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.