DESCRIPTIONS OF MEDICAL FUNGI

Descriptions of Medical Fungi 23
The black aspergilli, Aspergillus section Nigri (Gams et al. 1985) includes species
with uniseriate or biseriate conidial heads, spherical to pyriform vesicles, smoothwalled
stipes and black or near black-coloured conidia. This group contains about 26
species with Aspergillus niger being the most common species isolated. A. niger can
be isolated from all continents and is not very selective with respect to environmental
conditions. Other species within this group that have been linked to human and animal
infection include A. acidus, A. aculeatus, A. brasiliensis and A. tubingensis.
Molecular Identification: In Aspergillus section Nigri, all species can be distinguished
from each other using calmodulin sequence data, and all except one can be
distinguished using β-tubulin sequence data. ITS sequencing can only be used for a
rough classification of the uni- and biseriate species (Samson et al. 2007).
Aspergillus niger van Tieghem
Aspergillus niger is one of the most common and easily identifiable species of the genus
Aspergillus, with its white to yellow mycelial culture surface later bearing black conidia.
This species is very commonly found in aspergillomas and is the most frequently
encountered agent of otomycosis. It is also a common laboratory contaminant.
RG-1 organism.
Aspergillus niger complex
Morphological Identification: On Czapek Dox agar, colonies consist of a compact
white or yellow basal felt covered by a dense layer of dark-brown to black conidial
heads. Conidial heads are large (up to 3 mm by 15 to 20 µm in diameter), globose,
dark brown, becoming radiate and tending to split into several loose columns with age.
Conidiophore stipes are smooth-walled, hyaline or turning dark towards the vesicle.
Conidial heads are biseriate with the phialides borne on brown, often septate metulae.
Conidia are globose to subglobose (3.5-5 µm in diameter), dark brown to black and
rough-walled.
Key Features: Conidial heads are dark brown to black, radiate and biseriate with
metulae twice as long as the phialides. Conidia brown and rough-walled.
Antifungal Susceptibility: A. niger (Australian National data); MIC µg/mL.
No 16
AmB 75 16 27 16 13 3
VORI 71 3 5 8 16 28 10 1
POSA 60 1 7 7 15 18 12
ITRA 75 1 3 8 13 34 14 1 1