Pseudonocardia lacus sp. nov., An Actinomycete Isolated from a Lake Sediment Sample

A novel actinomycete strain, designated H11425^T, was isolated from a sediment sample collected from Baihua Lake, Guizhou Province, PR China, and a polyphasic approach was employed to determine its taxonomic position. 16S rRNA gene sequence comparisons showed that strain H11425^T is most closely related to Pseudonocardia sulfidoxydans JCM 10411^T (97.9%) and Pseudonocardia kunmingensis JCM 32122^T (97.8%). Both of phylogenetic analysis based on 16S rRNA gene sequence and phylogenomic analysis based on whole-genome sequence showed that strain H11425^T formed a separate clade within the genus Pseudonocardia. The draft genome had a length of 8,059,576 bp with a G + C content of 74.5%. The average nucleotide identity, average amino acid identity, and digital DNA-DNA hybridization values between strain H11425^T and its closely related Pseudonocardia species were 76.8-79.0%, 64.8-69.9% and 21.7-23.3%, respectively, which were significantly lower than the widely accepted species-defined threshold. Strain H11425^T contained meso-diaminopimelic acid, arabinose, galactose, glucose and ribose in its whole-cell hydrolysates. Mycolic acids were absent. The menaquinone was identifed as MK-8(H₄). The phospholipid profile consisted of diphosphatidylglycerol, phosphatidylethanolamine, hydroxy-phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, phosphatidylcholine, an unknown phospholipid and four unidentified aminophospholipids. The major fatty acids were iso-C_16:0, iso-C_14:0, iso H-C_16:1 and iso-C_16:0 2OH. On the basis of the taxonomic evidence, strain H11425^T represents a novel species of the genus Pseudonocardia, for which the name Pseudonocardia lacus sp. nov. is proposed. The type strain is H11425^T (= JCM 34851^T = CICC 25118^T).