Actinomadura adrarensis sp. nov., an actinobacterium isolated from Saharan soil

A novel actinobacterial strain, designated ACD12^T, was isolated from a Saharan soil sample collected from Adrar province, southern Algeria. A polyphasic study was carried out to establish the taxonomic position of this strain. Strain ACD12^T was observed to form extensively branched substrate mycelia. Aerial mycelium was absent or was weakly produced on all media tested, while spore chains were short with a hooked and irregular spiral form (2-3 turns). The dominant diaminopimelic acid isomer in the cell wall was meso-diaminopimelic acid. Glucose, ribose, galactose, mannose and madurose occured in whole-cell hydrolysates. The major phospholipid was diphosphatidylglycerol and phosphatidylinositol. The predominant menaquinone was MK-9(H6). The fatty acid profile was characterized by the presence of C16 : 0, C17 : 0, C15 : 0, C18 : 0, C18 : 1 cis9 and iso-C16 : 0. Results of 16S rRNA gene sequence comparisons revealed that strain ACD12^T shared the highest degree of 16S rRNA gene sequence similarity with Actinomadura sputi DSM 45233^T (98.3 %) and Actinomadura hallensis DSM 45043^T (97.8 %). All tree-making algorithms used also supported strain ACD12^T forming a distinct clade with its most closely related species. In addition, DNA-DNA hybridization indicated only 39.8 % relatedness with A. sputi DSM 45233^T and 18.7 % relatedness with A. hallensis DSM 45043^T. The combined phenotypic and genotypic data show that the novel isolate represents a novel species of the genus Actinomadura, for which the name Actinomadura adrarensis sp. nov., is proposed, with the type strain ACD12^T (=DSM 46745^T =CECT 8842^T).