Penicillium and Aspergillus Mold in Water Damage Buildings

Black mold fungi Aspergillus, which produce aflatoxins and cause pulmonary infection aspergillosis.

Something you will routinely see on lab results for mold air samples is the concentration of Penicillium/Aspergillus spores. This refers to a large group of molds consisting of the Penicillium genus (200+ species), the Aspergillus genus (200+) species and a number of other less common genera.

The reason they are lumped together in a group is because they all have small round spores, so are difficult to impossible to speciate accurately in spore trap air or tape-lift surface samples.  One small round spore looks a lot like another!

What Do Penicillium and Aspergillus Have in Common?

While The Penicillium and Aspergillus mold group is common outdoors, they also, at least in Florida, are the most common group of molds found growing in water damage buildings.  We may find a variety of other molds, but Penicillium/Aspergillus molds are essentially always present.

It is also a highly diverse mold group that can digest a wide variety of materials and thrive over a wide range of temperature and moisture levels. It includes organisms that are known to be toxigenic and allergenic, as well as some that are known opportunistic human pathogens.

The Penicillium and Aspergillus mold genera also have in common that their spores are released in long chains.  These are of course very fragile, so if there are a large number present in an air sample it is a strong indicator of a nearby source.

Related: Purpose of Mold Sampling During An Inspectionaspergillus penicillium mold diversity

However, don’t get the idea that Penicillium and Aspergillus and have much in common other than the size and shape of spores.  They are very diverse, growing in a multitude of temperatures, levels of moisture and food sources.

As an illustration of the diversity, see the 400x microscopic image from IET’s lab.  Here we have a single field from an air sample.  The three different color circles show the location of three different spore chains of the Penicillium/Aspergillus group.  Note the great difference in size.

What to Do When This Mold Group Is in Your Home

Whether it is Penicillium/Aspergillus or other common genera, mold should not be growing or contaminating an indoor environment. If it is, here is the basic process to deal with it properly. Note that the type of mold does not, in most cases, impact what needs to be done:

  1. Have an Indoor Environmental Professional (IEP), such as IET, perform a proper investigation to determine the extent and source of contamination and develop a Mold Remediation Protocol.
  2. A qualified mold remediator should then implement the Protocol.
  3. Then have a Post-Remediation Verification (PRV) inspection to document successful completion of remediation.
  4. Necessary reconstruction following.

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