In 1969, Brock and undergraduate student Hudson Freeze published their discovery of Thermus aquaticus, which they found thriving in temperatures up to 170 degrees Fahrenheit in the water of Yellowstone.

To survive extreme heat that can kill other living cells, T. aquaticus contains enzymes that are stable at high temperatures. One of these enzymes is a polymerase, which is a molecule used in replicating DNA. A specific polymerase, dubbed Taq Polymerase, was isolated from T. aquaticus and then used in PCR technology.