Nocardia sputi sp. nov. isolated from the sputum of patients with pulmonary infection

Abstract

Two Gram-stain-positive, aerobic and rod-shaped actinomycetes (strains CY18T and CY8) were isolated from the sputum of two patients with pulmonary infections, and their taxonomic status was investigated. The 16S rRNA gene sequences and the results of phylogenetic analyses indicated that CY18T and CY8 were identical (100 %) and were most closely related to Nocardia beijingensis CGMCC 4.1521T (99.9 %) and Nocardia araoensis NBRC 100135T (99.5 %). The predominant cellular fatty acids of CY18T and CY8 were C16 : 0, C18 : 0, C18 : 1ω9c and summed feature 3 (comprising C16 : 1ɷ7c and/or C16 : 1ɷ6c), and the major menaquinone was MK-8(H4ω-cycl).The diagnostic diamino acid in the cell-wall peptidoglycan was meso-diaminopimelic acid. The whole-cell hydrolytic sugar pattern consisted of arabinose and glucose. The polar lipid profile contained diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannoside, two unidentified phospholipids, three unidentified glycolipids and two unidentified lipids.The DNA G+C contents of CY18T and CY8 were 67.9 and 68.0 % respectively. The digital DNA–DNA hybridization and average nucleotide identity values between the two novel strains and closely related species were well under the 70 % and 95–96 % thresholds, respectively, but these values between the two novel strains were 95.5 % and 99.5 %, respectively. On the basis of morphological and chemotaxonomic characteristics and the results of phylogenetic analyses, strains CY18T and CY8 represent a novel species of the genus Nocardia , for which the name Nocardia sputi sp. nov. is proposed. The type strain is CY18T (=GDMCC 1.3318T = JCM 33932T).