It is frequently used in the polymerase chain reaction (PCR), a method for greatly amplifying the quantity of short segments of DNA.

T. aquaticus is a bacterium that lives in hot springs and hydrothermal vents, and Taq polymerase was identified[1] as an enzyme able to withstand the protein-denaturing conditions (high temperature) required during PCR.

Small amounts of potassium chloride (KCl) and magnesium ion (Mg2+) promote Taq's enzymatic activity.

Taq polymerase is well-suited for this application because it is able to withstand the temperature of 95 °C which is required for DNA strand separation without denaturing.

Thus, the use of Taq polymerase was the key idea that made PCR applicable to a large variety of molecular biology problems concerning DNA analysis.

[2] Hoffmann-La Roche eventually bought the PCR and Taq patents from Cetus for $330 million, from which it may have received up to $2 billion in royalties.

Kary Mullis received the Nobel Prize in Chemistry in 1993, the only one awarded for research performed at a biotechnology company.

By the early 1990s, the PCR technique with Taq polymerase was being used in many areas, including basic molecular biology research, clinical testing, and forensics.

[13] In December 1999, U.S. District Judge Vaughn Walker ruled that the 1990 patent involving Taq polymerase was issued, in part, on misleading information and false claims by scientists with Cetus Corporation.

The complete lack of exonuclease activity make these variants suitable for primers that exhibit secondary structure as well as for copying circular molecules.

[22] Because of the improvements Taq polymerase provided in PCR DNA replication: higher specificity, fewer nonspecific products, and simpler processes and equipment, it has been instrumental in the efforts made to detect diseases.

It has served an essential role in the detection of many of the world's worst diseases, including: tuberculosis, streptococcal pharyngitis, atypical pneumonia, AIDS, measles, hepatitis, and ulcerative urogenital infections.

PCR, the method used to recreate copies of specific DNA samples, makes disease detection possible by targeting a specific DNA sequence of a targeted pathogen from a patient's sample and amplifying trace amounts of the indicative sequences by copying them up to billions of times.

Although this is the most accurate method of disease detection, especially for HIV, it is not performed as often as alternative, inferior tests because of the relatively high cost, labor, and time required.