Streptomyces fildesensis sp. nov., a novel streptomycete isolated from Antarctic soil

A novel actinomycete strain, GW25-5T, was isolated from a soil sample collected from the Fildes Peninsula, King George Island, West Antarctica. The strain was characterized by white to grey aerial mycelia, which were differentiated to straight to flexuous spore chains, with rod-shaped smooth spores. The cell wall of strain GW25-5T contained LL-diaminopimelic acid (A2pm) and traces of meso-A2pm. Whole-cell sugars were galactose and minor amounts of mannose and glucose. The predominant menaquinones were MK-9(H6) (49%), MK-9(H8) (24%) and MK-9(H4) (12%). The phospholipids contained DPG, PE, PI, PIM and PL(s). The major cellular fatty acids were iso-C16:0 and anteiso-C15:0. Genomic DNA G+C content of strain GW25-5T was 70.0 mol%. BLAST result showed that strain GW25-5 has the 16S rRNA gene sequence highest similarity of 97.5% with members of genus Streptomyces and phylogenetic analysis indicated that this strain belongs to the genus Streptomyces. DNA–DNA relatedness values of strain GW25-5T with the closest species of Streptomycespurpureus LMG 19368T and Streptomycesbeijiangensis YIM 6T were significantly lower than 70% of the threshold value for the delineation of genomic species. A polyphasic taxonomic investigation based on a judicious combination of genotypic and phenotypic characteristics revealed that the organism represents a novel species of the genus Streptomyces. Thus, we propose strain GW25-5T as the type strain of this novel species, Streptomycesfildesensis (=CGMCC 4.5735T = YIM 93602T = DSM 41987T = NRRL B 24828T).