Aspergillus penicillioides

Aspergillus penicillioides is a species of fungus in the genus Aspergillus, and is among the most xerophilic fungi.

Aspergillus penicillioides is typically found in indoor air, house dust, and on substrates with low water activity, such as dried food, papers affected by foxing, and inorganic objects such as binocular lenses. The distribution of the fungus is worldwide; it has been found in bed dust from maritime temperate, Mediterranean, and tropical climates. The abundance of the fungus is influenced by outdoor climate, with highest numbers found in tropics and lowest numbers in cool climates. Cool temperature tends to decrease number of A. penicillioides in house dust.

A colony can arise from a single sexual or asexual spore under acidic conditions, and its diameter ranges from less than a milliliter to several centimeters, depending on the size and composition of the substrate. Germination of A. penicillioides was found to occur at lower water activity than growth. The lowest water activity for germination was 0.585.