia rotetzi skin, Nototodarus sloani ink. Anthocidaris crassispina skin, and four algae(Sargassum horneri, Agarum cribrosum, Odonthalia corymbifera and Desmarestia ligulata) was carried out. The minimum inhibitory concentrations(MIC, ${\mu}g/disk$) of ether and methanol fractions extracted from Sargassum horneri against Bacillus subtilis were 80 and 70 ${\mu}g/disk$, respectively. The MICs of the ether, acetone and methanol fractions extracted from Sargassum horneri against Staphylococcus aureus were 160, 180 and 70 ${\mu}g/disk$, respectively. In addition, the MICs of ether and acetone fractions extracted from Odonthalia corymbifera against Staphylococcus aureus were 50 and 170 ${\mu}g/disk$, respectively. These nonpolar fractions showed the strongest antimicrobial effect among several fractions extracted from tested marine resources.

• Research in Plant Disease
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• v.23 no.2
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• pp.177-185
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• 2017

Bacillus amyloliquefaciens LM11 was isolated from the feces of larvae of the rhino beetle and showed strong antifungal activities against various phytopathogenic fungi by producing biosurfactants. In this study, our overall goal was to determine relationship between biosurfactants produced from the LM11 strain and its role in growth inhibition of phytopathogenic fungi. Production and expression levels of B. amyloliquefaciens LM11 biosurfactants were significantly differed depending on growth phases. Transcriptional and biochemical analysis indicated that the biosurfactants of the LM11 strain were greatly enhanced in late log-phase to stationary phase. Inhibitions of phytopathogenic mycelial growth and spore germination were directly correlated (P<0.001, R=0.761) with concentrations of the LM11 cell-free culture filtrates. The minimum inhibitory surface tension of the culture filtrate of the B. amyloliquefaciens LM11 grown in stationary phase to inhibit mycelial growth of the phytopathogenic fungi was 38.5 mN/m (P<0.001, R=0.951-0.977). Our results indicated that the biosurfactants of B. amyloliquefaciens LM11 act as key antifungal metabolites in biocontrol of plant diseases, and measuring surface tension of the cell-free culture fluids can be used as an easy indicator for optimal usage of the biocontrol agents.

• Korean Journal of Plant Resources
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• v.25 no.2
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• pp.193-199
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• 2012

This study was carried out to evaluate the agronomic characteristics and biological activities of $Sorghum$ $bicolor$ germplasms introduced from USA. Plant height, stem diameter, tiller number, leaf length, leaf width, leaf vein color, ear type, ear length and ear width have different from the cultivated accessions. Sweet-N-Sterile (#4) showed the tallest height, widest ear-width and stem diameter. Most of $Sorghum$ $bicolor$ plants may be available to use for bio-energy from these results showing big biomass. Antioxidant activities of 11 cultivars collected from USA were examined by DPPH assay and reducing power. Among the cultivars, Premium stock (#1), Early Sumac (#7), SS Silage (#9) and WGF Grain Sorghum (#11) showed a significantly higher antioxidant activity in comparison to others. Early Sumac (#7) and SS silage (#9) showed more strong reducing power activities than ${\alpha}$-tocopherol, a positive control. Premium stock (#1), Sweet-N-Sterile (#4), Early Sumac (#7) and SS Silage (#9) were also showed high antioxidant activities by DPPH assay and reducing power experiment. BMR Gold I (#3) displayed strong antimicrobial activity against $Escherichia$ $coli$ at minimum inhibitory concentrations (125 ${\mu}g$/ml).

• Korean Journal of Medicinal Crop Science
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• v.20 no.2
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• pp.101-107
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• 2012

Effects of nitrogen (N), phosphorous (P) and potassium (K) on the shoot and bulb growth of wild garlic ($Allium$ $victorialis$ var. $platyphyllum$) were studied by adopting $in$ $vitro$ culture. These macronutrients influenced the growth of both the shoot and bulb of garlic depending upon their application doses. A minimum of 3% potassium nitrate ($KNO_3$) as a source of nitrogen was found to be critical for shoot elongation while higher concentrations were inhibitory. Garlic bulb growth was profuse on the usual $KNO_3$ strength and sucrose (7%), followed by $KNO_3$ (9.4 mM) supplement. On providing 41.22 mM ammonium nitrate ($NH_4NO_3$) as nitrogen source highest shoot growth was observed while 82.45 mM $NH_4NO_3$ as a source of nitrogen supported high bulb growth. With regard to potassium a good shoot growth was observed in medium that contained 0.31 mM $KH_2PO_4$ and 3% sucrose, while bulb growth was high on 2.5 mM $KH_2PO_4$ and 7% sucrose. These experiments may thus direct the development of excellent growth conditions for the commercial production of edible wild garlic.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.18 no.1
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• pp.42-63
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• 1992

In order to investigate the effect of nonionic surfactants on the antimicrobial activity of preservatives in the presence and absence of p.0.E(20) Sorbitan fatty acid ester commonly used in cosmetics and pharmaceutical systems, these experiments were carried out by determining Minimum Inhibitory Concentration(MIC) values and MIC values of adaptation against test organisms. And also the inactivation of the preservative against each microorganism in formula added with various concentrations of P.0.E(20) Sorbitan monostearate were measured by use of a preservative death time curve The results obtained were as fort low : 1) Nonionic surfactant inactivated Methylparaben to varying extents, but not Imidazolidinyl urea. 2) A combined preservative system was inactivated to a little extent (range of 0.16-0.20% Conc.), no adaptation was observed for the 5. aureus ATCC 6538. Imidazolidinyl urea complex combined with Methylparaben had a broad antibacterial spectrum against the Gram(.) and the Gram(-) bacteria It was found that preservatives had a synergistic effect by use of mixed form of preservatives, 3) In formula preserved with 0.2% Methylparaben containing 0.5, 1.0 and 2.0% P.0.E(20) Sorbitan monostearate, E. coli ATCC 10s36 and P. aeruginosa NCTC 10490 died quickly within in 2hr 4) However, from Fig.5, S. aereus ATCC 6538 died more slowly within increasing surfactant concentration and the D-values(Decimal reduction time) were 5.2, 8 and 14 hr. for samples containing 0.5, 1 0 and 2.0% P 0. E(20) Sorbitan monostearate, respectively. 5) In the case of Methylparaben, no adaptation for the E. coli ATCC 10536 6) All of the nonionic surfactant, p.0. E(20) Sorbitan fatty acid ester used in the experiments decreased the effectiveness of Methylparaben, but not of Imidazolidinyl urea.

• Korean Journal of Organic Agriculture
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• v.22 no.3
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• pp.469-481
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• 2014

IIn vitro antimicrobial and anti-inflammatory activities of nargenicin and its derivatives were investigated. Nargenicin, an unusual macrolide antibiotic with potent anti-MRSA (methicilin-resistant Staphylococcus aureus) activity, was purified from the culture broth of Nocardia sp. CS682. And variety of novel nargenicin derivatives was synthesized from nargenicin. Two compounds (4 and 5) exhibit a broad spectrum of antimicrobial activities against infectious bacteria. The antimicrobial activity of derivatives against fifteen organisms was assessed using the minimum inhibitory concentration (MIC). The MIC values were in the ranges of $0.15{\sim}80{\mu}g/mL$ (w/v) for compound 1 and 2, $5{\sim}80{\mu}g/mL$ (w/v) for compound 3, $1.25{\sim}40{\mu}g/mL$ (w/v) for compound 4, and $1.25{\sim}80{\mu}g/mL$ (w/v) for compound 5, depending on the pathogens studied. In vitro, we investigated cytotoxicity and inhibition of nitric oxide (NO) production of synthesized compounds 1-5 in Raw 264.7 cells. LPS-induced nitric oxide releases were significantly blocked by compound 3, 4 and 5 in a dose-dependent manner. At high concentrations ($5{\mu}g/mL$) compound 5 inhibited the NO production by 95%. Compound 4 inhibited the release of NO in LPS-activated Raw 264.7 cells by 75% at the concentration of $10{\mu}g/mL$. Compound 3 inhibited the release of NO in LPS-activated Raw 264.7 cells by 65% at the concentration of $100{\mu}g/mL$. On the other hand, nargenicin, compound 1 and 2 did not inhibit NO production. These results demonstrated that compound 4 and 5 displayed antimicrobial activity and blocked LPS-induced pro-inflammatory mediators such as NO in macrophages, which might be responsible for its therapeutic application.

• Korean Journal of Ecology and Environment
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• v.36 no.2 s.103
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• pp.150-160
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• 2003

This study was carried out to assess inhibitory effects of light-blocking on water quality and phytoplankton community in Lake Juam from August to November 2000. The values of water temperature, DO, TN, $NO_3-N$, $NH_4-N$, TP, DIP, COD, SS and PH did not show clear differences between inside and outside light-blocked areas. Concentrations of Chl-a decreased -6.6${\sim}$40% (mean 14.7%) from inside of the light-blocked area by light blocking. During the study, 55 species of phytoplankton were indentified, and the dominant species were Microcystis aeruginosa, Aulacoseira granulata, Peridinium sp., Synedra spp., Oscillatoria sp., Fragilaria construens, and Trachelomonas sp. The successional pattern of dominant phytoplankton was diatoms (July)${\to}$ diatoms/cyanophytes (August-September)${\to}$cyanophytes (October)${\to}$ diatoms (October-November). The standing crop of phytoplankton showed maximum density in 22 September with $1.1{\times}10^4$cells/L, and minimum in 25 October with $4.7{\times}10^3$ cells/L. The decreasing efficiency of standing crop by light-blocking was 8${\sim}$38% (mean 19.9%). Through this study we found that blocking light seems to have a decreasing effect on the density of phytoplankton.

• Korean Journal of Ecology and Environment
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• v.42 no.1
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• pp.75-84
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• 2009

The effect of various SNPs (silver nanoparticles) on the growth of Microcystis aeruginosa was investigated in laboratory and field experiment. Four SNPs, namely JS47N, JS47N-K2, JS47N/3-1 and JS47N/3-2 were used to this study. The Ag size, concentration and color of these solutions were about $20{\sim}40nm$, $200mg\;L^-1$ and brown, respectively. At 0.01 and $0.1mg\;L^-1$, SNPs inhibited the growth of unicellular M. aeruginosa by 99.4% and 99.9%, respectively. However, SNPs of $1mg\;L^-1$ inhibited the growth of colonial M. aeruginosa by 98.5%, whereas the other three concentrations (0.001, 0.01 and $0.1mg\;L^-1$) had little inhibitory effect. In experimental enclosures from eutrophic lake, cyanobacteria including M. aeruginosa were found to be more sensitive to the SNPs than green algae and diatoms. In conclusion, our study indicates that SNPs has a selective cyanocidal potential when used to M. aeruginosa. We believe that future studies need to test on various other organisms, and determine minimum concentration for field application.

• Annals of Laboratory Medicine
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• v.38 no.6
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• pp.555-562
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• 2018

Background: The emerging mobile colistin resistance gene, mcr-1, is an ongoing worldwide concern and an evaluation of clinical isolates harboring this gene is required in Korea. We investigated mcr-1-possessing Enterobacteriaceae among Enterobacteriaceae strains isolated in Korea, and compared the genetic details of the plasmids with those in Escherichia coli isolates from livestock. Methods: Among 9,396 Enterobacteriaceae clinical isolates collected between 2010 and 2015, 1,347 (14.3%) strains were resistant to colistin and those were screened for mcr-1 by PCR. Colistin minimum inhibitory concentrations (MICs) were determined by microdilution, and conjugal transfer of the mcr-1-harboring plasmids was assessed by direct mating. Whole genomes of three mcr-1-positive Enterobacteriaceae clinical isolates and 11 livestock-origin mcr-1-positive E. coli isolates were sequenced. Results: Two E. coli and one Enterobacter aerogenes clinical isolates carried carried IncI2 plasmids harboring mcr-1, which conferred colistin resistance (E. coli MIC, 4 mg/L; E. aerogenes MIC, 32 mg/L). The strains possessed the complete conjugal machinery except for E. aerogenes harboring a truncated prepilin peptidase. The E. coli plasmid transferred more efficiently to E. coli than to Klebsiella pneumoniae or Enterobacter cloacae recipients. Among the three bacterial hosts, the colistin MIC was the highest for E. coli owing to the higher mcr-1-plasmid copy number and mcr-1 expression levels. Ten mcr-1-positive chicken-origin E. coli strains also possessed mcr-1-harboring IncI2 plasmids closely related to that in the clinical E. aerogenes isolate, and the remaining one porcine-origin E. coli possessed an mcr-1-harboring IncX4 plasmid. Conclusions: mcr-1-harboring IncI2 plasmids were identified in clinical Enterobacteriaceae isolates. These plasmids were closely associated with those in chicken-origin E. coli strains in Korea, supporting the concept of mcr-1 dissemination between humans and livestock.