Genome taxonomy of the genus Thalassotalea and proposal of Thalassotalea hakodatensis sp. nov. isolated from sea cucumber larvae

The genus Thalassotalea is ubiquitous in marine environments, and up to 20 species have been described so far. A Gram-staining-negative, aerobic bacterium, designated strain PTE2(T) was isolated from laboratory-reared larvae of the Japanese sea cucumber Apostichopus japonicus. Phylogenetic analysis based on the 16S rRNA gene nucleotide sequences revealed that PTE2(T) was closely related to Thalassotalea sediminis N211(T) (= KCTC 42588(T) = MCCC 1H00116(T)) with 97.9% sequence similarity. ANI and in silico DDH values against Thalassotalea species were 68.5–77.0% and 19.7–24.6%, respectively, indicating the novelty of PTE2(T). Based on genome-based taxonomic approaches, strain PTE2(T) (= JCM 34608(T) = KCTC 82592(T)) is proposed as a new species, Thalassotalea hakodatensis sp. nov.