Abstract
Two Gram-stain-negative, strictly aerobic, non-motile, rod-shaped bacteria, designated as strains S88(T) and W115(T), exhibiting catalase- and oxidase-positive reactions, were isolated from marine red algae in South Korea. Strain S88(T) exhibited growth at 20-30 °C, pH 6.0-9.0 and 2.0-5.0% (w/v) NaCl, while strain W115(T) grew at 20-30 °C, pH 7.0-9.0 and 2.0-5.0% (w/v) NaCl. Strain S88(T) contained summed feature 8 (C(18 : 1) ω7c and/or C(18 : 1) ω6c), C(16 : 0) and C(16 : 0) 2-OH as major fatty acids (>5%), with major polar lipids being phosphatidylglycerol, phosphatidylcholine, an unidentified phospholipid, an unidentified aminolipid and two unidentified lipids. Strain W115(T) contained summed feature 8 (C(18 : 1) ω7c and/or C(18 : 1) ω6c) and C(16 : 0) as major fatty acids (>5%), with major polar lipids including phosphatidylglycerol, phosphatidylcholine, an unidentified phospholipid, an unidentified aminolipid and unidentified lipids. Ubiquinone-10 was the sole respiratory quinone in both strains, and the genomic DNA G+C contents were 57.0% for strain S88(T) and 56.5% for strain W115(T). Despite 99.86% 16S rRNA gene sequence similarity, strains S88(T) and W115(T) shared 88.8% average nucleotide identity (ANI) and 36.8% digital DNA-DNA hybridization (dDDH) value, indicating different species. Phylogenetic and phylogenomic analyses based on 16S rRNA gene and genome sequences, respectively, revealed that strains S88(T) and W115(T) formed a phylogenetic lineage within the genus Roseovarius. ANI and dDDH values of both strains with other type strains were less than 73.7 and 20.3%, respectively, confirming that they represent novel species. Based on phenotypic, chemotaxonomic and molecular characteristics, strains S88(T) and W115(T) represent two novel species of the genus Roseovarius, for which the names Roseovarius phycicola sp. nov. (S88(T) =KACC 23423(T) =JCM 36647(T)) and Roseovarius rhodophyticola sp. nov. (W115(T) =KACC 23690(T) =JCM 36651(T)) are proposed, respectively.