Oceanisphaera arctica sp. nov., isolated from Arctic marine sediment, and emended description of the genus Oceanisphaera

Abstract

A novel Gram-staining-negative, coccoid, non-motile bacterium, designated strain V1-41(T), was isolated from a sample of marine sediment collected, at a depth of 200 m, from Kongsfjorden (an inlet on the west coast of Spitsbergen, an island that forms part of the Svalbard archipelago in the Arctic Ocean). The strain formed cream-brown colonies on marine agar. Cells of the novel strain were positive in tests for catalase, oxidase, lysine decarboxylase and ornithine decarboxylase activities but negative for gelatinase and lipase activities. They hydrolysed aesculin, starch and urea, but not casein or DNA. Most of the cellular fatty acids were medium-chain and saturated (37.1%) or long-chain and unsaturated (27.8%), with C(12:0) (37.1%), C(18:1)ω7c, and summed features 2 (19.3%) and 3 (24.1%) predominating. The major respiratory quinone was Q-8. The polar lipids consisted of phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, two unidentified aminophospholipids, four unidentified phospholipids and one other unidentified lipid. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the novel strain's closest known relatives were Oceanisphaera litoralis DSM 15406(T) (98.5% sequence similarity) and Oceanisphaera donghaensis BL1(T) (98.3%). In DNA-DNA hybridizations, however, the levels of relatedness between strain V1-41(T) and O. litoralis DSM 15406(T) and between the novel strain and O. donghaensis DSM 17589(T) were found to be only 19% and 29%, respectively. Based on these low levels of similarity at the DNA-DNA level and the phenotypic and chemotaxonomic differences from O. litoralis DSM 15406(T) and O. donghaensis DSM 17589(T), strain V1-41(T) represents a novel species of the genus Oceanisphaera for which the name Oceanisphaera arctica sp. nov. is proposed. The type strain is V1-41(T) ( = CCUG 58690(T) = KCTC 23013(T) = NBRC 106171(T)).