Ruegeria discodermiae sp. nov., Ruegeria jejuensis sp. nov., and Ruegeria hyattellae sp. nov., Isolated from Marine Sponges.

Three Gram-stain-negative, strictly aerobic, cream-colored, catalase- and oxidase-positive bacterial strains, designated 2205SS24-7, 2304DJ69-11, and 2012CJ15-1, were isolated from marine sponges collected in the Republic of Korea. The three novel strains grew optimally at 25-28 °C, pH 7.0, and 2-3% (w/v) NaCl. Phylogenetic analyses based on 16S rRNA gene and draft genome sequences revealed that the three novel strains clustered together with Ruegeria spongiae 2012CJ41-6, forming a distinct clade within the genus Ruegeria. The 16S rRNA gene sequence similarities with R. spongiae were 97.6, 98.6, and 98.9%, respectively. Draft genome sequencing indicated genome sizes ranging from 5.2 to 6.1 Mb with DNA G+C contents between 59.0 and 60.5%. Average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values among the three novel strains ranged from 85.3-90.9% and 29.6-43.1%, respectively, indicating that each strain represents a separate species. Furthermore, ANI and dDDH values between the three novel strains and the type strains R. spongiae 2012CJ41-6, R. mediterranea M17, and R. litorea R-37 were ≤ 90.9% and ≤ 43.1%, respectively, both below the proposed thresholds for species delineation. The three novel strains possessed ubiquinone-10 as the major isoprenoid quinone and summed feature 8 (C ω7c and/or C ω6c) as the major fatty acid. The major polar lipids identified were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, and phosphatidylcholine. Taken together, these results support the proposal that strain 2205SS24-7 (= KACC 23237 = LMG 33064), 2304DJ69-11 (= KACC 23805 = MCCC 1K09534), and 2012CJ15-1 (= KACC 23842 = MCCC 1K09526) represent three novel species within the genus Ruegeria, for which the names Ruegeria discodermiae sp. nov., Ruegeria jejuensis sp. nov., and Ruegeria hyattellae sp. nov. are proposed, respectively.