Fulvimarina fulva sp. nov. and Fulvimarina thalattae sp. nov., isolated from seawater off Ganghwa Island, South Korea

Abstract

Two novel Gram-stain-negative strains, designated as MAC3T and MAC8T, which produced brownish-yellow and bright-orange colonies, respectively, were isolated from seawater collected off Minmeoru Beach, Ganghwa Island, Republic of Korea. These strains were facultatively anaerobic, catalase-and oxidase-positive, rod-shaped and motile with flagella. Both strains grew at 4–40 °C and at pH 4.0–10.0. Strain MAC3T grew in sodium chloride (NaCl) concentrations (w/v) of 0–15.0%, while strain MAC8T tolerated 0–14.0%. Both strains contained ubiquinone-10 as the predominant respiratory quinone and C<inf>18:1</inf> ω7c (or summed feature 8, comprising C<inf>18:1</inf> ω6c and/or C<inf>18:1</inf> ω7c) as the major fatty acid. The major polar lipids of both strains included diphos-phatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine and an unidentified aminoglycolipid. Phylogenetic analysis based on 16S rRNA gene sequences placed the two strains within the genus Fulvimarina. Strain MAC3T shared the highest sequence similarity (97.7%) with Fulvimarina endophytica 85T, while strain MAC8T shared 97.9% sequence similarity with Fulvimarina pelagi HTCC2506T. The DNA guanine and cytosine (G+C) content of both MAC3T and MAC8T was 61.5 mol%. The digital DNA–DNA hybridization and average nucleotide identity values between the novel strains and related type strains were 20.8–26.2% and 75.1–82.9%, respectively. Based on the results of the polyphasic analysis, strains MAC3T and MAC8T represent two novel species in the genus Fulvimarina, for which the names Fulvimarina fulva sp. nov. and Fulvimarina thalattae sp. nov. are proposed, respectively. The F. fulva and F. thalattae type strains are MAC3T (=KACC 23727T=TBRC 19011T) and MAC8T (=KACC 23726T=TBRC 19010T), respectively. © 2026 The Authors.