A DNA probe consists of a single stranded small segment of a DNA molecule which is tagged or labeled with a radioactive substance. It is also possible to label probes with enzymes, fluorescent chemicals, etc. to facilitate detection.

The unique segment DNA, in terms of its nucleotide sequence, that is used in the probe allows it to detect and quantify genetic material in biological samples that have a complementary sequence of nucleotides. In practice, the probe and single stranded DNA from a mixture of cells or clone to be tested are mixed together. Hybridization occurs with the formation of stable bonds between the DNA of only one specific type of cell or clone in the section where its nucleotides are complementary with the probe. This hybridization of segments of single stranded DNA is highly specific and denotes genetic similarity.

The rapid detection of Salmonella, a food...