Actinomadura scrupuli sp. nov., isolated from rock

A novel actinomycete, designated strain R-Ac121(T), was isolated from a small stone collected from an agricultural field in Jeju, Republic of Korea. The organism formed abundant vegetative mycelium that was branched and twisted. The reverse colour of colonies was brownish-yellow. Non-motile, wrinkled arthrospores were produced directly on the substrate mycelium. Aerial mycelium and sporangia were not observed. A neighbour-joining tree based on 16S rRNA gene sequences indicated that the isolate formed a distinct clade within the radiation of the family Thermomonosporaceae. The highest 16S rRNA gene sequence identity was found with the type strain of Spirillospora rubra (97.3 % sequence similarity) followed by those of Actinoallomurus purpureus (97.0 %), Actinomadura alba (96.5 %), Actinomadura fibrosa (96.5 %) and Actinomadura echinospora (96.4 %). The cell wall contained meso-diaminopimelic acid. The whole-cell sugars were rhamnose, glucose, ribose, xylose and arabinose. The polar lipids included diphosphatidylglycerol, phosphatidylglycerol and phosphatidylinositol. The major menaquinone was MK-9(H(6)) and the predominant fatty acids were iso-C(16 : 0), C(16 : 0), C(17 : 1)ω8c and 10-methyl C(17 : 0). The DNA G+C content was 71.8 mol%. The combination of morphological, chemotaxonomic and phylogenetic data clearly supports the separation of the organism from recognized species of the genus Actinomadura and related genera. On the basis of the data presented here, strain R-Ac121(T) represents a novel species of the genus Actinomadura, for which the name Actinomadura scrupuli sp. nov. is proposed. The type strain is strain R-Ac121(T) (=KCTC 19488(T) =DSM 45225(T)).