Abstract

Two novel bacterial strains, 273M-4^T and Sam97^T, were isolated from seawater in the Yellow Sea, Muan-gun, South Korea, and identified as members of the genus Thalassotalea. Both strains were Gram-stain-negative, aerobic, rod-shaped, non-motile, non-flagellated, and oxidase- and catalase-positive. Phylogenetic analysis based on 16S rRNA gene sequences showed that strains 273M-4^T and Sam97^T were most closely related to Thalassotalea ponticola KCTC 42155^T, with sequence similarities of 97.5% and 98.3%, respectively. Optimal growth for strain 273M-4^T occurred at 25-30 °C, pH 7.0, and 2% NaCl, while strain Sam97^T grew optimally at 30 °C, pH 8.0, and 2% NaCl. Genome sizes of strains 273M-4^T and Sam97^T were 3.37 and 3.31 Mb, with DNA G + C contents of 41.0 mol% and 42.9 mol%, respectively. The orthologous average nucleotide identity (OrthoANI) and digital DNA-DNA hybridization (dDDH) values between the two strains were 71.6% and 24.4%, respectively, indicating that they are distinct species. Further genomic analyses of these two strains revealed OrthoANI values of < 73.5% and dDDH values of < 26.7% within the genus Thalassotalea, suggesting their distinctiveness from other Thalassotalea species. The predominate fatty acids of strains 273M-4^T and Sam97^T were summed feature 3 (consisting of C_16:1 ω7c/C_16:1 ω6c) and C_16:0. All strains contained phosphatidylethanolamine and phosphatidylglycerol as the major polar lipids and ubiquinone-8 (Q-8) as the primary respiratory quinone. Based on phenotypic, phylogenetic, genotypic, and chemotaxonomic data, strains 273M-4^T (= KCTC 8644^T = LMG 33695^T) and Sam97^T (= KCTC 8645^T = LMG 33694^T) represent novel species of the genus Thalassotalea, named Thalassotalea aquiviva sp. nov. and Thalassotalea maritima sp. nov..

• Keywords: Thalassotalea; Thalassotalea aquiviva; Thalassotalea maritima; Genome