Planomonospora sp. PM18: ISOLATION AND TAXONOMY OF NEW ACTINOBACTERIAL STRAIN ISOLATED FROM ALGERIAN SAHARAN SOIL

Abstract

An actinobacterial strain, designated PM18, was isolated from a Saharan soil sample by agar plate dilution method on chitin-vitamin agar supplemented with polymyxin after pretreatment of the soil sample at 120°C (dry heat) for 1 h. The taxonomic status of this strain was determined basis on morphological and physiological characteristics and phylogenetic analysis based on the 16S rRNA gene sequence. Strain PM18 developed an extensively branched and non-fragmented substrate mycelium. The isolate was characterized by the presence of cylindrical monosporous sporangia, which were produced only on the aerial mycelium. Sporangia were arranged closely in parallel double rows. The monosporous sporangia were motile. The morphological features of this isolate corresponded to those of members of the genus Planomonospora. Furthermore, phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain PM18 is a member of the genus Planomonospora. The 16S rRNA gene sequence similarity showed that this strain was most closely related to Planomonospora sphaerica JCM 9374T (99.2%) and Planomonospora parontospora subsp. antibiotica JCM 3094T (98.8%). Based on phenotypic differences and the separate position of strain PM18 in the phylogenetic tree, this strain may be a representative of a putative novel species in the genus Planomonospora.