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A Close Look at a Molecular Detection Method
by Niki Montgomery
It’s hard to ignore the extreme danger that foodborne pathogens pose to human health; the high amount of Americans getting sick from foodborne diseases says it all. The threats these bugs present to businesses are similarly serious, but are more often overlooked. Economists forecast that pathogens cause between $10 and $83 billion dollars in annual losses worldwide. Clearly, the damage a brand suffers by being associated with an outbreak can be irreparable.
In 2009, 3M started a collaborative research process to understand the largest “pain points” its users were experiencing day in and day out. It consisted of 3M Food Safety experts speaking with food processors across different industry segments, from both developed and developing nations.
Themes of simplicity, speed, and efficiency in addition to accuracy ranked high on their wish-list of new tools that could be employed by their labs, whether it be internal food testing labs or outside reference labs. Users wanted to deploy detection technologies that were accurate, but also low maintenance. The tools would need to quickly spot pathogens in ways that were intuitive and contained fewer transfer steps that might compromise testing accuracy.
The 3M Molecular Detection System was conceived as a molecular microbiology approach that could detect pathogens from food samples and samples taken from processing environments. The system is based on a combination of two technologies: Isothermal DNA amplification and bioluminescence detection. These two “pillar” technologies work together to provide a molecular detection method that is pure and simple. Users only need an enriched sample, a standard laptop, and the 3M Molecular Detection Instrument, a small peripheral device that has a footprint the same size as a tablet computer. Corresponding pathogen-specific assays, or test kits, are also available specifically for identifying the unique characteristics of Salmonella, E.coli O157 (including H7), and Listeria.
The system identifies and targets multiple regions of a genome through loop-mediated isothermal DNA amplification.
With these components in place, users can run and read tests for multiple organisms in a single run with only two transfer steps after the samples have been enriched, which saves hours of technician time. They only need to power up their hardware, transfer enriched samples to the pre-filled, color-coded lysis tube rack, and then place the rack on the provided heating and cooling blocks. Once complete, the users transfer the lysed samples to special reagent tubes that are set inside the instrument via a 3M Molecular Detection Speedloader Tray. From there, they can press start to begin the real-time amplification and detection process.
To understand the science behind the 3M Molecular Detection System it helps to describe each part of the technologies—isothermal DNA amplification and bioluminescence detection. In terms of amplification, the system identifies and targets multiple regions of a genome through loop-mediated isothermal DNA amplification—commonly known as LAMP for short. An emerging method for rapid molecular detection, LAMP has now been cited in nearly 1,000 scientific articles and has been recognized for its ability to reliably and efficiently target DNA compared to conventional Polymerase Chain Reaction (PCR) methods. For example, whereas PCR typically requires multiple steps for reagent preparation and DNA extraction, the 3M Molecular Detection System uses pre-foiled, ready-to-use reagents and only requires two transfer steps with no separate extraction. More importantly, there is no time-consuming thermal cycling involved as in PCR. The system reaction operates at a consistent temperature of 60 degrees Celsius, and the targeted DNA is amplified continuously and as many as one billion copies of DNA can be generated in 15 minutes.
To read and report the DNA amplification taking place, the 3M Molecular Detection System uses bioluminescence technology that works simultaneously in real-time with the amplification. This enzymatic process occurs in two steps: First, pyrophosphate molecules are exponentially generated during DNA amplification and converted to Adenosine Tri Phosphate molecules, or ATP. Second, the system then uses a special temperature-stable luciferase, an enzyme best known for being present in fireflies, to convert that ATP into light. This light, or bioluminescence, is read by the instrument and used to determine the presence or absence of the organism being tested for in the sample.
The end result is a streamlined and automated method of pathogen detection with resistance to sample interference. Third-party validation bodies both inside and outside the U.S. have been consistently examining and validating the Molecular Detection System and its various assays. Companies are also putting the technology to the test with their food matrices. Based on the feedback received, the method is not only highly accurate, but good for business operations given that only one preparation protocol is necessary for all pathogens and matrices, and that batch-processing and simultaneous testing can happen for multiple pathogens.
Montgomery has more than 15 years of experience at 3M in quality control and operations, marketing, channel management, and finance. She can be reached at firstname.lastname@example.org.