Shewanella aestuarii sp. nov., a marine bacterium isolated from a tidal flat.

A Gram-stain-negative, non-spore-forming, facultatively anaerobic bacterium, designated strain SC18(T), was isolated from a tidal flat of Suncheon bay in South Korea. Cells were rod-shaped and motile by means of a polar flagellum. Cells were catalase-, oxidase- and β-haemolysis-positive. Growth was observed at 4-37 °C (optimum, 25-30 °C), at pH 5.0-9.0 (optimum, pH 7.0) and in the presence of 0-5.0 % (w/v) NaCl (optimum, 0-2 %). The major cellular fatty acids were summed feature 3 (comprising C16 : 1ω7c and/or C16 : 1ω6c), iso-C15 : 0 and C16 : 0. The polar lipid pattern indicated the presence of phosphatidylethanolamine, phosphatidylglycerol, phosphatidylmethylethanolamine, an unidentified aminolipid and three unidentified lipids. Strain SC18(T) contained Q-7, Q-8, MK-7 and MMK-7 as the dominant respiratory quinones and the G+C content of the genomic DNA was 41.3 mol%. Phylogenetic analysis based on 16S rRNA and gyrase B (gyrB) gene sequences showed that strain SC18(T) formed a tight phyletic lineage with members of the genus Shewanella. Strain SC18(T) was related most closely to Shewanella denitrificans OS217(T) (97.3 % 16S rRNA gene sequence similarity) and Shewanella gaetbuli TF-27(T) (97.1 %), but the DNA-DNA relatedness levels between strain SC18(T) and the type strains of S. denitrificans and S. gaetbuli were 18.3±2.8 and 22.5±1.6 % (mean±sd), respectively. On the basis of phenotypic, chemotaxonomic and molecular features, strain SC18(T) represents a novel species of the genus Shewanella, for which the name Shewanella aestuarii sp. nov. is proposed. The type strain is SC18(T) ( = KACC 16187(T) = JCM 17801(T)).