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

Two unique psychrophilic strains (CMS 76r(T) and CMS 81y(T)) 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 76r(T) and CMS 81y(T) 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 76r(T) (= MTCC 4210(T) = DSM 15304(T) = CIP 107783(T)) and CMS 81y(T) (= MTCC 4657(T) = DSM 15303 (T) = CIP 107785(T)) 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.