PCR become a standard analytical technique in many food laboratories today. Join us for the first installment of our five-part mini-series, where we discuss the technology behind the world-leading BAX™ PCR.
The major advances in molecular technology in recent years have revolutionized pathogen detection in food safety in many ways. While traditional culture-based methods still serve as “gold standards,” the new generation of genetic tests can deliver the same sensitivity, but in a simpler manner and in significantly less time.
Polymerase chain reaction
Nucleic acids are biopolymer macromolecules found in all living cells in the form of double-stranded deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). They contain genetic information—known as genes—that is unique to a particular type of organism.
Polymerase Chain Reaction (PCR) is a molecular biology analysis technique that can generate millions of copies of a specific DNA region within a few hours. Thanks to the “amplification” of the target, PCR can be used to detect very small amounts of organisms in a sample, including specific pathogens such as Listeria or E. coli O157:H.
The basic components of PCR primers, DNA polymerase, nucleotides, specific buffering ions, and target DNA template. Primers are short fragments of DNA that are complementary to specific segments of the target DNA.
Primers are designed to target unique regions of DNA, which gives PCR its high specificity. The reaction begins with the “denaturation step” at an elevated temperature, typically 95°C, which causes the double-stranded DNA template to separate into two individual strands. This is followed by cooling, which allows the primers to bind to their complementary regions on the separated DNA strands. The enzyme DNA polymerase then begins “extension” by attaching near the end of the primer and starts adding nucleotides, resulting in PCR called an amplicon. Multiple copies of the amplicon are created when the three steps are repeated for a certain number of cycles. The amplicons produced during PCR be detected by staining with ethidium bromide or fluorescent dyes such as SYBR Green. Detection can occur at the end of the reaction or during the reaction using a specialized PCR calledPCR.
The Benefits of PCR
Compared to traditional microbiological analysis methods, PCR pathogen detection has four major advantages:
- Rapid detection
Results are available within 1–2 hours, compared to 3–5 days for traditional methods.
PCR method is highly sensitive andPCR detect a single copy of DNA.- High specificity and selectivity
PCR can be designed to be highly specific and selective for particular species and strains. - Quantification
Allows for the enumeration of bacteria in samples.
Unlike traditional methods, PCR is PCR by the physiological state of the organism. The method works just as effectively even in cases where cell culture can be challenging. Conversely, the test cannot distinguish between live and dead cells without some form of sample preparation. Some samples may also contain material that interferes with the analysis, and solutions to these challenges must be investigated before proceeding with PCR.
PCR system
PCR BAX™ PCR has been used for industrial food applications for over 20 years and is currently the leading PCR in ISO worldwide. Each new generation of the system has seen advances in instrumentation, software, reagents, and capacity, leading to improvements in robustness, user-friendliness, and analysis times. These attributes have undeniably made PCR BAX™ PCR a pioneer in rapid pathogen detection methods.
Learn more about BAX PCR in our series of articles. You are also welcome to contact our application specialist, Frank Axelsson, to schedule a meeting to discuss your analytical needs and questions.