What are Extremophiles?

Extremophiles are incredible creatures, testing the limits of the types of environments where scientists think life can possibly survive.

Sabrina Stierwalt, PhD,
Episode #254

Did you know there is a creature that can produce its own antifreeze in order to keep its surroundings from freezing it to death? How about a creature that prefers to live in water but can survive being deprived of even a single drop of water? Creatures like these that can adapt to survive in extreme environments were first dubbed extremophiles (meaning “extreme-loving”) by NASA Ames scientist Dr. R.D. MacElroy in 1974.

What is an extremophile?

Extremophiles test the limits of the types of environments where scientists think life can possibly survive. These creatures have found ways to adapt to the most extreme conditions found here on Earth, which can include extreme temperatures, pressure, acidity, high salinity, high metal concentrations, or even radioactivity. For example, some extremophiles found in very high or very low temperatures are found to have modified the composition of their cell membranes to adapt to the temperatures. Other extremophiles may produce extra solutes inside their cells to balance extremely high concentrations of salt.

Some of the extreme environments here on Earth may represent more normal conditions on other planets. Thus, the search for extraterrestrial life includes efforts to study the extremophiles, and where they thrive on this planet, to understand where else we might find signs of life in our solar system.

The study of extremophiles, and in particular the enzymes they produce to deal with their harsh climates, also has potential applications in industry. The “extremozymes” or the enzymes produced by extremophiles are able to inspire chemical reactions despite their harsh living conditions, a trick that may be useful for triggering chemical reactions under the similarly harsh conditions of many industrial applications. Some of these enzymes are already used in the production of biofuels, as well as cosmetics. Extremozymes, and their ability to adapt to their environments, may also prove useful for developing medications like antibiotics or antifungal drugs.

Let’s investigate just a few examples of these extremely unique creatures.

Examples of Extremophiles

  • Thermophiles and the Rushing Fireball
  • Psychrophiles
  • Tardigrades (or Water Bears)

Let's explore these further.

Thermophiles and the Rushing Fireball

Thermophiles are a type of extremophile that can survive at very high temperatures. For example, the thermophile known as thermus aquaticus, found in the hot springs in Yellowstone National Park, not only survives but thrives at temperatures as high as 160 degrees Fahrenheit (or 70 degrees Celsius).

One kind of microbe so extreme even by thermophile standards that it is known as a hyperthermophile is Pyrococcus furiosus, or the “rushing fireball.” The fireball microbe was first discovered in the geothermally-heated waters around Italy’s Vulcano Islands. Scientists from the University of Georgia have been investigating how to use this little extremophile to take in carbon dioxide and turn it into fuel.  


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