Aureispira anguillae sp. nov., isolated from Japanese eel Anguilla japonica leptocephali

A novel filamentous eel-leptocephalus pathogenic marine bacterium, designated strain EL160426^T, was isolated from Japanese eel, Anguilla japonica, leptocephali reared at a laboratory in Mie, Japan. In experimental infection studies on eel larvae, the strain EL160426^T caused massive larval mortality and was reisolated from moribund leptocephali. Characteristically, observations of infected larvae found that EL160426^T forms columnar colonies on the cranial surface of larvae. The novel isolate exhibited growth at 15-30 °C, pH 7-9, and seawater concentrations of 60-150% (W/V). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain EL160426^T was most closely related to Aureispira maritima 59SA^T with 97.7% sequence similarity. The whole genome sequence analysis of the strain EL160426^T showed that the strain maintained a circular chromosome with a size of approximately 7.58 Mbp and the DNA G + C content was 36.2%. The major respiratory quinone was MK-7 and the predominant cellular fatty acids were 16:0, 20:4 w6c (arachidonic acid), 17:0 iso and 16:0 N alcohol. DNA relatedness between the closest phylogenetic neighbor strain EL160426^T and A. maritima (JCM23207^T) was less than 13%. On the basis of the polyphasic taxonomic data, the strain represents a novel species of the genus Aureispira, for which the name Aureispira anguillae sp. nov. is proposed. The type strain is EL160426^T (= JCM 35024 ^T = TSD-286 ^T).