The Most Common Types of Mold

It is no secret that mold is mother nature’s way of taking out the trash. After all, without decomposition, there would be no room on the planet for us to live on since there would already be so much taking up space on the planet. However, when mold starts to show up on the walls of your basement, it is less of a helper and more of a hindrance. What’s more, there is a wide variety of mold species that exists on the planet. Over 100,000 to be exact.  So, that leads to a couple of questions. Which ones are the most common in the Chattanooga, Tennessee area? Which ones are harmful or harmless? Where are they most commonly found? There is only one way to find out. With a little bit of research, you will have the answers to the questions you need.


Aspergillus is the first common genus of mold that we are going to talk about.  What I was surprised to learn about the most of this species, was that there were some that came under the camp of helpful, just as much as some that came under the camp of harmful. What was even more amazing was that this was one of the oldest named genera of mold in the world.

It was named by an Italian priest who studied biology in 1729, Pier Antonio Micheli. He had been using a microscope when he discovered a spore that had a spoon-shaped ‘head’ and a long rod for a body. It reminded him of one of the tools he had often used for the Catholic Church, a holy water sprinkler, or aspergillum, and named it accordingly.

On the helpful side, some species of Aspergillus are made for our daily food production. Some species of this genus are part of soy sauce and sake production by breaking down starches into simple sugars. There are also other species such as Aspergillus niger, that is 99% responsible for the production of citric acid.

On the harmful side, there are more than 60  out of the 185 Aspergillus that are deemed medically important. The side effects of some of these at best involve allergy symptoms, such as a runny nose, or a sore throat. Other times, it could lead to asthma attacks, lung infections and respiratory infections for those with weak immune systems. At its worst, some species are capable of the production of aflatoxins, a deadly carcinogen.

While it is common to find species of Aspergillus outdoors, they are more commonly the first species of mold to show up on water damaged materials.


This most commonly known for its role as an antibiotic for certain diseases. However, that is only true for one specific species of this mold, Penicillium chrysogenum. That particular species was ‘discovered’ by Sir Alexander Fleming in 1928. The man was a brilliant scientist who accidentally came upon this species of mold because of his poor cleaning habits. He found it in one of his messes that he left for weeks in his laboratory, tested it, then learned it cured some diseases.

But he did not name this genus of mold. That honor belonged to Johann Heinrich Friedrich Link in his published 1809 scientific journal, Observationes. He wrote down that the mold looked like a pencil, which at the time was a small paintbrush utilized by artists.

Other helpful species of penicillin exist outside the realm of the medical field, such as Penicillium camemberti and Penicillium roqueforti, which are responsible for cheese production. Specifically, Camembert, Roquefort and bleu cheeses.

However, there are other species of Penicillium out there that are less friendly. There are some species that grow in both water-damaged homes and other damp areas. In worst case scenarios they are even found in places like mattresses, leather, and carpeting.

One can usually tell when mold growing on the walls is a strain of Penicillium. Because when it grows, it is either a light blue or green circular dot with a fuzzy texture. Exposure to this dangerous version of mold commonly causes allergies when it is airborne. At its worst, it can cause pulmonary inflammation and asthma. Long-term exposure can cause chronic sinus issues and can weaken people who suffer from immune disorders. There are even some species that can produce mycotoxins, just like black mold. Those can damage a person’s kidney or can even be cancer inducing.


This is only the tip of the iceberg of the most common species of mold in the Chattanooga, Tennessee area. The world of mold is fascinating and full of both helpful and hurtful examples, depending on its species and what it can do. It is important to make sure you know what you are dealing with before you expose yourself to anything that could be harmful. The only way to make sure you aren’t playing with anything dangerous is to follow these two steps.

  • Wear proper safety equipment such as gloves, goggles, or a mask when handling mold.
  • Get a testing kit to find out the best way to remove mold from your house.

If you do not feel comfortable handling the sudden appearance of mold in your home, you can always call a professional to do the job. Allied Crawlspace is here to help with your mold removal needs in the Chattanooga, Tennessee area.


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