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

Abstract

A Gram-stain-negative, non-spore-forming, facultatively anaerobic bacterium, designated strain SC18T, 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 SC18T 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 SC18T formed a tight phyletic lineage with members of the genus Shewanella . Strain SC18T was related most closely to Shewanella denitrificans OS217T (97.3 % 16S rRNA gene sequence similarity) and Shewanella gaetbuli TF-27T (97.1 %), but the DNA–DNA relatedness levels between strain SC18T 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 SC18T represents a novel species of the genus Shewanella , for which the name Shewanella aestuarii sp. nov. is proposed. The type strain is SC18T ( = KACC 16187T = JCM 17801T).