Shewanella polaris sp. nov., a psychrotolerant bacterium isolated from Arctic brown algae

A Gram-stain-negative, facultatively anaerobic, flagellated and rod-shaped bacterium, designated strain SM1901 T , was isolated from a brown algal sample collected from Kings Bay, Svalbard, Arctic. Strain SM1901 T grew at −4‒30 °C and with 0–7.0 % (w/v) NaCl. It reduced nitrate to nitrite and hydrolysed DNA and Tween 80. Results of phylogenetic analyses based on 16S rRNA gene sequences indicated that strain SM1901 T was affiliated with the genus Shewanella , showing the highest sequence similarity to the type strain of Shewanella litoralis (97.5%), followed by those of Shewanella vesiculosa , Shewanella livingstonensis and Shewanella saliphila (97.3 % for all three). The major cellular fatty acids were summed feature 3 (C 16 : 1 ω 7 с and/or C 16 : 1 ω 6 с ), C 16 : 0 , C 18 : 0 , iso-C 15 : 0 and C 17 : 1 ω 8 с and the major polar lipids were phosphatidylethanolamine and phosphatidylglycerol. The respiratory quinones were ubiquinones Q-7, Q-8, menaquinones MK-7(H) and MK-8. The genome of strain SM1901 T was 4648537 nucleotides long and encoded a variety of cold adaptation related genes, providing clues for better understanding the ecological adaptation mechanisms of polar bacteria. The genomic DNA G+C content of strain SM1901 T was 40.5 mol%. Based on the polyphasic evidence presented in this paper, strain SM1901 T was considered to represent a novel species, constituting a novel psychrotolerant lineage out of the known SF clade encompassed by polar Shewanella species, within the genus Shewanella , for which the name Shewanella polaris sp. nov. is proposed. The type strain is SM1901 T (=KCTC 72047 T =MCCC 1K03585 T ).