Three Gram-stain-negative, strictly aerobic, non-motile, oxidase- and catalase-positive, short-rod-shaped bacteria, designated as strains G8-12T, SS1-5T and BS5-3T, were isolated from marine algae in South Korea. Strain G8-12T exhibited optimal growth at 20-25 °C, pH 8.0 and 2.0-2.5% (w/v) NaCl, while strains SS1-5T and BS5-3T grew optimally at 25 °C, pH 7.0 and 1.5% NaCl. All strains contained ubiquinone-10 as the sole respiratory quinone, with phosphatidylglycerol and phosphatidylcholine as major polar lipids, and C18 : 1 ω7c and C16 : 0 as major fatty acids (>5 %); C18 : 1 ω7c 11-methyl and C18 : 1 2-OH were additionally identified as major fatty acids in strain SS1-5T. The genomic DNA G+C contents were 57.0, 58.3 and 56.4% for strains G8-12T, SS1-5T and BS5-3T, respectively. Strains G8-12T, SS1-5T and BS5-3T exhibited less than 74.8% average nucleotide identity (ANI) and 19.7% digital DNA-DNA hybridization (dDDH) values with each other, indicating that they represent different species. Phylogenetic analyses based on both 16S rRNA gene and genome sequences revealed that strains G8-12T, SS1-5T and BS5-3T form distinct phylogenetic lineages within the genus Yoonia. Relative to other closely related Yoonia species, these strains exhibited ANI and dDDH values below 83.5 and 26.9%, respectively, suggesting that they constitute novel species within the genus Yoonia. Based on their phenotypic, chemotaxonomic and phylogenetic characteristics, strains G8-12T, SS1-5T and BS5-3T represent three novel species of the genus Yoonia, for which the names Yoonia algicola sp. nov. (G8-12T=KACC 22753T=JCM 35790T), Yoonia rhodophyticola sp. nov. (SS1-5T=KACC 22649T=JCM 35753T) and Yoonia phaeophyticola sp. nov. (BS5-3T=KACC 22648T=JCM 35751T) are proposed, respectively.
Keywords: Yoonia algicola; Yoonia phaeophyticola; Yoonia rhodophyticola; marine algae; new taxa.