A hyperthermophile is an organism that thrives in extremely hot environments—from 60 °C (140 °F) upwards. An optimal temperature for the existence of hyperthermophiles is above 80 °C (176 °F). Hyperthermophiles are a subset of extremophiles, which are often micro-organisms within the domain Archaea, although some bacteria are able to tolerate temperatures of around 100 °C (212 °F), as well – Wikipedia.
Sulfolobus acidocaldarius, both a hyperthermophile and an acidophile, was found in the late 1960s in a hot, acidic spring in Yellowstone National Park, Wyoming. It was the first hyperthermophile to be identified in the scientific history. It was found to grow optimally between 75 and 80 °C, with pH optimum in the range of 2-3.
The Aquifex genus of bacteria has been found living in hot sprigs in Yellowstone National Park, where temperatures can reach 205 degrees Fahrenheit (96 degrees Celsius).
However, scientists thought that it is unlikely for microbes to survive at temperatures above 150 °C, as the cohesion of DNA and other vital molecules begins to break down at this point.