Arthrobacter polaris sp. nov., a new cold-adapted member of the family Micrococcaceae isolated from Antarctic fellfield soil
Abstract
An aerobic, Gram-stain-positive and non-spore-forming strain, designated C1-1(T), was isolated from a fellfield soil sample collected from frost-sorted polygons on Jane Col, Signy Island, Maritime Antarctic. Cells with a size of 0.65-0.9x1.2-1.7 µm have a flagellar motile apparatus and exhibit a rod-coccus growth cycle.
Optimal growth conditions were observed at 15-20 °C, pH 7.0 and NaCl concentration up to 0.5% (w/v) in the medium. The 16S rRNA gene sequence of C1-1(T) showed the highest pairwise similarity of 98.77% to Arthrobacter glacialis NBRC 113092(T).
Phylogenetic trees based on the 16S rRNA and whole-genome sequences revealed that strain C1-1(T) belongs to the genus Arthrobacter and is most closely related to members of the 'Arthrobacter psychrolactophilus group'. The G+C content of genomic DNA was 58.95mol%.
The original and orthologous average nucleotide identities between strain C1-1(T) and A. glacialis NBRC 113092(T) were 77.15% and 77.38%, respectively. The digital DNA-DNA relatedness values between strain C1-1(T) and A. glacialis NBRC 113092T was 21.6%.
The polar lipid profile was composed mainly of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and an unidentified glycolipid. The predominant cellular fatty acids were anteiso-C(15:0) (75%) and anteiso-C(17:0) (15.2%).
Menaquinone MK-9(H2) (86.4%) was the major respiratory quinone in strain C1-1(T). The peptidoglycan type was determined as A3α (l-Lys-l-Ala(3); A11.6).
Based on all described phylogenetic, physiological and chemotaxonomic characteristics, we propose that strain C1-1(T) (=DSM 112353(T)=CCM 9148(T)) is the type strain of a novel species Arthrobacter polaris sp. nov.