A novel Gram-stain positive, rod-shaped, non-motile and mycolic acid containing strain, FMN18(T), isolated from soil, was characterised using a polyphasic approach. The organism showed a combination of morphological, biochemical, physiological and chemotaxonomic properties that were consistent with its classification in the genus Nocardia and it formed a phyletic line in the Nocardia 16S rRNA gene tree. The cell wall contained meso-diaminopimelic acid (type IV) and whole cell sugars were galactose, glucose, arabinose and ribose. The predominant menaquinone was MK-8(H4ω-cyclo). The major phospholipids are diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannosides. Major fatty acids are C16:0, 10-methyl C18:0 (TBSA), C18:1 cis9 and C16:1 trans9. These chemotaxonomic traits are in good agreement with those known for representatives of the genus Nocardia. The phylogenetic analysis based on the 16S rRNA gene sequence of strain FMN18(T) showed it to be closely related to Nocardia grenadensis GW5-5797(T) (99.2 %), Nocardia speluncae N2-11(T) (99.1 %), Nocardia jinanensis 04-5195(T) (99.0 %) and Nocardia rhamnosiphila 202GMO(T) (98.3 %). The phylogenetic analysis based on the gyrB gene sequence of strain FMN18(T) showed it to be closely related to N. rhamnosiphila 202GMO(T) (99.0 %), N. grenadensis DSM 45869(T) (96.6 %), N. jinanensis DSM 45048(T) (93.1 %), N. carnea IFM 0237(T) (89.7 %) and N. speluncae DSM 45078(T) (89.1 %). A combination of DNA-DNA hybridization results and phenotypic properties demonstrated that strain FMN18(T) was clearly distinguished from all closely related Nocardia species. It is proposed that the organism be classified as representing a novel species of the genus Nocardia, for which the name Nocardia zapadnayensis (type strain FMN18(T) = DSM 45872(T) = KCTC 29234(T)) is proposed.
Keywords: 16S rRNA gene; Nocardia zapadnayensis; Polyphasic taxonomy.