Polymerases are enzymes that synthesize DNA from an existing template. Polymerases require a primer, nucleotides, and magnesium in order to function.
Taq polymerase is isolated from the thermophilic organism Thermus aquaticus (Taq), a bacterium found in thermal springs. The Taq polymerase has optimal activity at 72°C but it can survive in temperatures up to 95°C, hence maintaining stability and function throughout the complete PCR cycling temperatures.
Today, several other kinds of thermostable enzymes are available for PCR, such as Pfu and Tli DNA polymerase. However, Taq is the DNA polymerase that is used most often in PCR procedures.
