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Three bacterial strains, namely HYN0069T, HYN0085T and HYN0086T, were isolated from freshwater samples taken from the Namhangan River system in Korea. 16S rRNA gene sequence similarities and phylogenetic tree topologies indicated that the three strains belonged to the genera Gemmobacter , Runella and Flavobacterium by showing the highest sequence similarities with Gemmobacter straminiformis (98.4 %), Runella aurantiaca (98.3 %) and Flavobacterium chungangense (98.1 %). No bacterial species with validly published names showed 98.7 % or higher sequence similarity with the novel isolates. The average nucleotide identities between the genome sequences of the three new isolates and the three closest neighbours were 80.2–92.0 %, all below the threshold for bacterial species delineation (95–96 %). Many biochemical and physiological features also discriminated the isolates from previously known species of the genera Gemmobacter , Runella and Flavobacterium . Based on the phylogenetic and phenotypic data presented in this study, we suggest three novel species with the following names: Gemmobacter aquarius sp. nov. (type strain HYN0069T=KACC 19488T=NBRC 113115T), Runella rosea sp. nov. (type strain HYN0085T=KACC 19490T=NBRC 113116T) and Flavobacterium fluviale sp. nov. (type strain HYN0086T=KACC 19489T=NBRC 113117T).

A Gram-stain-negative, yellow-pigmented, aerobic bacterial strain, designated LPB0140T, was isolated from sea water. The 16S rRNA gene sequence similarity analysis demonstrated that the closest relative of the isolate is Sphingorhabdus contaminans (96.4 %), but the new isolate formed an independent phyletic line within the genus Sphingorhabdus . Its genome is composed of a circular chromosome of 2.53 Mb with DNA G+C content of 46.1 mol%. The genome includes 2359 protein-coding genes, and two copies of rRNA operons. Strain LPB0140T possessed C14 : 0 2-OH, C16 : 1ω7c and/or C16 : 1ω6c, and C18 : 1ω7c and/or C18 : 1ω6c as the major cellular fatty acids and Q-10 as the isoprenoid quinone. The major polar lipids were phosphatidylethanolamine, phosphatidylcholine, phosphatidylglycerol, diphosphatidylglycerol, and sphingoglycolipid, but phosphatidylmonomethylethanolamine and phosphatidyldimethylethanolamine were also detected as minor polar lipids. The chemotaxonomic properties and enzymatic activities of the novel isolate clearly differed from those of its closest relatives. Thus, based on the phylogenetic and phenotypic data presented in this study, strain LPB0140T should be classified as a novel species in the genus Sphingorhabdus . The type strain is LPB0140T (=KACC18891T=JCM31568T).

A Gram-stain-negative, aerobic, short rod-shaped, motile, brownish-coloured bacterium, termed strain LPB0137T, was isolated from a squid. Its cells could grow weakly on marine agar 2216 with 0.04 % 2,3,5-triphenyl tetrazolium chloride (TTC). Each cell of strain LPB0137T has a circular chromosome with a length of 2.87 Mb and 27.7 mol% DNA G+C content. The genome includes 2698 protein-coding genes and six rRNA operons. In 16S rRNA gene sequence trees, strain LPB0137T formed a robust monophyletic clade with Poseidonibacter antarcticus SM1702T with a sequence similarity of 98.3 %. However, the average nucleotide identity and in silico DNA–DNA hybridization values between the two type strains were low (83.9 and 28.1 %, respectively). The overall phenotypic and genomic features of strain LPB0137T supported its assignment to the genus Poseidonibacter . However, the relatively low gene and genome sequence similarity between this strain and other type strains of the genus Poseidonibacter and several enzymatic characteristics indicated the taxonomic novelty of the isolated strain as a new member of the genus Poseidonibacter . Therefore, based on the phylogenetic and phenotypic characteristics of LPB0137T, we proposed a novel species of the genus Poseidonibacter for it, with the name Poseidonibacter parvus sp. nov. The type strain of this new species is thus LPB0137T (=KACC 18888T=JCM 31548T).