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, 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 belongs to the genus Microvirga and was most closely related to 'Microvirga brassicacearum' CDVBN77 (98.3%), Microvirga subterranea DSM 14364 (96.8%), Microvirga guangxiensis 25B (96.5%) and Microvirga aerophila DSM 21344 (96.5%). The predominant quinone was ubiquinone 10 (Q-10), and the major fatty acids were summed feature 8 (Cω7c and/or Cω6c) and C cyclo ω8c. The predominant polar lipids were phosphatidylcholine and phosphatidylethanolamine. The genomic DNA G + C content of strain 3D7 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 and its closely related species were below the threshold range for species determination. Phenotypic, chemotaxonomic, phylogenetic and genomic analyses suggested that strain 3D7 represents a novel species of the genus Microvirga, for which the name Microvirga antarctica sp. nov. is proposed. The type strain is 3D7 (= CGMCC 1.13821 = KCTC 72465).