Pacificoceanicola niger sp. nov. and Pacificoceanicola algae sp. nov., isolated from the brown alga Saccharina japonica, with the reclassification of Tropicibacter oceani as Pacificoceanicola oceani comb. nov.

Two Gram-stain-negative, non-motile and oval-shaped bacterial strains, designated 2E107 ^T and 2E233 ^T , were isolated from the brown alga Saccharina japonica collected in Rongcheng, Weihai, China (122° 33′ E 37° 15′ N). The two strains shared 98.0% 16S rRNA gene sequence similarity. Both strains grew at 4–37 °C, with optimum growth at 35 °C, and tolerated 0.5–10% ( w/v ) NaCl. Strain 2E107 ^T grew at pH 6.5–9.5, with optimum growth at pH 7.0 and 1.5% ( w/v ) NaCl, whereas strain 2E233 ^T grew at pH 5.5–9.0, with optimum growth at pH 6.5 and 4% ( w/v ) NaCl. Strain 2E107 ^T produced melanin, whereas strain 2E233 ^T was non-pigmented. The genomic DNA G+C contents of strains 2E107 ^T and 2E233 ^T were 62.8 and 60.5 mol%, respectively. In both strains, summed feature 8 (C _18 : 1  ω7 c and/or C _18 : 1  ω6 c) was the predominant cellular fatty acid, and ubiquinone-10 was the sole respiratory quinone. The major polar lipids of strain 2E107 ^T were phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine and an unidentified lipid, whereas those of strain 2E233 ^T were phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, an unidentified aminolipid and an unidentified lipid. The average nucleotide identity and average amino acid identity values between strain 2E107 ^T and Pacificoceanicola onchidii XY-301 ^T were 78.5 and 81.8%, respectively, whereas the corresponding values between strain 2E233 ^T and P. onchidii XY-301 ^T were 76.4 and 78.6%, respectively. On the basis of phylogenetic, phylogenomic, phenotypic and chemotaxonomic evidence, strains 2E107 ^T and 2E233 ^T are considered to represent two novel species of the genus Pacificoceanicola , for which the names Pacificoceanicola niger sp. nov. and Pacificoceanicola algae sp. nov. are proposed, respectively. The type strains are 2E107 ^T (=MCCC 1H01529 ^T =KCTC 8819 ^T =SDUM152014 ^T ) and 2E233 ^T (=MCCC 1H01530 ^T =KCTC 8818 ^T =SDUM152015 ^T ), respectively. Furthermore, on the basis of phylogenomic and comparative taxonomic evidence, Tropicibacter oceani Zhou et al . 2025 is proposed to be reclassified as Pacificoceanicola oceani comb. nov.