Strain Llam7T was isolated from microbial mat samples from the hypersaline lake Salar de Llamará, located in Taracapá region in the hyper-arid core of the Atacama Desert (Chile). Phenotypic, chemotaxonomic and genomic traits were studied. Phylogenetic analyses based on 16S rRNA gene sequences assigned the strain to the family Micromonosporaceae with affiliation to the genera Micromonospora and Salinispora. Major fatty acids were C17 : 1ω8c, iso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0. The cell walls contained meso-diaminopimelic acid and ll-2,6 diaminopimelic acid (ll-DAP), while major whole-cell sugars were glucose, mannose, xylose and ribose. The major menaquinones were MK-9(H4) and MK-9(H6). As polar lipids phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol and several unidentified lipids, i.e. two glycolipids, one aminolipid, three phospholipids, one aminoglycolipid and one phosphoglycolipid, were detected. Genome sequencing revealed a genome size of 6.894 Mb and a DNA G+C content of 71.4 mol%. Phylogenetic analyses with complete genome sequences positioned strain Llam7T within the family Micromonosporaceae forming a distinct cluster with Micromonospora (former Xiangella) phaseoli DSM 45730T. This cluster is related to Micromonospora pelagivivens KJ-029T, Micromonospora craterilacus NA12T, and Micromonospora craniellae LHW63014T as well as to all members of the former genera Verrucosispora and Jishengella, which were re-classified as members of the genus Micromonospora, forming a clade distinct from the genus Salinispora. Pairwise whole genome average nucleotide identity (ANI) values, digital DNA-DNA hybridization (dDDH) values, the presence of the diamino acid ll-DAP, and the composition of whole sugars and polar lipids indicate that Llam7T represents a novel species, for which the name Micromonospora tarapacensis sp. nov. is proposed, with Llam7T (=DSM 109510T,=LMG 31023T) as the type strain.
Keywords: Actinobacteria; Atacama; Micromonospora tarapacensis; hypersaline lake; polyphasic taxonomy.