Euzebya tangerina gen. nov., sp. nov., a deeply branching marine actinobacterium isolated from the sea cucumber Holothuria edulis, and proposal of Euzebyaceae fam. nov., Euzebyales ord. nov. and Nitriliruptoridae subclassis nov.

Abstract

A tangerine-coloured, Gram-positive actinobacterial strain, designated F10T, was isolated from the abdominal epidermis of a sea cucumber, Holothuria edulis, collected in seawater off the coast of Japan. A 16S rRNA gene sequence analysis indicated that strain F10T was a member of the class Actinobacteria and was most closely related to Nitriliruptor alkaliphilus ANL-iso2T (87.4 % sequence similarity). Phylogenetic analyses showed that strain F10T represented a novel, deep-rooted, and distinct phylogenetic lineage within the class Actinobacteria and clustered with N. alkaliphilus and uncultured bacteria. The organism had meso-diaminopimelic acid as the diagnostic diamino acid in the cell-wall peptidoglycan, and rhamnose and galactose as the diagnostic cell-wall sugars. Strain F10T contained C16 : 1 ω7c, C16 : 0 and C17 : 1 ω8c as the major cellular fatty acids. The predominant isoprenoid quinone was MK-9 (H4). The G+C content of the DNA was 68.3 mol%. Based on data from the current polyphasic study, it is proposed that the new marine isolate be placed in a novel genus and be considered a novel species designated Euzebya tangerina gen. nov., sp. nov. within the new family, order and subclass Euzebyaceae fam. nov., Euzebyales ord. nov. and Nitriliruptoridae subclassis nov. in the class Actinobacteria. The type strain of Euzebya tangerina is F10T (=NBRC 105439T =KCTC 19736T).