Pseudarthrobacter psychrotolerans sp. nov., a cold-adapted bacterium isolated from Antarctic soil

A novel cold-tolerant bacterium, designated strain YJ56(T), was isolated from Antarctic soil collected from the Cape Burk area. Phylogenetic analysis through 16S rRNA gene sequence similarity revealed that strain YJ56(T) was most closely related to the genus Pseudarthrobacter, including Pseudarthrobacter oxydans DSM 20119(T) (99.06% similarity), Pseudarthrobacter polychromogenes DSM 20136(T) (98.98%) and Pseudarthrobacter sulfonivorans ALL(T) (98.76 %). The genome size (5.2 Mbp) of strain YJ56(T) was the largest among all the published genomes of Pseudarthrobacter type strains (4.2-5.0 Mbp). The genomic G+C content of strain YJ56(T) (64.7mol%) was found to be consistent with those of other Pseudarthrobacter strains (62.0-71.0 mol%). The average nucleotide identity and average amino acid identity values between strain YJ56(T) and P. sulfonivorans ALL(T) were estimated at 84.1 and 84.2 %, respectively. The digital DNA-DNA hybridization value between the two strains was calculated to be 28.0 %. This rod-shaped and obligate aerobic strain exhibited no swimming or swarming motility. It had catalase activity but no oxidase activity. Cells grew at 4-28 degrees C (optimum, 13 degrees C) and pH 5.0-11.0 (optimum, pH 7.0) and with 0-6.0 % (w/v) NaCl (optimum, 0%) in Reasoner's 2A medium. MK-9 (H2) was the sole menaquinone. Two-dimensional TLC results revealed that the primary polar lipids were diphosphatidylglycerol, phosphatidylglycerol, two glycolipids and phosphatidylinositol. Fatty acid methyl ester analysis showed that anteiso-C-15:0, anteiso-C-17:0, iso-C-15:0, C-16:0 and iso-C-16:0 were the major cellular fatty acids in strain YJ56(T). Based on phenotypic and genotypic characteristics, strain YJ56(T) represents a novel species of the genus Pseudarthrobacter, and thus the name Pseudarthrobacter psychrotolerans sp. nov is proposed. The type strain is YJ56(T) (=JCM 33881(T)=KACC 21510(T)).