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PMAxx™ and PMA Viability PCR Dyes

Dead cell-specific dyes covalently modify DNA, allowing selective PCR amplification from live cells
PMAxx™ is our newest v-PCR dye, with improved live/dead discrimination compared to our original PMA
Easily get started with viability PCR, with any cell type
Improve PMA & PMAxx™ modification of dead gram-negative bacteria
LED photolysis devices for tubes or plates
Everything you need for v-PCR of common strains



Introduction to viability PCR (v-PCR)

Viability PCR is a powerful technology for the sensitive and rapid detection of viable microorganisms. Unlike time-consuming culturing methods, qPCR is a fast and sensitive method of detection. However, normal qPCR does not distinguish between live and dead cells. With v-PCR using PMAxx™ or PMA, you get the speed, sensitivity and specificity of PCR, plus quantifiable viability. And because no culturing is required, you can even detect viable but not culturable (VBNC) bacteria. The v-PCR technology can be applied not only to bacteria but to other organisms like yeast, viruses, eukaryotes, and archaea.

How does v-PCR work?

The infographic below shows the basic mechanism of v-PCR. PMAxx™ and PMA are photoreactive dyes with high affinity for DNA. The dyes intercalate into dsDNA and form a covalent linkage upon exposure to intense visible light. The reaction inhibits PCR amplification of modified DNA templates by a combination of removal of modified DNA during purification and inhibition of template amplification by DNA polymerases. Because the dyes are cell membrane-impermeable, when a sample containing both live and dead bacteria is treated with dye, only dead bacteria with compromised cell membranes are susceptible to DNA modification. In a qPCR reaction, dead cell DNA will show delayed amplification and higher Ct than live cells.

Viability PCR dyes like PMAxx™ or PMA are membrane-impermeant, which makes them dead cell specific. Once inside of a dead cell, they bind to DNA. Exposure to intense visible light renders the dyes reactive, and causes them to covalently attach to the DNA. This DNA modification prevents amplification in subsequent PCR reactions.

v-PCR Workflow

The basic workflow for v-PCR is shown in the infographic below (detailed protocols can be found on product pages). It is adaptable for many different sample types and experimental set-ups. For a small number of cultures, the samples can be prepared in microcentrifuge tubes, and exposed to light in the PMA-Lite™. For high-throughput experiments, 96-well microplates can be used, and exposed to light on the Glo-Plate™ Blue. (See lower on this page for information on photoactivation devices).

Workflow Modifications

Many publications have used modifications of the basic protocol for specialty applications. For example, for large, dilute volumes, samples can be filtered onto a membrane, followed by dye treatment and photolysis on the membrane itself. Opaque, complex samples such as soil or feces generally need a higher dye concentration and longer light exposure; sample dilution can also help. And some users choose to perform qPCR directly on bacterial lysates, instead of purifying the DNA first.

The basic v-PCR workflow involves the following 5 steps: dye addition, incubation, light exposure, DNA extraction, and qPCR.
PMAxx technology is covered by granted and/or pending US and international patents.

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PMA is the original dye developed at Biotium for v-PCR. It has been validated in a wide variety of bacterial strains, as well as yeast and viruses (see PMA & PMAxx™ References and PMA & PMAxx™ Validated Bacterial Strains). However, 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.

PMAxx™ was designed by Biotium scientists to be a superior alternative to PMA. PMAxx™ is much more effective at eliminating PCR amplification of dead cell DNA, and therefore provides the best discrimination between live and dead bacteria.

Download the PMA and PMAxx™ flyer to learn more.

Live or dead bacteria treated with either PMA or PMAxx™ prior to qPCR. Dead bacteria treated with either PMA or PMAxx™ show delays in amplification compared to either live cells, or untreated dead cells. Bacteria treated with PMAxx™ show a larger delay than those treated with PMA. Therefore PMAxx™ is better able to differentiate live vs dead bacteria by viability PCR.

PMA & PMAxx™ for Viability PCR
Product NameCatalog No.Features
PMAxx™, 20 mM in H2O40069•    Next-generation v-PCR dye
•    Gives the best live/dead discrimination
PMA Dye40013•    Original v-PCR dye developed at Biotium
•    Validated in hundreds of publications and a wide variety of organisms
PMA Dye, 20 mM in H2O40019

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The customizable Viability PCR Starter Kits contain the materials that you need for selective detection of viable cells using either PMA or PMAxx™ viability dye and qPCR. These kits can be used with any cell type of your choosing (see the PMA/PMAxx™ Reference List and Validated Bacterial Strains List for published validated cell types). All of the kits contain Forget-Me-Not™ EvaGreen® qPCR Master Mix, and your choice of PMA or PMAxx™ dye. You also have the choice of selecting a kit with or without the Enhancer for Gram Negative Bacteria (not to be used with other cell types). The user will need to supply their own primers to amplify their species of interest (see this blog post for primer design considerations). Each kit contains reagents sufficient to treat 80 bacterial cultures and perform 200 PCR reactions.

Kits include:

• PMA dye OR PMAxx™ dye
• Forget-Me-Not™ EvaGreen® qPCR Master Mix
• ROX reference dye
• PMA Enhancer (gram-negative strains only)

Not included but required:

• primers to amplify your cell type of interest
• DNA extraction kit or reagents

Product NameCatalog No.Viability DyeTarget Cell Type
Viability PCR Starter Kit with PMA31075PMAAny cells
Viability PCR Starter Kit with PMAxx™31075-XPMAxx™Any cells
Viability PCR Starter Kit with PMA and Enhancer31076PMAGram-negative bacteria
Viability PCR Starter Kit with PMAxx™ and Enhancer31076-XPMAxx™Gram-negative bacteria

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PMA Enhancer for Gram Negative Bacteria was designed to improve discrimination between live and dead gram-negative bacteria during viability PCR. PMA Enhancer is provided as a 5X solution, and is added to a sample before the addition of viability dye. 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. PMA Enhancer is compatible with PMAxx™ as well as PMA. PMAxx™ plus Enhancer is the optimal way to perform viability PCR on gram-negative bacteria. PMA Enhancer is available as a stand-alone product, and is also a component of our PMA Bacterial Viability Kits (gram-negative strains only) (see below).

The mechanism by which Enhancer improves live/dead discrimination has not been determined. It may improve passive permeability of dead cell walls or membranes to the dye, and/or improve access of the dye to the dead cell DNA.

E. coli were killed with mild heat treatment (56°C for 3 hrs) and treated with PMAxx™ or PMAxx™ + Enhancer, followed by light exposure using PMA-Lite™, DNA purification, and qPCR with Fast EvaGreen® qPCR Master Mix. dCt values were calculated by subtracting the Ct without dye from the Ct with dye. Only dead cells treated with PMAxx™ + Enhancer showed a large dCt, indicating that the dye successfully inhibited PCR of dead cell DNA.

PMA Enhancer for Gram-Negative Bacteria

Product NameCatalog No.Features
PMA Enhancer for Gram Negative Bacteria, 5X Solution31038•    Improves live/dead discrimination in gram-negative strains

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The PMA-Lite™ LED photolysis device allows for time- and temperature-controlled light treatment of PMAxx™- or PMA-treated samples in microcentrifuge tubes.

PMA-Lite™ Features:

  • Provides even illumination to up to 18 microcentrifuge tubes
  • Internal fan keeps temperature < 37°C
  • Four timer settings for 10, 15, 20 or 30 minutes of light exposure
  • Durable LED lights with 465-475 nm emission
  • Best results are achieved with PMAxx™ dye

Glo-Plate™ Blue
The Glo-Plate™ Blue LED Illuminator is designed for even light treatment of PMAxx™- or PMA-treated samples in plates or larger tubes.

Glo-Plate™ Blue Features:

  • Provides even illumination across a flat surface, ideal for multi-well plates
  • Four timer settings for 10, 15, 20 or 30 minutes of light exposure
  • Durable LED lights with blue emission
  • Light exposure surface stays cool
  • For use with of PMAxx™, PMA, or Biotium’s DNAzure® Visible Gel Stain

PMA-Lite™ LED photolysis device
Glo-Plate™ Blue LED Illuminator
Glo-Plate™ Blue LED Illuminator

Photoactivation Devices

Product NameCatalog No.Features
PMA-Lite™ LED Photolysis DeviceE90002•    Photoactivation device, holds 16 microcentrifuge tubes
Glo-Plate™ Blue LED IlluminatorE90004•    Photoactivation device for plates or larger tubes

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Strain-specific v-PCR kits are designed for selective detection of viable bacteria from a specific strain using PMAxx™ or PMA dye and real-time PCR. The kits contain PMA dye OR PMAxx™ dye, Forget-Me-Not™ EvaGreen® qPCR Master Mix, and validated PCR primers for detection of selected strains of bacteria that are of widespread interest to food safety, public health, and/or antibacterial research.

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Kits include:

• PMA dye OR PMAxx™ dye
• Forget-Me-Not™ EvaGreen® qPCR Master Mix
• ROX reference dye
• PMA Enhancer (gram-negative strains only)
• Validated PCR primers for specific bacterial strain

PMA Real-Time PCR Bacterial Viability Kits are available for:

Salmonella enterica
Mycobacterium tuberculosis
Staphylococcus aureus
Staphylococcus aureus (methicillin-resistant)
Listeria monocytogenes
E. coli
E. coli O157:H7
Legionella pneumophila

Strain-Specific Bacterial Viability PCR Kits

Bacteria StrainGene nameKit with PMA (catalog #)Kit with PMAxx™ (catalog #)
Salmonella entericainvA3103331033-X
Mycobacterium tuberculosisgroEL231034N/A
Staphylococcus aureusnuc31035N/A
E. coli O157:H7Z32763103731037-X
E. coliuidA3105031050-X
Listeria monocytogeneshly3105131051-X
Legionella pneumophilamip31053N/A


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PMA Enhancer for Gram Negative Bacteria, 5X Solution

From: $79 Sizes: 16 mLCatalog #: 31038

Glo-Plate™ Blue LED Illuminator

From: $650 Sizes: EachCatalog #: E90004

PMA Real-Time PCR Bacterial Viability Kit – Listeria monocytogenes (hly)

From: $340 Sizes: 200 assaysCatalog #: 31051, - 31051-XView allHide

PMAxx™ Dye, 20 mM in H2O

From: $137 Sizes: 100 uLCatalog #: 40069

PMA-Lite™ LED Photolysis Device

From: $2,102 Sizes: EachCatalog #: E90002

PMA Real-Time PCR Bacterial Viability Kit – E. coli O157:H7 (Z3276)

From: $368 Sizes: 200 assaysCatalog #: 31037, - 31037-XView allHide