• Journal of fish pathology
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• v.21 no.1
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• pp.21-27
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• 2008

Mass mortality occurred in mud loaches, Misgurnus mizolepis, cultured in ponds located in Kunsan. External signs of affected fish showed hemorrhage of skin and fins, Internally, pale liver with congestion, enlarged kidney, and spleen and enteritis exhibited. Causative bacteria isolated from liver, spleen, and kidney of the disease fish. In biochemical tests, the isolates were similar with those of the reference strains, A. sobria. The aerolysine gene from the present isolate was amplified PCR with the primer SOBF and SOBB for A. sobria. The isolate was identified as A. sobria on the basis of those tests. In virulence test, the present isolate resulted in the development of clinical signs identical to those in naturally infected fish. The present results conclude that the present isolate is A. sobria and can be a pathogen which causes motile aeromonad septicemia to mud loach.

• Food Science and Preservation
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• v.9 no.4
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• pp.434-440
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• 2002

The growth characteristics of 5. coli O157:H7 CDFI, A. sobria CDF3 and S. aureus CDF2 isolated from surface of carcass were investigated to improve hygienic quality of beef. The total count of carcass surface before washing was higher than that of after washing. Total count of after cooling decreased about 10$^1$∼ 10$^2$/㎠ compare with before cooling. Total count of carcass surface after transfer increased regardless seasons. The growth E. coli O157:H7 CDF1 occurred at pH 4 and 6% NaCl but A. sobria CDF3 and S. aureus CDF2 did not grow at the same conditions. Although the growth of E. coli O157:H7 CDF1 and S. aureus CDF2 was inhibited by 0.3％ lactic acid, but A sobria CDF3 did not grow in TSB containing 0.3％ lactic acid. E. coli O157:H7 CDF1 grew rapidly after 3 days incubation at 10$\^{C}$ but did not grow at 4$\^{C}$. But A. sobria CDF3 grew rapidly after 3 days incubation at 4$\^{C}$. E. coli O157:H7 CDF1 and A. sobria CDF3 were destroyed by heat treatment for 3 min at 60$\^{C}$. S. aureus CDF2 did not detect after heat treatment for 2 min at 70$\^{C}$.

• Korean Journal of Microbiology
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• v.36 no.3
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• pp.173-180
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• 2000

The intern1 spacer regions (ISR) between the 16s and 23s $1_RNA$ genes of Aeronzonus iwonii blogroupsobria and A. caviae were investigated by PCR fragment length typing and DNA sequencing. A. iwonii bv.sobria has a speciIic 16s-23s pattern of 2-4 fiagments ranging Goin 479-539 bp, with the exception of thespecies Aeron7onns cmiae, which has 3 fragments ranglog from 470-602 bp. In all of the.4 vei*onii bv. sobr,iaand A, caviae strains examined in this study, the 470-481bp Tragnent, designated TSR-1, invariably contained $tDNA^{uc(GAT)$ and $tDNA^{Ala(TGC)$ in contrast to ISR-2 (513-525 bp). ISR-3 (537-539 bp) and ISR-4 (568-602 bp)containing TEX>$tDNA^{Olu(ITC)$ A stretch of 20 nucleotides (178-197 bp) in the ISR-4 was conserved only wit11mA.caiiue, from which the A. caiiae specific primer, named prAC-F, was designed and used for PCR with aAcaviae coimnon reverse primer A PCR product of 450 bp was apparent alnong I , caiizne strains, but not ii1.4.ijeronii bv. sob~ia strains. The PCR product was oot detected t"-om strains belonging to A. hjili-o~~hila, Ebrio,aud the family Ef\ulcornertei,obncteriaceae. This study provides the first molecular tool for mdentifying the species 8.caviae.ing the species 8. caviae.

• Food Science and Preservation
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• v.10 no.3
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• pp.421-426
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• 2003

Effects of acid, salt, heat treatment and natural antimicrobials on survival of E. coli O157:H7 CDF1, A. sobria CDF3 and S. aureus CDF2 isolated from surface of carcass in minced meat was investigated. The growth of E. coli O157:H7 CDF1 and A. sobria CDF3 inhibited in minced meat containing above 4％ NaCl but not in 1％ lactic acid. The growth of S. aureus CDF2 was not inhibited significantly by addition of 4％ NaCl but inhibited completely in minced meat containing 1％ lactic acid. Survival of A. sorbia CDF3 did not show any differences during storage at 4 and 10$^{\circ}C$. E. coli O157:H7 CDF10 and A. sobria CDF3 did not detect after heat treatment at 60$^{\circ}C$ for 10 min but S. aureus CDF2 decreased only 1 log after the same treatment. Viable cell of E. coli O157:H7 CDF1 decreased 2 log in TSB containing 0.5％ Oolong tea extract after incubation for 12 hr compared with control but A. sobria CDF3 and S. aureus CDF2 did not detect at the same condition. The growth of E. coli O157:H7 CDF1, A. sobria CDF3 and S. aureus CDF2 was not inhibited by addition of 0.3％ Oolong tea extract but inhibited by addition of 0.5％ Oolong tea extract in minced meat at 20$^{\circ}C$ for 24hr.

• Journal of Microbiology
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• v.45 no.4
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• pp.297-304
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• 2007

The detection of virulence factors of Aeromonas is a key component in determining potential pathogenicity because these factors act multifunctionally and multifactorially. In this study water samples were collected from a trout farm on a seasonal basis, and diseased fish and Aeromonas species were isolated and identified. For rapid detection of six virulence factors of isolated Aeromonas, a hexaplex-polymerase chain reaction (hexaplex-PCR) assay was used. The detected virulence factors include aerolysin (aer), GCAT (gcat), serine protease (ser), nuclease (nuc) lipase (lip) and lateral flagella (laf). The dominant strain found in our isolates was Aeromonas sobria, and the dominant virulence factors were aer and nuc for all seasons. We confirmed that A. sobria and two of the virulence genes (aer and nuc) are related. We proposed a method by which one can identify the major strains of Aeromonas: A. hydrophila, A. sobria, A. caviae, and A. veronii, using hexaplex-PCR.

• Journal of Veterinary Clinics
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• v.27 no.1
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• pp.62-65
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• 2010

Arowana (Scleropages formosus) is the most valuable group of ornamental fishes and very much in demand in the ornamental fish trade and commands high price ranging from hundreds to thousands of dollars per fish. In this paper, we described a case of mortality of arowana from a private aquarium in Korea. A bacterial pathogen from fish organs (brain, kidney, liver) was cultured, identified and confirmed using Vitek System 2, API 20E test, multiplex PCR and 16S rRNA gene sequencing. The morphological and biochemical properties of the bacterium isolated from the brain, kidney and liver of the fish were similar to Aeromonas sobria. Positive amplification products using the multiplex PCR assay for detection of A. sobria were obtained from these organs. The 16S rRNA gene of the isolates from fish was identical and exhibited 100% sequence similarity with A. sobria (AY987762.1) strain available from GenBank. This bacterium contained hemolysin gene, a virulence factor that plays an important role in outbreaks of disease and is pathogenic to humans as well as in fish. Although this opportunistic bacterium was isolated from a fish without any external symptoms, this pathogen may act as a reservoir and enhance chances of zoonosis to human such as during handling.

• Microbiology and Biotechnology Letters
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• v.33 no.2
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• pp.123-129
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• 2005

Isolation and identification of pathogens from slaughter and meat processing plant were investigated. Antimicrobial activity of Amaranthus lividus against isolated pathogens such as Aeromonas sobria, Escherichia coli, Escherichia coli O157, Listeria monocytogenes, Salmonella spp., and Staphylococcus aureus was investigated. Among the chloroform, ethyl acetate and buthanol fraction of amaranthus lividus showed inhibitory effect against Aeromonas sobria CLFM1 and Escherichia coli CLFM2. Antimicrobial substance in chloroform fraction was isolated by silica gel adsorption column chromatography, sephadex LH-20 column chromatography and silica gel partition column chromatography. The antimicrobial compound of amaranthus lividus was identified as diethyl phtalate by HPLC, GC-MS, H-NMR and C-NMR.

• Korean Journal of Microbiology
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• v.43 no.2
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• pp.106-110
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• 2007

The detection and distribution of Aeromonas in water supplies were investigated by using the USEPA Method 1605. Water samples were collected from the Han River, finished waters and tap waters supplied from Water Treatment Plants in Seoul monthly from July 2002 to December 2003. Aeromonas species in each water sample were quantified based on the development of yellow colonies on the surface of membrane filter using a selective medium (Ampicillin-Dextrin Agar with Vancomycin). The Quality Control (QC) for this study met the acceptance criteria of Method 1605. The concentrations of Aeromonas species in surface water samples ranged from $1.0{\times}10^{0}\;to\;9.8{\times}10^{3}\;CFU/ml$. Aeromonas species were found only in one tap water sample with concentration of 1 CFU/500 ml. No Aeromonas species were found in any finished water samples. Aeromonas species detected here were identified as A. salmonicida(51%), A. caviae(4.7%), A. schubertti(3.4%), A. sobria(3.8%), A. hydrophila(2.1%), and A. ichithiosmia(0.4%). A. salmonicida was the dominant species, which is of no significance to human health. Chlorine resistance of A. salmonicida was evaluated and as a result, 99.99% of A. salmonicida decreased after 30 seconds exposure at residual free chlorine 0.2 mg/L. These suggest that the waters supplied in Seoul may be safe against the pathogenic agent Aeromonas.

• Journal of fish pathology
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• v.30 no.2
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• pp.79-88
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• 2017

At the present, fish farms are suffering a lot of economic losses due to infectious diseases caused by various pathogens including aeromonad. Aeromonad is ubiquitous bacteria that causes infectious diseases. At least 26 species in the genus Aeromonas have been reported to cause fatal infections not only in salmonid fishes, but also in other freshwater and seawater fishes. Molecular techniques based on nucleic acid sequences of 16S rDNA and housekeeping genes can be used to identify the Aeromonas species. In this study, The genus Aeromonas was isolated from salmonid fishes of sixteen fish farms in Gangwon-Do, Korea and phylogenetically identified based on the sequences of 16S rDNA and housekeeping genes for Aeromonad, i.e. RNA polymerase sigma factor ${\sigma}^{70}$ (rpoD) or DNA gyrase subunit B (gyrB). Consequently, 96 strains were collected from Atlantic salmon (Salmo salar), coho salmon (Oncorhynchus kisutch), masou salmon (Oncorhynchus masou) and rainbow trout (Oncorhynchus mykiss), and 36 isolates were identified as the genus Aeromonas by 16S rDNA analysis. Thirty six Aeromonad isolates were further analysed based on rpoD or gyrB gene sequences and found Aeromonas salmonicida (24 isolates), A. sobria (10 isolates), A. media (1 isolates) and A. popoffii (1 isolates), indicating that A. salmonicida is a main infectious bacteria in Salmonid fishes in Gangwon-Do. It was also proved that the phylogenetic identification of Aeromonas species based on the sequences of housekeeping gene is more precise than the 16S rDNA sequence.

• Journal of fish pathology
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• v.35 no.2
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• pp.215-223
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• 2022

Disease including parasite, bacteria and virus cause serious mortality to salmonid fish in the aquaculture. In this study, we investigated the current disease status of the rainbow trout (Oncorhynchus mykiss) and coho salmon (Oncorhynchus kisutch) in Yanayang, Pyeongchang, Jeongseon and Yeongwol of Gangwon province in 2021 and performed molecular characterization of those pathogen. For parasites, Ichthyophthirius multifiliis was observed at 2 farms. For bacteria, we identified Aeromonas sobria from kidney of rainbow trout using phylogenetic analysis of gyrB gene. A. salmonicida were isolated from necrosis site of gill cover and fin in coho salmon and necrotic lesion of fin in rainbow trout. Phylogenetic analysis using vap gene indicated that A. salmonicida isolated in this study were clustered with previously reported A. salmonicida subsp. salmonicida isolates. For virus, JRt-Nagano type of infectious haematopoietic necrosis virus was detected in rainbow trout, but infectious pancreatic necrosis virus and Oncorhynchus masou virus were not detected. These results provide useful information for the prevention of disease spread and transmission when cultivating new species such as Atlantic salmon in Korea.