Thermus aquaticus colonies, Emerald Pool hot spring, Yellowstone National Park

    DNA polymerases used in the polymerase chain reaction were originally isolated from naturally-occurring bacteria (such as T. aquaticus) that grow in near-boiling water of hot springs (90 ~ 100 ^oC). The DNAPols and other proteins in these "extremophile" organisms have adapted evolutionarily to be stable and functional at high temperature. Temperature-resistant DNAPols are now genetically engineered to possess the particular properties required for optimal PCR.