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PMAxx, 20 mM in H2O

PMAxx™ dye is a DNA modifier used for viability PCR, invented by scientists at Biotium. PMAxx™ is a new and improved version of our popular viability dye PMA (propidium monoazide).

PMAxx, 20 mM in H2O
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40069

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100 uL

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Product Description

PMAxx™ dye is a DNA modifier used for viability PCR, invented by scientists at Biotium. PMAxx™ is a new and improved version of our popular viability dye PMA (propidium monoazide). Like PMA, PMAxx™ is a photo-reactive dye that binds to dsDNA with high affinity. Upon photolysis with visible light, PMAxx™ dye becomes covalently attached to dsDNA. The PMAxx™-modified dsDNA cannot be amplified by PCR. PMAxx™ 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 makes PMAxx™ highly useful in selective detection of live bacteria by qPCR.

PMAxx™ was designed by Biotium scientists to be a superior alternative to PMA. While PMA is generally effective at differentiating between live and dead bacteria by qPCR, it does not completely eliminate PCR products from dead cell DNA. This could potentially give false positive results. Biotium’s new dye PMAxx™ is much more effective at eliminating PCR amplification of dead cell DNA, and therefore provides the best discrimination between live and dead bacteria.

Since Biotium first developed PMA dye, there have been numerous publications on the use of the dye in pathogenic bacterial detection related to food and water safety, medical diagnosis and biodefense (download the PMA Reference List). PMAxx™ should be compatible with all existing PMA protocols, but with superior activity. Of course we also still sell the classic PMA dye, in water (40019) or lyophilized format (40013).

For viability PCR of Gram-negative bacteria we highly recommend using our PMA Enhancer (31038) in conjunction with PMAxx™. 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 dye and Enhancer show a decrease in the signal from dead cells, with no change in the signal from live cells. PMA Enhancer is particularly useful for samples in which bacteria were killed using mild methods such as low heat.

Biotium also provides strain-specific PMA Real-Time PCR Bacterial Viability kits with validated primers for 7 selected pathogens: M. tuberculosis, S. aureus, MRSA, Salmonella, E. coli, E. coli O157:H7 and Listeria. These kits provide everything that you need for the selective detection of your favorite species of live bacteria by real-time PCR. Don’t see your favorite strain? Let us know at techsupport@biotium.com.

Real-Time PCR Bacterial Viability Kits

For photoactivation of PMAxx™ dye (or PMA or EMA), we recommend the use of Biotium’s PMA-Lite™ LED Photolysis Device (E90002), which is designed to conduct photolysis under controlled conditions.

  • Abs = 466 nm (before photolysis)
  • Abs/Em = ~510/~610 nm (following photolysis and covalent attachment to DNA/RNA)
  • Dark red solution
  • Store at -20°C and protect from light at all times

References

PMAxx References

Randazzo, W., et al. (2016) Evaluation of viability PCR performance for assessing norovirus infectivity in fresh-cut vegetables and irrigation water. Int. J. Food Microbiol. Jul 16; 229: 1-6.

Garcia-Fontana, C., et al. (2016) A New Physiological Role for the DNA Molecule as a Protector against Drying Stress in Desiccation-Tolerant Microorganisms. Front. Microbiol. Dec 22; 7: 2066.

PMA References

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), 310-320.

Download the full PMA Reference List.

 

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Support & Faq

PMA and PMAxx™ for viability PCR

Both PMA and PMAxx™ are both offered as 20 mM solutions in water. We also offer PMA as a solid, and customers often ask whether it needs to be dissolved in DMSO. While in some publications users have prepared their PMA stock solution in DMSO, this is not necessary. Unlike the older viability dye EMA, which is not soluble in water, PMA and PMAxx™ are very water soluble.

Category: PMA and PMAxx™ for viability PCR

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We have compared PMA and PMAxx™ for their ability to differentiate between live and dead cells in viability PCR assays, and in all bacteria strains tested*, PMAxx™ had better activity. Therefore, while we haven’t tested every bacterial strain, we recommend PMAxx™ for bacterial viability PCR.

A recent publication by Randazzo et al. compared several viability PCR dyes in norovirus, and found that PMAxx™ worked the best for that organism.

We have also compared PMA and PMAxx™ in viability PCR assays with the yeast Saccharomyces cerevisiae, and found that PMA was equal to or better than PMAxx™. Therefore we recommend PMA for yeast and fungus viability PCR.

*E. coli, Salmonella enterica, Listeria monocytogenes, Bacillis subtilis, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Lactobacillus casei.

Category: PMA and PMAxx™ for viability PCR

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Biotium offers the PMA-Lite™ LED Photolysis Device for light-induced cross-linking of PMAxx™ and PMA to dsDNA. The PMA-Lite™ is designed for samples in microcentrifuge tubes.

For users that have samples in a different format (for example, 96-well plates or filters), we will soon be releasing a new light box that will allow for greater flexibility of assay format.

Commercial halogen lamps (>600 W) for home use have been employed for photoactivating PMA in some publications, though results have not been consistent due to inevitable variation in the set-up configurations. If you decide to use a halogen lamp, we recommend that you lay tubes on a block of ice set 20 cm from the light source, on a rocking platform to ensure continuous mixing. Set the lamp so that the light source is pointing directly downward onto the samples (up to 45° downward slant is OK). Expose samples to light for 5-15 min.

Category: PMA and PMAxx™ for viability PCR

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Shipping/Shelf-life

Shipment Method: Shipping and handling methods will be assessed and calculated at time of shipment based upon item(s) storage temperature conditions. Expedited shipment may be requested at time of checkout. Please note that products with recommended storage at 4°C or -20°C may ship at ambient temperature. This will not affect product performance. When you receive the product, place it under the recommended storage conditions.