Leucothrix sargassi sp. nov., isolated from a marine alga [Sargassum natans (L.) Gaillon]

A novel bacterial strain, C3212^T, was isolated from a marine alga collected from the sea shore of Yantai, China. The strain was Gram-stain-negative, rod-shaped, aerobic, non-motile, and oxidase- and catalase-positive. Growth was observed at 8-37 °C (optimum, 28 °C), at pH 6.0-9.0 (optimum, pH 7.0) and in the presence of 1.0-7.0 % (w/v) NaCl (optimum, 4.0 %). The major respiratory quinone was ubiquinone-8 (Q-8). The polar lipids of strain C3212^T consisted of diphosphatidylglycerol (cardiolipin), phosphatidylglycerol, phosphatidylethanolamine, an unidentified aminophospholipid, an unidentified phospholipid and an unidentified polar lipid. The major fatty acids were C_16 : 1ω6c and/or C_16 : 1ω7c, and C_18 : 1ω6c and/or C_18 : 1ω7c. The DNA G+C content of strain C3212^T was 44.3 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that the novel strain was related most closely to Leucothrix pacifica XH122^T, Leucothrix arctica IMCC 9719^T and Leucothrix mucor DSM 2157^T with similarities of 98.0, 97.5 and 94.3 %, respectively. Estimated DNA-DNA hybridization values were 14.2, 20.7 and 13.9 % between strain C3212^T and L. pacifica XH122^T, L. arctica IMCC 9719^T and L. mucor DSM 2157^T, respectively. Phenotypic, phylogenetic and genomic analyses revealed that strain C3212^T represents a novel species of the genus Leucothrix, for which the name Leucothrix sargassi sp. nov. is proposed. The type strain is C3212^T (=MCCC 1K03600^T=KCTC 72121^T).