RESUMO
A novel aerobic, psychrotolerant marine bacterium was isolated at 4 degrees C from seawater samples collected from Spitzbergen in the Arctic. The strain was a polar-flagellated, Gram-negative bacterium that grew optimally at 10-15 degrees C and pH 7-8 in media containing 2-3% NaCl (w/v), using various carbohydrates and organic acids as substrates. The main fatty acid components included 16:0 (12.7% of total fatty acids), straight-chain saturated fatty acid methyl ester (FAME) and 16:1omega7c (40.2%) monounsaturated FAME. Phylogenetic analysis revealed a close relationship (99% 16S rRNA gene sequence similarity) between the novel isolate and Pseudoalteromonas elyakovii KMM 162T and some other species of the genus Pseudoalteromonas. The DNA G+C content of the novel strain was 39 mol%. DNA-DNA hybridization showed only 47.6% DNA-DNA relatedness with P. elyakovii KMM 162T, 44.2% with Pseudoalteromonas distincta KMM 638T and 22.6% with Pseudoalteromonas nigrifaciens NCIMB 8614T. Based on phylogenetic and phenotypic characteristics, this isolate represents a novel species of the genus Pseudoalteromonas for which the name Pseudoalteromonas arctica is proposed; the type strain is A 37-1-2T (=LMG 23753T=DSM 18437T).