Rhizopus microsporus var. rhizopodiformis

Rhizopus microsporus var. rhizopodiformis is the second most frequently isolated zygomycete, accounting for between 10% and 15% of reported human cases (Scholer et al. 1983; Kwon-Chung and Bennett 1992). Colonies are dark greyish-brown, up to 10 mm high with simple rhizoids. Sporangiophores are brownish, up to 500 µm high and 8 µm wide, with 1-4 produced together. Sporangia are bluish to greyish-black, spherical and up to 100 µm in diameter. Columellae are pyriform comprising 80% of the sporangium. Sporangiospores are subglobose to globose, quite equal in size, up to 6 µm in diameter and minutely spinulose. Zygospores, when formed by crosses of compatible mating strains, are reddish-brown, spherical, up to 100 µm in diameter, with stellate projections and unequal suspensor cells. There is good growth at 45C with a maximum of 50–52C.   RG-2 organism.

Sporangia showing sporangiophores, columellae, sporangiospores and rhizoids of R. microsporus var. oligosporus.

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.