A novel Gram-stain-negative, facultatively anaerobic, rod-shaped and non-motile bacterial strain, designated as 4C16AT, was isolated from a tidal flat sediment and characterized by using a polyphasic taxonomic approach. Strain 4C16AT was found to grow at 10-40 °C (optimum, 28 °C), at pH 5.0-10.0 (optimum, pH 6.0-7.0) and in 0-6 % (w/v) NaCl (optimum, 1 %). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain 4C16AT fell into the genus Roseibium, and shared the highest identity of 98.9 % with the closest type strain Roseibium suaedae KACC 13772T and less than 98.0 % identity with other type strains of recognized species within this genus. The phylogenomic analysis indicated that strain 4C16AT formed an independent branch within this genus. The 28.6 % digital DNA-DNA hybridization estimate and 85.0 % average nucleotide identity between strains 4C16AT and R. suaedae KACC 13772T were the highest, but still far below their respective threshold for species definition, implying that strain 4C16AT should represent a novel genospecies. The predominant cellular fatty acid was summed feature 8; the polar lipids were diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylmonomethylethanolamine; the respiratory quinones were Q-9 and Q-10. The genomic DNA G+C content was 59.8mol %. Based on phylogenetic analyses and phenotypic and chemotaxonomic characteristics, strain 4C16AT is concluded to represent a novel species of the genus Roseibium, for which the name Roseibium litorale sp. nov. is proposed. The type strain of the species is 4C16AT (=GDMCC 1.1932T=KACC 22078T). We also propose the reclassification of Labrenzia polysiphoniae as Roseibium polysiphoniae comb. nov. and 'Labrenzia callyspongiae' as Roseibium callyspongiae sp. nov.
Keywords: Roseibium litorale; genomic analysis; genotypes and phenotypes; polyphasic taxonomy.