A pink-coloured, Gram-stain-positive, aerobic and rod-shaped strain, designated 75T, was isolated from Collins glacier front till, Antarctica. Strain 75T was non-motile and non-spore-forming. Growth was observed at pH 6.0-9.0 (optimum, pH 7.0), at 4-45 °C (optimum, 20 °C) and with 0-9 % (w/v) NaCl (optimum, 1%). Phylogenetic analyses based on 16S rRNA gene sequences showed that strain 75T belongs to the genus Rhodococcus, and is related to Rhodococcus gannanensis DSM 104003T, Rhodococcus aerolatus KCTC29240T and Rhodococcus agglutinans KCTC 39118T (96.1, 96.0 and 95.7 % sequence similarity, respectively). The main polar lipids were identified as diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannoside and a phosphoglycolipid. The major cellular fatty acids were identified as C16 : 0, iso- C16 : 0, 10-methyl C17 : 0 and C17 : 1 ω8c. MK-7 and MK-8(H4) were found to be the dominant menaquinones. Whole-cell hydrolysates contained meso-diaminopimelic acid, ribose, galactose, glucose and rhamnose. The genome of strain 75T is 3.82 Mb long in size with a G+C content of 73.1 mol%. On the basis of phenotypic, molecular and chemotaxonomic characteristics, strain 75T is considered to represent a novel species of the genus Rhodococcus, for which the name Rhodococcus antarcticus sp. nov. is proposed. The type strain is 75T (=CCTCC AA 2019032T=KCTC 49334T).
Keywords: Antarctica; Rhodococcus antarcticus; glacier; till.