Sulfitobacter pacificus sp. nov., isolated from the red alga Pyropia yezoensis

Three Gram-negative, aerobic, halophilic bacterial strains, SCM2-10T, SCM-4, and 14C-6, were isolated from the algal medium of the red alga Pyropia yezoensis (previously classified as Porphyra yezoensis) grown in laboratory experiments. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the organisms with high similarities to the three isolates are Sulfitobacter geojensis MM-124T (98.7 %), Sulfitobacter noctilucicola NB-77T (98.7 %), Sulfitobacter noctilucae NB-68T (98.6 %), Sulfitobacter mediterraneus CH-B427T (97.6 %), and Sulfitobacter porphyrae SCM-1T (97.6 %), and that the three isolates belong to the genus Sulfitobacter, within the class Alphaproteobacteria. The DNA G+C contents of the three isolates were found to be in the range of 56.5–57.1 mol%. DNA–DNA hybridization experiments demonstrated that the genomic relatedness between strain SCM2-10T and type strains of other Sulfitobacter species was in the range of 6.2–27.1 %. The predominant respiratory quinone of the three isolates was identified as ubiquinone-10. The dominant polar lipids in the three isolates were found to be phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, and an unidentified amino lipid. The major fatty acid in the three isolates is C18:1 ω7c. Strain SCM2-10T demonstrated unique phenotypic characteristics, which differed from those of type strains of other Sulfitobacter species. Based on the phylogenetic, genetic, phenotypic, and chemotaxonomic data, we propose a novel species of the genus Sulfitobacter, which we named as Sulfitobacter pacificus sp. nov. The type strain of this species is strain SCM2-10T (=LMG 27113T = NBRC 109915T).