• Journal of Food Hygiene and Safety
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• v.32 no.2
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• pp.163-169
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• 2017

The purpose of this study was to estimate the antimicrobial activity of Maesil (Japanese apricot, Prunus mume) extract against Vibrio vulnificus. The strains tested in the study were 28 V. vulnificus isolates originated from fish, seawater, mud flat and seawater in fish restaurant. The vvhA gene was detected using real-time PCR and biochemical identification expressed above good identification in 28 isolates of V. vulnificus. All of V. vulnificus used in this study was susceptible to tetracycline and chloramphenicol antibiotics. These two antibiotics were considered to be useful for the treatment of patients. Maesil extracts 2.5% and 5% showed antimicrobial activity against V. cholerae NCCP 13589 and V. parahemolyticus NCCP 11143. V. vulnificus isolate and V. vulnificus NCCP 11135 showed growth inhibition at 1.25%, 2.5% and 5% of Maesil extract, respectively. Compared with V. cholerae and V. parahemolyticus, the antibacterial activity of Maesil extract against V. vulnificus was high. The minimum bactericidal concentration of Maesil extract for V. vulnificus was 1.6%. These results revealed that Maesil extract was found to be very useful for inhibiting the growth of V. vulnificus and can be expected to prevent food poisoning caused by V. vulnificus.

• Journal of Environmental Health Sciences
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• v.47 no.5
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• pp.479-485
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• 2021

Background: Vibrio vulnificus has been frequently detected in seawater, fish, and shellfish mainly in the coastal areas of Chungcheongnam-do Province. Objectives: This study was conducted to investigate the analyzed biochemical properties, genetic characteristics, and distribution of Vibrio vulnificus isolated from environmental sources in coastal areas of Chungcheongnam-do Province from 2019 to 2020. Methods: A total of 1,510 samples were obtained from six different sites in Chungcheongnam-do Province. Isolated strains from the samples were identified by a VITEK 2 system and MALDI-TOF. Antibiotic susceptibility testing for 85 isolates was done by microdilution minimum inhibitory concentration methods, and 11 isolates were analyzed for 16s rRNA sequences in multiple alignments. Results: Among the 1,510 samples taken during the investigation period, 306 strains were isolated and the detection rate of V. vulnificus was 20.3%. One hundred eighty-eight strains (24.6%) from seawater and 118 strains (15.8%) from mud flats were isolated. It was mainly detected in July (17.3%), August (36.5%), and September (28.8%), and the proportion was 82.0%. Based on the CLSI-recommended breakpoints, V. vulnificus isolates were all susceptible to amoxicillin/clavulanic acid, amikacin, gentamicin, ciprofloxacin and trimethoprim/sulfamethoxazole. However, nonsusceptible isolates to ampicillin, ampicillin/sulbactam, cefazolin, cefoxitin, imipenem, tetracycline and chloramphenicol were identified. In the analysis of the nucleotide sequences for 16s rRNA of V. vulnificus isolates, it was confirmed that mutations frequently occurred between nucleotide number 922 and 952, and 98.2% to 100% nucleotide identities between isolates was verified. Conclusions: The results of this study can be used as a basic data for infection control and prevention of Vibrio vulnificus infection by describing the distribution and characteristics of Vibrio vulnificus strains isolated in coastal areas of Chungcheongnam-do Province.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.4
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• pp.337-348
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• 2007

Characteristics in distributions of T, S, nutrients, chlorophyll ${\alpha}$ concentrations and meso-zooplankton abundances and the relations among these parameters were investigated with the data collected in Asan Bay around the rainy season from May 24 till August 25, 2006 at about 10 days interval. Freshwater input during the rainy season clearly affected the distributions of zooplankton and phytoplankton (chlorophyll ${\alpha}$). Freshwater discharge resulted in high nutrients decreased zooplankton abundances. On the contrary, chlorophyll ${\alpha}$ concentrations increased at the end of the rainy season. It seemed that the increase of chlorophyll ${\alpha}$ concentrations was the result of the decreased zooplankton and enriched nutrients caused by freshwater discharges. Seawater temperatures were certainly the reason for the zooplankton succession. However, overall abundance of zooplankton and abundances of some zooplankton such as Noctiluca scintillans, Acartia pacifica, and Sagitta crassa seemed to be influenced by lowered salinity caused by heavy rain rather than seawater temperatures.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.2
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• pp.203-214
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• 2018

Ballast water treated by sodium dichloroisocyanurate (NaDCC) injection method in ballast water management system (BWMS) contains reactive bromine, chlorine species and disinfection by-products (DBPs). In this study, we conducted whole effluent toxicity (WET) testing and ecological risk assessment (ERA) to investigate its ecotoxicological effects on the marine environment. WET testing was carried out for eight marine and fresh water organisms, i.e. diatom, Skeletonema costatum, Navicula pelliculosa, green algae, Dunaliella tertiolecta, Pseudokirchneriella subcapitata, rotifer, Brachionus plicatilis, Brachionus calyciflorus and fish, Cyprinodon variegatus, Pimephales promelas. The WET test revealed that diatom and green algae were the only organisms that showed apparent toxicity to the effluent; it showed no observed effect concentration (NOEC), lowest observable effect concentration (LOEC) and effect concentration of 50 % (EC50) values of 25.0 %, 50.0 % and over 100.0 %, respectively, in seawater conditions. In contrast, rotifer and fish showed no toxicities to the effluent in the all salinity conditions. Meanwhile, chemical analysis revealed that the BWMS effluent contained total of 25 DBPs such as bromate, isocyanuric acid, formaldehyde, chloropicrin, trihalomethanes (THMs), halogenated acetonitriles (HANs) and halogenated acetic acids (HAAs). Based on ERA, the 25 DBPs were not considered to have persistency, bioaccumulation and toxicity (PBT) properties. The ratio of predicted environmental concentration (PEC) to predicted no effect concentration (PNEC) of the all DBPs did not exceed 1.0 for general harbour environments, but isocyanuric acid, tribromomethane, chloropicrin and monochloroacetic acid exceed 1.0 for near ship environments. However, when NOEC (25.0%) of the WET test results where actual effluent was applied, it was concluded that the NaDCC injection method did not have unacceptable ecological risks to the general harbor including near ship environments.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.297-306
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• 2023

Saemangeum Lake is the largest artificial lake in Korea. The continuous deterioration of lake water quality necessitates the introduction of novel water quality management strategies. Therefore, this study aims to identify the spatiotemporal water quality characteristics of Saemangeum Lake using data from the National Water Quality Measurement Network and provide basic information for water quality management. In the water quality parameters of Saemangeum Lake, water temperature and total phosphorous content were correlated, and salt, total nitrogen content, pH, and chemical oxygen demand were significantly correlated. Other parameters showed a low correlation. The spatial principal component analysis of Saemangeum Lake showed the characteristics of its four zones. The mid-to-downstream section of the river affected by freshwater inflow showed a high nutrient salt concentration, and the deep-water section of the drainage gate and the lake affected by seawater showed a high salt concentration. Two types of water qualities were observed in the intermediate water area where river water and outer sea water were mixed: waters with relatively low salt and high chemical oxygen demand, and waters with relatively low salt and high pH concentration. In the principal component analysis by time, the water quality was divided into four groups based on the observation month. Group I occurred during May and June in late spring and early summer, Group II was in early spring (March-April) and late autumn (November-December), Group III was in winter (January-February), and Group IV was in summer (July-October) during high temperatures. The water quality characteristics of Saemangeum Lake were found to be affected by the inflow of the upper Mangyeong and Dongjin rivers, and the seawater through the Garuk and Shinshi gates installed in the Saemangeum Embankment. In order to achieve the target water quality of Saemangeum Lake, it is necessary to establish water quality management measures for Saemangeum Lake along with pollution source management measures in the upper basin.

• Journal of Soil and Groundwater Environment
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• v.13 no.1
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• pp.24-31
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• 2008

Sulfate reducing bacteria (SRB) is universally distributed in the sediment, especially in marine environment. SRB reduce sulfate as electron acceptor to hydrogen sulfide in anaerobic condition. Hydrogen sulfide is reducing agent enhancing the reduction of the organic and inorganic compounds. With SRB, therefore, the degradability of organic contaminants is expected to be enhanced. Ferrous iron reduced from the ferric iron which is mainly present in sediment also renders chlorinated organic compounds to be reduced state. The objectives of this study are: 1) to investigate the reduction of TCE by hydrogen sulfide generated by tht growth of SRB, 2) to estimate the reduction of TCE by ferrous iron generated due to oxidation of hydrogen sulfide, and 3) to illuminate the interaction between SRB and ferrous iron. Mixed bacteria was cultivated from the sludge of the sewage treatment plant. Increasing hydrogen sulfide and decreasing sulfate confirmed the existence of SRB in mixed culture. Although hydrogen sulfide lonely could reduce TCE, the concentration of hydrogen sulfide produced by SRB was not sufficient to reduce TCE directly. With hematite as ferric iron, hydrogen sulfide produced by SRB was consumed to reduce ferric ion to ferrous ion and ferrous iron produced by hydrogen sulfide oxidation decreased the concentration of TCE. Tests with seawater confirmed that the activity of SRB was dependent on the carbon source concentration.

• Journal of Life Science
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• v.21 no.10
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• pp.1487-1493
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• 2011

E. tarda, a fish pathogen, can survive in seawater under relatively high salt conditions as well as in fish under physiological salt conditions. Bacterial growth under different salt concentrations may influence the expression of genes involved in bacterial structure and physiology. The growth rate of E. tarda culture in high salt (3.5% NaCl) was similar to that in low salt (1.0% NaCl, physiological salt concentration). Interestingly, the strain moved much faster in low salt conditions than in high salt conditions. Electron microscopic observation demonstrated that the bacterial cells grown in high salt had less or no flagellation. Obvious flagellation was observed in the parental strain E. tarda CK41 grown in low-salt condition. Two putative genes coding flagellin were identified in the E. tarda genome sequences. The amino acid sequence comparison of each gene revealed 93% identities. A flagellin gene was PCR amplified and cloned into a cloning vector. Using an E. coli protein expression system, a part of flagellin protein was overexpressed. Using the purified protein, an anti-flagellin antibody was raised in the rabbit. Immunoblot analyses with flagellin specific antibody demonstrated that E. tarda CK41 expressed falgellin in low salt conditions, which is consistent with the results seen in motility assay and microscopic observation. This is the first report of salt regulated flagella expression in E. tarda.

• Journal of Aquaculture
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• v.12 no.2
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• pp.123-135
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• 1999

In order to investigate the effect of salinity on growth and osmoregulation of the sweetfish, Plecoglossus altivelis, the fish (post-larva, juvenile, adult) reared in seawater were directly transferred into the experimental rearing water of the different salinities (post-larva : $0\textperthousand$, $5\textperthousand$, $10\textperthousand$, $15\textperthousand$, $20\textperthousand$, $30\textperthousand$. juvenile : $0\textperthousand$, $\10textperthousand$, $20\textperthousand$, $30\textperthousand$. adult : $0\textperthousand$, $15\textperthousand$, $35\textperthousand$, respectively). Fish samples were taken in time courses after transfer for blood and body fluid collection. The changes of sodium, potassium concentration and osmolality of the body fluid and plasma, muscle water content, gonadosomatic index (GSI) and hepatosomatic index (HSI) in the experimental fish were observed in time courses. Growth rate of the post-larva in $\5~25\textperthousand$ were faster than in $0\textperthousand$ (P<0.05). Survival rate was very low in $0\textperthousand$ (P<0.05). No fish survived more than 50 days after transferred into $0\textperthousand$. The concentration of sodium, potassium and osmolality in body fluid of the juvenile sweetfish were slightly decreased at 0.25 day after the beginning of the maintainable level of sodium, potassium and osmolality were $36.4\pm6.2 mM/\ell, 47.5\pm0.7 mM/\ell, 366.3\pm19.1 mOsm/kg, respectively. Except potassium concetration, fish in $0\textperthousand$ and $10\textperthousand$ displayed the pattern of hypoosmotic regulation. Growth rate and survival rate of juveniles of $30\textperthousand$ are significantly low than other groups (P＜0.05). The concentration of sodium, potassium and osmolality in plasma of adult sweetfish were slightly decreased at 1 day after the beginning of the maintainable level of sodium, potassium and osmolality were $159.0\pm2.5 mM/\ell, 5.8\pm0.9 mM/\ell, 338.1$\pm13.3 mOsm/kg respectively. Compared with these values, fish in $0\textperthousand$ and $15\textperthousand$ displayed hypoosmotic regultion. Growth and survival rate of adult in $35\textperthousand$ are significantly low than other experimental groups. GSI was the highest in $15\textperthousand$ after 60 days. HSI was the lowest in $35\textperthousand$. With decreased salinities, oxygen consumption was found to be decreased in the other experimental groups compared to the more than $30\textperthousand$.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.5
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• pp.468-482
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• 2016

To understand variations in the seawater quality of Asan Bay over four seasons form December 2011 to February 2013, we applied two methods: an in-situ observation of water quality and a comparison study of nutrient budgets among three parts (No. 1, 2, and 3) of Asan Bay. We found a significantly high nutrient concentration in the central part of the bay (No. 2) in July 2012 both in the mass balance study and in situ observation. We presumed the source of these nutrients to be both benthic effluence from old dam reservoirs and incompletely-treated municipal waste-water. This elevated nutrient concentration in the central part of Asan Bay (No. 2) expended to off-shore area and eventually triggered an intense Chl-a concentration in Asan Bay. Based on this result, we suggest improved waste-water quality control around the drainage area of Asan Bay.

• Journal of fish pathology
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• v.4 no.1
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• pp.31-39
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• 1991

Vibrio sp. S-1-2 was isolated from seawater in the Masan bay and its bacterial characteristics and bioaccumulation of $CdCl_2$ in the cell were investigated. As the result of microscopic and biochemical test, the S-1-2 strain was identified to Vibrio sp. and this strain can be tolerated even in 200 ppm $CdCl_2$ media, however its growth was inhibited. In 25 ppm $ZnCl_2$ media, the growth of Cd resistant Vibrio sp. S-1-2 was promoted at later stage of growth. The growth of Vibrio sp. S-1-2 was inhibited on 25 ppm $CuCl_2$ and $PbCl_2$ media and was not able to grow in 25 ppm $HgCl_2$ media at all. The uptake of cadium in the cells was increased exponentially with increasing concentration of $CdCl_2$ in media. But the uptake rate of cadmium was suddenly inhibited at 50 ppm $CdCl_2$ media. Optimal pH and NaCl concentration for bioaccumulation of $CdCl_2$ were 8-9 and 1-2%, respectively. In the case of pH, maximum dpm value was found at pH 7 after 96 hours culture and in the case of NaCl concentration, it was detected in 2% NaCl media after 36 hours culture.