A non-Streptomyces actinomycete, designated as strain S265T, was isolated from rhizosphere collected under an elephant ear plant (Colocasia esculenta) in Bangkok, Thailand. The taxonomic position of this strain was determined by a polyphasic approach. Strain S265T formed single globose spores on long, branching, aerial hyphae. It produced abundant aerial mycelium with green colour. The cell wall contained meso-diaminopimelic acid, and diagnostic whole-cell sugars were arabinose and galactose. Phosphatidylethanolamine and diphosphatidylglycerol were detected predominantly as polar lipids, whereas mycolic acids were not found. The major menaquinone was MK-9(H4), and principal cellular fatty acids were C15 : 1 B, iso-C16 : 1 H, anteiso-C15 : 0 and C15 : 0 2-OH. The DNA G+C content was 69 mol%. According to phylogenetic analysis, strain S265T was clustered with Saccharomonospora glauca K62T (98.1 %) and Saccharomonosporaviridis DSM 43017T (97.1 %) despite its 16S rRNA gene sequence showing the highest similarity value to that of Saccharomonosporaazurea NA-128T (98.6 %). DNA-DNA relatedness values between strain S265T and the closely related strains were in the range of 7-50 %, thus strengthening the evidence derived from the polyphasic study that strain S265T represents a novel species within the genus Saccharomonospora, for which the name Saccharomonosporacolocasiae sp. nov. is proposed. The type strain is S265T (=TBRC 7235T=NBRC 112945T).
Keywords: Saccharomonospora; rhizosphere.