Pseudonocardia mahuensis sp. nov., Isolated from Sediment of Mahu Lake in China

An actinomycete, designated strain H11422^T, was isolated from sediment collected from Mahu Lake, Sichuan Province, P.R. China, and characterized by a polyphasic taxonomic approach. Strain H11422^T, based on the 16 S rRNA gene sequence analysis, exhibited the highest similarities to Pseudonocardia acidicola K10HN5^T (98.5%), Pseudonocardia bannensis YIM63101^T (97.9%), Pseudonocardia nigra ATK03^T (97.8%) and Pseudonocardia saturnea IMSNU 20,052^T (97.7%). Phylogenetic analysis based on the 16 S rRNA gene sequence placed strain H11422^T into the genus Pseudonocardia, where it formed a subclade with Pseudonocardia acidicola K10HN5^T. Genomic comparison with the closest type strain revealed average nucleotide identity (ANI) value of 84.8%, average amino acid identity (AAI) value of 81.6%, and digital DNA-DNA hybridization (dDDH) value of 28.9%, all significantly below the accepted species delineation thresholds. The whole-cell hydrolysates of strain H11422^T were composed of meso-diaminopimelic acid (meso-DAP) as the diagnostic diamino acid, and arabinose, galactose, glucose and ribose as the major sugars. Mycolic acids were not present. The only menaquinone was determined to be MK-8(H₄). The phospholipid profile included diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, three unidentified phospholipids, two unidentified aminophospholipids and two unidentified lipids. The predominant fatty acid was iso-C_16:0. Based on this comprehensive taxonomic evidence, strain H11422^T represents a novel species within the genus Pseudonocardia, for which the name Pseudonocardia mahuensis sp. nov. is proposed. The type strain is H11422^T (= JCM 34850^T = CICC 25117^T).