Description of Sphingobium psychrophilum sp. nov., a cold- adapted bacterium isolated from Arctic soil

A yellow-coloured, Gram-stain-negative, non-sporulating, psychrotolerant and motile bacterium, designated AR-3-1(T), was iso-lated from the Arctic soil of Cambridge Bay, Nunavut, Canada. Strain AR-3-1(T) could grow at 4-32 degrees C and pH 5.0-11.0. Phy-logenetic analysis based on its 16S rRNA gene sequence indicated that strain AR-3-1(T) formed a lineage within the family Sphingomonadaceae and clustered as a member of the genus Sphingobium. The closest members within this genus were Sphingobium cupriresistens CU4T (98.1 % sequence similarity), Sphingobium vermicomposti VC-230T (97.6 %) and Sphingobium lactosutens DS20(T) (97.5 %). The only respiratory quinone was the ubiquinone Q-10. Spermidine was the predominant polyamine. The principal cellular fatty acids were summed feature 8 (C-18:1 omega 7c and/or C18.1 omega 6c), summed feature 3 (iso-C15.0 2-OH and/or C16:1 omega 7c), C16.0 and C-14.0 2-OH. The major polar lipids were phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidyldimethylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, sphingoglycolipid and phosphoglycolipid. The DNA G+C content was 63.1 %. The average nucleotide identity and in silico DNA-DNA hybridization relatedness values between strain AR-3-1T and its most closely related genus members were ?89.6 and 39.6 %, respectively. The genome was 5 162 327 bp long, with 83 scaffolds and 4824 protein-coding genes. The genome showed six putative biosynthetic gene clusters responsible for various secondary metabolites. Based on this polyphasic study, strain AR-3-1(T) represents a novel species within the genus Sphingobium, for which the name Sphingobium psychrophilum sp. nov. is proposed. The type strain is AR-3-1T (=KACC 21613(T)=NBRC 114604(T)).