• Journal of Life Science
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• v.24 no.8
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• pp.880-886
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• 2014

In this study, we isolate and identify bacteria from seawater collected from Jeju coast, to evaluate the antimicrobial activity against the fish pathogenic bacteria. 14 bacterial strains were isolated and identified using physiological, biochemical and molecular tools. Antibacterial activity of all the 14 isolates were screened against four major fish pathogens namely, two Gram-positive: Streptococcus iniae, Streptococcus parauberis and two Gram-negative: Vibrio anguillarum, Edwardsiella tarda. Results revealed that among the 14 isolates, MK-11 was found to have antibacterial activity against S. iniae, S. parauberis, V. anguillarum Particularly, S. iniae was susceptibility with the MIC value of $250{\mu}g/ml$. The biochemical and physio-chemical results reveal that MK-11 had the sugar-alcohol disassemble ability of the D-sorbitol and D-mannitol. Also the utilization of the yeast extract, sorbitol and di-potassium phosphate were noted to be high. The optimum culture condition such as pH and temperature was recorded as pH 6.0, $25^{\circ}C$ and along with 1% NaCl which differs from the previous reports particularly in nutrient resolutions. As results of the analysis of 16S rDNA sequences, MK-11 show the high similarity with Paenibacillus polymyxa, P. jamilae, P. brasilensis 99.78%, 99.43%, 99.39%, repectively. Hence, in the present study, the isolated Paemibacillus sp. MK-11 from Jeju seawater possesses the antibacterial activity against fish pathogens and it could be used as a new antibiotic agents against the gram positive fish pathogens.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.45 no.1
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• pp.35-42
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• 2012

We investigated the effect of dietary supplementation with probiotics on growth performance, feed utilization, innate immunity and disease resistance against Streptococcus iniae in juvenile olive flounder Paralichthys olivaceus. Four experimental diets were made by supplementation with three Bacillus sp. probiotics (B. subtilis, B. pumilus and B. licheniformis) into a basal diet (control) at 0.5% each. Three-hundred fish (average BW, 20 g) were randomly distributed (25 per tank) into twelve 150 L capacity polyvinyl circular tanks with three replicates per dietary treatment. Triplicate groups of fish were fed the experimental diets to apparent satiation (twice per day, 09:00 and 17:00 h) for nine weeks. After the feeding trial, a challenge test was directly conducted against S. iniae. The results indicated that dietary supplementation with the probiotic, Bacillus sp, seemed to improve growth performance of olive flounder. Hematological parameters and innate immunity as determined by nitroblue tetrazolium, myeloperoxidase or superoxide dismutase activities were not significantly affected by the probiotic supplementation. The result from the challenge test suggested that dietary supplementation with probiotics Bacillus sp. can improve the disease resistance of olive flounder against S. iniae.

• Journal of Food Hygiene and Safety
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• v.27 no.3
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• pp.290-294
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• 2012

Vibrio spp. and Streptococcus spp. have caused a considerable disease of farmed fish and economic loss in fish farming and seafood industry. In this study, the efficacy of an aquatic disinfectant tablet composed to calcium hypochlorite was evaluated against V. anguillarum and S. iniae. A bactericidal efficacy test by broth dilution method was used to determine the lowest effective dilution of the disinfectant following exposure to test bacteria for 30 min at $4^{\circ}C$. An aquatic disinfectant tablet and test bacteria were diluted with distilled water (DW), hard water (HW) or organic matter suspension (OM) according to treatment condition. V. anguillarum on the DW, HW and OM condition was completely inactivated with 16,000 15,000 and 13,000 fold dilutions of the disinfectant, respectively. On the DW, HW and OM condition, S. iniae was absolutely inactivated with 17,000 16,000 and 14,000 fold dilutions of the disinfectant, respectively. As an aquatic disinfectant tablet possesses bactericidal efficacy against fish pathogenic bacteria such as V. anguillarum and S. iniae this disinfectant solution can be used to control the spread of fish infective bacterial diseases.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.5
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• pp.567-574
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• 2022

Immunostimulating effects of fucoidan administration to rockfish Sebastes schlegelii at a concentration of 20 g/kg of diet were evaluated under high water temperature condition. The oral administration of fucoidan mixed with feed at a concentration of 20 g/kg of diet for 2 weeks increased the interleukin 1β gene in the intestine and kidney of fish by 5.7 and 6.3 times, respectively. In addition, when the water temperature was gradually increased from 24 to 31.4℃ for 2 weeks, LT₅₀ delayed by 24 h in the fucoidan treated group compared to that in the control group, and mortality also reduced. Streptococcus iniae infection at a concentration of 1.50×10⁰ CFU/fish at 28℃ delayed LT₅₀ by 12 h in the fucoidan-treated group. Furthermore, the overall survival rate was 0% in the control group and 20% in the fucoidan-treated group. This study confirmed the applicability of dietary additives such as fucoidan as an immune activator of rockfish under high temperature condition.

• Journal of fish pathology
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• v.27 no.1
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• pp.35-45
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• 2014

In this study, we investigated the effects of dietary 1% garlic extract on nonspecific immune responses and fish diseases (Viral Hemorrhagic Septicemia Virus, Vibrio anguillarum, Streptococcus iniae and Edwardsiella tarda) resistance in olive flounder Paralichthys olivaceus. Fish were fed a commercial diets supplemented with 1% garlic extract for 4 weeks. After the 4 weeks feeding experiment, the artificial infection was made by V. anguillarum, S. iniae, E. tarda and VHSV. And the cumulative mortality was monitored for 2 weeks after artificial infection. The cumulative mortalities decreased in all experiments except for group of E. tarda compared to control group. We observed significantly higher levels of the hematocrit, glucose, total protein, lysozyme activity and the macrophage activity in the experimental group compared to the control group. In the experiments of drug sensitivity and MIC using the three bacteria (V. anguillarum, S. iniae and E. tarda), 1% garlic extract was more effective than the previously reported fermented garlic powder. These results suggested that garlic extract can increase the disease resistance of olive flounder against V. anguillarum, S. iniae and VHSV and the ability of nonspecific immune responses.

• Journal of fish pathology
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• v.26 no.3
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• pp.231-240
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• 2013

Adjuvants are immune enhancers that are often used in vaccination to augment the immune response of a vaccine, thereby enhancing the protective immunity against the targeted disease. In the present study, we used the recombinant protein, such as rRbCC1, this protein was produced from rock bream CC chemokine 1. To verify the adjuvant effects of this recombinant protein, the immune responses of rock bream to Streptococcus iniae (S. iniae) FKC vaccination, which alone or in combination with recombinant protein was analyzed and then also performed experimental challenge with live S. iniae. The result of serum agglutination titres was showed relatively low levels however, the efficacy of FKC vaccine still conferred protection against S. iniae. Moreover, the adverse effects result showed that no statistically significant difference was revealed between high concentration injected and non-injected fish groups, generally. The relative percent survival (RPS) of FKC + recombinant vaccination group was significantly higher than that of vaccinated group with FKC alone. After experimental challenge to the rock bream by injection with live bacteria (S. iniae), the FKC + rRbCC1 vaccination group was showed 87.0% RPS, however, the RPS of FKC alone vaccination was 68.2%. The results indicated that the recombinant protein as an adjuvant had a clear synergism to injection vaccine of rock bream.

• Korean Journal of Microbiology
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• v.42 no.3
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• pp.199-204
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• 2006

Streptococcosis of olive flounder(Paralichthys olivaceus) is an important bacterial disease in Jeju island. In this study, we investigated monthly infection pattern of this disease in different size of the flounder fish. Even though the disease occurred throughout the year, the infection ratio was relatively higher in the months with warm water season. The infection was more prevalent in adult flounder over 30 cm total length compare to these of small size fish. Two infectious species of streptococcosis pathogens were detected by multiplex PCR assay. Detection ratios of Streptococcus iniae and S. parauberis reached up to 46% and 54%, respectively, from June 2003 to May 2005 in Jeju island. S. iniae occurred intensively from September to October, whereas S. parauberis reported from March to May. S. iniae and S. parauberis infections of cultured flounder share some common features, but clinical findings showed considerable differences between two diseases. Distended abdomen, protruded anus and ascitic fluid in the peritoneal cavity are evident lesions detected in S. iniae infection, whereas, flounders infected by S. parauberis showed prominent lesions such as darkened surface and haemorrhaging in the non-ocular side. Both streptococcosis pathogens were sensitive to antibiotics, such as ampicillin and amoxicillin. However, S. iniae strains were more sensitive to doxycycline, erythromycin and oxytetracycline than S. parauberis strains.

• Journal of fish pathology
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• v.20 no.2
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• pp.109-117
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• 2007

This study was performed to identity non hemolytic streptococcus from cultured flounder (Paralichthys olivaceus) with Streptococcosis in the Jeju island. The result of BIOLOGTM test was Streptococcus uberis that simility of 0.5 and 98% identified in MicroLogTM system (Release 4.05). Carbohydrate utility pattern was dextrin, N-acetyl-D-glucosamine, arbutin, maltose, maltotriose, D-cellobiose, D-fructose, D-mannose, α-D-glucose, D-mannitol, β-methyl D-glucoside, salicin, sucrose, D-trehalose, pruvatic acid methyl ester, mono-methyl succinate, glycerol. In addition hemolysis test for S. parauberis and were S. iniae hemolysis in BAP (Blood agar plate). Antibiotic test for S. parauberis were Ampicillin, Amoxicillin and Fluoroquinolone sensitivity. Mutiplex PCR assay were detected S. pauberis (718 bp), S. iniae (870 bp) L. garviae (1,100 bp). Dectected S. parauberis (718 bp) were result of 16S rRNA sequence identified with S. parauberis (Gene bank accession number X89967). All isolated S. parauberis that with bouned by one group. The result were S. pauberis that γ-hemolytic chain form cocci and negative reaction of catalase, Multiplex PCR assay were 718 bp amplicon size.

• Journal of fish pathology
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• v.19 no.1
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• pp.17-33
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• 2006

• 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.