Shewanella insulae sp. nov., isolated from a tidal flat

Abstract

A Gram-stain-negative, aerobic, non-spore-forming, motile by single polar flagellum and ovoid or rod-shaped bacterial strain, designated JBTF-M18^T, was isolated from tidal-flat sediment collected from the Yellow Sea, Republic of Korea. The neighbour-joining phylogenetic tree of 16S rRNA gene sequences showed that strain JBTF-M18^T fell within the clade comprising the type strains of Shewanella species. Strain JBTF-M18^T exhibited 16S rRNA gene sequence similarity values of 97.1-98.8 % to the type strains of S. loihica, S. aquimarina, S. waksmanii and S. marisflavi and of less than 96.9 % to the type strains of the other Shewanella species. The average nucleotide identity and digital DNA-DNA hybridization values between strain JBTF-M18^T and the type strains of S. waksmanii and S. loihica were 72.0 and 89.5% and 18.9 and 38.1 %, respectively. DNA-DNA relatedness values between strain JBTF-M18^T and the type strains of S. aquimarina and S. marisflavi were 14 and 19 %, respectively. The DNA G+C content of strain JBTF-M18^T from genomic sequence data was 52.9 %. Strain JBTF-M18^Tcontained MK-6 as the predominant menaquinone and Q-7 and Q-8 as the predominant ubiquinones. It had iso-C_{15 : 0}, summed feature 3 (C_{16 : 1} ω7c and/or C_{16 : 1} ω6c) and C_{16 : 0} as the major fatty acids. The major polar lipids of strain JBTF-M18^T were phosphatidylethanolamine and phosphatidylglycerol. Distinguished phenotypic properties, along with the phylogenetic and genetic distinctiveness, revealed that strain JBTF-M18^T is separated from recognized Shewanella species. On the basis of the data presented, strain JBTF-M18^T is considered to represent a novel species of the genus Shewanella, for which the name Shewanella insulae sp. nov. is proposed. The type strain is JBTF-M18^T (=KACC 19869^T=NBRC 113583^T).

Keywords: Shewanella insulae; genome; novel species; polyohasic taxonomy; tidal flat.