One of the mold analysis techniques that has gained popularity is Mold Specific Quantitative Polymerase Chain Reaction (MSQPCR) or PCR for short. If you have heard of ERMI - PCR is the analysis technique that is used by the laboratories to analyze for a number of different molds associated with water damaged and normal environments.
One of the limitations of PCR is that certain substances will inhibit the amplification of the DNA. When inhibitors are present in a sample the results can come back as "None Detected" or with very low levels - when in fact high levels of mold may be present but are inhibited and unable to be identified. It is therefore important to know when a sample is inhibited and the results are a false negative. Otherwise you may get lab negative lab results when lots of mold is in fact present.
There are ways for laboratories to check for inhibition - it is called the "Geotrichum Control". The dust sample is spiked with a known quantity of the yeast Geotrichum candidum. The sample is then analyzed for the full complement of molds being studied as well as the Geotrichum. If inhibitors are present then the Geotrichum is inhibited right along with the rest of the mold in the sample. If the results don't find the quantity of Geotrichum that was added - then one or more inhibitors are present and the results are not valid.
Other industries have compiled databases of substances known to cause PCR inhibition. As an example: urine and bile commonly inhibit the identification of DNA when using PCR. Medical professionals and crime scene investigators using PCR are aware of this and are frequently able to overcome the inhibitors by special processing or making sure the samples they submit aren't contaminated with an inhibitor. Every mold investigator, laboratory that analyses DNA and person that submits ERMI or other DNA samples needs this information.
This week I began a preliminary study to help establish a list of common household chemicals and substances that can cause DNA inhibition. Your contributions are being used to help fund this study. I want to help answer the question - If the cat misses the litter box and sprays the carpet, will the dried urine prevent an accurate analysis of the sample? What about spilled common substances like table salt, milk or common household cleaners?
Here is a list of some of the substances I want to test:
Table Salt (Sodium Chloride)
Borax (Sodium Borate)
Acetic Acid (vinegar)
Epsom Salts (Magnesium Sulfate)
Rust (Iron Oxide)
The first five samples have been sent to the laboratory for a preliminary study. Additional samples will be submitted once our research protocol is finalized and we receive the necessary funds.
Your $75 contribution will be earmarked to help fund this important research.