Rubritalea squalenifaciens sp. nov., a squalene-producing marine bacterium belonging to subdivision 1 of the phylum 'Verrucomicrobia'

A taxonomic study was carried out to clarify the status of a Gram-negative, heterotrophic mesophile that was isolated from the marine sponge Halichondria okadai. The strain, designated HOact23^T, was a non-motile, rod-shaped (0.440.53x0.650.79 µm) bacterium. The strain produced squalene and a redpink carotenoid pigment. The cell-wall peptidoglycan contained meso-diaminopimelic acid, glutamic acid and alanine. The G+C content of the genomic DNA was 52.4 mol%. The major fatty acids were iso-C_{14 : 0} (43.1 %), iso-C_{16 : 0} (20.6 %) and anteiso-C_{15 : 0} (18.1 %), and the major isoprenoid quinone was MK-9 (90.8 %). Based on 16S rRNA gene sequence data, the strain formed a distinct group within subdivision 1 in the phylum Verrucomicrobia. It showed a range of phenotypic properties that distinguished it from its closest relative, Rubritalea marina Pol012^T (94.3 % 16S rRNA gene sequence similarity). On the basis of polyphasic taxonomic evidence, it was concluded that strain HOact23^T should be classified within a novel species in the genus Rubritalea. The name proposed for the taxon is Rubritalea squalenifaciens sp. nov., with the type strain HOact23^T (=MBIC08254^T=DSM 18772^T).