Abstract

Arid soils are complex ecosystem that maintains topographically distinct mycoflora populations. A total of 45 soil samples collected from the arid soils in Iraqi desert were cultured by dilution plate method and screened for Aspergillus terreus. The aim of this study was to enhance ecological knowledge of cultured colonies variation of A. terreus as well as environmental interactions in arid soils. An attempt is made to comprehensively screen desert soil for the wild type A. terreus producing lovastatin. The results show that the most frequent Aspergillus spp. included: A. niger (159 isolates), A. terreus (143), A. flavus (115) and A. fumigates (42) and other fungi. Genetically, the diagnoses of 19 isolates of A. terreus were in the scope of our interest. The specific primer pair had monomorphic bands of approximately PCR product of 450 bp. Ribotyping isolates of A. terreus with primer pairs (ITS1/ITS4 and ITS1/ITS2) were 19 isolates, with a single PCR product of 550-600 bp and 280-380 bp, respectively. RAPD-PCR was also used to distinguish between ecological patterns generated and allowed a distinction of very closely related environmental isolates. Lovastatin production was carried out with thin layer chromatography. Results suggest that phenotypic variations in A. terreus isolates were not useful for identifying them, and showed no significance in the identification in all the sites studied. However, using discriminatory molecular methods, such as amplification of the targeted regions by specific and universal characterization of the isolates could be pivotal in understanding ecological variation. Wild type soil isolates of A. terreus have the ability to produce lovastatin.

Key words: Molecular ecological typing, Aspergillus terreus, arid soils, lovastatin, Iraq.