Roseovarius arcticus sp. nov., a bacterium isolated from Arctic marine sediment.

An aerobic, Gram-stain-negative, motile, rod or long-rod-shaped bacterial isolate, strain MK6-18T, was isolated from a marine sediment sample from Kongsfjorden, Arctic. The bacterium grew optimally at 20 °C, pH 7.0 and in the presence of 1.0-2.0 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain MK6-18T belonged to the genus Roseovarius. Its closest phylogenetic neighbour was Roseovarius nanhaiticus NH52JT showing 96.97 % 16S rRNA gene sequence similarity. The genome of strain MK6-18T is 4.2 Mb long in size with a G+C content of 59.5 mol%. The average nucleotide identity value between the genomes of strain MK6-18T and Roseovarius nanhaiticus NH52JT, was 78.0 %. Similar to other species of the genus Roseovarius, strain MK6-18T had ubiquinone 10 as the predominant ubiquinone and C12 : 0, C16 : 0, summed feature 3 (C16 : 1ω7c/ω6c) and summed feature 8 (C18 : 1ω7c/ω6c) as the major fatty acids. The polar lipid pattern consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phosphatidylcholine; one unidentified polar lipid, one unidentified aminolipid and one unidentified lipid were also detected. This is the first time that a member of the genus Roseovarius has been isolated from the Arctic, which may promote the study of the distribution characteristics and environmental adaptability of this genus. On the basis of the data provided here, strain MK6-18T should be classed as representing a novel species of the genus Roseovarius, for which the name Roseovarius arcticus sp. nov. is proposed. The type strain is MK6-18T (=CCTCC AB 2018219T=KCTC 72187T).