Pseudoalteromonas xishaensis sp. nov., isolated from Acanthaster planci in the Xisha islands

A Gram-negative, aerobic, motile by means of single polar flagellum, short rod-shaped marine bacterium, designated strain E418^T, was isolated from the spines on the body surface of starfish Acanthaster planci in the Xisha islands, China. Cells of strain E418^T were found to grow optimally at pH 7–8, at 25–37 °C, and in the presence of 2–5 % (w/v) NaCl. Phylogenetic analysis based on the comparison of 16S rRNA gene sequences revealed that strain E418^T is a member of the genus Pseudoalteromonas. The closest relative to this strain was found to be P. ruthenica LMG 19699^T, with a similarity level of 97.7 %. DNA relatedness between the novel isolate and this phylogenetically related species was 57.4 %. Strain E418^T decomposed Tween 80, gelatin, and casein, but was unable to decompose starch and grow on DNase Agar. The cellular fatty acid profile consisted of significant amounts of C16:1ω7c/C16:1ω6c, C18:1ω7c/C18:1ω6c, C16:0, and C17:1ω8c. The G+C content of DNA of this strain was determined to be 46.7 mol%. Phenotypic characteristics, phylogenetic analysis and DNA–DNA relatedness data suggest that strain E418^T represents a novel species of the genus Pseudoalteromonas, for which the name Pseudoalteromonas xishaensis sp. nov. is proposed. The type strain of P. xishaensis is strain E418^T (DSM 25588^T = NBRC 108846^T = CCTCC AB 2011177^T).