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

A novel filamentous eel-leptocephalus pathogenic marine bacterium, designated strain EL160426, 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 caused massive larval mortality and was reisolated from moribund leptocephali. Characteristically, observations of infected larvae found that EL160426 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 was most closely related to Aureispira maritima 59SA with 97.7% sequence similarity. The whole genome sequence analysis of the strain EL160426 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 and A. maritima (JCM23207) 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 (= JCM 35024 = TSD-286).