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Home • Basidiobolus microsporus NRRL 2992 v1.0
Elongated microspores of Basidiobolus microsporus. Image by Kerry O'Donnell.
Elongated microspores of Basidiobolus microsporus. Image by Kerry O'Donnell.

Basidiobolus microsporus (R.K. Benjamin 1962) is a gastrointestinal gut fungus of reptiles and amphibians.  The type culture was isolated from lizard dung, but the species is also known from the dung of other reptiles and amphibians and from soil.  B. microsporus grows easily on synthetic media (e.g., corn meal agar), producing hyaline vegetative hyphae that become segmented by the development of cross walls resulting in uninucleate hyphal segments.  Intercalary hyphal segments frequently become emptied of cytoplasm due to spore production or concentrated in terminal hyphal segments.  

Like other species of Basidiobolus, B. microsporus produces multiple spore types including smooth-walled zygospores (meiospores) typically formed through the conjugation of adjacent hyphae, and multiple types of asexual spores including: chlamydospore-like hyphal bodies, and forcibly ejected, globos primary spores, which may develop into sporangia that give rise to endogenous sporangiospores, or germinate a sporophore that produces adhesive spores for dispersal by insects.  Unique to B. microsporous, and the basis of its name, are apically elongated microspores that develop exogenously from sporangiospores. As such, Basidiobolus has evolved numerous spore types that function in dispersal by insects, forcible dispersal through air, and resting spores for long-term survival in the host gut and in the environment.

Basidiobolus has several unique genetic and genomic features, which distinguish it from the rest of fungal world. It has possibly the largest nuclei among all known fungi. Its genome has been reported to contain a significant HGT signal from co-occurring gut bacteria.  Furthermore, the structure of its mitosis-associated organelle is similar to the centrioles of all flagellated eukaryotes, and its genome is comprised of a large number of small chromosomes. As such, Basidiobolus represents a system of gut fungi that exhibits noncanonical traits in fungal evolution.