Mucor ramosissimus

Colonial growth is restricted, greyish and does not grow at 37C (maximum temperature for growth is 36C). Sporangiophores are hyaline, slightly roughened, tapering towards the apex and are erect with repeated sympodial branching. Sporangia are grey to black, globose or somewhat flattened, up to 80 µm in diameter and have very persistent sporangial walls. Columellae are applanate (flattened), up to 40-50 µm in size and are often absent in smaller sporangia. Sporangiospores are faintly brown, smooth-walled, subglobose to broadly ellipsoidal, 5-8 x 4.5-6 µm in size. Oidia may be present in the substrate hyphae, chlamydospores and zygospores are absent. Assimilation of ethanol is negative and that of nitrate is positive.  Mucor ramosissimus differs from other species of Mucor by its low, restricted growth on any medium, extremely persistent sporangial walls, columellae that are applanate or absent in smaller sporangia (often resembling Mortierella species), short sporangiophores that repeatedly branch sympodially as many as 12 times, and the occurrence of racket-shaped enlargements in the sporangiophores (Hesseltine and Ellis 1964, Schipper 1976, Scholer et al. 1983, de Hoog et al. 2000, Schipper and Staplers 2003). RG-1 organism.

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.