Aspergillus nidulans. Laboratory petri-dish culture of the fungus Aspergillus nidulans, cause of aspergillosis and mycetoma. Here the fungus is growing on agar in concentric circles from the centre outwards. The dark growth at the edges is the mycelium which forms the body of the fungus. The brown regions at the centre are spores, the reproductive bodies. A.nidulans produces the toxin sterigmatocysin which can cause food contamination. Inhalation of the spores causes the allergic lung reaction aspergillosis in asthmatics and those with lowered resistance. Mycetoma (madura foot) may result when the fungus infects tissue, bone and skin.