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Roses are Red, Mold is Green

Penicillium, Alexander Fleming

With a pandemic unfolding, a near-blizzard happening outside in Chicago, and February 14th quickly approaching, it’s the perfect time to cuddle up indoors with your special someone. When I hear “Valentine’s Day”, I think of flowers and candies swapped with friends and loved ones, hand-written letters full of sweet nothings, and… mold! That’s right, it’s long-rumored that Alexander Fleming introduced a medicinal application for Penicillium mold (similar to what you might find on an old loaf of bread) on February 14th, 1929 — which later developed into the antibiotic that we now know as Penicillin.

There are only a few sources to back up the claim that his announcement was, in fact, made on February 14th. Some say that it was February 13th instead, but it is widely agreed that he made his discovery of the medicine in September of 1928 — by accident!

Fleming’s discovery: Penicillium

Fleming discovered the mold’s potential for medicinal application by accident, when he left a dish of staphylococcus bacteria lying out in his lab. He left for a vacation and when he returned he noticed that a mold, which he identified as penicillium notatum, landed in the dish and killed many of the bacteria. This chance event led to the discovery of an antibiotic that is still one of the most widely-used to this day! Check out Dylan’s previous blog for more information about How Illinois Mold Saved the World.

Penicillin’s impact

Fleming was described by a colleague as having a “frolicsome mind” and his accidental discovery by way of a messy lab speaks to that notion. Great news for my fellow Type B personalities — we get things done! After some follow-up experiments to test penicillin’s safety for animals and humans, an injectable form of the medicine became instrumental in treating WWII soldiers, and in 1945 Fleming and his colleagues won a Nobel Prize in Physiology or Medicine for “the discovery of penicillin and its curative effects in various infectious diseases”. 


While this particular application was able to help millions fight sickness and infection, that’s not the case with all mold. In fact, mold growth in an indoor environment can be a health hazard. A musty odor, visible water damage, or dark staining are a few signs that there may be a problem, but mold can appear in many different colors, shapes, and textures. It can also grow in settled dust, behind walls, or in other hard-to-see areas. The only way to know for sure if you might have a problem is to have a professional mold inspection. Call us at 312-920-9393 for a free quote over the phone! 


Hare, Ronald. 1979. “Penicillin—Setting the Record Straight.” New Scientist 81(1142):466–68.




Ian Cull

Ian Cull is a nationally recognized expert in the field of indoor air quality. He is the Chief Science Officer of Indoor Science, a company he started in 2004. He speaks around the world on air quality topics and is a training provider of the Indoor Air Quality Association. Mr. Cull is a Licensed Professional Engineer (PE) and Certified Industrial Hygienist (CIH). His degree is in Environmental Engineering from the University of Illinois - Urbana Champaign. Mr. Cull has developed 50 air quality related courses for the IAQA University and is the author of the book, “Fundamentals of Mold Remediation”. In his words… “Besides being passionate about indoor air quality, I enjoy cycling, music, the Chicago Bulls, and having fun with my three kids.”