A strictly aerobic, Gram-stain-negative, pale-golden, rod-shaped bacterium, designated as R18H21T, was isolated from marine sediment collected from the Ross Sea, Antarctica. Strain R18H21T grew at 4-40 °C (optimum 25 °C), at pH 6.3-9.2 (optimum 7.5-8.5) and in 0.5-6 % (w/v) NaCl (optimum 2 %). Phylogenetic analyses based on 16S rRNA gene sequences showed that strain R18H21T belonged to the genus Arenibacter, with the highest similarity to two type strains, Arenibacter latericius KMM 426T (96.6 %) and Arenibacter certesii KMM 3941T (96.6 %), and lower similarities (95.2-95.9 %) to five other members of the genus Arenibacter. The major fatty acids were iso-C17 : 0 3-OH, Summed Feature 3 (C16 : 1ω6c and/or C16 : 1ω7c), iso-C15 : 0, iso-C15 : 1 G. The major polar lipids were phosphatidylethanolamine, an unidentified aminolipid and an unidentified phospholipid. The respiratory quinone of strain R18H21T was menaquinone-6. The DNA G+C content was 40.0 mol%. Based on phylogenetic, physiological and chemotaxonomic features, strain R18H21T has been classified as a novel species in the genus Arenibacter, for which the name Arenibacterantarcticus sp. nov. is proposed. The type strain of the novel species is R18H21T (=GDMCC 1.1159T=KCTC 52924T).
Keywords: Antarctica; Arenibacter; Flavobacteriaceae; Ross Sea; marine sediment; polyphasic taxonomy.