Maribacter luteocoastalis sp. nov., a novel marine bacterium isolated from the tidal flat sediments of the East China Sea.

A Gram-stain-negative, halophilic, rod-shaped, aerobic bacterial strain, designated as CXY002, was isolated from intertidal seawater of the East China Sea. Strain CXY002 exhibited growth at 4-33 °C (optimum 28 °C), pH 5.5-10 (optimum pH 6-7), and 2-10% (w/v) NaCl (optimum 6%). Based on 16S rRNA gene sequence phylogenetic analysis, strain CXY002 exhibited sequence similarities of 98.20% with Maribacter orientalis DSM 16471, 98.12% with M. spongiicola W15M10, 98.00% with M. stanieri DSM 19891, 98.00% with M. cobaltidurans B1, and 97.72% with M. aquivivus DSM 16478. Phylogenomic reconstruction confirmed its affiliation within the genus Maribacter. Digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between CXY002 and closely related species ranged from 15.20 to 16.30% and 71.90 to 72.46%, respectively, both below the recommended thresholds for species demarcation (70% for dDDH and 95-96% for ANI). The genomic DNA G+C content was determined to be 36.5 mol%. The predominant respiratory quinone was menaquinone-6 (MK-6), while the major fatty acids comprised iso-C (26.7%), 3-OH iso-C (19.9%), and iso-C (16.6%). Polar lipids included phosphatidylethanolamine, two unidentified aminolipids, and four unidentified lipids. Genomic annotation identified complete carotenoid biosynthesis pathways (crt-B, crt-I, crt-Z), supporting which may contribute to oxidative stress resistance via β-carotene and zeaxanthin biosynthesis. Based on polyphasic taxonomic evidence encompassing phenotypic, chemotaxonomic, and genomic characteristics, strain CXY002 represents a novel species within the genus Maribacter, for which the name Maribacter luteocoastalis sp. nov. is proposed. The type strain is CXY002 (= MCCC 1K09937 = KCTC 102438).