Laboratory of Aquatic Animal Diseases; Animal, Plant and Fisheries Quarantine and Inspection Agency, Republic of Korea
Abstract
Eels (Anguilla japonica) have been most important freshwater aquaculture fish in Korea.7 Genus Aeromonas containing esp. A. hydrophila have been one of the importantbacterial pathogens both in freshwater aquaculture industry including eels and in wild freshwater habitat animals in the world-wide.3-5 Some kinds of Aeromonas sp. esp. A. hydrophila have been known to cause Aeromonad septicemia in aquatic animals from fish to mammals.1,2,5,6,8 We isolated kinds of Aeromonas sp. from aquaculture eels and its aquatic environment. The A. hydrophila was the most prevalent species (45%) among Aeromonas sp. and A. veronii was the next (25%). Although the isolation rate was low, A. jandaei, A. media, A. caviae and A. viridians were also isolated. Unidentified Aeromonas sp. by 16S rRNA sequencing and phenotypic identification system was also isolated (16%). Seventy seven isolates among 168 Aeromonas sp. isolates were identified as A. hydrophila with 16S rRNA sequencing and multiplex PCR which developed for identification of 4 kinds of Aeromonas sp. In the comparison with two commercial identification systems, the two systems were showed identical results as an A. hydrophila (65%). The differences of the two identification systems for A. hydrophila were A. sobria/veronii (27%) and Vibrio sp.(7.8%). We investigated the biochemical characteristics using conventional manual methods and commercial identification systems and compared the positive reactions of the tests. We also checked the virulence genes using PCR amplification with 5 specific virulence genes as part of genotypic characteristics.
Acknowledgements
This work was supported by a grant from Animal, Plant and Fisheries Quarantine and Inspection Agency. We are thankful to members of aquatic animal diseases lab., especially Byeong-Yup Sohn, Ji-Yun Jung, Sung-Ki Jeon, Jun-Chul Bae and Yu-Jeong Choi for supporting the works in our laboratory.
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