Actinomadura rhizosphaerae sp. nov., isolated from rhizosphere soil of the plant Azadirachta indica.

A novel actinomycete, strain SDA37, belonging to the genus Actinomadura, was isolated from rhizosphere soil collected from Udon Thani Province, Thailand. The taxonomic position of the strain was characterized using a polyphasic approach. Meso-diaminopimelic acid, glucose, ribose, galactose and madurose were detected in cell-wall and whole-cell hydrolysates. The N-acyl type of muramic acid was acetyl. Menaquinones were MK-9(H6), MK-9(H8) and MK-9(H4). The predominant cellular fatty acids were iso-C16 : 0, C16 : 0, 10-methyl C18 : 0 and iso-C14 : 0. The major polar lipids were phosphatidylglycerol, diphosphatidylglycerol and phosphatidylinositol. blast analysis of the almost-complete 16S rRNA gene sequence showed 98.8 % similarity to Actinomadura oligospora NBRC 104149, 98.7 % similarity to Actinomadura gamaensis DSM 100815 and 97.2 % similarity to Actinomadura rupiterrae KCTC 19559. The DNA G+C content was 73.1 mol%. Strain SDA37 showed low DNA-DNA relatedness (44.3±7.3 to 58.5±8.7 %) to A. oligospora NBRC 104149, Actinomadura gamaensis DSM 100815 and Actinomadura rupiterrae KCTC 19559. The new strain could also be distinguished from its closely related strains by the differences in the phenotypic characteristics. The results of taxonomic analysis suggested that strain SDA37 represented a novel species of the genus Actinomadura for which the name Actinomadura rhizosphaerae sp. nov. is proposed. The type strain is SDA37 (=KCTC 39965=NBRC 112909=TISTR 2523).