A novel bacterial strain, CDC141T, was isolated from sputum samples of a patient with pulmonary infection in Hainan Province, PR China. We performed a polyphasic study to assess the taxonomic position of the new species. Based on the results of 16S rRNA gene sequence analyses, strain CDC141T belonged to the genus Nocardia with the highest sequence similarity to Nocardia nova NBRC 15556T (98.84 %) and Nocardia macrotermitis RB20T (98.54 %). The dapb1 gene sequence-based phylogenetic and phylogenomic trees further showed that the novel strain was clustered in a distinct clade adjacent to Nocardia pseudobrasiliensis DSM 44290T. The DNA G+C content of strain CDC141T was 68.57 mol%. The genomic diversity analysis revealed low average nucleotide identity and in silico DNA‒DNA hybridization values (<84.7 and <28.9 %, respectively) with its closest relative. Growth occurred at 20-40 °C, pH 6.0-9.0 and with NaCl concentrations of 0.5-2.5 % (w/v). The main fatty acids of strain CDC141T were C16 : 0, C18 : 0 10-methyl, TBSA, C16 : 1 ω6c/C16 : 1 ω7c, C18 : 1 ω9c, C18 : 0, C17 : 1 iso I/anteiso B and C17 : 0. The polar lipid profile was dominated by diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannoside, unidentified glycolipids, unidentified phospholipids and unidentified lipids. MK8 (H4ω-cycl) and MK8 (H4) were the major respiratory quinones. These characteristics were consistent with the typical chemotaxonomic properties of members of the genus Nocardia. Based on the results of phenotypic and genetic analyses, strain CDC141T was identified as representing a new species of the genus Nocardia, with the proposed name Nocardia pulmonis sp. nov. (CDC141T=JCM 34955T=GDMCC 4.207T).
Keywords: Nocardia; dapb1 gene; novel species; phylogenomics; pulmonary infection.