Description of Spongiibacter borealis sp. nov., isolated from Arctic seawater, and reclassification of Melitea salexigens Urios et al. 2008 as a later heterotypic synonym of Spongiibacter marinus Graeber et al. 2008 with emended descriptions of the genus Spongiibacter and Spongiibacter marinus

A Gram-negative, rod-shaped and motile strain, designated CL-AS9T, was isolated from polar seawater of the Arctic. Analysis of the 16S rRNA gene sequence of the strain showed an affiliation with the genus Spongiibacter, sharing 93.9 % and 93.7 % sequence similarities with the type strains of Spongiibacter tropicus CL-CB221T and Spongiibacter marinus HAL40bT, respectively. Phylogenetic analyses revealed that strain CL-AS9T formed a separate branch that was distinct from a clade comprising Spongiibacter marinus HAL40bT, Spongiibacter tropicus CL-CB221T and Melitea salexigens 5IX/A01/131T. Cells of the strain grew optimally at 20–25 °C and pH 6.6–8.0 in the presence of 3–4 % (w/v) sea salts. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and an unidentified aminophospholipid. The major quinone was ubiquinone 8. The major cellular fatty acids were C16 : 1ω7c and/or iso-C15 : 0 2-OH (23.1 %), C17 : 1ω8c (22.1 %) and C18 : 1ω7c (15.6 %). The genomic DNA G+C content was 53.6 mol%. Based on the phylogenetic, chemotaxonomic and phenotypic data presented, we propose the name Spongiibacter borealis sp. nov. with the type strain CL-AS9T ( = KCCM 90094T = JCM 17304T) and the reclassification of Melitea salexigens as a later heterotypic synonym of Spongiibacter marinus. We also provide emended descriptions of the genus Spongiibacter and Spongiibacter marinus.