PMAqPCR

PMAqPCR, which stands for Propidium Monoazide quantitative Polymerase Chain Reaction, is a molecular biology technique used to differentiate between viable and dead cells in a sample. This method is particularly useful in microbiology and environmental science when analyzing microbial communities where the presence of dead cells can interfere with accurate viability assessments.

The core principle of PMAqPCR relies on the ability of propidium monoazide (PMA) to penetrate only the cell membranes of dead or dying cells. These cells have compromised membrane integrity, allowing the intercalating dye to enter the cell and bind to the DNA. Once bound, PMA acts as a photochemistry agent. Upon exposure to light, it forms covalent bonds with the DNA, effectively cross-linking it and preventing its amplification by PCR.

In contrast, PMA cannot enter cells with intact cell membranes, meaning viable cells with healthy membranes exclude the dye. Consequently, the DNA from live cells remains unamplified. By performing PCR on DNA extracted from a PMA-treated sample, only the DNA from viable cells will be successfully amplified, allowing for accurate quantification of the living population. This distinguishes PMAqPCR from standard qPCR, which would amplify DNA from both live and dead cells. The technique requires a specific workflow including PMA treatment, light activation, DNA extraction, and subsequent qPCR.