Amycolatopsis pithecelloba sp. nov., a novel actinomycete isolated from roots of Pithecellobium dulce in Thailand.

An actinomycete strain RM579 isolated from roots of Pithecellobium dulce in Thailand was studied using the polyphasic taxonomic approach. The results of comparative 16S rRNA gene sequence and phylogenetic analysis showed that strain RM579 belonged to the family Pseudonocardiaceae and it was most closely related to members of the genera Amycolatopsis (≤94.5% sequence similarity) and Haloechinothrix (≤93.4% sequence similarity). A phylogenetic tree constructed by neighbor-joining method indicated that strain RM579 was positioned within the clade of the genus Amycolatopsis and formed a monophyletic cluster with Amycolatopsis taiwanensis 0345M-7, Amycolatopsis pigmentata TT00-43 and Amycolatopsis helveola TT99-32. Strain RM579 formed white aerial mycelium and yellowish-brown substrate mycelium that fragments into rod-shaped elements. Morphological features and chemotaxonomic characteristics of strain RM579 were consistent with those of the genus Amycolatopsis. The cell wall of strain RM579 contained meso-diaminopimelic acid. Arabinose, galactose, mannose, and ribose were detected as whole-cell sugars. Mycolic acids were absent. The acyl type of the muramic acid in the cell wall was N-acetyl. Diphosphatidylglycerol, hydroxyl-phosphatidylethanolamine, phosphatidylinositol, and an unidentified phospholipid were detected as polar lipids. The major cellular fatty acids (>10%) were iso-C, iso-C 2-OH, and C cis9. The resultant data indicated that strain RM579 should be classified as representative of a novel species in the genus Amycolatopsis, for which the name Amycolatopsis pithecelloba sp. nov. is proposed. The type strain is RM579 (=TBRC 1849 =NBRC 106096).