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

Abstract

A yellow-coloured, Gram-stain-negative, non-sporulating, psychrotolerant and motile bacterium, designated AR-3-1T, was isolated from the Arctic soil of Cambridge Bay, Nunavut, Canada. Strain AR-3-1T could grow at 4-32 °C and pH 5.0- 11.0. Phylogenetic analysis based on its 16S rRNA gene sequence indicated that strain AR-3-1T 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 DS20T (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 (C18 : 1 ω7c and/or C18 : 1 ω6c), summed feature 3 (iso-C15 : 0 2-OH and/or C16 : 1 ω7c), C16 : 0 and C14 : 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-3-1T 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 21613T=NBRC 114604T).