The genus Mucor consists of approximately 50 species having widespread distribution and of considerable economic importance. M. plumbeus is found world-wide in the soil, hay, stored seeds, dung, and frequently in house dust. It can be found in old, dirty carpets, and in ventilation ducts.[1]Gravesen S. Frisvad J.C. Samson R.A. Microfungi. Munksgaard, Copenhagen1994: 118-121Google Scholar It may degrade left-overs, soft fruits, marmalade, or juices.[1]Gravesen S. Frisvad J.C. Samson R.A. Microfungi. Munksgaard, Copenhagen1994: 118-121Google Scholar Mucor was found frequently in the indoor air of homes and schools during winter in northern Norway.[2]Dotterud L.K. Vorland L.H. Falk E.S. Viable fungi in indoor air in homes and schools in the Sør-Varanger community during winter.Pediatr Allergy Immunol. 1995; 6: 181-186Crossref PubMed Scopus (27) Google Scholar Mucor is frequently identified on air samples in the vicinity of Istanbul, but less commonly in The Netherlands.3Colakoğlu G. Airborne fungal spores at the Belgrad forest near the city of Istanbul (Turkey) in the year 2001 and their relation to allergic diseases.J Basic Microbiol. 2003; 43: 376-384Crossref PubMed Scopus (17) Google Scholar, 4Beaumont F. Kauffmn H.F. de Monchy J.G. Sluiter H.J. de Vries K. Volumetric aerobiological survey of conidial fungi in the North-East Netherlands. II. Comparison of aerobiological data and skin tests with mould extracts in an asthmatic population.Allergy. 1985; 40: 181-185Crossref PubMed Scopus (54) Google Scholar Mucor and related genera are used in Asia in the production of fermented foods and beverages.1Gravesen S. Frisvad J.C. Samson R.A. Microfungi. Munksgaard, Copenhagen1994: 118-121Google Scholar, 5Al-Doory Y. Domson J.F. Mould Allergy. Lea & Febiger, Philadelphia1984: 22Google Scholar Mucor species for the most part are thermo-intolerant, but a half-dozen species can grow in temperatures up to 42°C, making them potential animal or human pathogens.[6]Ellis D. Mycology Online: Mucor sp. http://www.mycology.adelaide.edu.au/Fungal_Descriptions/Zygomycetes/Mucor. Accessed June 13, 2015.Google Scholar Mucor sensitivity by specific IgE RAST has been shown in 40% of a group of allergic Scandinavian patients.[7]Aas K. Leegaard J. Aukrust L. Grimmer O. Immediate type hypersensitivity to common moulds. Comparison of different diagnostic materials.Allergy. 1980; 35: 443-451Crossref PubMed Scopus (58) Google Scholar However, only 3.8% of a group of asthmatic patients from the Netherlands revealed Mucor sensitization on skin testing.[4]Beaumont F. Kauffmn H.F. de Monchy J.G. Sluiter H.J. de Vries K. Volumetric aerobiological survey of conidial fungi in the North-East Netherlands. II. Comparison of aerobiological data and skin tests with mould extracts in an asthmatic population.Allergy. 1985; 40: 181-185Crossref PubMed Scopus (54) Google Scholar Mucor has been incriminated in a case of fatal anaphylaxis from the ingestion of mold contaminated pancake mix.[8]Bennett A.T. Collins K.A. An unusual case of anaphylaxis.Am J Forensic Med Pathol. 2001; 22: 292-295Crossref PubMed Scopus (22) Google Scholar Occupational asthma has been induced by Mucor contaminating esparto grass fibers.[9]Enríquez A. Fernández C. Jiménez A. Seoane E. Alcorta A.R. Rodríguz J. Occupational asthma induced by Mucor species contaminating esparto fibers.J Investig Allergol Clin Immunol. 2011; 21: 251-252PubMed Google Scholar Occupational hypersensitivity pneumonitis in cork workers, suberosis, has been attributed to Mucor.[10]Villar A. Muñoz X. Jesús Cruz M. Morell F. Hypersensitivity pneumonitis caused by Mucor species in a cork worker.Arch Bronconeumol. 2009; 45: 405-407Crossref PubMed Scopus (8) Google Scholar In Shanghai, a cluster of 20 cases of hypersensitivity pneumonitis in teachers occurred with exposure to Mucor contaminated sugarcane.[11]He Z.Y. Investigation on the outbreak of allergic pulmonary alveolitis.Zhonghua Liu Xing Bing Xue Za Zhi. 1989; 10: 129-132PubMed Google Scholar Mucor and Aspergillus are the most common causes of invasive fungal rhinosinusitis in immunocompromised patients.[12]Cho H.J. Jang M.S. Hong S.D. Chung S.K. Kim H.Y. Dhong H.J. Prognostic factors for survival in patients with acute invasive fungal rhinosinusitis.Am J Rhinol Allergy. 2015; 29: 48-53Crossref PubMed Scopus (43) Google Scholar Mixed infection of these same two fungi were seen in 146 of 180 (81.1%) patients with fungal ball sinusitis.[13]Ma L. Xu R. Shi J. et al.Identification of fungi in fungal ball sinusitis: comparison between MUC5B immunochemical and Grocott methenamine silver staining.Acta Otolaryngol. 2013; 133: 1181-1187Crossref PubMed Scopus (15) Google Scholar Mucormycosis may be caused by Mucor, as well as a different family member, Apophysomyces elegans.14Kusaba G. Ohsawa I. Ishii M. et al.Evidence of immunopathological traces in mucormycosis: an autopsy case.Clin Exp Nephrol. 2010; 14: 396-400Crossref PubMed Scopus (6) Google Scholar, 15Mucor. https://en.wikipedia.org/?title=Mucor. Accessed June 20, 2015.Google Scholar Mucor is within family Mucoraceae, order Mucorales, class Mucormycotina, and division Zygomycota. Other family members include Absidia (Lichtheimia), Rhizomucor, and the common bread mold, Rhizopus. No allergens have been characterized at present, and there is no information on cross-reactivity. Colonies are rapidly growing, cottony to fluffy, white to yellow, turning dark or olive gray with the development of sporangia, the spore containing bodies. The stalks, or sporangiophores, may be 2 cm tall, and the sporangia having spiny walls.1Gravesen S. Frisvad J.C. Samson R.A. Microfungi. Munksgaard, Copenhagen1994: 118-121Google Scholar, 6Ellis D. Mycology Online: Mucor sp. http://www.mycology.adelaide.edu.au/Fungal_Descriptions/Zygomycetes/Mucor. Accessed June 13, 2015.Google Scholar These asexual spores are globose, hyaline, gray or brownish 7–8 μm in diameter. Sexual reproduction may occur through specialized short hyphae called gametangia. When compatible gametangia fuse, a thick-walled spherical zygosporangium is formed which contains a single zygospore, in which meiosis occurs.[15]Mucor. https://en.wikipedia.org/?title=Mucor. Accessed June 20, 2015.Google Scholar Such zygospores are long-lived and impervious to adverse conditions.