Penicillium with spores. Species of Penicillium are recognized by their dense brush-like spore-bearing structures. The common occurrence of Penicillium species in food is a particular problem. Some species produce toxins and may render food inedible or even dangerous. On the other hand some species of Penicillium are beneficial to humans. Cheeses such as Roquefort, Brie, Camembert, Stilton, etc. are ripened with species of Penicillium and are quite safe to eat. The drug penicillin is produced by Penicillium chrysogenum, a commonly occurring mold in most homes.