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

A novel actinobacterial strain, designated ACD12, 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 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 shared the highest degree of 16S rRNA gene sequence similarity with Actinomadura sputi DSM 45233 (98.3 %) and Actinomadura hallensis DSM 45043 (97.8 %). All tree-making algorithms used also supported strain ACD12 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 and 18.7 % relatedness with A. hallensis DSM 45043. 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 (=DSM 46745 =CECT 8842).