Principle of viability PCR using PMA or PMAxx
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 PCR 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.
How does v-PCR work?
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. PMAxx™ and PMA inhibit 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 PMAxx™ and PMA 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 real-time PCR reaction, dead cell DNA will show delayed amplification and higher Ct than live cells. In a mixed population, v-PCR permits quantitation of cell viability. The v-PCR technology can be applied not only to bacteria but to other cell types as well.
PMAxx™ for Viability PCR
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.
PMA Enhancer for Gram-Negative Bacteria
Real-Time strain-specific PCR Bacterial Viability Kits
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™ 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.
• PMA dye OR PMAxx dye
• Forget-Me-Not 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
PMA-Lite™ for photoactivation of PMA
- 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.
- Long-lasting LED lights with 465-475 nm emission
- For efficient activation of PMA, PMAxx™, EMA or similar dyes