• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.2
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• pp.115-121
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• 2002

To develop a new method of conjugation and to determine the distribution of R plasimds, we isolated multi-drug resistant strains from fish pathogenic bacteria in the farms of south and east seacoasts of Korea. Out of the 134 isolates examined, 10 showed resistance to chloramphenicol, tetracycline, streptomycin, ampicillin, colistin, nalidixic acid, oxolinic acid and kanamycin. One out of 10 multi-drug resistance bacteria, Vibfio damsela JE1 (V. damsela JE1), contained transferable R plasmid of chlorarnphenicol- tetracycline resistance genes and other nucleic acids encoding ampicillin and kanamycin resistance. The presence of the R plasmid was confirmed by conjugation using the chromocult medium (CC) as a selective and differential medium for transconiugants with identification based on the growth or colors of the colonies. The frequency of R plasmid transfer with filter mating method was come out much higher than that of broth mating method and appeared to be dependent upon the mating time and temperature. The optimum conditions for filter mating method were found to be 30$^{\circ}C$ and 24hrs as mating temperature and period, respectively, Moreover, donor cells with R plasmid, both isolate and standard bacteria, were shown to have an ability to transfer the plasmid against Escherichia coli K-12 HB101 (E. coli HB101) and Edwardsiella tarda (E. tarda) RE14 at fairly high frequencies, finally, we isolated 3 isolates of Sphingomonas sp., carrying R plasmid from 12 multi-drug resistant bacteria in normal microflora of the flounder (Paralichthys olivaceus) group used for the isolation of V emsela JE1 four months before. The same size and gene transfer chayateristics of R plasimds with those of V damsela JE1 confirmed that normal microflora have the reservoir activity for R plasmid in natural aquatic environment.

• Journal of fish pathology
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• v.37 no.1
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• pp.61-69
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• 2024

In this study, bacterial disease monitoring was conducted from July to November 2022 for three representative bacterial species (Streptococcus parauberis, Vibrio spp. and Edwardsiella piscicida) to investigate the occurrence of bacterial diseases in farmed olive flounder (Paralichthys olivaceus) on Jeju. Over a period of five months, 3,146 olive flounders were tested. The average length and weight of the olive flounder that were sampled for the disease were found to be 32.1 cm and 357.9 g, respectively. Bacteria were detected in 1,228 olive flounders, of which 24.6% were identified as Vibrio spp.. S. parauberis and E. piscicida were identified in 6.3% and 3.2% respectively, and 3% were unknown strains that could not be identified. Also, 41 (1.3%) olive flounders were found to have both S. parauberis and Vibrio spp. and 23 (0.7%) olive flounders were found to have both E. piscicida and Vibrio spp.. In particular, S. parauberis, Vibrio spp. (V. scophthalmi) and E. piscicida were detected simultaneously in one olive flounder. In fish infected with E. piscicida, the most obvious external signs were hernias and ascites.

• Journal of fish pathology
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• v.33 no.2
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• pp.127-138
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• 2020

We attempted to isolate and identify potentially pathogenic bacteria from geoduck clam (Panopea japonica) larvae, juvenile and adult, focusing on Vibrios. The isolates were identified by molecular approach and biochemical characterization. In particular, we applied MLSA (multilocus sequence analysis) to the isolated Vibrios for clear identification and phylogenetic relationships, by combining 16s rDNA and several houskeeping genes (pyrH, recA, rpoA). We obtained 141 isolates; 10 from healthy adults, 52 from moribund adults with blisters and 79 from larvae. 46 from the moribund adults and 39 from the larvae were identified as Vibrio species, while the rest of these samples and all the isolates from healthy adult were identified as marine general bacteria. Among Vibrio species, Vibrio splendidus was the most frequently identified from the moribund adults and clustered with the known V. splendidus in GenBank by MLSA. However, it was still unclear that V. splendidus was the cause of blisters because the artificial infection experiment was not conducted and V. splendidus was isolated also from the larvae. Further studies are necessary to clarify the etiological agent of the blisters found in geoduck clam in this study.

• Korean Journal of Microbiology
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• v.40 no.2
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• pp.133-138
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• 2004

A lot of cultured flounders died by ascitic disease blooming during the summer season in 2002, southern parts of Korea. This study was conducted to investigate the microbial flora for the ascitic cultivated olive flounder (Paralichthys olivaceus) which were collected in the Koe-je island in the southern of Korea from July 2002 to October 2003. Three Genera (Vibrio, Photobacterium and Edwardsiella), seven species of bacteria (V. harveyi, V. alginolyticus, V. parahaemolyticus, V. carcariae, V. metschenikovii, P. damsela and E. tarda) and a fish pathogenic birnavirus (marine birnavirus, MABV) were isolated from the liver, dropsy, spleen and identified by biochemical and molecular biological characterization.

• Journal of Life Science
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• v.17 no.11
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• pp.1547-1554
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• 2007

In this study was investigated the growth effect of Prunella vulgaris. aleutica Fernald(leaf and flower) extracts on various lactic acid bacterias, electron donating ability and hydroxyl radical scavenging activity. The total cell count of Enterococcus faecium KCCM 12118, Lactobacillus rhamnosus KCCM 32826, Lactobacillus plantarum KCCM 11542, Pediococcus pentosaceus KCCM 40464 in the absence at $37^{\circ}C$ after 48hr were $2.2{\times}10^9\;cfu/ml,\;2.1{\times}10^9\;cfu/ml,\;2.3{\times}10^9cfu/ml,\;2.2{\times}10^9\;cfu/ml$. On the other hand, the total cell count of E. faecium KCCM 12118, L. rhamnosus KCCM 32826, L. plantarum KCC 11542, P. pentosaceus KCCM 40464 in the presence of Prunella vulgaris. aleutica Fernald(leaf and flower) extracts(10%) at $37^{\circ}C$ after 48hr were $4.3{\times}10^9-4.5{\times}10^9\;cfu/ml,\;4.3{\times}10^9-4.5{\times}10^9\;cfu/ml,\;4.8{\times}10^9-4.9{\times}10^9\;cfu/ml,\;4.1{\times}10^9-4.1{\times}10^9\;cfu/ml$. The electron donating ability indicated to E. faecium KCCM 12118, L. rhamnosus KCCM 32826, L. plantarum KCCM 11542, P. pentosaceus KCCM 40464 added by 10% Prunella vulgaris. aleutica Fernald(leaf and flower) extracts, respectively. when 10% native plant extracts were added lactic acid bacterias, the electron donating ability is the highest. Hydroxyl radical scavenging activity of L. plantarum KCCM 11542, L. rhamnosus KCCM 32826, E. faecium KCCM 12118, P. pentosaceus KCCM 40464 showed higher than that of control.

• Journal of fish pathology
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• v.29 no.1
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• pp.35-43
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• 2016

In comparison to the numbers of such studies of fish, few studies have been carried out on the immunity, physiology and ecology of abalone, while studies on abalone disease are also extremely rare. Moreover, mass mortality of cultured abalone due to pathogenic bacteria has not been reported in the southern coast of Korea. However, Vibrio-like bacteria have been isolated from dead abalone, which indicates that a review is required in order to determine the cause of abalone mortality. Use of an antimicrobial agent to minimize the damage caused by disease in abalone farms is common, but the therapeutic effects are insignificant. Demand for probiotics has increased, but research on the development of probiotics for use in abalone culture is very rare. Therefore, the present study isolated KC16-2 from fermented kimchi soup and investigated the characteristics of the isolate as a candidate probiotic bacterium in abalone. KC16-2 was identified as Bacillus amyloliquefaciens (B. amyloliquefaciens KC16-2) based on its biochemical properties and 16S rRNA gene sequence. B. amyloliquefaciens KC16-2 showed inhibitory effects against the growth of various vibrios in vitro, and kept the numbers constant until four days after inoculation in marine water at a temperature of $15{\sim}25^{\circ}C$, indicating the possible use of KC16-2 as a probiotic, except in the winter. The growth of KC16-2 was inhibited by bile salt, but the numbers increased over time suggesting the bacteria were still alive in the abalone's digestive tract. Abalone fed with a diet including KC16-2 for 12 weeks showed good growth, but showed no significant differences from the control group. However, the mortality of the abalone supplied the probiotic diet was reduced to half that of the control group in a challenge test with Vibrio tubiashii. Therefore, we suggest that B. amyloliquefaciens KC16-2 could be used as a probiotic bacterium for control of the mortality of abalone caused by opportunistic pathogenic vibrios.

• Journal of fish pathology
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• v.20 no.3
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• pp.281-289
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• 2007

We have investigated lysozyme activity and protectivity of starry flounder, Platichthys stellatus against olive flounder pathogenic bacteria, Edwardsiella tarda, Vibrio ichthyoenteri and Streptococcus iniae in varying salinities, water temperatures and stocking density. Starry flounders were susceptible to E. tarda but not V. ichthyoenteri and S. iniae. Under low salinity condition, the lysozyme activity was decreased a little compared to the control but not significant. The physiological and immune activities were normal up to 26 ℃ culture temperature and 100% stocking density; they were compromised from 29℃ and 200%, respectively.

• Journal of fish pathology
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• v.22 no.1
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• pp.9-14
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• 2009

Fifteen diseased rockfish (Sebastes schlegeli) were collected from 4 net-cage farms in Huksan island. Some round transparent nodules were observed on gill filaments in fish. Bacteriological and histopathological examinations on the diseased fish were performed. Any pathogenic bacteria could not be isolated from the internal tissues and histopathological alterations were not found in any of the tissues except the gills. Rock fish were infected with epitheliocystis, Microcotyle sebastes and unknown aetiology on the gills. Cysts of epitheliocystis measuring 44.1-68.9 $\mu{m}$ in diameter were mainly found in the distal portion of the gill filaments and sometimes in the middle portion. But host responses were moderate in spite of formation of the epithelial cysts. Some Microcotyle sebastes captured the secondary filaments with clamps on the opisthohaptor. Attachment of the parasites provoked epithelial proliferation and resulted in gill lamellar fusion.Cysts of unknown origins measuring 26-425 $\mu{m}$ in diameter were found in the cartilage of gill filaments. These cysts contained eosinophilic materials and proliferation of cartilage cells was confirmed around the cysts. But there was no significant pathological changes associated with the presence of the cysts except enlargement of the gill filament with the cysts.

• Microbiology and Biotechnology Letters
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• v.35 no.3
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• pp.210-219
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• 2007

In this study was investigated the growth effect of native plant (Microlepia marginata(panzer Christ., Prunella vulgaris. aleutica Fernald, Perillafrutescens var. japonica Hara., Gleichenia japonica Spreng) extracts on various lactic acid bacterias, electron donating ability, total cell count and hydroxyl radical scavenging activity. The total cell count of Enterococcus faecium KCCM 12118, Lactobacillus rhamnosus KCCM 32826, Lactobacillus plantarum KCCM 11542, Pediococcus pentosaceus KCCM 40464 in the absence of native plant extracts (10%) at $37^{\circ}C$ after 48hr were $2.2{\times}10^9\;cfu/ml$, $2.1{\times}10^9\;cfu/ml$, $2.3{\times}10^9\;cfu/ml$, $2.2{\times}10^9\;cfu/ml$. On the other hand, the total cell count of E. faecium KCCM 12118, L. rhamnosus KCCM 32826, L. plantarum KCCM 11542, P. pentosaceus KCCM 40464 in the presence of native plant extracts (10%) at $37^{\circ}C$ after 48hr were $4.3{\times}10^9\;cfu/ml$, $4.3{\times}10^9\;cfu/ml$, $4.8{\times}10^9\;cfu/ml$, $3.9{\times}10^9\;cfu/ml$. The electron donating ability indicated to E. faecium KCCM 12118, L. rhamnosus KCCM 32826, L. plantarum KCCM 11542, P. pentosaceus KCCM 40464 added by 10% native plant extracts, respectively. when 10% native plant extracts were added lactic acid bacterias, the electron donating ability is the highest. Hydroxyl radical scavenging activity of E. faecium KCCM 12118, L. rhamnosus KCCM 32826, L. plantarum KCCM 11542, P. pentosaceus KCCM 40464 showed higher than that of control.

• Microbiology and Biotechnology Letters
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• v.44 no.4
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• pp.535-539
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• 2016

The prevalence of pathogenic bacteria such as Streptococcus parauberis (Sp), Streptococcus iniae (Si), and Edwardsiella tarda (Et) in flounder fish farms in Jeju Island and their management by gallium treatment was studied. Sp, Si, and Et were found to exhibit a low rate of cell growth and high biofilm formation. Hence, in the present study, cell growth and biofilm formation were measured spectrophotometrically 72 h after the addition of different concentrations of gallium (2, 4, or 8 mg/ml). In addition, cell death was measured by resazurin and propidium iodide staining assays. The results showed that bacterial cell death increased and biofilm formation decreased with an increasing concentration of gallium. Hence, the present study signifies that the use of gallium against bacterial pathogens could be useful for disease management in flounder farms.