Octadecabacter algicola sp. nov. and Octadecabacter dasysiphoniae sp. nov., isolated from a marine red alga and emended description of the genus Octadecabacter

Two Gram-stain-negative, strictly aerobic, catalase- and oxidase-positive and non-motile rod-shaped bacteria, strains D2-3 and G9-8 , were isolated from a marine red alga. Both strains contained ubiquinone-10 as the sole isoprenoid quinone. As the major cellular fatty acids (>5.0 %), D2-3 contained C , 11-methyl-C ω7 , summed feature 3 (C ω7 and/or C ω6 ), and summed feature 8 (C ω7 and/or C ω6 ), whereas G9-8 contained C , 11-methyl-C ω7 , C 3-OH, and summed feature 8. The DNA G+C contents of D2-3 and G9-8 were 54.4 % and 56.0 %, respectively. As the major polar lipids, phosphatidylglycerol, diphosphatidylglycerol and unidentified phospholipid, aminolipid and lipid were identified from both strains, and phosphatidylcholine was additionally detected from G9-8 only. The 16S rRNA gene sequence similarity of D2-3 and G9-8 was 98.5 % and their digital DNA-DNA hybridization (DDH) value was 19.1 %. Phylogenetic analyses based on 16S rRNA gene and genome sequences revealed that D2-3 and G9-8 formed respectively distinct phylogenetic lineages within the genus . D2-3 and G9-8 were most closely related to RA1-3 and 307 , with 98.9 % and 98.5 % 16S rRNA gene sequence similarities, respectively, and digital DDH values between D2-3 and and between G9-8 and were 18.3 % and 19.5 %, respectively. Phenotypic, chemotaxonomic and molecular features support the hypothesis that D2-3 and G9-8 represent two novel species of the genus , for which the names sp. nov. and sp. nov. are proposed. The type strains of and are D2-3 (=KACC 22493 =JCM 34969 ) and G9-8 (=KACC 22488 =JCM 34973 ), respectively.