Taq polymerase is an enzyme that is used by scientists in the polymerase chain reaction because it is stable at high temperatures. It is the polymerase used by a bacteria, Thermus auquatics, which... Taq polymerase is an enzyme that is used by scientists in the polymerase chain reaction because it is stable at high temperatures. Large amounts of a sample of DNA are necessary for molecular and genetic analyses, and the polymerase chain reaction is used to amplify very small amounts of DNA.