Description and genome analysis of Microvirga antarctica sp. nov., a novel pink-pigmented psychrotolerant bacterium isolated from Antarctic soil

A novel pink-pigmented bacterium, designated strain 3D7^T, was isolated during an investigation of potential psychrotolerant species from Antarctic soil. Cells of the isolate were observed to be rod-shaped (0.7–0.9 × 1.0–2.2 µm), Gram-stain negative and non-motile. It was able to grow at 4–32 °C, pH 7.0–10.0 and in the presence of 0–3% (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain 3D7^T belongs to the genus Microvirga and was most closely related to ‘Microvirga brassicacearum’ CDVBN77^T (98.3%), Microvirga subterranea DSM 14364 ^T (96.8%), Microvirga guangxiensis 25B^T (96.5%) and Microvirga aerophila DSM 21344 ^T (96.5%). The predominant quinone was ubiquinone 10 (Q-10), and the major fatty acids were summed feature 8 (C_18:1ω7c and/or C_18:1ω6c) and C_19:0 cyclo ω8c. The predominant polar lipids were phosphatidylcholine and phosphatidylethanolamine. The genomic DNA G + C content of strain 3D7^T was 63.5 mol%. Its genome sequence showed genes encoding phosphatases and lipases. Genetic machinery related to carbohydrate-active enzymes and secondary metabolites were also observed. The average nucleotide identity and digital DNA–DNA hybridization values based on whole genome sequences of strain 3D7^T and its closely related species were below the threshold range for species determination. Phenotypic, chemotaxonomic, phylogenetic and genomic analyses suggested that strain 3D7^T represents a novel species of the genus Microvirga, for which the name Microvirga antarctica sp. nov. is proposed. The type strain is 3D7^T (= CGMCC 1.13821^T = KCTC 72465^T).