Ketobacter nezhaii sp. nov., a marine bacterium isolated from coastal sediment

Abstract

A Gram-stain-negative, motile, aerobic and heterotrophic bacterium, designated as GYS_M3HT, was isolated from marine coastal sediment sampled at Xiamen Island. Cells were rod-shaped with one polar flagellum and weakly positive for oxidase and catalase. Growth of the strain occurred at pH 6–9 (optimum, pH 7–8), at 15–37 °C (optimum, 28 °C) and with NaCl concentrations of 1.0–6.0 % (optimum, 2.0 %). It had highest 16S rRNA similarity (97.7 %) toKetobacter alkanivoransGI5T, followed by the members of the genusAlcanivorax(lower than 91.2 %). The results of phylogenetic analysis indicated that it belonged to the genusKetobacterwithin the familyAlcanivoracaceae. In addition, the average nucleotide identity and digital DNA–DNA hybridization values between strain GYS_M3HTandK. alkanivoransGI5Twere 71.4 and 19.7 %, respectively, indicating that strain GYS_M3HTbelonged to a novel species. Its genome consisted of 5 318 758 bp, with a genomic DNA G+C content of 50.0 mol%. The respiratory quinone was Q-8 and the dominant fatty acids were identified as iso-C15 : 0(25.4 %), C16 : 1 ω6c/C16 : 1 ω7c(14.4 %) and iso-C13 : 0(7.2 %). The main polar lipids were phosphatidylethanolamine and phosphatidylglycerol. Therefore, based on phenotypic, chemotaxonomic and phylogenetic results, strain GYS_M3HTrepresents a novel species within the genusKetobacter, for which the nameKetobacter nezhaiisp. nov. is proposed, with the type strain GYS_M3HT(=MCCC 1A13808T=KCTC 72247T).