• Journal of Microbiology
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• v.43 no.5
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• pp.443-450
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• 2005

The multi-host pathogen, Pseudomonas aeruginosa, possesses an extraordinary versatility which makes it capable of surviving the adverse conditions provided by environmental, host, and, presumably, competing microbial factors in its natural habitats. Here, we investigated the P. aeruginosa-Bacillus subtilis interaction in laboratory conditions and found that some P. aeruginosa strains can outcompete B. subtilis in mixed planktonic cultures. This is accompanied by the loss of B. subtilis viability. The bactericidal activity of P. aeruginosa is measured on B. subtilis plate cultures. The bactericidal activity is attenuated in pqsA, mvfR, lasR, pilB, gacA, dsbA, rpoS, and phnAB mutants. These results suggest that P. aeruginosa utilizes a subset of conserved virulence pathways in order to survive the conditions provided by its bacterial neighbors.

• Applied Chemistry for Engineering
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• v.33 no.3
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• pp.235-241
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• 2022

According to the World Water Development Report 2015 released by the United Nations, drinking water is expected to decrease by 40% by 2030. This does not mean that the amount of water decreases, but rather that the water source is contaminated due to environmental pollution. Because microbes are deeply related to water quality, the analysis of microbe is very important for water quality management. While the most common method currently used for microbial analysis is microscopic examination of the shape and feature after cell culture, as the gene analysis technology advances, quantitative polymerase chain reaction (qPCR) can be applied to the microscopic microbiological analysis, and the application method has been studied. Among them, a reverse transcription (RT) step enables the analysis of RNA by RT-PCR. Integrated cell culture (ICC)-qPCR shortens the test time by using it with microbial culture analysis, and viability qPCR can reduce the false positive errors of samples collected from natural water source. Multiplex qPCR for improved throughput, and microfluidic qPCR for analysis with limited amount of sample has been developed In this paper, we introduce the case, principle and development direction of the qPCR method applied to the analysis of microorganisms.

• Korean Journal of Food Science and Technology
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• v.32 no.6
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• pp.1341-1349
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• 2000

The addition of 5% NaCI to standard plate count (SPC) and bromcresol purple (BCP) agar showed the highest viable cell counts for Jeot-kal samples. The use of 15% glycerol as cryoprotectant showed the highest microbial survival rate at both temperatures, $-20^{\circ}C$ and $-170^{\circ}C$, and on both colony count media, SPC and BCP. During the aging, the pH of Bajirak Jogae-Jeot (fermented clam) decreased from 6.8 to 5.0. Crude protein content was 10% for Bajirak Jogae-Jeot and $6{\sim}7%$ for Myeolchi-Jeot (fermented anchovy). Microbial population of Bajirak Jogae-Jeot was $10^9\;CFU/g$ after 4 weeks of aging, but was only $10^{3-5}\;CFU/g$ in the case of Myeolchi-Jeot. The proportion of Gram positive and catalase negative bacteria in Bajirak Jogae-Jeot increased drastically during the 4 weeks of aging, which showed typical lactic bacterial fermentation. After 2 years' storage of Jeot-kal in liquid nitrogen tank, the cell counts of total aerobic or lactic bacteria were decreased, resulting in about 10% survival rate. Microbial floral change of Jeot-kal was also investigated. In the case of Bajirak Jogae-jeot, the ratio of rod to cocci and that of Gram negative to positive increased after liquid nitrogen storage. But, rod to cocci ratio of Myeolchi-jeot decreased after liquid nitrogen storage. The ratio of yeasts decreased in both cases after storage.

• Journal of Korean Medicine for Obesity Research
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• v.16 no.1
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• pp.11-18
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• 2016

Objectives: To confirm microbiological change and cytoprotective effect of Samjung-hwan (SJH) which fermented by Lactic acid bacteria from natural fermented SJH. Methods: SJH was fermented by Lactobacillus brevis and Lactococcus lactis subsp. lactis from natural fermented SJH. After 1 week of fermentation, we analysed pH and microbial profiling. We also performed measuring total polyphenol total flavonoid contents and 1,1-Diphenyl-2-picryhydrazyl (DPPH) free radical scavenging activity to investigate antioxidant ability. Cell viability was performed by using HepG2 cell. Results: pH of lactic acid bacteria inoculated group and non-inoculated group was decreased and total counts of lactic acid bateria for both group was increased after fermentation of SJH. Total polyphenol and flavonoid contents and DPPH free radical scavenging activity was increased in both group. Total polyphenol contents of lactic acid bacteria Inoculated group is more increased than non-inoculated group. HepG2 cell viability was increased in both group. Conclusions: SJH fermentd by Lactobacillus brevis and Lactococcus lactis subsp. lactis shows change in microbiological character and has cytoprotective effect. Further studies are required for investigating function of lactic acid bacteria during fermentation of SJH.

• Herbal Formula Science
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• v.26 no.3
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• pp.251-259
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• 2018

Objective : Kurarinone is one of the flavonoids isolated from Sophorae Radix with various biological activities including anti-microbial effect. In this study, we investigated the effects of Kurarinone on tert-butyl hydroperoxide (tBHP)-induced oxidative stress finally leading to apoptosis in human hepatoma cell line HepG2. Methods : To determine the effects on cell viability, the cells were exposed to tBHP ($100{\mu}mol/l$) after pretreatment with kurarinone (0.5 and $1{\mu}g/ml$). Cell viability was measured by MTT assay. To reveal the possible mechanism of cytoprotectivity of kurarinone, levels of reactive oxygen species, intracellular glutathione, mitochondrial membrane potential, and expression of caspase were examined. Results : tBHP-induced cell death was due to oxidative stress and the resulting apoptosis. Kurarinone dose-dependently protected cells from apoptosis when determined by MTT and TUNEL assay. Consistent with this observation, decreased expression of pro-caspase 3/9 protein by tBHP was restored by kurarinone. Kurarinone also showed anti-oxidative effects by inhibiting generation of ROS and depletion of GSH in tBHP-stimulated HepG2 cells. In addition, kurarinone significantly recovered disruption of mitochondrial membrane potential (MMP) as a start sign of hepatic apoptosis induced by oxidative stress. Conclusion : From these results, it was concluded that kurarinone protected tBHP-induced hepatotoxicity with anti-oxidative and anti-apoptotic activities. Our results suggest that kurarinone might be beneficial to hepatic disorders caused by oxidative stress.

• Microbiology and Biotechnology Letters
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• v.43 no.2
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• pp.120-125
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• 2015

In this study, the probiotification of mango juice was carried out by lactic acid bacteria fermentation. Mango juice fermentation was performed at 30℃ for 72 h under micro-aerophilic conditions. The microbial population, pH, titrable acidity, sugar, and organic acid metabolism were measured during the fermentation period and the viability of the strains was determined under the storage conditions at 4℃ for 4 weeks. The lactic acid bacteria reduced the pH to as low as 3.2 from 4.5 within 72 h of fermentation. The substrate concentration was reduced to 5.8% (w/v) from 12% (w/v). Lactobacillus plantarum exhibited the fastest utilization of sugar and reduction of pH in the mango juice when compared to the other strains used. The viability of the cells was maintained at 1.0 × 10⁷ CFU/ml throughout the storage period. From this investigation, it can be concluded that mango juice is suitable for the production of probiotic beverage.

• Korean Journal of Food Science and Technology
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• v.39 no.1
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• pp.61-65
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• 2007

In order to extend the viability of aerotolerant Bifidobacterium animalis DY-64, fructooligosaccharide was added to kimchi containing the bifidobacteria. Baechu-kimchi made with Chinese cabbage was prepared with B. animalis DY-64 and fructooligosaccharide. Physicochemical and microbial changes of the kimchi were evaluated during fermentation at $4^{\circ}C$. Bifidobacteria survived longer in kimchi containing fructooligosaccharide than in kimchi not containing the oligosaccharide. The viable cell counts of Lactobacillus spp. and Leuconostoc spp. and the organic acid content of fructooligosaccharide-added kimchi were higher than those of bifidobacteria or conventional kimchi. The sour taste and sourness of fructooligosaccharide-added kimchi were as high as that of conventional kimchi. These results show that the addition of prebiotic fructooligosaccharide in kimchi enhanced the viability of bifidobacteria during functional kimchi fermentation.

• Journal of Microbiology and Biotechnology
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• v.15 no.1
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• pp.29-34
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• 2005

W/O/W (water-in-oil-in-water) type multiple emulsion was applied to improve the storage stability of an antagonistic microorganism, Burkholderia gladioli. Encapsulation of microorganism into a W/O/W emulsion was conducted by using a two-step emulsification method. W/O/W emulsion was prepared by the incorporation of B. gladioli into rapeseed oil and the addition of polyglycerin polyriconolate (PGPR) and castor oil polyoxyethylene (COG 25) as the primary and secondary emulsifier, respectively. Microcrystalline cellulose was used as an emulsion stabilizer. To evaluate the usefulness of W/O/W emulsion formulation as a microbial pesticide for controlling the bacterial wilt pathogen (Ralstonia solanacearum), the storage stability and antagonistic activity of emulsion formulation were tested in vitro. The storage stability test revealed that the viability of formulated cells in emulsion was higher than that of unformulated cells in culture broth. At $4^{\circ}C$, the viabilities of formulated cells and unformulated cells at the end of 20 weeks decreased to about 2 and 5 log cycles, respectively. At $37^{\circ}C$, the viability of formulated cells decreased to only 2 log cycles at the end of storage. On the other hand, the viable cells in culture broth were not detected after 13 weeks. In activity test, formulated cells in emulsion were more effective in inhibiting the growth of pathogen than unformulated cells in culture broth. Unformulated cells completely lost their antagonistic activity during storage under similar conditions. The W/O/W multiple emulsion formulation was shown to be useful as the novel liquid formulation for biological control.

• Nutrition Research and Practice
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• v.14 no.1
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• pp.3-11
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• 2020

BACKGROUND/OBJECTIVES: Oxidative stress causes cell damage and death, which contribute to the pathogenesis of neurodegenerative diseases. Urolithin A (UA), a gut microbial-derived metabolite of ellagitannins and ellagic acid, has high bioavailability and various health benefits such as antioxidant and anti-inflammatory effects. However, it is unknown whether it has protective effects against oxidative stress-induced cell death. We investigated whether UA ameliorates H₂O₂-induced neuronal cell death. MATERIALS/METHODS: We induced oxidative damage with 300 μM H₂O₂ after UA pretreatment at concentrations of 1.25, 2.5, and 5 μM in SK-N-MC cells. Cytotoxicity and cell viability were determined using the CCK-8 assay. The formation of reactive oxygen species (ROS) was measured using a 2,7-dichlorofluorescein diacetate assay. Hoechst 33342 staining was used to characterize morphological changes in apoptotic cells. The expressions of apoptosis proteins were measured using Western blotting. RESULTS: UA significantly increased cell viability and decreased intracellular ROS production in a dose-dependent manner in SK-N-MC cells. It also decreased the Bax/Bcl-2 ratio and the expressions of cytochrome c, cleaved caspase-9, cleaved caspase-3, and cleaved PARP. In addition, it suppressed the phosphorylation of the p38 mitogen-activated protein kinase (MAPK) pathway. CONCLUSIONS: UA attenuates oxidative stress-induced apoptosis via inhibiting the mitochondrial-related apoptosis pathway and modulating the p38 MAPK pathway, suggesting that it may be an effective neuroprotective agent.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.5
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• pp.518-525
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• 2012

In this study, the feasibility of hyperspectral reflectance imaging technique was investigated for the discrimination of viable and non-viable lettuce seeds. The spectral data of hyperspectral reflectance images with the spectral range between 750 nm and 1000 nm were used to develop PLS-DA model for the classification of viable and non-viable lettuce seeds. The discrimination accuracy of the calibration set was 81.6% and that of the test set was 81.2%. The image analysis method was developed to construct the discriminant images of non-viable seeds with the developed PLS-DA model. The discrimination accuracy obtained from the resultant image were 91%, which showed the feasibility of hyperspectral reflectance imaging technique for the mass discrimination of non-viable lettuce seeds from viable ones.