single strand conformation polymorphism analysis of pcr-amplified rdna to differentiate medically important aspergillus species

background: aspergillus species are associated with allergic bronchopulmonary disease, mycotic keratitis, otomycosis, na­sal sinusitis and invasive infection. in this study, we developed a pcr-single strand confomational polymorphism method to identify the most common aspergillus species and we showed some advantages of this method comparing a pcr-restric­tion fragment length polymorphism with our designed restriction enzyme. methods: we selected its2, as a short fragment within the rdna region (length size: 330 bp) to be amplified as small size pcr product. we mixed 5 ml of the pcr product with an equal volume of loading buffer and followed by incubation for 5 min at 95º c and quenching in an ice bath. the mixture was applied to a 6%-12% gradient poly acryl amide gel to run in a verti­cal electrophoresis, then gel was stained with ethidium bromide and silver nitrate which followed by an ethidium bro­mide staining. results: our results of restriction digestion showed a fine identification of 7 tested aspergillus species dur­ing 5-6 hours af­ter an overnight mycelial growth. as our results some of tested aspergillus species: a. nidulans , a. fisheri, a. quad­ricincta, (a. fumigatus and a. niger) as a group and ( a. flavus, a. tereus and a. ochraceus) as another group, can be dis­criminated. more­over sscp analysis enabled us to identify above aspergillus species within 8-12 h after an over night growth without us­ing an expensive restriction enzyme. conclusion: it is concluded that single strand conformational polymorphism is a simple and rapid method for identifica­tion of some medically important aspergillus .