Thermus aquaticus

Despite the fact that Thermus aquaticus does not cause infection it is probably more important to microbiology than any other bacterial species. Yet few clinicians have heard of it. At least under its proper name. Many more will have mention of Taq, in ‘Taq polymerase’, the enzyme needed to run the polymerase chain reaction (PCR). This critical molecular biology reagent was first isolated from Thermus aquaticus in 1976.

Thermus aquaticus

T. aquaticus, for short, was first isolated from hot springs in the lower geyser basin of Yellowstone National Park during an investigation of heat-tolerant bacteria in 1969. Conventional wisdom insisted that bacteria could not survive at the high temperatures found in hot springs. And yet there were bacteria there, thriving at 70°C and tolerating conditions up to 80°C. Their ability to survive these extreme conditions depends on a heat-tolerant DNA polymerase; just what the molecular biologist needed.

These unusual bacteria belong to the Deinococcus-Thermus group of Archaea; ancient organisms that have features of both Gram positive (thick peptidoglycan cell wall) and Gram negative (double membrane) bacteria. They are chemotrophs, obtaining energy from inorganic chemicals in their environment. Their enzyme product Taq polymerase is used every day in clinical and research laboratories even if T. aquaticus can’t cause a single infection.

Author Credit: Dr Tim Inglis