sentences:  Sterigmatocystin is a toxic metabolite structurally closely related to the aflatoxins, and consists of a xanthone nucleus attached to a bifuran structure.Sterigmatocystin is mainly produced by the fungi "Aspergillus nidulans" and "A. versicolor".It has been reported in mouldy grain, green coffee beans and cheese although information on its occurrence in foods is limited.