The taxonomic position of strain 15-057AT, an acidophilic actinobacterium isolated from the bronchial lavage of an 80-year-old male, was determined using a polyphasic approach incorporating morphological, phenotypic, chemotaxonomic and genomic analyses. Pairwise 16S rRNA gene sequence similarities calculated using the GGDC web server between strain 15-057AT and its closest phylogenetic neighbours, Streptomyces griseoplanus NBRC 12779T and Streptacidiphilus oryzae TH49T, were 99.7 and 97.6 %, respectively. The G+C content of isolate 15-057AT was determined to be 72.6 mol%. DNA-DNA relatedness and average nucleotide identity between isolate 15-057AT and Streptomyces griseoplanus DSM 40009T were 29.2±2.5 % and 85.97 %, respectively. Chemotaxonomic features of isolate 15-057AT were consistent with its assignment within the genus Streptacidiphilus: the whole-cell hydrolysate contained ll-diaminopimelic acid as the diagnostic diamino acid and glucose, mannose and ribose as cell-wall sugars; the major menaquinone was MK9(H8); the polar lipid profile consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, glycophospholipid, aminoglycophospholipid and an unknown lipid; the major fatty acids were anteiso-C15 : 0 and iso-C16 : 0. Phenotypic and morphological traits distinguished isolate 15-057AT from its closest phylogenetic neighbours. The results of our taxonomic analyses showed that strain 15-057AT represents a novel species within the evolutionary radiation of the genus Streptacidiphilus, for which the name Streptacidiphilus bronchialis sp. nov. is proposed. The type strain is 15-057AT (=DSM 106435T=ATCC BAA-2934T).
Keywords: Actinobacteria; bronchial lavage; phenotyping; polyphasic taxonomy.