* To whom all correspondence should be addressed. Mob.: +989133094852; Fax: +983135354033; E-mail: Zia.mohammadali@gmail.com JOURNAL OF PURE AND APPLIED MICROBIOLOGY, March 2016. Vol. 10(1), p. 81-88 Occurrence of Important Mucormycosis Agents in the Soil of Populous Areas of Isfahan and Their Pathogenicity in Immunocompromised Patients Ardeshir Ziaee 1 , Mohammadali Zia 2 *, Mansour Bayat 1 and Jamal Hashemi 3 1 Department of Medical and Veterinary Mycology, Faculty of Veterinary Specialized Sciences, Science and Research Branch, Islamic Azad University, Tehran, Iran. 2 Department of Basic Sciences, Khorasgan (Isfahan) Branch, Islamic Azad University, Isfahan, Iran. 3 Department of Medical Parasitology and Mycology, School of Public Health &Institute of public Health Research, Tehran university of Medical Sciences, Tehran, Iran. (Received: 01 November 2015; accepted: 04 December 2015) Soils are the main habitat of saprophytic and pathogenic fungi. Zygomycetes are one of the most parts of soil fungi and certain members are among opportunistic fungi and can cause systemic fungal infections in immunocompromised patients. The majority of human and animal infections are caused by members of the genera Rhizopus, Mucor, Rhizomucor, Absidia, Cunninghamella, Mortierella. The objective of this research was to isolate and identify the main genera of Zygomycetes, especially family Mucoraceae. A total of 340 soil samples were collected from seven different public parks and 14 municipality districts in Isfahan. All samples were cultured on appropriate media and incubated at 25-30° C for 2 weeks, examined daily for visible fungal growth. Five hundred fungal colonies belonging to various classes of filamentous fungi were obtained. Finally 400 pure colonies belonging to six genera of Zygomycetes including Absidia, Rhizopus, Rhizomucor, Mucor, Cunninghamella and Mortierella were identified. The genus Rhizopus (35.5%) was the most frequent isolate, followed by Mucor (32.25%) and Rhizomucor (27.5%). These finding may help us to understand about the importance of opportunistic fungi in public areas and the risk of exposure with immuno-compromised persons. Key words: Soil-borne fungi; Zygomycetes; Immuno-compromised patients; Mucoraceae. Mucormycosis is rapidly progressing and fatal infection that is caused by members of the Mucorales order. The importance of mucormycosis has grown in recent year as the number of patients with predisposing factors has increased dramatically. Zygomycosis the term used previously has become accurate based on a recent taxonomic reclassification that abolished Zygomycetes as a class. Mucormycetes are ubiquitous filamentous fungi in nature, belonging to the subphylum Mucormycotina 1-3 , and are increasingly becoming recognized as opportunistic pathogens in immuncompromised and immunosuppresed patients 4, 5 . Invasive fungal Infection (IFI) is a life threatening complication in immunocompromised hosts and a cause of mortality in such patients 4, 6, 7 . The overall mortality associated with IFI is high and ranges from 40 to 60%, but can approach 100% in the presence of some pathogens such as Zygomycetes molds 8 . The term mucormycosis is used to refer to infections due to molds belonging to the order mucorales 9 . Several members of this order are among important agents of several human infections 10 . These organisms can cause rhinocerebral, pulmonary, gastrointestinal, cutaneous or