Penicillium - Ecology

Ecology

Species of Penicillium are ubiquitous soil fungi preferring cool and moderate climates, commonly present wherever organic material is available. Saprophytic species of Penicillium and Aspergillus are among the best-known representatives of the Eurotiales and live mainly on organic biodegradable substances. Commonly known as molds, they are among the main causes of food spoilage, especially species of subgenus Penicillium. Many species produce highly toxic mycotoxins. The ability of these Penicillium species to grow on seeds and other stored foods depends on their propensity to thrive in low humidity and to colonize rapidly by aerial dispersion while the seeds are sufficiently moist. Some species have a blue color, commonly growing on old bread and giving it a blue fuzzy texture.

Some Penicillium species affect the fruits and bulbs of plants, including P. expansum, apples and pears; P. digitatum, citrus fruits; and P. allii, garlic. Some species are known to be pathogenic to animals; P. corylophilum, P. fellutanum, P. implicatum, P. janthinellum, P. viridicatum, and P. waksmanii are potential pathogens of mosquitoes. P. marneffei, which causes mortality in the Vietnamese bamboo rats, has become a common opportunistic infection of HIV-infected individuals in southeast Asia.

Penicillium species are present in the air and dust of indoor environments, such as homes and public buildings. The fungus can be readily transported from the outdoors, and grow indoors using building material or accumulated soil to obtain nutrients for growth. Penicillium growth can still occur indoors even if the relative humidity is low, as long as there is sufficient moisture available on a given surface. A British study determined that Aspergillus- and Penicillium-type spores were the most prevalent in the indoor air of residential properties, and exceeded outdoor levels. Even ceiling tiles can support the growth of Penicillium—as one study demonstrated—if the relative humidity is 85% and the moisture content of the tiles is greater than 2.2%.

Some Penicillium species cause damage to machinery and the combustible materials and lubricants used to run and maintain them. For example, P. chrysogenum, P. steckii, P. notatum, P. cyclopium, and P. nalgiovensis affect fuels; P. chrysogenum, P. rubrum, and P. verrucosum cause damage to oils and lubricants; P. regulosum damages optical and protective glass.