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Asked by anon-277068 on 2 Nov 2021.
Question: How do you ensure that your DNA samples haven't been contaminated?
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Sophie Potter answered on 8 Oct 2021:
We have very careful sampling processes to try and make sure that when we collect a sample, we just take the target species and nothing else. When @graeme and the lab team extract the DNA, they work in sterile conditions to reduce the risk of contamination.
One thing that can be quite exciting though is when the analysis teams find contaminants we weren’t expecting- such as parasites and bacteria. When that happens, we sometimes get two genetic codes for the price of one! @Marcela, @Sujai, @Lewis and others have neat methods for when this happens- they may be able to tell you more
Comments
Kes commented on :
We collect a lot of our samples from the marine environment, a very open and messy place for contamination! We have to deal with everything differently, for example seaweeds often have all sorts of things growing on them, we clean these off with tiny sponges under the microscope, so we can make sure we are removing everything, and then we rinse them in filtered sea water. We have lots of other methods to keep everything as clean as possible, like changing the gloves we are wearing between each sample and sterilizing all our equipment properly.
Michelle commented on :
There are ways to test DNA after it has been extracted, for contamination, but it is best to avoid any beforehand. We decontaminate work surfaces and keep each sample in separate tubes/bags when collecting in the field.
I grew up fungi from grass roots so I cleaned the roots with a diluted bleach and water solution to avoid soil contamination.
We also have hoods we can work in or under which moves the air in certain directions to keep yourself or your samples free from airborne contaminants. Laminar hoods keep your samples safe and fume hoods keep the user safe.