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Dive into the research topics where Se-Wook Oh is active.

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Featured researches published by Se-Wook Oh.


Anaerobe | 2015

Synergistic inhibition of Clostridium difficile with nisin-lysozyme combination treatment

Changhoon Chai; Kyung-Soo Lee; Se-Wook Oh

Clostridium difficile vegetative cells were not inhibited completely after a 120-min treatment with 40xa0nM nisin or 0.8xa0mM lysozyme. However, these cells were completely inhibited after only a 30-min incubation with both 20xa0nM nisin and 0.2xa0mM lysozyme.


Toxicological research | 2009

Genotoxicity Studies on Carrageenan : Short-term In Vitro Assays

Young-Shin Chung; Ki-Hwan Eum; Seon-A Choi; Se-Wook Oh; Sue Nie Park; Young-Na Yum; Joo-Hwan Kim; Young-Rok Seo; Michael Lee

Carrageenan is a naturally-occurring sulfated polygalactan which has been widely used in the dairy industry and a gelling agent in non-dairy products. In this study, four short-term in vitro genotoxicity assays were investigated to evaluate the potential genotoxic effects of carrageenan. The mutagenic-ity of carrageenan was evaluated up to a maximum dose of 5 mg/plate in Ames test. There was no increase in the number of revertant colonies compared to its negative control at any dose in all of strains tested. To assess clastogenic effect, the in vitro chromosomal aberration assay was performed using Chinese hamster lung cells. Carrageenan was not considered to be clastogenic in this assay at up to the highest feasible concentration which could be evaluated. The in vitro comet assay and micronucleus test results obtained on L5178Y cells also revealed that carrageenan has no genotoxicity potential, although there was a marginal increase in micronuclei frequencies and DNA damage in the respective micronucleus and comet assays. Taken together, our results indicate that carrageenan was not genotoxic based on four in vitro genotoxicity results.


Toxicological research | 2008

Evaluation of Genotoxicity of Water and Ethanol Extracts from Rhus verniciflua Stokes(RVS)

Ji-Young Kim; Se-Wook Oh; Daeseok Han; Michael Lee

Rhus verniciflua Stokes (RVS), one of traditional medicinal plants in Asia, was found to have pharmacological activities such as antioxidative and antiapoptotic effects, raising the possibility for the development of a novel class of anti-cancer drugs. Thus, potential genotoxic effects of RVS in three short-term mutagenicity assays were investigated, which included the Ames assay, in vitro Chromosomal aberration test, and the in vivo Micronucleus assay. In Ames test, the addition of RVS water extracts at doses from 313 up to 5000 mg/plate induced an increase more than 2-fold over vehicle control in the number of revertant colonies in TA98 and TA1537 strains for detecting the frame-shift mutagens. The similar increase in reversion frequency was observed after the addition of RVS ethanol extracts. To assess clastogenic effect, in vitro chromosomal aberration test and in vivo micronucleus assay were performed using Chinese hamster lung cells and male ICR mice, respectively. Both water and ethanol extracts from RVS induced significant increases in the number of metaphases with structural aberrations mostly at concentrations showing the cell survival less than 60% as assessed by in vitro CA test. Also, there was a weak but statistically significant increase in number of micronucleated polychromatic erythrocytes (MNPCEs) in mice treated with water extract at 2000 mg/kg while ethanol extracts of RVS at doses of up to 2000 mg/kg did not induce any statistically significant changes in the incidence of MNPCEs. Therefore, our results lead to conclusion that RVS acts as a genotoxic material based on the available in vitro and in vivo results.


Applied Biological Chemistry | 2016

Contamination patterns and molecular typing of Bacillus cereus in fresh-cut vegetable salad processing

Hyun Jung Kim; Minseon Koo; Daekeun Hwang; Jeong Hee Choi; Seung Min Kim; Se-Wook Oh

Microbiological contamination of fresh vegetables is a recent food safety concern. Bacillus cereus has been recognized as the most frequently detected foodborne pathogen in fresh-cut salads in Korea. Prevalence and level of contamination of B. cereus was determined in samples from processing lines of packaged fresh-cut vegetable salad manufacturing companies (A, B, C, and D). B. cereus was detected in the 27.3–30.8xa0% of food samples (raw material, salads in washing steps, and final products) and the contamination levels were up to 9.5xa0×xa0102 CFU/g, while detection rates in environmental samples were very low. Molecular subtyping of B. cereus strains detected in the processing environments (company A) and retail products (companies A and E) was conducted to reveal the contamination sources during processing. High genetic similarity was found in the bacterial strains obtained from the processing lines and retail products of company A. This result suggested that B. cereus strains of same clone may have circulated in the products prepared in the same company. Genetic similarities were also observed among part of the B. cereus isolates obtained from the processing line of company A and from the retail products of company E, suggesting that some of the B. cereus clones may have originated from the raw materials. The identified information can be used to develop the intervention technology for fresh-cut vegetable processing.


Food Science and Biotechnology | 2016

Effects of malic acid or/and grapefruit seed extract for the inactivation of common food pathogens on fresh-cut lettuce

Jin-Hee Kim; Ki-Hyun Kwon; Se-Wook Oh

This study investigated the antimicrobial activity of malic acid (MA), grapefruit seed extract (GSE), and combined (MA+GSE) treatment against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on fresh-cut lettuce. The antimicrobial effects of 1% MA and 0.5% GSE alone and in combination (1% MA+0.5% GSE) were tested on artificially inoculated lettuce during storage at 5°C for 14 days. The maximum reductions of E. coli O157:H7, S. Typhimurium, and L. monocytogenes were 4.96, 4.80, and 3.95 log CFU/g observed with MA+GSE during storage for 14 days, respectively. MA+GSE showed the greatest reduction against in E. coli O157:H7 and L. monocytogenes. These results indicate that the combined treatment was more effective than MA and GSE alone treatment. Therefore, it suggests that MA + GSE could be used as an effective intervention method for improving microbiological safety of fresh-cut lettuce.


Journal of Microbiological Methods | 2015

Non-selective and selective enrichment media for the recovery of Clostridium difficile from chopped beef

Changhoon Chai; Kyung-Soo Lee; Da-Young Lee; Soyeon Lee; Se-Wook Oh

Clostridium difficile exists within the intestines of animals and in meat products. Enrichment of C. difficile in an appropriate medium is necessary for the detection of C. difficile in meat products. Non-selective media (brain heart infusion medium [TBHI] and cooked meat medium containing sodium taurocholate [TCM]) and selective media (cycloserine-cefoxitin-fructose medium [TCCFB] and C. difficile moxalactam-norfloxacin medium containing antibiotics and sodium taurocholate [TCDMN]) can be used to enrich C. difficile. This study aimed to evaluate non-selective and selective enrichment media for the recovery of C. difficile from beef specimens. The efficiency of the enrichment media was investigated on the basis of the recovery frequency of C. difficile from beef specimens inoculated with C. difficile. The beef specimens were inherently contaminated with bacteria (around 10(4)CFUg(-1)), and further inoculated with C. difficile (around 10(0)CFUg(-1)). The antibiotics in TCCFB and TCDMN adversely affected C. difficile growth. The bacteria inherent to these specimens exhibited resistance to antibiotics and grew during the enrichment of C. difficile-inoculated chopped beef in TCCFB and TCDMN, which hindered the recovery of C. difficile. The frequency of recovery of C. difficile from beef specimens in TCM was higher than that from any other enrichment medium.


Journal of The Korean Society for Applied Biological Chemistry | 2012

Contamination patterns and molecular typing of Bacillus cereus in red pepper powder processing

Se-Wook Oh; Minseon Koo; Hyun Jung Kim

Prevalence of Bacillus cereus was determined in red pepper powder samples obtained from various processing steps (n=60), swabs of machinery surfaces (n=35), and air samples of the processing room (n=17) during red pepper powder production. The detection rate of B. cereus was high (over 85%) in samples of raw materials and washing steps and decreased to 40% in samples obtained from later stages of processing, i.e. milling, metal detection, and final products. B. cereus was detected in 2.9 and 11.8% of swabs and air samples, respectively. The genetic similarity of B. cereus isolates obtained from various processing steps was compared to identify the sources of contamination for red pepper powder using the repetitive-sequence-based polymerase chain reaction method. For 20 isolates of B. cereus from two independent samplings, 50% of the isolates, which were clustered, consisted of two or more isolates with a similarity greater than 95%. For the isolates obtained from raw materials, crude milling, and milling step of the independent sampling, high genetic similarity (>99.4%) was observed, suggesting that these isolates may have originated from the same clone. The prevalence of B. cereus and molecular typing result suggest possible routes of contamination, such as the transfer of clone contaminated in raw materials to the red pepper powder and cross contamination during processing. Based on this result, more intervention studies to prevent pathogen contamination during red pepper powder processing are needed to insure good hygienic level of products.


International Journal of Biological Macromolecules | 2018

Shelf life extension of Pacific white shrimp (Litopenaeus vannamei) using chitosan and ε-polylysine during cold storage

Soyoung Na; Jin-Hee Kim; Hye-Jin Jang; Hee Jung Park; Se-Wook Oh

In this study, we examined the effects of an ε-polylysine (PL) and chitosan (CH) coating on the quality of shrimp under refrigeration. Pacific white shrimp (Litopenaeus vannamei) were coated with PL, CH, or CHu202f+u202fPL and stored at 4u202f°C for 15u202fdays. The quality of shrimp was measured by observing changes in microbiota, pH, total volatile basic nitrogen (TVB-N), and sensory characteristics. Among the coating films, the CHu202f+u202fPL coating most effectively inhibited the growth of mesophilic and psychrotrophic bacteria, Pseudomonas spp., and H2S-producing bacteria. This coating increased the shelf life of shrimp by decreasing the amount of mesophilic and psychrotrophic bacteria, with inhibition greater than three log cycles on the ninth day of storage. In addition, the CH and CHu202f+u202fPL coatings effectively suppressed the formation of TVB-N compared with that in the control by 43% and 30%, respectively. The pH of all treated samples increased slowly compared with that of the control, but no significant difference was observed. Sensory quality was similar to microbial and physicochemical properties, and the acceptability of all treated samples gradually decreased.


Canadian Journal of Microbiology | 2017

Inactivation of Clostridium difficile spore outgrowth by synergistic effects of nisin and lysozyme

Changhoon Chai; Kyung-Soo Lee; Goo-Sang Imm; Young Soon Kim; Se-Wook Oh

Inactivating Clostridium difficile spores is difficult, as they are resistant to heat, chemicals, and antimicrobials. However, this note describes inactivation of C. difficile spore outgrowth by incubation in a solution containing a germinant (1% (m/v) sodium taurocholate), co-germinants (1% (m/v) tryptose and 1% (m/v) NaCl), and natural antimicrobials (20 nmol·L-1 nisin and 0.2 mmol·L-1 lysozyme). Clostridium difficile spores were resistant to nisin and lysozyme but became susceptible during germination and outgrowth triggered and promoted by sodium taurocholate, tryptose, and NaCl. The degree of inactivation of germinated and outgrowing C. difficile spores by both nisin and lysozyme was greater than the sum of that by nisin and lysozyme individually, suggesting synergistic inactivation of C. difficile spores. The germinant, co-germinants, and natural antimicrobials used in this study are safe for human contact and consumption. Therefore, these findings will facilitate the development of a safe and effective method to inactivate C. difficile spore.


Journal of Food Science | 2014

Impedimetric Characterization of Adsorption of Listeria monocytogenes on the Surface of an Aluminum‐Based Immunosensor

Changhoon Chai; Joo Young Lee; Se-Wook Oh; Paul Takhistov

The impedimetric characteristics of an immunosensor depend on the electrical properties of an immunosensor substrate. The impedimetric characteristics of an immunosensor compared with adsorption of Listeria monocytogenes were investigated on an aluminum surface insulated with an electrically resistive aluminum oxide layer. Antibody for L. monocytogenes (anti-L. monocytogenes) was immobilized on an aluminum surface that was insulated with a native air-formed aluminum oxide layer. The resistance of impedance (R) value of an aluminum-based immunosensor decreased, especially at 10(4) to 10(6) Hz, where the effect of the reactance of impedance (X) was minimal when L. monocytogenes was adsorbed on the immunosensor surface. The R value of the immunosensor at 81 kHz decreased proportionally to the concentration of L. monocytogenes from 1.3 to 4.3 log CFU mL(-1) . The adsorption of L. monocytogenes produced local protrusions on the immunosensor surface, causing physicochemical changes in the ionic layer formed on the immunosensor surface by a sinusoidal electrical signal input, which might help electrical current to flow and cause the R value to decrease.

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Yun-Ji Kim

University of Science and Technology

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Ki-Hwan Eum

Incheon National University

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