PMA-PCR kits are designed for selective detection of viable bacteria from a specific strain using PMA or PMAxx™ dye and real-time PCR. The kits contain PMA or PMAxx™ dye, Forget-Me-Not™ qPCR Master Mix, and PCR primers for detection of selected strains of bacteria that are of widespread interest to food safety, public health, and/or antibacterial research.
This kit contains primers for amplification of E. coli uidA gene, with reagents sufficient to treat 80 bacterial cultures with PMA or PMAxx™, and perform 200 PCR reactions. There is an option to choose either PMA or PMAxx™ for the viability dye (see below for more information about these dyes). The number of samples that can be treated with PMA or PMAxx™ using the kit may vary depending on sample type. See the product protocol under the downloads tab and references for more information.
PMA is a high affinity photoreactive DNA binding dye developed by Biotium. The dye is weakly fluorescent by itself but becomes highly fluorescent upon binding to nucleic acids. It preferentially binds to dsDNA with high affinity. Upon photolysis, the photoreactive azido group on the dye is converted to a highly reactive nitrene radical, which readily reacts with any hydrocarbon moiety at the binding site to form a stable covalent nitrogen-carbon bond, thus resulting in permanent DNA modification. The dye is cell membrane-impermeable and thus can be used to selectively modify DNA from dead cells with compromised membrane integrity, while leaving DNA from viable cells intact. PMA 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 (see Reference 1 under the references tab). Consequently the dye is useful in the selective detection of viable pathogenic cells by quantitative real-time PCR.
PMAxx™ is a new and improved version of PMA designed by Biotium scientists. 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.
Forget-Me-Not™ qPCR Master Mix is a hot-start EvaGreen® dye-based master mix for use in real time PCR applications and DNA melt curve analysis. Forget-Me-Not™ master mix contains a low concentration of blue dye which allows you to see at a glance whether you forgot to add master mix to any of your tubes, so you can catch pipetting mistakes and avoid wasting time, reagents, and your precious DNA samples. It is formulated for qPCR using a fast cycling protocol, but also can be used for qPCR using regular cycling protocols. EvaGreen® dye is a unique DNA-binding dye with features ideal for both qPCR and melt curve analysis. EvaGreen® dye binds to dsDNA via a novel “release-on-demand” mechanism, which permits the use of a relatively high dye concentration in qPCR without PCR inhibition. Forget-Me-Not™ Master Mix contains Cheetah™ Taq, Biotium’s fast-activating chemically-modified hot-start Taq polymerase, which is particularly suitable for fast PCR cycling protocols.
Escherichia coli is a species of bacteria that is commonly used in laboratories. Some strains of E. coli are food-borne pathogens and can cause digestive illness. For specific detection of the pathogenic E. coli strain O157:H7, please see kit number 31037. PCR to amplify the gene uidA has been published and shown to be highly specific for E. coli (see Reference 2 under the references tab). The primers provided in the kit have been validated at Biotium for real-time qPCR using Forget-Me-Not™ Master Mix (see product protocol under downloads for details).
Also see our other PMA-PCR kits for detection of Mycobacterium tuberculosis, Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Listeria monocytogenes, Legionella pneumophila, and Salmonella enterica. Don’t see your favorite strain? Let us know at firstname.lastname@example.org.
Materials from Biotium are sold for research use only.
1. Nocker, A., et al. Comparison of propidium monoazide with ethidium monoazide for differentiation of live vs. dead bacteria by selective removal of DNA from dead cells. J. Microbiol. Meth. 67(2), 310-320 (2006).
2. Maheux AF, et al. Analytical comparison of nine PCR primer sets designed to detect the presence of Escherichia coli/Shigella in water samples. Water Res. (43) 3019-3028 (2009).
3. Fittipaldi, M., et al. Progress in understanding preferential detection of live cells using viability dyes in combination with DNA amplification. J. Microbiol. Meth. 91(2), 276-289 (2012).
Download the PMA reference list