Fingerprinting

Technique for identifying organisms (e.g. microbes) and individuals by comparing DNA sequences

DNA fragments from a test sample are matched against known patterns characteristic for certain soil microorganisms, or, in forensic practice, against a sample taken from a suspect.

The technique is based on DNA hybridisation (q.v.). Identification depends on the exact matching of certain characteristic patterns.

Example of fingerprints from different samples A, B, and C represent different microorganisms; D could therefore be a soil sample containing all three of these microbes.

The analysis of large numbers of samples (screening) is made possible by "DNA chips" which carry a large number of probes (DNA fragments) complementary to the DNA sequence of interest on a tiny surface. A DNA sample can thus be tested simultaneously for many different sequences, or many samples can be screened for one sequence.