Aquimarina ulvae sp. nov. and Polaribacter litoreus sp. nov., isolated from the green alga Ulva prolifera

Two Gram-negative, orange-pigmented, strictly aerobic, rod-shaped, catalase- and oxidase-positive bacterial strains, designated M1 ^T and M15 ^T , were isolated from the green alga Ulva prolifera collected in Muan Bay, Republic of Korea. Strain M1 ^T grew at 10–30 °C (optimum, 25 °C), pH 6–9 (optimum, pH 7), and in the presence of 1–6% (w/v) NaCl (optimum, 3%), whereas strain M15 ^T grew at 10–30 °C (optimum, 25 °C), pH 6–8 (optimum, pH 7), and with 1–5% (w/v) NaCl (optimum, 2%). The sole respiratory quinone in both strains is menaquinone-6. Major fatty acids in strain M1 ^T are iso-C _17 : 0 3-OH (27.8%), iso-C _15 : 0 (20.8%), summed feature 9 (C _16 : 0 10-methyl/iso-C _17 : 1  ω9c; 17.2%), and iso-C _15 : 1 G (13.4%); in strain M15 ^T , they are iso-C _15 : 0 (27.3%), iso-C _15 : 0 3-OH (16.0%), and C _15 : 1  ω6c (12.2%). The major polar lipids in strain M1 ^T were two unidentified aminolipids and seven unidentified lipids, whereas those in strain M15 ^T were phosphatidylethanolamine, one unidentified phospholipid, one unidentified aminophospholipid, and four unidentified lipids. Phylogenetic analyses based on 16S rRNA gene nucleotide sequences revealed that strains M1 ^T and M15 ^T were most closely related to Aquimarina muelleri KMM 6020 ^T and Polaribacter reichenbachii 6Alg 8 ^T with 96.5 and 98.3% nucleotide sequence identities, respectively. The genomes of strains M1 ^T and M15 ^T were 5.5 Mb with a G+C content of 33.8 mol% and 4.1 Mb with a G+C content of 30.6 mol%, respectively. The average nucleotide identity and digital DNA–DNA hybridization values between the genomic sequences of strain M1 ^T and A. muelleri KMM 6020 ^T were 74.2 and 19.4%, respectively, and between those of strain M15 ^T and P. reichenbachii 6Alg 8 ^T were 82.0 and 25.8%, respectively. Based on the polyphasic data, strains M1 ^T and M15 ^T are considered to represent novel species in the genera Aquimarina and Polaribacter , respectively, for which the names Aquimarina ulvae sp. nov. (M1 ^T =JCM 36757 ^T =KCTC 102217 ^T ) and Polaribacter litoreus sp. nov. (M15 ^T =JCM 36759 ^T =KCTC 102246 ^T ) are proposed.