extremophile

Microbe able to thrive in extreme conditions, such as very high temperatures (thermophiles), low temperatures (psychrophiles), high acidity (acidophiles), or high alkalinity (alkaliphiles). Examples of extremophiles are found in both bacteria and Archaea.

Thermophiles live at temperatures above 45°C/113°F and some, known as hyperthermophiles, thrive at temperatures greater than 80°C/176°F, and are even found in sea water above its boiling point of 100°C/212°F, such as those living around deep-sea vents. The archaeon Sulfolobus acidocaldarius is a hyperthermopile that is also an acidophile. It lives in the hot sulphur springs of Yellowstone Park, Wyoming, USA.

In 2000, new species of psychrophiles were discovered living in Antarctica, where temperatures range between −85°C/−121°F and −13°C/−11°F.

Extremophiles are of commercial interest because they are able to continue producing their enzymes in conditions when other enzymes would have broken down. These extremozymes are able to catalyse chemical reactions for the biomedical and other industries at very high temperatures, for example. The most widely used example is the DNA polymerase from thermophiles, which is required for the polymerase chain reaction.

Discovery of extremophiles in environments previously considered uninhabitable has also led to a reappraisal of the likelihood of life on other planets, and has influenced the exploration of Mars and of Saturn's moon Titan.