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Isolation and identification of fish pathogen Edwardsiella tarda from mariculture in China
Author(s) -
Xiao Jingfan,
Wang Qiyao,
Liu Qin,
Wang Xin,
Liu Huan,
Zhang Yuanxing
Publication year - 2008
Publication title -
aquaculture research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.646
H-Index - 89
eISSN - 1365-2109
pISSN - 1355-557X
DOI - 10.1111/j.1365-2109.2008.02101.x
Subject(s) - edwardsiella tarda , biology , turbot , microbiology and biotechnology , scophthalmus , virulence , pathogen , outbreak , mariculture , aquaculture , bacteria , virology , fish <actinopterygii> , fishery , gene , genetics
The causative agent was isolated from diseased turbots ( Scophthalmus maximus ) stricken by a high‐mortality outbreak of bacterial septicaemia occurring in a mariculture farm in Yantai, a northern coastal city of China. Seven pure isolates, namely EH‐15, EH‐103, EH‐107, EH‐202, EH‐203, EH‐305 and EH‐306, belonged to Edwardsiella tarda . The phenotypic features of the cultures were analysed extensively. Three of the isolates showed high 16S rDNA sequence similarities with E. tarda sequence (GenBank accession no. EF467289). However, unlike the E. tarda ATCC 15947, all the isolates, except EH‐15, contained a novel large plasmid sized about 23.7 kb. Furthermore, pathogenicity of the isolates was addressed by experimental challenges with fish models. The isolates exhibited strong virulence to swordtail fish with LD 50 ranging between 3.8 × 10 3 and 3.8 × 10 5 CFU g −1 , and EH‐202 displaying the lowest LD 50 value among them. Antibiotic susceptibilities of E. tarda isolates were assayed. Compared with E. tarda ATCC 15947, the isolates displayed strong resistance to chloramphenicol, and the probable dominant chloramphenicol resistance determinant was cat III . Depicting the main biological properties of turbot‐borne E. tarda strains in China, the study provided useful information for further unveiling their pathogenic mechanisms.