| Edwardsiella bacteria are leading fish pathogens causing huge losses to aquaculture industries worldwide. However, the taxa are widely recognized to be misclassified, which hurdled the understanding of the epidemiology and development of effective diagnostics and vaccines. At present the genus Edwardsiella is divided into three species Edwardsiella tarda, E. ictaluri, E. hoshinae. Previous phylogenomic analysis revealed that two genotypes, EdwGI and EdwGII, exist in E. tarda, and EdwGI represents a genotype offish pathogens in the Edwardsiella lineage and is proposed as E. piscicida, sp. nov. Here we used the genomic data and multiple phylogenetic analysis of EdwGI strains to disclose the isolates from diseased eel to represent a novel species E. anguillarum within the genus Edwardsiella, with strain ET080813T (=DSM27202T=CCUG64215T=CCTCC AB20131181T=MCCC1K002381) as the type strain. The typical phenotypes of the species were described. Multiple locus sequence analysis (MLSA) sequence similarity between strain ET0808131and the other species of genus Edwardsiella were82.99-95.38%. The DNA-DNA hybridization estimate values between strain ET0808131and the other species of genus Edwardsiella were from24.4%to60.1%. The G+C content of the chromosomal DNA was determined from the complete genome sequence to be58.72%. The respiratory quinone was determined to be MK-8(100%). Phosphatidylethanolamine, phosphatidylglycerol, aminolipid, phospholipid and one unknown lipid were found to be present. Further comparative genomics revealed that E. anguillarum strains have acquired the locus of enterocyte effacement (LEE) and as a result these bacteria contain at least two sets of distinct T3SS and three sets of T6SS gene clusters, respectively. These findings will definitely contribute to the exploration of species-specific control measures against specific linage of Edwardsiella bacterium in aquatic animals, while also shedding light on the evolution of pathogenesis in Edwardsiella bacterium. |
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