What to Know About Penicillium Mold

Some molds are beneficial, others are dangerous, and some are both. Learn about Penicillium mold, its many helpful abilities plus its dangers.

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No one is happy to discover mold indoors. If you find some, it’s important to remove it quickly and thoroughly. And yet, some molds can be useful. Learn all about a variety of mold called Penicillium, how to get rid of it when it’s a problem, and how it helps us when it’s not.

What Is Penicillium Mold?

This family of molds was first identified in 1809 in a book by German naturalist Johann Heinrich Friedrich Link. Most of the estimated 300 or more species produce blue, green or yellow spores, and are one of the most common causes of fruit and vegetable spoilage. Spores are mostly spread in the air, and grow best in cool or moderate climates and damp environments. Some species of Penicillium are extremely useful in the production of certain meats, cheeses and antibiotics like Penicillin, which comes from Penicillium chrysogenum.

Where Is It Commonly Found?

Penicillium is found all over the world in cool, damp environments. It grows most often on decaying organic materials such as fruits, vegetables and vegetation. Old bread, spoiling apples and pears, and rotting plant bulbs are all perfect habitats for various Penicillium species, which often show up as blue or green fuzzy growths. It’s also known to grow on indoor building materials such as ceiling tiles and wood surfaces.

What Are the Health Effects?

Like many molds, Penicillium can threaten those with weak or compromised immune systems, causing allergic reactions or infections. Some species produce mycotoxins which are known carcinogens. Others species cause measurable organ damage when inhaled. When ingested, one species, called Penicillium marneffei, can cause serious infections that affect the lungs, kidneys, spleen, liver and bone marrow.

How to Remove and Prevent Penicillium Mold

Like most molds, Penicillium can only grow where there’s sufficient moisture. Some molds grow best in homes with high relative humidity, which is easy to fix: Open windows or install a heat recovery ventilator (HRV) in a cool climate, or run your air conditioning in hot regions.

Pencillium has relatively low moisture needs, sometimes growing in homes with normal airborne humidity as long as there’s at least one moist surface somewhere. To prevent Penicillium spreading, make sure your home is dry and well ventilated. Don’t keep spoiling food of any sort, because it’s a perfect environment for spores to take root.

If you find a small amount of mold, soak it thoroughly with a non-toxic registered fungicide. For infestations larger than about 36 x 36 inches, call mold specialists.

Steve Maxwell
Steve Maxwell is an award-winning content creator who has published more than 5,000 articles, shot countless photos and produced video since 1988. Using his experience as a carpenter, builder, stone mason and cabinetmaker, he has created content for Mother Earth News, Reader's Digest, Family Handyman, Cottage Life, Canadian Contractor, Canadian Home Workshop, and many more. Steve lives on Manitoulin Island, Canada with his wife and children in a stone house he built himself. His website gets 180,000+ views each month, his YouTube channel has 58,000+ subscribers and his weekly newsletter is received by 31,000 subscribers each Saturday morning.