• Journal of Environmental Science International
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• v.14 no.12
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• pp.1129-1139
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• 2005

A series of experiments was conducted to identify the potential of five phytoplankton species as standard test species for marine ecotoxicological tests. The candidate phytoplankton species are Skeletonema costatum, Heterosigma akashiwo, Prorocentrum micans, Isochrysis galbana, and Tetraselmis suecica. Salinity tolerance and sensitivity on potassium dichromate as a reference material were identified. Toxicity of eleven ocean dumped sewage sludges and four red tide expellent extracts were estimated by the inhibition of population growth rates (PGR) of marine diatom S. costatum, While most species revealed relatively weak tolerance on salinity, T. suecica demonstrated the highest salinity tolerance ranged from $5\~35$ psu and the others $15\~35$ psu. H. akashiwo revealed the highest sensitivity as 72h $IC_{50}$=0.76mg/L and T. suecica the lowest as 72h $IC_{50}$=8.89mg/L on potassium dichromate. Sludge extracts from industrial waste, domestic sewage and livestock farm waste sludge showed high toxicity as 72h $IC_{50}$<$2\%$ and lowest toxicity from filtration bed sludge as 72h $IC_{50}$=$30.50\%$ NOEC (No Observed Effective Concentration) of sludge extract ranged from <$0.4\%$ to $1.6\%$ and this indicated high phytotoxicity of ocean dumped sewage sludge. The test sensitivity of phytoplankton PGR inhibition was much higher than those of marine rotifer Brachionus plicatilis mortality test and bioluminescent inhibition test by marine bacteria Vibrio fischeri, and comparable with the sea urchin (Strongylocentrotus intermedius) fertilization test. As a result the phytotoxicity test using phytoplankton PGR inhibition ($IC_{50}$) must be a useful tool for marine phyto-toxicological evaluation of ocean dumped materials.

• Korean Journal of Ichthyology
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• v.29 no.1
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• pp.62-68
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• 2017

The Alaska pollock (Gadus chalcogrammus) belongs to the family Gadidae; it is a cold water fish, and has been developed as a novel aquaculture species in Korea. In this study, we describe ongoing surveillance for aquatic animal pathogens based on growth stages. We investigated bacterial flora in rearing water, and monitored pathogens; we also analyzed histopathological traits of abnormal fish. In rearing water, the total bacterial counts were $2.1{\times}10^3cfu/mL$ and Vibrio spp. (52%) were predominant in the larvae stage. In the juvenile and adult stages, the total bacterial counts were $3.4{\times}10^3$ and $3.2{\times}10^2cfu/mL$, respectively (with Pseudomonas sp. as the predominant species; 90% and 52%). This result revealed that the bacterial flora in rearing water changed depending on the feeding types. No virulent-bacteria or problematic viruses (VHSV, viral hemorrhagic septicemia virus; NNV, nervous necrosis virus; MBV, marine birnavirus) were detected from outwardly healthy fish using either culture or PCR assay. Some juveniles (less than 5%) had gas bubbles on the gill lamellae, degeneration of the corneal epithelium, and choroid gland degeneration, suggesting that these symptoms were caused by external injury and secondary infection by opportunistic bacteria. Disease management is important to cope with disease emergence in the novel aquaculture species Alaska pollock.

• Journal of Aquaculture
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• v.22 no.1
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• pp.51-55
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• 2009

Transcriptional response of the second isoform of glyceraldehyde (GAPDH-2) to infectious challenges using various bacterial species and the rockbream iridovirus (RBIV) was examined in the spleen of the barred knifejaw (Oplegnathus fasciatus). Bacterial challenges of the juvenile barred knifejaws with Escherichia coli, Edwardsiella tarda, Vibrio anguillarum and Streptococcus iniae resulted in the significant elevation of the GAPDH-2 transcripts in the spleen up to 12-fold relative to that in the non-challenged controls (PBS-injected). In addition, the barred knifejaw fingerlings injected with RBIV stock also represented the highly upregulated mRNA expression of the GAPDH-2 up to more than 20-fold when compared to that of control fingerings. Results obtained from this study strongly suggest that the GAPDH-2 is no longer a housekeeping glycolytic protein and rather than that it might be associated with immune-relevant cellular activities. From this finding, the traditional dogma for the use of GAPDH as an invariant standard for gene expression assays should be carefully revised depending on the kinds of biological stimulations applied in this species.

• Preventive Nutrition and Food Science
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• v.7 no.3
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• pp.305-309
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• 2002

Raw soybean sprouts were tested for contamination with the following bacteria which have potential for pathogenesis or food spoilage : Salmonella spp., Escherichia coli O157:H7, Yersinia enterocolitica, Vibrio parahae-molyticus, Aeromonas hydrophila, Plesidomonas shigeloides, Pseudomonas aeruginosa, Staphylococcus aureus, Lis-teria monocytogenes, Bacillus cereus, Clostridium perfringens, Campylobacter jejuni, Erwinia spp., and Fusarium spp. Three of the above strains were isolated from the sprouts, and identified by morphological and biochemical methods including an API kit and ATB automated identification system. The isolate cultured in Cereus selective agar, a selective medium, was a Gram-positive, rod shaped, anaerobic spore former. The biochemical and culture tests revealed the following characteristics: catalase-positive, no growth on Simmon's citrate, NO₂ production and requirement of arginine for growth; the ATB automated identification system gave 99.8 % agreement for the identification of Bacillus cereus to the species level. The isolate cultured in Macconkey agar selective medium was Gram-negative, rod shaped and a gas former; the ATB-system gave 99.9% agreement for the identification of Aeromonas hydrophila to the species level. The isolate found in Pseudomonas isolation agar was Gram-negative, rod shaped, cytochrome oxidase-positive, a reducer of nitrates to nitrogen, and pyocyanin producer; the ATB-system gave 99.9 % agreement for the identification of Pseudomonas aeruginosa to the species level. These results indicate that the three bacteria species present in the soybean sprouts were Bacillus cereus, Aero-monas hydrophila, and Pseudomonas aeruginosa. Salmonella spp., Escherichia coli O157:H7, and Yersinia enter-ocolitica, which are associated with serious disease in humans, were not isolated from soybean sprouts examined in this study.

• Journal of Microbiology and Biotechnology
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• v.17 no.12
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• pp.2046-2055
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• 2007

Wild-type V. vulnificus cannot grow using lactose as the sole carbon source or take up the sugar. However, prolonged culture of this species in media containing lactose as the sole carbon source leads to the generation of a spontaneous lactose-utilizing (LU) mutant. This mutant showed strong ${\beta}$-galactosidase activity, whereas the wild-type strain showed a barely detectable level of the activity. A mutant with a lesion in a gene homologous to the lacZ of E. coli in the bacterium no longer showed ${\beta}$-galactosidase activity or generated spontaneous LU mutants, suggesting that the lacZ homolog is responsible for the catabolism of lactose, but the expression of the gene and genes for transport of lactose is tightly regulated. Genetic analysis of spontaneous LU mutants showed that all the mutations occur in a lacI homolog, which is located downstream to the lacZ and putative ABC-type lac permease genes. Consistent with this, a genomic library clone containing the lad gene, when present in trans, made the spontaneous LU mutants no longer able to utilize lactose as the sole carbon source. Taken together with the observation that excessive amounts of exogenously supplemented possible catabolic products of lactose have negative effects on the growth and survivability of V. vulnificus, we suggest that V. vulnificus has evolved to carry a repressor that tightly regulates the expression of lacZ to keep the intracellular toxic catabolic intermediates at a sublethal level.

• 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℃.

• Journal of Food Hygiene and Safety
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• v.11 no.4
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• pp.277-285
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• 1996

Retrospective study on the comparison of outbreaks of food poisoning for food hygiene in Korea and Japan. The average value of morbidity rate by year in Korea during the period of 1971 to 1992 was 2.9 per 100,000 population, and that of Japan was 29.1. The mean value of mortality rates in case of food poisoning by year in Korea was 2.33%, and that of Japan was 0.07%. When compared the rates of morbidity and mortality between Korea and Japan during the same period, the morbidity rates of Japan were much higher than those of Korea (p<0.01). However, mortality rate of patients in Korea were much higher then those of Japan(p<0.01). Resulting from comparative observation of food poisoning by preparing facilities between Korea and Japan. The highest list the places where the outbreaks occurred was home-made foods accounted for 48.8% of the total cases in Korea and that of Japan was restaurants accounted for 33.0%. Causative foods in Korea, the most common incrimination vehicles were seafood, meat and animal products and grain and vegetables, including mushroom. However, in the case of the common incrimination vehicles Japan were unknown and other foods, seafood, vegetables and meat and animal products etc.. Food poisoning of pathogenic substance in Korea were 60.9% of bacterial food poisoning of the total cases showing that Vibrio species, Salmonella spp., Staphylococcus spp., pathogenic E. coli, Clostridium spp. and other spp. were 33.3%, 26.2%, 16.3%, 5.3%, 0.4% and 18.5%, respectively. On the other hand, in Japan, major causes were Vibrio spp. (45.7%), Staphylococcus spp. (23.7%), Salmonella spp. (16.8%), pathogenic E. coli (3.8%), Clostridium spp. (0.2%) and other spp. (9.6%).

• Korean Chemical Engineering Research
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• v.44 no.1
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• pp.81-86
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• 2006

This study was carried out to investigate the antimicrobial and antioxidant activities for applications of food additives and medicine using Rumex crispus which widely grown in domestic area. Antimicrobial activities of extract fractions were observed in all microbial species except for Pseudomonas areuginosa. Especially, Vibrio vulificus and Saccharomyces cerevisiae presented obvious antimicrobial activity. Antioxidant activities of the fractions of R. crispus extract were determined by DPPH radical scavenger activity. The fraction of ethyl acetate was presented similar antioxidant activities compared with that of BHA and ascorbic acid. Also, ethyl acetate fraction contained higher phenolic compounds than that of others. The antioxidant activity in the fractions of R. crispus extract was closely related with the content of phenolic compounds in that.

• Journal of fish pathology
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• v.13 no.1
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• pp.67-73
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• 2000

This study was carried out to elucidate the preliminary ecosystem of the heterotrophic bacterial flora in Kunsan Bay located in western costal area of Korea. Samples were collected at 5 sampling stations. Among 123 bacterial isolates, 9 genera of bacteria were appeared as follows; Vibrio spp.(44 isolates/35.7%), Pseudomonas spp.(42 isolates/34.1%), Aeromonas spp.(11 isolates/8.9%), Moraxella spp.(9 isolates/7.3%), Enterobacteria spp.(6 isolates/4.8%), Bordetella spp.(3 isolates/2.4%), Alkaligenesis spp.(3 isolates/2.4%), Flavobacterium spp.(2 isolates/1.6%), and Staphylococcus spp.(3 isolates/2.4%) respectively. Total viable heterotrophic bacteria was ranged from $5{\times}10^3$ to $1{\times}10^5$ CFU/ml and the most abundant viable counts of bacterial population were showed at the stations 2 and 3. This result indicates that the coastal area around Kunsan bay is getting to contaminate far more by municipal wastewaters and industrial byproducts. and so the outbreak of the bacterial diseases will be increased in fish farms.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.5
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• pp.495-504
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• 2022

This study examined the antimicrobials properties of bacteria using the minimum inhibitory concentration method. The bacteria were isolated from 30 shellfish (oysters and short neck clams) collected from Jawol-myeon, Ongjin-gun, Incheon and Iwon-myeon, Taean-gun, Chungcheongnam-do, on the west coast of Korea. A total of 528 bacteria were isolated from June to October 2020 and were classified into land-originating (LB; 264 strains) and marine-originating (MB; 264 strains) bacterial groups. Of the LB strains, 10 genera were identified, of which nine were Enterobacteriaceae. All MB strains were identified as species of the genus Vibrio spp.. Antimicrobial resistance to one or more agents was observed in 77.3% of the LB strains, and 90-100% of them were resistant to ampicillin Escherichia spp. were not resistant to ampicillin. The overall multidrug resistance rate of the LB strains was 49.2%, with 85 resistance patterns. Antimicrobial resistance to one or more agents was observed in 98.1% of the MB strains, because most of the V. alginolyticus and V. parahaemolyticus strains were resistant to ampicillin. The overall multidrug resistance rate of the MB strains was 1.9% with 19 resistance patterns.