FOODBORNE pathogens remain a critical area of concern for both public health officials and the food industries across the world. According to World Health Organization, an estimated of 600 million or almost 1 in 10 people in the world, fall ill after eating contaminated food and 420,000 die every year, resulting in the loss of 33 million healthy life years (DALYs). Foodborne illnesses are usually infectious or toxic in nature and caused by bacteria, viruses, parasites, or chemical substances entering the body through contaminated food or water. To date, quality testing of food has relied almost entirely on conventional microbiological methods, which involve isolating and enumerating bacteria from food products on specialized microbiological media. Although these methods are comprehensive, they are typically work intensive and requires several days to generate results which results in downtime.
Therefore, there is an urgent need for fields of molecular biology to develop innovative solutions for rapid, high-throughput tests that will allow the food industries to make timely assessments on the microbiological safety on its food products.
3M™ Molecular Detection System
Faced with the challenges of controlling the most common and prevalent of foodborne pathogen, 3M Food Safety introduced the 3M™ Molecular Detection System, a fast, accurate and easy-to-use method of detecting treacherous pathogens, like Salmonella, E. coli O157 and Listeria species. It is an innovative approach to pathogen screening that comes with a space saving design and the ability to test for multiple types of pathogens simultaneously. 3M™ Molecular Detection System is an advanced technology powered by unique technologies known as Loop-Mediated Isothermal Amplification (LAMP) and Bioluminescence Detection.
3M™ Molecular Detection System includes the 3M™ Molecular Detection Assay, 3M™ Molecular Detection Instrument, 3M™ Molecular Detection software, media, and accessories as components of a total solution. As a result of recent development capabilities, 3M Food Safety has successfully expanded the wing to detect other foodborne pathogens like Listeria monocytogenes, STEC, Campylobacter, and Cronobacter.
The 3M™ Molecular Detection Assay 2 collection is the next generation of assays for the 3M™ Molecular Detection System which are based on a unique combination of technologies namely loop mediated isothermal DNA amplification (LAMP) and bioluminescence detection, which enables it to be a robust, efficient, sensitive, and specific system for food pathogen detection. Combining these technologies, the 3M™ Molecular Detection Assay platform makes molecular detection of foodborne pathogens simpler and faster, providing food manufacturers with never-before-available speed and ease in simultaneously identifying Salmonella, Listeria, Listeria monocytogenes, E. coli O157 (including H7), STEC, Campylobacter, and Cronobacter in food and environmental samples.
The 3M™ Molecular Detection Assay uses isothermal (60°C) for the DNA amplification that involves a set of multiple primers and an enzyme called Bst DNA polymerase with strand displacement activity that does not require any thermal cycling process. The Bst DNA polymerase efficiently and continuously amplifies large amount of the target DNA between the period of 15 to 75 minutes. Moreover, the rapid amplification is enabled through the autocycling strand displacement process where multiple primers recognize distinct regions of the target gene. In addition, the Bst DNA polymerase used in the 3M™ Molecular Detection Assays is more tolerant of low-quality samples than the Taq DNA polymerase, which is normally used in a molecular method known as PCR (Polymerase Chain Reaction).
As the target DNA is amplified, the detection works by coupling the generation of pyrophosphate, a by-product of the exponential DNA amplification to the emission of light from a thermostable firefly luciferase which results in light outputs. The simplicity of the detection technology delivers ease of use and cost effectiveness as no sophisticated equipment is required.
The 3M™ Molecular Detection System offers a single enrichment step and only two post-enrichment sample transfers steps (Lysis and amplify & detect) making the pathogen testing simpler and faster. Generally, when methods require different protocols, it can be more difficult to batch the samples together due to differences in time and protocol. Hence, 3M™ Molecular Detection System improves the productivity of the testing laboratories by offering a single and simple streamlined preparation protocol for all target pathogens and all matrices allowing for more efficiency, easier training, and less chance for human error.
Furthermore, the software has a robust algorithm that interprets and displays the results in real time using simple color-coded symbols while amplification curves can be displayed on the screen. It showcases a modern, tabbed user interface for ease of use while allowing the multitasking capability such as setting up the next run or viewing the results by the users while runs are in progress.
Apart from that, one of the most important criteria while choosing the testing methods is to consider its acceptance and recognition. 3M Food Safety continues to pursue method validations from internationally recognized third-party agencies, such as AOAC® INTERNATIONAL, NF VALIDATION by AFNOR Certification, and USDA, in addition to the recognition from government and regulatory organizations worldwide.
Loop-mediated isothermal amplification (LAMP)
The chemistry in the 3M™ Molecular Detection System is based on LAMP. This is a low-cost alternative method to detect pathogens in clinical specimens and food matrices as Polymerase Chain Reaction (PCR) based assays are relatively expensive. The whole procedure is very simple and rapid wherein the amplification can be completed in less than 1 hour under isothermal conditions employing a set of six specially designed primers spanning eight distinct sequences of a target gene, by incubating all the reagents in a single tube. Designing a highly sensitive and specific primer set is crucial for performing LAMP amplification.
Generally, the primer set for LAMP amplification comprises of a set of six primers encompassing two outers, two internals and two loop primers that identify eight distinct regions on the target sequence. The two outer primers act as forward outer primer and backward outer primer which play an important role in strand displacement activity solely during the non-cyclic step. The internal primers, on the other hand, function as Forward Internal Primer and Backward Internal Primer which helps in the formation of a loop. Furthermore, two loop primers namely Forward Loop Primer and Backward Loop Primer operate to speed up the amplification reaction by binding to additional sites that are not accessed by internal primers. The chemistry of LAMP amplification is based on the principle of auto cyclic strand displacement reaction being executed at an isothermal condition (constant temperature) using a DNA polymerase.
The LAMP amplification is two steps process comprising of non-cyclic and cyclic steps. There is the formation of DNA with stem-loops at each end that serves as the starting structure for the amplification by LAMP cycling in the non-cyclic step. During this stage, the double stranded DNA is in the form of dynamic equilibrium at the temperature about 65°C. One of the LAMP primers can anneal to the complimentary sequence of double stranded target DNA, then initiates DNA synthesis using the DNA polymerase with strand displacement activity, displacing, and releasing a single stranded DNA. Subsequently in the LAMP cycling, one internal primer hybridizes to the loop on the product and initiates displacement DNA synthesis, yielding the original stem-loop DNA and a new stem-loop DNA with a stem twice as long.
LAMP technology allows the 3M™ Molecular Detection System to offer a simple sample preparation process only with two transfer steps, in contrast to the more complex DNA extraction and purification steps typically used in PCR.
A Toolkit with Superior Results
The 3M™ Molecular Detection System has provided food processors and testing laboratories with a robust, cost effective and easy to use pathogen detection method. The next generation 3M™ Molecular Detection Assay 2 offers a streamlined workflow with a faster time to result and less technician labour time that enables laboratories to operate with greater efficiency and productivity.
In a nutshell, the 3M™ Molecular Detection System is a family of products that works together to provide superior results, including enrichment media designed to enhance the growth and recovery of organisms, custom accessories that increase productivity and reduce the chance of cross contamination, high-throughput assay kits, a compact instrument and intuitive software that runs up to four instruments simultaneously.
For more information, please visit: https://www.3m.com/3M/en_US/food-safety-us/foodandbeveragetests/molecular-detection-systems/ .
