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

A Gram-stain-negative, motile, aerobic and heterotrophic bacterium, designated as GYS_M3H^T, 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 %) to Ketobacter alkanivorans GI5^T, followed by the members of the genus Alcanivorax (lower than 91.2 %). The results of phylogenetic analysis indicated that it belonged to the genus Ketobacter within the family Alcanivoracaceae. In addition, the average nucleotide identity and digital DNA-DNA hybridization values between strain GYS_M3H^T and K. alkanivorans GI5^T were 71.4 and 19.7 %, respectively, indicating that strain GYS_M3H^T belonged 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-C_15 : 0 (25.4 %), C_16 : 1  ω6c/C_16 : 1  ω7c (14.4 %) and iso-C_13 : 0 (7.2 %). The main polar lipids were phosphatidylethanolamine and phosphatidylglycerol. Therefore, based on phenotypic, chemotaxonomic and phylogenetic results, strain GYS_M3H^T represents a novel species within the genus Ketobacter, for which the name Ketobacter nezhaii sp. nov. is proposed, with the type strain GYS_M3H^T (=MCCC 1A13808^T=KCTC 72247^T).