Phenotypic and genotypic analysis of Edwardsiella tarda isolated from olive founder (Paralichthys olivaceus) and Japanese eel (Anguilla japonica)

Edwardsiella tarda is an important bacterial pathogen of olive flounder (Paralichthys olivaceus) and Japanese eel (Anguilla japonica). Here, a total of 66 strains of E. tarda isolated from olive flounder and Japanese eel were compared using biochemical tests, whole-cell protein analysis, lipopolysaccharide (LPS) profiling, and random amplified polymorphic DNA (RAPD) analysis to determine the host-related homogeneity of these pathogens. The E. tarda strains isolated from olive flounder were highly homogenous in the analyzed parameters, whereas the isolates from Japanese eel were highly heterogeneous. E. tarda isolated from Japanese eel did not demonstrate any pathogenic effect against olive flounder in challenge experiments. The phenotypic and genotypic homogeneity observed in the isolates from olive flounder may be helpful to develop an effective vaccine for edwardsiellosis in olive flounder.