• Korean Journal of Microbiology
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• v.51 no.4
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• pp.448-452
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• 2015

The bacterial strain that was isolated from chinese cabbage rhizosphere, showed inhibition of yeast growth. This strain was identified as Pseudomonas fluorescens BB2 by API 20NE test and 16S rRNA gene sequence analysis. P. fluorescens BB2 strain produced antibiotics against yeast as a secondary metabolite effectively when the culture was carried out in YM medium with 3% glucose at $20^{\circ}C$. The protein antibiotic of BB2 strain which was concentrated by ammonium sulfate precipitation and n-butanol extraction inhibited the growth of yeast with the minimal inhibitory concentration of $10{\mu}g/ml$ against Candida albicans KCTC 7965, and the growth of yeast was completely inhibited at $80{\mu}g/ml$. The hydrophilic fraction of n-butanol extraction inhibited the growth of Bacillus cereus ATCC 21366, showed orange halo on chrome azurol S plate, which means the fraction contained iron chelating siderophore. The results of crystal violet uptake through the cell membrane showed that membrane permeability was increased about 9% than control, when the concentration of hydrophobic antibiotic against yeast C. albicans was $60{\mu}g/ml$. As a result, the antibiotic produced by P. fluorescens BB2 against yeast Candida is considered antimicrobial peptide, and this is the first report in the genus Pseudomonas.

• Environmental Mutagens and Carcinogens
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• v.22 no.2
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• pp.112-124
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• 2002

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been reported to exert detrimental toxicities on various organ systems including reproductive, cardiovascular, nervous, or dermal system. Immunomodulatory effects of TCDD is thymic atrophy, downregulation of cytotoxic T or B lymphocyte differentiation and activation, which were demonstrated using experimental animals, whereas immunotoxicity in human has not been investigated well. This study was proceeded to evaluate general immunologic spectrum of the Korean Vietnam War veterans exposed to TCDD during their operation, and compare with that of the non-exposed control subjects with similar age. Regarding composition and quantity, immune cells in peripheral blood collected from the TCDD-exposed was not much different from those of the control except decreased red blood cell, hemoglobin and hematocrit level. Furthermore, plasma IgG2, G3, and G4 isotype distribution was similar between two groups, but IgG1 level was significantly lowered in the TCDD-exposed, indicating a TCDD-mediated functional alteration of B cells. Significantly enhanced level of IgE in plasma, a hallmark of dermal or respiratory allergic response, was also observed in the TCDD-exposed compared with that of the control. Elevated generation of IL-4 and IL-10 was resulted from in vitro stimulation of T cells with PMA plus ionomycin or PHA, respectively, from the TCDD-exposed in comparison to those of the control, suggesting a skewed type-2 response. In addition, the level of IFN${\gamma}$, a multifunctional cytokine for T cell-mediated immunity, was lowered in the TCDD-exposed with upregulation of tumor necrosis factor $\alpha$. The present study suggests that TCDD exposure disturbs immunohomeostasis in humans observed as an aberrant plasma IgE and IgG1 levels and dysregulation of T cell activities.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2020.08a
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• pp.33-33
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• 2020

Watermelon (Citrullus lanatus) is a non-seasonal, economically important, cucurbit cultivated throughout the world with Asia as a continent contributing the most. As part of the effort in diversifying watermelon genetic resources in the already cultivated group, this study was devoted to providing baseline data on morphological quality traits and health-beneficial phytonutrients of watermelon germplasm collections, thereby promoting watermelon research and cultivation programs. To this end, we reported morphological traits, citrulline, and arginine levels of watermelon genetic resources obtained from the gene bank of Agrobiodiversity Center, Republic of Korea, and discussed the relationship between each other. Diverse characteristics were observed among many of the traits. But, most of the genetic resources (>90%) were either red or pink-fleshed. Korean origin fruits contained intermediate levels of soluble solid content (SSC) while The USA, Russian, Tajikistan, Turkmenistan, Taiwan, and Uruguay originated had generally the highest levels of soluble solids. The citrulline and arginine contents using HPLC method were ranged from 6.9 to 52.1 mg/g (average, 27.3 mg/g) and 1.8 to 21.3 mg/g (average, 9.8 mg/g), respectively. The citrulline content determined using Citrulline Assay Kit was ranged from 6.5 to 42.8 mg/g (average, 27.0 mg/g). Resources with high citrulline and arginine levels contained low SSC. Whereas, red- and pink-colored flesh samples had less citrulline compared to yellow and orange. In addition to the profiling of morphological characters and phytonutrients, molecular marker characterization and identification of sources of resistance to diseases and pests are recommended for a more complete diversity analysis of watermelon genetic resources.

• Bulletin of the Korean Chemical Society
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• v.33 no.5
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• pp.1741-1747
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• 2012

Water-dispersible ZnS:Mn nanocrystals were synthesized by capping the surface of the nanocrystals with conventional aminoacids ligands: serine and threonine. The aminoacids capped ZnS:Mn nanocrystal powders were characterized by XRD, HR-TEM, EDXS, ICP-AES and FT-IR spectroscopy. The optical properties were also measured by UV/Vis and solution photoluminescence (PL) spectroscopies in aqueous solvents. The solution PL spectra showed broad emission peaks around 600 nm with PL efficiencies of 9.7% (ZnS:Mn-Ser) and 15.4% (ZnS:Mn-Thr) respectively. The measured particle sizes for the aminoacid capped ZnS:Mn nanocrystals by HR-TEM images were about 3.0-4.0 nm, which were also supported by Debye-Scherrer calculations. In addition, cytotoxic effects of four aminoacids capped ZnS:Mn nanocrsystals over the growth of wild type E. coli were investigated. Although toxicity in the form of growth inhibition was observed with all the aminoacids capped ZnS:Mn nanocrystals at higher dose (1 mg/mL), ZnS:Mn-Met and ZnS:Mn-Thr appeared non-toxic at doses less than 100 ${\mu}g$/mL. Low biological toxicities were seen at doses less than 10 ${\mu}g$/ mL for all nanocrystals.

• Journal of Microbiology and Biotechnology
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• v.12 no.4
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• pp.544-552
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• 2002

Several microorganisms from rat and human feces and lumen fluid of cows were screened for their ability to decolorize the synthetic dyes. Consequently, a novel dye-degrading strain AB&J was isolated. Taxonomic identification including 165 rDNA sequencing and phylogenetic analysis indicated that the isolate had 99.9% homology in its 165 rDNA base sequence with Clostridium perfringens. After 27 h Incubation with the strain, brilliant blue R, bromophenol blue, crystal violet, malachite green, methyl green, and methyl orange were decolorized by about 69.3%, 97.7%, 96.3%, 97.9%, 75.1%, and 97.2%, respectively. The triphenlmethane dye, bromophenol blue, was decolorized extensively by growing Clostridium perfringens AB&J cells in liquid cultures under anaerobic condition, although their growth was strongly inhibited in the initial stage of incubation. This group of dyes is toxic, depending on the concentration used. The dye was significantly decolorized at a relatively lower concentration of below 50 $\mu g \;ml^{-1}$, however, the growth of the cells was mostly suppressed at a dye concentration of 100 $\mu g \;ml^{-1}$. The decolorization activity in cell-free extracts was much higher in cytoplasm than in periplasm and cytoplasmic membrane. Therefore, the enzyme related uptake of bromophenol blue seemed to be localized in cytoplasm. The optimal pH and temperature of bromophenol blue uptake fur decolorization activities were 7.0 and 4$0^{\circ}C$, respectively.

• Korean Journal of Microbiology
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• v.43 no.1
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• pp.59-65
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• 2007

The optimal conditions for Monascus pigments production of Monascus sp. KM 1001, pigment overproducing mutant, in submerged culture was investigated. The optimal medium for the production of pigment from KM 1001 mutant is determined to be composed of 4% rice powder, 0.15% Bacto-peptone, 0.1% glycine, 0.01% $FeSO_{4}{\cdot}7H_{2}O,\;0.1%\;MgSO_{4}{\cdot}7H_{2}O,\;0.25%\;KH_{2}PO_{4},\;pH4.5$. On optimal conditions,10.0 g/L of the cell mass was obtained at $30^{\circ}C$ for 5 days. Yellow, orange and red pigment of Monascus sp. KM 1001 were produced 3.25 units, 1.59 units and 0.88 units in extracellular part, and 84.96 units, 78.84 units and 91.80 units in intracellular part, respectively.

• Journal of Microbiology and Biotechnology
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• v.17 no.1
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• pp.52-57
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• 2007

Growth promotion of wild plants by some plant growth-promoting rhizobacteria (PGPR) was examined in the microcosms composed of soils collected separately from a grass-covered site and a nongrass-covered site in a lakeside barren area at Lake Paro, Korea. After sowing the seeds of eight kinds of wild plants and inoculation of several strains of PGPR, the total bacterial number and microbial activity were measured during 5 months of study period, and the plant biomasses grown were compared at the end of the study. Acridine orange direct counts in the inoculated microcosms, $1.3-9.8{\times}10^9\;cells{\cdot}g\;soil^{-1}$ in the soil from the grass-covered area and $0.9-7.2{\times}10^9\;cells{\cdot}g\;soil^{-1}$ in the soil from the nongrass-covered site, were almost twice higher than those in the uninoculated microcosms. The number of Pseudomonas sp., well-known bacteria as PGPR, and the soil dehydrogenase activity were also higher in the inoculated soils than the uninoculated soils. The first germination of sowed seeds in the inoculated microcosm was 5 days earlier than the uninoculated microcosm. Average lengths of all plants grown during the study period were 26% and 29% longer in the inoculated microcosms starting with the grass-covered soil and the nongrass-covered soil, respectively, compared with those in the uninoculated microcosms. Dry weights of whole plants grown were 67-82% higher in the inoculated microcosms than the uninoculated microcosms. Microbial population and activity and growth promoting effect by PGPR were all higher in the soils collected from the grass-covered area than in the nongrass-covered area. The growth enhancement of wild plants seemed to occur by the activities of inoculated microorganisms, and this capability of PGPR may be utilized for rapid revegetation of some barren lands.

• Microbiology and Biotechnology Letters
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• v.46 no.1
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• pp.40-44
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• 2018

An isolate capable of inhibiting the growth of gram-positive bacteria was obtained from the soil of Mushim stream, Cheongju. The isolate was identified as Pseudomonas otitidis PS by 16S rRNA gene sequence analysis. P. otitidis PS produced antibiotics as a secondary metabolite when cultured in 1% soybean meal with 0.5% glucose. The maximum yield was about 0.1%. The antibiotic substance of P. otitidis PS extracted using ethyl acetate displayed a minimum inhibitory concentration of $2{\mu}g/ml$ for Staphylococcus aureus KCTC 1261. The antibiotic substance produced an orange halo on chrome azurol S agar due to siderophore activity. Growth inhibition was decreased when the iron was depleted. Since the antibiotic activity was lost upon the addition of the reducing agent ascorbic acid or during anaerobic culture, it was considered that antibiotic of P. otitidis PS strain exerts its bactericidal effect by the generation of reactive oxygen species.

• Journal of Microbiology and Biotechnology
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• v.13 no.3
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• pp.415-421
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• 2003

A bacterium, Pseudomonas fluorescens 2112, that is antagonistic against a red-pepper blight-causing fungus, Phytophthora capsici, was isolated from the local soil of Gyongju, Korea. This strain formed an orange-colored clear halo zone on chrome azurol S (CAS) blue agar, suggesting the production of a siderophore in addition to an antifungal antibiotic. The optimal culture conditions for siderophore production by P. fluorescens 2112 were 30-h cultivation at $25^{\circ}C$ and pH 6.5 in King's B medium. The presence of $20{\mu}g/ml\;of\;Fe^3+$ ion or EDDHA promoted the production of siderophore in King's B medium. The siderophore was purified from culture broth by CM-Sephadex C-25 and Sephadex G-25 column chromatographies. The UV spectra of the purified siderophore was the same as that of pyoverdins or pseudobactins. The molecular mass was 1,958 Da determined by FAB-rlass spectrometer, and the amino acid composition analysis showed that the purified siderophore consisted of glycine/threonine/serine/glutamic acid/alanine/lysine with the molar ratio of 3:2:1:1:1:1, DL-Threo-${\beta}$-hydroxyaspartic acid and $N^{\delta}$-hydroxyornithine, two of the essential constituents of pyoverdin, were also found. The purified siderophore pyoverdin showed strong in vitro and in vivo antagonistic activities against phytophthora blight-causing P. capsici. Especially in an in vivo pot test, the siderophore protected red-pepper Capsicum annum L. very well from the attack of P. capsici. These results indicated that the purified siderophore of P. fluorescens 2112 played a critical role in the biocontrol of the red-pepper blight disease, equivalent to treatment by P.fluorescens 2112 cells.

• BMB Reports
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• v.38 no.4
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• pp.391-398
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• 2005

3-hydrogenwadaphnin (3-HK) is a new daphnane-type diterpene ester isolated from Dendrostellera lessertii with strong anti-tumoral activity in animal models and in cultures. Here, prolonged effects of this new agent on proliferation and viability of several different cancerous cell lines were evaluated. Using [$^3H$]thymidine incorporation, it was found that the drug inhibited cell proliferation and induced G1/S cell cycle arrest in leukemic cells 24 h after a single dose treatment. The cell viability of Jurkat cells was also decreased by almost 10%, 31% and 40% after a single dose treatment (7.5 nM) at 24, 48 and 72 h, respectively. The drug-treated cells were stained with acridine orange/ethidium bromide to document the chromatin condensation and DNA fragmentation. These observations were further confirmed by detection of DNA laddering pattern in the agarose gel electrophoresis of the extracted DNA from the treated cells. Treatment of K562 cells with the drug at 7.5, 15 and 30 nM caused apoptosis in 25%, 45% and 65% of the cells, respectively. Exogenous addition of $25-50\;{\mu}M$ guanosine and/or deoxyguanosine to the cell culture of the drug-treated cells restored DNA synthesis, released cell arrest at G1/S checkpoint and decreased the apoptotic cell death caused by the drug. These observations were not made using adenosine. However, the drug effects on K562 cells were potentiated by hypoxanthine. Based on these observations, perturbation of GTP metabolism is considered as one of the main reasons for apoptotic cell death by 3-HK.