

Penicillium species are very common moulds. About
200 species have been described. They are commonly called the
blue or green moulds because they produce enormous quantities
of greenish, bluish or yellowish spores which give them their
characteristic colours. Spores of Penicillium are
found everywhere in the air and soil. Penicillium
species are one of the most common causes of spoilage of
fruits and vegetables. For example, Penicillium
italicum and Penicillium digitatum are common
causes of rot of citrus fruits, while Penicillium
expansum is known to spoil apples. Most
Penicillium species are active producer of
toxins.
Penicillium chrysogenum is the most common Penicillium species in indoor environment. It is widespread and has a wide range of habitats. In indoor environment, it is extremely common on damp building materials, walls and wallpaper, floor, carpet mattress and upholstered furniture dust. It produces a number of toxins of moderate toxicity. It is allergenic and can infect immuno-compromised patients.