Abstract

A polyphasic approach was used for evaluating the taxonomic status of strain HST21(T) isolated from Salar de Huasco in the Atacama Desert. The results of 16S rRNA gene and multilocus sequence phylogenetic analyses assigned strain HST21(T) to the genus Streptomyces with Streptomyces albidochromogenes DSM 41800(T) and Streptomyces flavidovirens DSM 40150(T) as its nearest neighbours. Digital DNA-DNA hydridization (dDDH) and average nucleotide identity (ANI) values between the genome sequences of strain HST21(T) and S. albidochromogenes DSM 41800(T) (35.6 and 88.2%) and S. flavidoyirens DSM 40105(T) (47.2 and 88.8 %) were below the thresholds of 70 and 95-96 % for prokaryotic conspecific assignation. Phenotypic, chemotaxonomic and genetic results distinguished strain HST21(T) from its closest neighbours. Strain HST21(T) is characterized by the presence of LL-diaminopimelic acid in its peptidoglycan layer; glucose and ribose as whole cell sugars; diphosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylethanolamine, phosphatidylinositol, glycophospholipids, unknown lipids and phospholipids as polar lipids; and anteiso-C-15:0 (21.6%) and anteiso-C-17:0 (20.5%) as major fatty acids (>15%). Based on these results, strain HST21(T) merits recognition as a novel species, for which the name Streptomyces altiplanensis sp. nov. is proposed. The type strain is HST21(T) =DSM 107267(T) =CECT 9647(T). While analysing the phylogenies of strain HST21(T), Streptomyces chryseus DSM 40420(T) and Streptomyces helvaticus DSM 40431(T) were found to have 100% 16S rRNA gene sequence similarity with digital DNA-DNA hydridization (dDDH) and average nucleotide identity (ANI) values of 95.3 and 99.4%, respectively. Therefore, S. helyaticus is considered as a later heterotypic synonym of S. chryseus and, consequently, we emend the description of S. chryseus.