Propidium monoazide
Propidium monoazide (PMA) is a photoreactive DNA-binding dye that preferentially binds to dsDNA. It is used to detect viable microorganisms by qPCR. Visible light (high power halogen lamps or specific LED devices) induces a photoreaction of the chemical that will lead to a covalent bond with PMA and the dsDNA. The mechanism of DNA modification by PMA can be seen in this protocol. This process renders the DNA insoluble and results in its loss during subsequent genomic DNA extraction.