Phycobacter azelaicus gen. nov. sp. nov., a diatom symbiont isolated from the phycosphere of Asterionellopsis glacialis .

A diatom-associated bacterium, designated as strain F10 ^T , was isolated from a pure culture of the pennate diatom Asterionellopsis glacialis A3 and has since been used to characterize molecular mechanisms of symbiosis between phytoplankton and bacteria, including interactions using diatom-derived azelaic acid. Its origin from a hypersaline environment, combined with its capacity for quorum sensing, biofilm formation, and potential for dimethylsulfoniopropionate methylation/cleavage, suggest it is within the family Roseobacteraceae . Initial phylogenetic analysis of the 16S rRNA gene sequence placed this isolate within the Phaeobacter genus, but recent genomic and phylogenomic analyses show strain F10 ^T is a separate lineage diverging from the genus Pseudophaeobacter . The genomic DNA G+C content is 60.0 mol%. The predominant respiratory quinone is Q-10. The major fatty acids are C _18 : 1  ω7 c and C _16 : 0 . Strain F10 ^T also contains C _10 : 0 3-OH and the furan-containing fatty acid 10,13-epoxy-11-methyl-octadecadienoate (9-(3-methyl-5-pentylfuran-2-yl)nonanoic acid). The major polar lipids are diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. Based on genomic, phylogenomic, phenotypic and chemotaxonomic characterizations, strain F10 ^T represents a novel genus and species with the proposed name, Phycobacter azelaicus gen. nov. sp. nov. The type strain is F10 ^T (=NCMA B37 ^T =NCIMB 15470 ^T =NRIC 2002 ^T ).