The DuPont™ BAX® System uses PCR technology to amplify (replicate) specific fragments of bacterial DNA, which are stable and unaffected by growth environment. These fragments are genetic sequences that are unique to the targeted organism.
In a typical application, sample DNA is combined with DNA polymerase, nucleotides and primers. Primers are specific for a given nucleotide sequence and determine the specificity of the reaction.
This mixture then undergoes a series of timed heating and cooling cycles. Heating denatures the DNA, separating it into single strands. As the mixture cools, the primers recognize and anneal (bind) to the targeted DNA sequence. The polymerase then uses the nucleotides to extend the primers, thus creating two copies of the fragment (amplification). Repeating the cycle of denaturing, annealing and extending produces an exponential increase in the number of target DNA fragments, creating millions of copies in a very short time.
If the target sequence is not present, no detectable amplification takes place.
If the target sequence is present, the BAX® System detects amplified fragments by measuring fluorescent signal, either through probes in real-time or through intercalating dye in a subsequent phase. See next section for details on detection.