DESCRIPTIONS OF MEDICAL FUNGI

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Descriptions of Medical Fungi
Mortierella wolfii Mehrotra & Baijal
The genus Mortierella has now been placed in a separate order, the Mortierellales
(Cavalier-Smith 1998). The genus contains about 90 recognised species, however
Mortierella wolfii is probably the only pathogenic species being an important causal
agent of bovine mycotic abortion, pneumonia and systemic mycosis in New Zealand,
Australia, Europe and USA. RG-2 organism.
Morphological Description: Cultures are fast growing, white to greyish-white, downy,
often with a broadly zonate or lobed (rosette-like) surface appearance and no reverse
pigment. Sporangiophores are typically erect, delicate, 80-250 µm in height, 6-20 µm
wide at the base, arising from rhizoids or bulbous swellings on the substrate hyphae
and terminating with a compact cluster of short acrotonous (terminal) branches.
Sporangia are usually 15-48 µm in diameter, with transparent walls and a conspicuous
collarette is usually present following dehiscence of the sporangiospores. Columellae
are generally lacking and sporangiospores are single-celled, short-cylindrical, 6-10 x
3-5 µm, with a double membrane. Chlamydospores with or without blunt appendages
(amoeba-like) may be present, zygospores have not been observed. Temperature:
grows well at 40-42 O C; maximum 48 O C.
Key Features: Mucorales, rapid growth at 40 O C (thermotolerant), and characteristic
delicate acrotonous branching sporangia without columellae.
References: Domsch et al. (1980), McGinnis (1980), Rippon (1988), de Hoog et al.
(2000, 2015).
a
b
20 µm
b
20 µm
Mortierella wolfii (a) culture showing a broadly zonate or lobed rosette-like surface
appearance, and (b) sporangium, showing a sporangiophore, wide at the base, arising
from rhizoids, and acrotonous (terminal) branches, collarettes and sporangiospores.