Streptomyces altiplanensis sp. nov., an alkalitolerant species isolated from Chilean Altiplano soil, and emended description of Streptomyces chryseus (Krasil'nikov et al. 1965) Pridham 1970.

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 Streptomyceswith 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. flavidovirens 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-C15 : 0 (21.6 %) and anteiso-C17 : 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. helvaticus is considered as a later heterotypic synonym of S. chryseus and, consequently, we emend the description of S. chryseus.