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 (62.0–71.0mol%). 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 °C (optimum, 13 °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).