A Gram-stain-negative, aerobic, non-flagellated and rod- or ovoid-shaped bacterium, designated as strain S4J41T, was isolated from Antarctic intertidal sediment. The isolate grew at 0-37 °C and with 0.5-10 % (w/v) NaCl. It reduced nitrate to nitrite and hydrolysed Tween 80 and gelatin. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain S4J41T constituted a distinct phylogenetic line within the family Rhodobacteraceae and was closely related with some species in the genera Ruegeria, Phaeobacter, Pseudopuniceibacterium, Sulfitobacter, Puniceibacterium and Poseidonocella with 98.6-95.7 % 16S rRNA gene sequence similarities. The major cellular fatty acids were C16 : 0, summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c) and C18 : 0 and the major polar lipids were phosphatidylglycerol, phosphatidylcholine, diphosphatidylglycerol, phosphatidylethanolamine and one unidentified aminolipid. The sole respiratory quinone was Q-10. The genomic DNA G+C content of strain S4J41T was 60.3 mol%. Based on the phylogenetic, chemotaxonomic and phenotypic data obtained in this study, strain S4J41T is considered to represent a novel species in a new genus within the family Rhodobacteraceae, for which the name Antarcticimicrobium sediminis gen. nov., sp. nov. is proposed. The type strain is S4J41T (=MCCC 1K03508T=KCTC 62793T). Moreover, the transfer of Ruegeria lutea Kim et al. 2019 to Antarcticimicrobium gen. nov. as Antarcticimicrobium luteum comb. nov. (type strain 318-1T=JCM 30927T=KCTC 72105T) is also proposed.
Keywords: Antarctic; Rhodobacteraceae; gen. nov.; intertidal sediment.