Actibacterium pelagium sp. nov., a novel alphaproteobacterium, and emended description of the genus Actibacterium.

A Gram-stain-negative, non-motile, rod-shaped bacterium, designated JN33, was isolated from seawater collected from the western Pacific Ocean. Strain JN33 was positive for hydrolysis of aesculin and gelatin. On the basis of 16S rRNA gene sequence analysis, strain JN33 showed high 16S rRNA gene sequence similarity to Actibacterium atlanticum 22II-S11-z10 (97.3 %), A. mucosum KCTC 23349 (96.6 %) and A. ureilyticum LS-811 (95.7 %) and exhibited less than 97.0 % 16S rRNA gene sequence similarity with respect to the other type strains within the family Rhodobacteraceae. Phylogenetic analysis revealed that strain JN33 fell within the cluster of the genus Actibacterium. The average nucleotide identity and in silico DNA-DNA hybridization values between strain JN33 and the type strains of Actibacterium species were 73.1-73.8 % and 19.8-20.1 %, respectively. The sole respiratory quinone was ubiquinone 10 (Q-10). The principal fatty acids were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) and C16 : 0. The major polar lipids were phosphatidylglycerol, one unidentified phospholipid and two unidentified aminolipids. The DNA G+C content was 57.8 mol%. Distinctly different phylogenetic characteristics, chemotaxonomic differences, as well as phenotypic properties, revealed that strain JN33 could be differentiated from the Actibacterium species with validly published names. Therefore, it is proposed that strain JN33 represents a novel species of the genus Actibacterium, for which the name Actibacterium pelagium sp. nov. (type strain, JN33=CGMCC 1.16012=KCTC 52653) is proposed.