• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.3
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• pp.443-450
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• 2020

No established method can be used to select effective antibiotics in antibiotic susceptibility tests for fish bacterial pathogens quickly and accurately. Here, we established the optimal conditions for determining the minimal inhibitory concentration (MIC) of major fish bacterial pathogens (Streptococcus spp., Edwardsiella tarda, Vibrio spp., Aeromonas spp., and Pseudomonas spp.) using the KRAQ1 and CAMPY2 panels. The MIC panel used 18 antibiotics of two types and we conducted experiments to establish the optimal culture medium and temperature for each species. The optimal conditions for incubating Streptococcus spp. were in cation-adjusted Mueller-Hinton broth with TES buffer (CAMHBT) at 28℃, using 5% lysed horse blood (LHB) as recommended by the Clinical Laboratory Standards Institute. For Vibrio spp., the optimal culture conditions were 28℃ in CAMHBT supplemented with 1% NaCl. The optimal conditions for culturing E. tarda, Aeromonas spp., and Pseudomonas spp. were in CAMHBT at 28℃.

• Korean Journal of Veterinary Service
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• v.38 no.2
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• pp.65-70
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• 2015

The present study was to investigate in vitro antimicrobial effects of propolis against six different fish bacterial pathogens, Aeromonas hydrophila, Edwardsiella tarda, Vibrio vulnificus, V. parahaemolyticus, A. salmonicida subsp. masoucida, A. salmonicida subsp. salmonicida) using minimum inhibitory concentration (MIC) and minimum bacteriocidal concentration (MBC) tests. In the results, propolis exhibited antimicrobial activity against all bacteria used in the present study, but there was no marked difference in bacterial species except Vibrio species. Collectively, propolis was thought to be an usefulness antimicrobial substance for controlling bacterial diseases in the fish industry.

• Journal of Food Hygiene and Safety
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• v.31 no.5
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• pp.380-385
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• 2016

The object of this study was to evaluate antibacterial activity of edible seaweed extracts against marine bacterial pathogens including Edwardsiella tarda, Streptococcus iniae, Streptococcus parauberis, Vibrio anguillarum, Vibiro harveyi and Vibrio scophthalm, which are associated with human or fish infectious disease. Ecklonia cava methanolic extract showed a strong and broad spectrum antibacterial activity against marine bacterial pathogens used in this study. Among solvent-soluble fractions of the E. cava extract, the ethyl acetate (EtOAc) soluble fraction showed the strongest antibacterial activity against marine bacterial pathogens tested in this study with MIC in the range of $128-256{\mu}g/mL$. Furthermore, HPLC analysis revealed that the soluble fraction contains abundant dieckol, a phlorotannin compound, compared to other solvent soluble fractions, suggesting that phlorotannins including dieckol would be a key antibacterial agent against marine bacterial pathogens.

• Journal of fish pathology
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• v.5 no.2
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• pp.87-92
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• 1992

Lysozymes were isolated and purified from various organs of cultured flounder by using chitin-coated cellulose column chromatography. The molecular weights of them were compared with each other in 15% SDS-PAGE gels. The result showed that all lysozymes isolated from various organs of flounder had the same molecular weight of about 14000. To clarify the role of lysoryme as a body defence, the antibacterial activities of flounder lysozyme on seven bacterial pathogens, five Gram-negative and two Gram-positive species, were investigated. The lysozyme had substancial antibacterial activity on four strains, two Gram-negative and two Gram-positive species. These suggest that flounder lysozyme plays a role in body defence against both Gram-negative and Gram-positive bacterial pathogens.

• Journal of fish pathology
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• v.25 no.3
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• pp.231-241
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• 2012

Diagnostic monitoring in fish farms with land-based tanks and netpen cases were conducted in eastern, western, southern and Jeju island of Korea during summer of 2007~2011. In total, 2413-fish samples of 4 marine fish species were tested for the detection of bacteria and parasite. Fish species tested were olive flounder (Paralichthys olivaceus), black rockfish (Sebastes schlegeli), red sea bream (Pagrus major), pacific white shrimp (Litopenaeus vannamei). During the diagnostic monitoring from 2007 to 2011, the infection rates by single infection of bacterial or parasitic pathogens were relatively higher than the mixed infections. The main bacterial pathogens in olive flounder, black rockfish and pacific white shrimp were Vibrio spp. (V. harveyi, V. ichthyoenteri, Vibrio sp.). The main bacterial pathogens in red sea bream were also Vibrio sp. and Photobacterium damselae subsp. damselae. The main parasitic pathogens were both Miamiensis avidus and Trichodina sp. in olive flounder, Microcotyle sebastes in black rockfish, Microcotyle tai in red sea bream and Zoothamnium sp. in pacific white shrimp.

• Fisheries and Aquatic Sciences
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• v.26 no.10
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• pp.593-604
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• 2023

Post-harvest handling and hygienic level of aquatic products significantly affect the quality and level of safety. Cold chain control is one of the determining factors for the quality of fish and the bacterial community that grows on the fish. Identification of spoilage bacteria and pathogens in aquatic products must be made because it will determine the physical and chemical quality. A molecular identification method with high sensitivity is the solution. This study aims to identify the quality of fish and bacterial communities that grow. The research procedures included sample collection, pH measurement, drip loss measurement, transportation and cold storage treatment, DNA extraction, DNA sequencing, sequence analysis, and bioinformatics analysis. The conclusion obtained from this study is that the simulation of the cold chain system applied to eastern little tuna does not significantly affect changes in the water activity value, pH, and drip loss. The insignificant change indicates that the eastern little tuna samples are still in good quality. The bioinformatics analysis showed the highest diversity and abundance of the bacterial community came from the Gammaproteobacterial class.

• Korean Journal of Veterinary Research
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• v.34 no.3
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• pp.627-633
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• 1994

A study on efficacy and safety of Bio-Gammamix was performed to use for the preventive drug against bacterial diseases to mirror carp(Cyprinus carpio), rainbow trout(Salmo gairdneri), eel(Anguilla japonica) and flounder(Paralichthys olivaceus). The main ingredients of Bio-Gammamix were ferrous fumarate and mixed extrated powders of licorice root, ox bile and garlic. The test drug was proved to improve feeding habit and feed efficiency and decrease cumulative mortality remarkably. After administration, no side effects and histopathological changes were observed. We can prevent outbreaks of bacterial diseases of fish by the dosage of 1kg/ton of fish body weight perorally once or two times in a day for 7 days and Bio-Gammamix is thought to be used effectively an widely against most bacterial fish pathogens.

• Journal of fish pathology
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• v.22 no.1
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• pp.75-83
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• 2009

Disease surveillance was performed to monitor the prevalence of fish pathogens in wild marine fish caught in coastal offshore water from February to October in 2008. A total of 401 fish samples were collected at set net or fish market at landing port on the coast of Pohang, Geoje, Yeosu and Jeju. In this study, 17 kinds of fish pathogens were isolated from 152 fish samples. The detection rates of parasites, bacteria or viruses were 21.4%, 17.0% and 2.7%, respectively. The detected parasites were Scutica, Trichodina, Cryptocaryon, Dactylogyrus, Microcotyle, Benedenia, Bivagina, Heteraxin, Caligus, Epistylis and nematode. The dominant bacterial pathogens were Vibrio, Streptococcus, Photobacterium and Psuedomonas. Red sea bream iridovirus (RSIV) and lymphocystis disease virus (LDV) were detected in 6 species of fish virus examined in this study. The detection rates of fish pathogens from Scorpaenidae, Monacanthidae, Pleuronectidae, Sparidae and Carangidae investigated over 30 samples were 59.2%, 48.4%, 34.2%, 30.6% and18.2%, respectively.

• Journal of fish pathology
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• v.19 no.3
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• pp.207-214
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• 2006

Diagnostic monitoring in fish farms with land-based tanks and net cases was conducted in eastern, western, southern and Jeju island of Korea for the summer period from 2000 to 2006. Total 3,518-fish samples of marine and freshwater fishes in 25 fish species were tested for pathogens. Fish species tested were olive flounder (Paralichthys olivaceus), fleshy prawn (Fenneropenaeus chinensis Osbeck), black rockfish (Sebastes schlegeli), rock bream (Oplegnathus fasciatus), red sea bream (Pagrus major), black seabream (Acanthopagrus schlegeli), sea bass (Lateolabrax japinicus), gray mullet (Mugil cephalus), rainbow trout (Onchorhynchus mykiss) and others. The infection rates by bacterial pathogens in the years of 2000, 2001, 2002, 2003, 2004, 2005 and 2006 were 22.4%, 34.5%, 14.1%, 15.3%, 17.7%, 13.5% and 5%, respectively. The infection rates by parasitic pathogens were 20%, 33.8%, 12.4%, 14.1%, 9.2%, 10.5% and 10.7%, respectively. The infection rates by viral pathogens were 22.4%, 13.5%, 10.3%, 5.4%, 9.7%, 10.2% and 15.8%, respectively. The infection rates by mixed pathogens were 10.3%, 0%, 44.9%, 50.9%, 31.9%, 38.4% and 39.6%, respectively. The rates of mixed infections were very low until 2001. The rates were higher than those of singer infections from 2002 to 2006. During the diagnostic monitoring from 2000 to 2006, the main bacterial pathogens were Vibrio (41.2%) and Streptococcus (28.8%). The infection rate by protozoa (85.7%) mainly including Scuticociliates and Trichodina was highest. The infection rate by viral necrosis virus (VNNV, 42.2%) was the highest of the viral pathogens.

• Journal of Microbiology and Biotechnology
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• v.25 no.4
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• pp.511-520
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• 2015

Triclosan, the widely used biocide, specifically targets enoyl-acyl carrier protein reductase (ENR) in the bacterial fatty acid synthesis system. Although the fish pathogen Aeromonas salmonicida subsp. salmonicida exhibits triclosan resistance, the nature of this resistance has not been elucidated. Here, we aimed to characterize the triclosan resistance of A. salmonicida subsp. salmonicida causing furunculosis. The fosmid library of triclosan-resistant A. salmonicida subsp. salmonicida was constructed to select a fosmid clone showing triclosan resistance. With the fosmid clone showing triclosan resistance, a subsequent secondary library search resulted in the selection of subclone pTSR-1. DNA sequence analysis of pTSR-1 revealed the presence of a chromosomal-borne fabV-encoding ENR homolog. The ENR of A. salmonicida (FabVas) exhibited significant homology with previously known FabV, including the catalytic domain YX₍₈₎K. fabVas introduction into E. coli dramatically increased its resistance to triclosan. Heterologous expression of FabVas might functionally replace the triclosan-sensitive FabI in vivo to confer E. coli with triclosan resistance. A genome-wide search for fabVas homologs revealed the presence of an additional fabV gene (fabVas2) paralog in A. salmonicida strains and the fabVas orthologs from other gram-negative fish pathogens. Both of the potential FabV ENRs expressed similarly with or without triclosan supplement. This is the first report about the presence of two potential FabV ENRs in a single pathogenic bacterium. Our result suggests that triclosan-resistant ENRs are widely distributed in various bacteria in nature, and the wide use of this biocide can spread these triclosan-tolerant ENRs among fish pathogens and other pathogenic bacteria.