Syncephalestrum sp.

The genus Syncephalastrum is characterised by the formation of cylindrical merosporangia on a terminal swelling of the sporangiophore. Sporangiospores are arranged in a single row within the merosporangia.   Syncephalastrum racemosum is the type species of the genus and a potential human pathogen; however, well-documented cases are lacking. It is found mainly from soil and dung in tropical and subtropical regions. It can also be a difficult laboratory aerial contaminant. The sporangiophore and merosporangia of Syncephalastrum species may also be mistaken for an Aspergillus species, if the isolate is not looked at carefully.

Colonies are very fast growing, cottony to fluffy, white to light grey, becoming dark grey with the development of sporangia. Sporangiophores are erect, stolon-like, often producing adventitious rhizoids, and show sympodial branching (racemose branching) producing curved lateral branches. The main stalk and branches form terminal, globose to ovoid vesicles which bear finger-like merosporangia directly over their entire surface. At maturity, merosporangia are thin-walled, evanescent and contain 5-10(18) globose to ovoid, smooth-walled sporangiospores (merospores). Optimum growth temperature 20-40C. RG-2 organism.

Key Features: zygomycete producing sympodially branching sporangiophores with terminal vesicles bearing merosporangia.

Terminal vesicle, merosporangia and sporangiospores of Syncephalastrum racemosum.

Clinical significance:

Syncephalastrum racemosum is the principle member of the genus and a potential human pathogen, however well documented cases are lacking. It often isolated from soil and dung in tropical and subtropical regions and it can be a persistent laboratory contaminant. The sporangiophore and merosporangia of Syncephalastrum could also be mistaken for Aspergillus if the isolate is not looked at carefully.

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.