Mucor sp.

The genus Mucor can be differentiated from Absidia, Rhizomucor and Rhizopus by the absence of stolons and rhizoids.   Colonies are very fast growing, cottony to fluffy, white to yellow, becoming dark-grey, with the development of sporangia. Sporangiophores are erect, simple or branched, forming large (60-300 µm in diameter), terminal, globose to spherical, multispored sporangia, without apophyses and with well-developed subtending columellae. A conspicuous collarette (remnants of the sporangial wall) is usually visible at the base of the columella after sporangiospore dispersal. Sporangiospores are hyaline, grey or brownish, globose to ellipsoidal, and smooth-walled or finely ornamented. Chlamydospores and zygospores may also be present.

Key Features: zygomycete, large, spherical, non-apophysate sporangia with pronounced columellae and conspicuous collarette at the base of the columella following sporangiospore dispersal.

Sporangia, columella and sporangiospores of Mucor sp.

MIC data is limited.  Antifungal susceptibility testing of individual strains is recommended.

Clinical significance:

The genus Mucor contains about 50 recognised taxa, many of which have widespread occurrence and are of considerable economic importance (Zycha et al. 1969, Schipper 1978, Domsch et al. 1980). However, only a few thermotolerant species are of medical importance and human infections are only rarely reported.  Most infections reported list M. circinelloides and similar species such as M. indicus (M. rouxii), M. ramosissimus and M. amphibiorum as the causative agents. However, M. hiemalis and M. racemosus have also been reported as infectious agents, although their inability to grow at temperatures above 32C raises doubt as to their validity as human pathogens and their pathogenic role may be limited to cutaneous infections (Scholer et al. 1983, Goodman and Rinaldi 1991, Kwon-Chung and Bennett 1992, de Hoog et al. 2000).

Maximum temperature for growth of the reported pathogenic species of Mucor.

Mycosis: Zygomycosis

Further reading:

Domsch, K.H., W. Gams, and T.H. Anderson. 1980. Compendium of soil fungi. Volume 1. Academic Press, London, UK.

Ellis, D.H. 1997. Zygomycetes. Chapter 16 In Topley and Wilson's Microbiology and Microbial Infections. 9th edition Edward Arnold London pp247-277.