• Journal of fish pathology
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• v.20 no.3
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• pp.221-227
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• 2007

In this study, one hundred strains of bacterial flora were isolated from the intestine of cultured and wild black rockfish Sebastes inermis collected in Yeosu and examined for drug resistance to 9 antibiotics. From cultrued fish, the isolated bacteria were Photobacterium group (26 strains) and Acinetobacter group (18 strains) of Gram-negative, and unidentified marine sediment bacterium (6 strains) of Gram-positive. From wild fish, Photobacterium group (18 strains), Acinetobacter group (12 strains) and Shewanella group (5 strains) of Gram-negative and Bacillus group (8 strains), Staphylococcus group (4 strains), and unidentified marine sediment bacterium (3 strains) of Gram-positive. Intestine flora of wild black rockfish was more diverse than that of one cultured. The drugs tested were tetracyclines (oxytetracycline), aminoglycosides (gentamicin), macrorides (erythromycin) and quinolones (flumequine, oxolinic acid, norfloxacin, ofloxacin, enrofloxacin and ciprofloxacin). Sensitivity to all seven antibiotics except oxytetracycline and oxolinic acid was higher in bacteria from wild fish than from cultured ones, although wild isolates were more resistant than control strain Escherichia coli ATCC9637. This suggests that use of antibiotics in the fish farm might have some resistance in intestinal flora of wild fish.

• Journal of Veterinary Clinics
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• v.26 no.2
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• pp.150-154
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• 2009

In this paper, we described a case of mass mortality of doctor fish from a private fish hatchery farm in Korea with a history of abnormal swimming behavior, diffuse bleeding on the skin and fins and sudden death caused by fish pathogenic bacteria, Citrobacter freundii. Twelve moribund fish fingerling samples were submitted to College of Veterinary Medicine, Seoul National University in October 2008 for diagnostic examination. Diagnostic results showed that the morphological and biochemical properties of the bacteria isolated from the moribund fish were C. freundii. The remaining diseased fish from the hatchery farm were given treatment based on our recommendation and successfully recovered.

• Korean Journal of Ecology and Environment
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• v.39 no.2 s.116
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• pp.219-225
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• 2006

Bacterial community structure in the Juam Reservoir was analysed using fluorescent in situ hybridization (FISH) technique from April 2005 to January 2006. Total bacterial numbers varied in the range of 1.58 ${\sim}\;2.73{\times}\;10^6\;cells\;mL^{-1}$ proportional to the concentration of chi-a and had the minimal value in January. The ratios of ${\alpha}\;{\cdot}\;{\beta}\;{\cdot}\;{\gamma}$-subclass proteobacteria and Cytophaga-Flavobacterium (CF) group to total bacteria ranged from 45.1% to 77.5%, and the ratios of ${\alpha}\;{\cdot}\;{\beta}\;{\cdot}\;{\gamma}$-subclasses to total bacteria in June and September with the concentration of chi-a measured were lower than those ratios in April and January. It suggests that enriched growth of Microcystis aeruginosa may inhibit the metabolic activlty of ${\alpha}\;{\cdot}\;{\beta}\;{\cdot}\;{\gamma}$-subclass proteobacteria. However, the ratio of CF group bacteria represented no large change depending on algal bloom. In terms of nitrifying bacteria, the numbers of ammonia-oxidizing bacteria ranged from 9.9 ${\times}\;10^4\;to\;25.5\;{\times}10^4\;cells\;mL^{-1}$ with sharp fluctuation whereas those of nitrite-oxidizing bacteria varied in 8.7${\sim}9.8{\times}10^4\;cells\;mL^{-1}$ without noticeable change except the maximal value of $20.3{\times}10^4\;cells\;mL^{-1}$ in January maybe due to the high DO.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.10a
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• pp.375-376
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• 2001

Many studies have been made on antimicrobial activity of Sawa-wasabi (Wasabia japonica). It has been reported that the essential oil of Sawa-wasabi has a particularly strong antimicrobial effect against Escherichia coli, Salmonella typhi, Pseudomonas aeruginosa and fish pathogenic bacteria such as Edwardtarda siella and Vibrio hollisae (Nishida, 1958; Inoue et al. 1983;).(omitted)

• Journal of fish pathology
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• v.37 no.1
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• pp.37-48
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• 2024

This study evaluated in vitro antimicrobial properties of Bacillus subtilis KCTC 1326 as an environmentally friendly alternative to antibiotics. B. subtilis KCTC 1326 was characterized on biochemical properties and antibiotics susceptibility. It exhibited antimicrobial effects against all 12 species of fish bacteria used in this experiment. Among them, the largest antibacterial zone was observed for Streptococcus parauberis (34 mm), while the smallest antibacterial zone was observed for Citrobacter freundii (8 mm). Additionally, in the co-culture inhibitory assay of B. subtilis and Edwardsiella piscicida, the growth of E. piscicida was suppressed with increasing concentrations of B. subtilis KCTC 1326, with complete inhibition observed at 107 and 108 CFU/mL of B. subtilis KCTC 1326 after 24 hours of incubation. Moreover, at 48 hours of incubation, the growth of E. piscicida was inhibited across all concentration ranges of B. subtilis KCTC 1326. Therefore, this study indicated the utilizing of B. subtilis KCTC 1326 as an antimicrobial for controlling fish bacterial diseases.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.2
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• pp.221-225
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• 2005

An in vitro study was conducted to examine the effect of monensin or fish oil addition on bio-hydrogenation of $C_{18^-} unsaturated fatty acids and CLA production by mixed ruminal bacteria when incubated with safflower oil. Commercially manufactured concentrate (1%, w/v) with safflower oil (0.2%, w/v) were added to mixed solution (600 ml) of strained rumen fluid and McDougalls artificial saliva (control). Monensin $Rumensin^{(R)}$, 10 ppm, w/v, MO), mixed fish oil (0.02%, w/v, absorbed to 0.2 g alfalfa hay, FO) or similar amounts of monensin and fish oil (MO+FO) to MO and FO was also added into the control solution. All the culture solutions prepared were incubated in the culture jar anaerobically at $39^{\circ}C$ up to 12 h. Higher pH (p<0.047) and ammonia concentration (p<0.042) were observed from the culture solution containing MO at 12 h incubation than those from the culture solutions of control or FO. The MO supplementation increased (p<0.0001-0.007) propionate proportion of culture solution but reduced butyrate proportion at 6 h (p<0.018) and 12 h (p<0.001) of incubations. Supplementation of MO or MO+FO increased (p<0.001) the proportions of $C_{18:2}$. The MO alone reduced (p<0.022-0.025) the proportion of c9,t11-CLA compared to FO in all incubation times. The FO supplementation increased the proportion of c9,t11-CLA. An additive effect of MO to FO in the production of c9,t11-CLA was observed at 6 h incubation. In vitro supplementation of monensin reduced hydrogenation of $C_{18^-}$UFAs while fish oil supplementation increased the production of CLA.

• Journal of Aquaculture
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• v.16 no.2
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• pp.118-123
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• 2003

This study was conducted to investigate the disinfection effects of chlorine dioxide ($ClO_2$) on 4 fish pathogenic bacteria (Vibrio anguillarum, Edwardsiella tarda, Streptococcus sp. and Staphylococcus sp.) isolated from infected olive flounders. The bacteria were exposed to different concentrations of ClO$_2$ (0.129, 0.246 and 0.455 ppm) and response times (0.5, 1, 3, 5 and 10 min), and then were incubated for 12 hr. The effective disinfection concentrations of $ClO_2$ against experimental bacteria by $ClO_2$ for 0.5 min were observed with 0.455 ppm for Staphylococcus sp., 0.246 ppm for V. anguillarum and E. tarda, and 0.129 ppm for Streptococcus sp., respectively. The duration of exposure at low concentration of $ClO_2$ increased for the disinfectant ability to experimental bacteria.

• Journal of fish pathology
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• v.17 no.1
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• pp.39-55
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• 2004

Hundreds of medicinal herbs have been using for the purpose of diseases treatment and immune enhancement for human being and other animals including fishes. Among them, 49 species of medicinal herbs were selected and tested for antibacterial activities against 19 strains of fish pathogenic bacteria in different 4 species. The 49 medicinal herbs were extracted by water and ethyl alcohol. The extracts were freeze dried and some paper discs from the extracts were prepared for the evaluation of antibacterial activity. The tested pathogenic bacteria were 5 strains of Edwardsiella tarda, 5 strains of Vibrio sp., 4 strains of Lactococcus garvieae, 1 strain of Lactococcus raffinose, 1 strain of Streptococcus parauberius, and 3 strains of Streptococcus iniae. The Galla rhois (Obaeja), Gaeonnamu and Hwangleyon showed antibacterial activities on both gram negative and gram positive fish pathogenic bacteria. The Youkgae, Sangbaekpi, Bogolji and Gamcho showed very effective antibacterial activities on gram positive pathogens while Jiyu, Aeyoeb and Yeonkyo showed very effective on gram negative pathogens.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.4
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• pp.1194-1201
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• 2015

This study conducted to investigate the impact of raw material freshness on the quality and hygienic safety of anchovy fish sauce and suggest the importance of raw material freshness to make high-quality and hygienic anchovy fish sauce by measuring the chemical compositions and histamine. To devide the raw material's freshness levels, raw anchovy was left for 24 hours and was sampled every 4 hour(Group I-VII). As a result, the levels of VBN(volatile basic nitrogen) and histamine increased as time passed each contents were 16.29-87.65 mg/100 g and 6.14-1499.63 mg/100 g respectively. As fish sauce fermented for 18 months, the contents of VBN were 205.31-270.51 mg/100 g and histamine were 120.54-1707.22 mg/100 g, respectively. These results means the levels of VBN and histamine of raw materials are significantly associated with the hygiene of anchovy fish sauce. To investigate the reason of different contents of histamine at each fish sauce, bacteria from each groups were isolated and identified. At group V-VII those the lowest three groups, Leconostoc mesenteroides ssp. cremoris was identified and that produced the highest content of histamine 22.88-101.69 mg/kg and the others produced histamine 3.79-20.2 mg/kg. This means that fish sauce made by low freshness materials contain bacteria have strong ability to make histamine from histidine. Therefore, the freshness of raw material influences the hygiene and safety of fish sauce, and it is most important to manage the freshness of raw material to make the high quality and hygienically safe fish sauce.

• Journal of fish pathology
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• v.24 no.2
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• pp.113-120
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• 2011

In this study, we examined antimicrobial activity of the bee venom isolated from honeybee (Apis mellifera L.) against fish pathogenic bacteria, Edwardsiella tarda, Vibrio ichthyoenteri and Streptococcus iniae of cultured olive flounder, Paralichthys olvaceus. The bee venom exhibited significant antimicrobial activity against the both Gram-negative bacteria, E. tarda and V. ichthyoenteri and Gram-positive bacteria, S. iniae. Minimum inhibitory concentration (MIC) and minimun bactericidal concentration (MBC) of the bee venom were 17.6 ${\mu}g$/ml 34.6 ${\mu}g$/ml against E. tarda., and 1.76 ${\mu}g$/ml, 6.8 ${\mu}g$/ml against V. ichthyoenteri, respectively. MIC and MBC of the bee venom were 3.49 ${\mu}g$/ml, 11 ${\mu}g$/ml, respectively against S. iniae. The postantibiotic effect (PAE) of the bee venom was 5 hr, 6 hr, and 7 hr against E. tarda, V ichthyoenteri, and S. iniae, respectively. In addition, its antimicrobial activity was stable under various pH conditions. According to these results, the bee venom showed the excellent antimicrobial activity against the tested pathogenic bacteria.