Question: What processes do soil samples go though in order to find bacteria within them?

David Mark answered on 12 Mar 2020:

The bacteria I look for exist in the soil as spores, so they’re what I have to isolate. When I have the soil I heat it at 100 degrees Celsius to kill any bacteria that don’t produce spores get killed off. Once I have done that, I mix the soil in a salt solution that’s about isotonic to the spores so I don’t burst them, then I pour the soil solution over a petri dish of agar that has selective antibiotics in them that kill bacteria and fungi that I don’t want. It takes about a week for me to see the bacteria that I’m looking for because they grow slowly.