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 M1T and M15T, were isolated from the green alga Ulva prolifera collected in Muan Bay, Republic of Korea. Strain M1T 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 M15T 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 M1T are iso-C17 : 0 3-OH (27.8%), iso-C15 : 0 (20.8%), summed feature 9 (C16 : 0 10-methyl/iso-C17 : 1 ω9c; 17.2%), and iso-C15 : 1 G (13.4%); in strain M15T, they are iso-C15 : 0 (27.3%), iso-C15 : 0 3-OH (16.0%), and C15 : 1 ω6c (12.2%). The major polar lipids in strain M1T were two unidentified aminolipids and seven unidentified lipids, whereas those in strain M15T were phosphatidylethanolamine, one unidentified phospholipid, one unidentified aminophospholipid, and four unidentified lipids. Phylogenetic analyses based on 16S rRNA gene nucleotide sequences revealed that strains M1T and M15T were most closely related to Aquimarina muelleri KMM 6020T and Polaribacter reichenbachii 6Alg 8T with 96.5 and 98.3% nucleotide sequence identities, respectively. The genomes of strains M1T and M15T 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 M1T and A. muelleri KMM 6020T were 74.2 and 19.4%, respectively, and between those of strain M15T and P. reichenbachii 6Alg 8T were 82.0 and 25.8%, respectively. Based on the polyphasic data, strains M1T and M15T are considered to represent novel species in the genera Aquimarina and Polaribacter, respectively, for which the names Aquimarina ulvae sp. nov. (M1T=JCM 36757T=KCTC 102217T) and Polaribacter litoreus sp. nov. (M15T=JCM 36759T=KCTC 102246T) are proposed.