Bacteria from hot springs greatly helped the development of PCR by producing heat-stable DNA polymerase, Taq polymerase.
This enzyme is originally isolated from the thermophilic bacterium Thermus aquaticus (first discovered in the Lower Geyser Basin of Yellowstone National Park). Taq polymerase enzymatically synthesizes a new DNA strand from single nucleotides, by using single-stranded DNA as a template and DNA oligonucleotides (the primers) to initiate DNA synthesis.