PMA (propidium monoazide) dye is a DNA modifier invented by scientists at Biotium. It is a photo-reactive dye that binds to dsDNA with high affinity. Upon photolysis with visible light, PMA dye covalently attaches itself to dsDNA. The PMA-modified dsDNA cannot be amplified by PCR. The dye is designed to be cell membrane-impermeable. Thus, in a population of live and dead cells, only dead cells are susceptible to DNA modification due to compromised cell membranes. This unique feature of PMA dye makes it highly useful in selective detection of live bacteria by qPCR. A bacterial sample can be first pre-treated with PMA under light to inactivate dsDNA from dead cells. DNA is then extracted and analyzed by PCR. PMA is also available in lyophilized format (40013).
Since Biotium first developed PMA dye, there have been hundreds of publications on the use of the dye in many sample types including dozens of bacterial strains, biofilms, yeast, fungi, viruses, and eukaryotic cells. It has been used in such applications as food and water safety and environmental testing, and has been used in conjunction with qPCR, NextGen Sequencing (NGS), Sanger sequencing, and Loop-mediated Isothermal Amplification (LAMP). Check the Downloads section to view the PMA&PMaxx™ Reference List and the PMA&PMAxx™ Validated Bacterial Strains List.
For photoactivation of PMA dye, we recommend our PMA-Lite™ LED Photolysis Device for microcentrifuge tubes, or the Glo-Plate Blue™ LED Illuminator for larger tubes or 96-well plates.
PMA Molecular Information:
- Molecular weight: 511
- Abs = 464 nm (before photolysis)
- Abs/Em = 510/610 nm (following photolysis and covalent attachment to DNA/RNA)
- Dark red liquid
- Store at -20°C and protect from light at all times
PMAxx™ Dye for Viability PCR
PMAxx™ (40069) is a new and improved dye for viability PCR. It functions in a manner very similar to PMA, but has much greater activity and ability to distinguish between live and dead bacteria. PMAxx™ can be used as a replacement for PMA in any bacterial viability-PCR assay. We recommend that customers new to viability PCR try PMAxx™ instead of PMA, for improved detection of viable bacteria.
PMA Enhancer for Gram-Negative Bacteria
For viability PCR of gram-negative bacteria we highly recommend using PMA Enhancer (31038) in conjunction with PMA. PMA Enhancer for Gram Negative Bacteria was designed to improve PMA-mediated discrimination between live and dead gram-negative bacteria. When a sequence from a gram-negative bacteria is amplified by PCR, samples pre-treated with Enhancer show a decrease in the signal from dead cells, with no change in the signal from live cells.
Viability PCR Kits
To more easily get started with viability PCR, learn about our customizable Viability PCR Starter Kits. You choose which viability PCR dye you prefer, and whether or not you need Enhancer for gram-negative bacteria. All of the starter kits come with an EvaGreen® qPCR master mix and a detail protocol to get you started.
Biotium also provides strain-specific PMA Real-Time PCR Bacterial Viability Kits with validated primers for selected pathogens: M. tuberculosis, S. aureus, MRSA, Salmonella, E. coli, E. coli O157:H7, Legionella and Listeria. These kits provide everything that you need for the selective detection of your favorite species of live bacteria by real-time PCR.
Nocker, A., Cheung, C.Y., and Kamper, A.K. (2006). Comparison of propidium monoazide with ethidium monoazide for differentiation of live vs. dead bacteria by selective removal of DNA from dead cells. J. Microbio Meth. 67(2), 310-32
See a full list of PMA & PMAxx™ References and Validated Strains