Leifsonia rubra sp. nov. and Leifsonia aurea sp. nov., psychrophiles from a pond in Antarctica.

Two unique psychrophilic strains (CMS 76rT and CMS 81yT) were isolated from a cyanobacterial mat sample from a pond in Wright Valley, McMurdo, Antarctica. Both isolates were assigned to the genus Leifsonia, since they were gram-positive, curved rods, non-motile, catalase-positive, contained DL-2,4-diaminobutyric acid, menaquinone MK-11, phosphatidylglycerol and diphosphatidylglycerol, had a high content of anteiso- and iso-branched fatty acids and had a DNA G + C content of 64-66 mol%. In addition, both isolates were related to the five reported species of Leifsonia at a level of about 95-96% 16S rDNA sequence similarity and differed from one another by 2.5%. Strains CMS 76rT and CMS 81yT also differed from one another in many other phenotypic characteristics and exhibited only 30% relatedness at the DNA-DNA level, thus indicating that they represent two different species. Furthermore, these two isolates also showed many distinct differences with respect to the reported species of Leifsonia in terms of their phenotypic characteristics, biochemical properties, chemotaxonomic features, sensitivity to various antibiotics and 16S rDNA similarity, clearly indicating that strains CMS 76rT (= MTCC 4210T = DSM 15304T = CIP 107783T) and CMS 81yT (= MTCC 4657T = DSM 15303T = CIP 107785T) represent the type strains of two novel species of Leifsonia, for which the names Leifsonia rubra sp. nov. and Leifsonia aurea sp. nov. are proposed.