Colwellia maritima sp. nov. and Polaribacter marinus sp. nov., isolated from seawater

Two Gram-stain-negative, catalase- and oxidase-positive, and aerobic bacteria, strains MSW7^T and MSW13^T, were isolated from seawater. Cells of strains MSW7^T and MSW13^T are motile and non-motile rods, respectively. Strain MSW7^T optimally grew at 25 °C and pH 7.0 and in the presence of 3 % (w/v) NaCl, whereas strain MSW13^T optimally grew at 25 °C and pH 6.0-7.0 and in the presence of 2 % NaCl. As the sole respiratory quinone and the major fatty acids and polar lipids, strain MSW7^T contained ubiquinone-8, C_16 : 0, C_15 : 1  ω8c, C_17 : 1  ω8c and summed feature 3 (C_16 : 1  ω7c and/or C_16 : 1  ω6c), and phosphatidylethanolamine and phosphatidylglycerol, respectively, whereas strain MSW13^T contained menaquinone-6, C_15 : 1  ω6c, iso-C_15 : 0, anteiso-C_15 : 0, and iso-C_15 : 0 3-OH, and phosphatidylethanolamine, respectively. The DNA G+C contents of strains MSW7^T and MSW13^T were 37.3 and 29.9 %, respectively. Phylogenetic analyses based on 16S rRNA gene sequences showed that strains MSW7^T and MSW13^T were most closely related to Colwellia echini A3^T and Polaribacter atrinae WP25^T with 98.8 and 98.1 % sequence similarities, respectively. The average nucleotide identity and digital DNA-DNA hybridization values between strain MSW7^T and C. echini A3^T and between strain MSW13^T and P. atrinae KACC 17473^T were 73.6 and 22.6 % and 80.4 and 23.8 %, respectively. Based on phenotypic, chemotaxonomic and phylogenetic data, strains MSW7^T and MSW13^T represent novel species of the genera Colwellia and Polaribacter, respectively, for which the names Colwellia maritima sp. nov. and Polaribacter marinus sp. nov. are proposed, respectively. The type strains of C. maritima sp. nov. and P. marinus sp. nov. are MSW7^T (=KACC 22339^T=JCM 35001^T) and MSW13^T (=KACC 22341^T=JCM 35021^T), respectively.