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Extremophilic microorganisms cause the color gradations in this hot spring at Yellowstone National Park.

Extremophiles, derived from the Latin extremus and the Greek philiā (φιλία), loosely translated as “extreme-lovers,” is a variety of organisms belonging to all three domains of life (archaea, bacteria, and eukarya) that are classified according to their respective environments, which are unsuitable for most life on Earth. Extremophiles grow and thrive in these conditions through adapted mechanisms that facilitate their survival.[1]

Extremophiles have extensive applications in both medical and commercial industries.[2]


Extremophiles live in intense environments like this geyser in Yellowstone National Park.

Most life on Earth thrives in environments with temperatures ranging between 4°C and 40°C (39°F-104°F), and pH content levels between 5 and 9. Most animals also live in the presence of oxygen. Extremophiles are an exception to this majority. Extremophilic environments range in temperatures as high as 114°C; 237°F and as low as -15°C; 5°F (organic material breaks down above 130°C; 266°F). Additionally, microbial life forms range in pH levels from 1.4 to 13.5, acidic to alkaline.[3] Extremophiles can survive in aphotic environments, or those without light, and anoxic environments, or those without oxygen. [2]

Extremophiles are found virtually everywhere—in the Mariana trench, beneath oceanic crust,[4] 6.7 km inside the Earth’s crust,[5] in ice cores drilled from frozen lakes in Antarctica,[6] within hot springs in Yellowstone, in the Gobi desert, in the alkaline Lake Magadi in Kenya, and may represent the best possible chance for extraterrestrial life in the solar system (Europa may harbor life within hydrothermal vents).[3]


Extremophiles utilize a variety of adaptations to grow and thrive in their intense environments. Psychrophiles, for instance, have adapted to the cold water by developing protons that prevent ice crystal formation of body liquids.[7] Some extremophiles have mechanisms to lower pH levels in highly acidic environments.[1] Thermophiles that live in hydrothermal vents have mechanisms for metabolizing hydrogen sulfide, a chemical poisonous to most life on the planet. These particular extremophiles convert the sulfur material into a form of energy called chemosynthesis, which does not involve sunlight for energy conversion. Many extremophilic mechanisms have yet be identified.[8]


Extremophiles are loosely classified based on where they thrive.[9] The taxonomy of extremophiles relies heavily on the particular environments in which they are found, but may also incorporate the specific mechanisms by which they survive. These classifications are not by any means fixed, and may change with additional research and discoveries. Divided into a more basic classification, extremophiles are separated as extremophillic and extremotolerant. The former need one or more intense conditions to grow while the latter can tolerate such conditions but operate the best under relatively “extreme” conditions.[5]


Category Environment
Thermophiles Extreme heat
Psychrophiles Extreme cold
Acidophiles extremely Acidic pH
Alkaliphiles extremely Basic pH
Barophiles High pressure
Polyextremophiles More than one extreme condition


Extremophiles were first discovered more than fifty years ago, but they are now becoming the subject of intense research due to the potential applications for their extracted enzymes, which have impacts in both medicine and commercial industry.[9] Some applications include the extraction of thermophile deoxyribonucleic acid (DNA) polymerase enzyme utilized in PCR (polymerase chain reaction) in biological research[2] and commercial use in laundry detergent.[10]

See also

Other closely related articles in this wiki include:


  1. 1.0 1.1 [1], Cavicchioli, R., Amils, R., Wagner, D., & McGenity, T. (2011). Life and applications of extremophiles. Environmental Microbiology, 13(8), 1903–1907.
  2. 2.0 2.1 2.2 [2], Farmer, J. D. (2003). Life in Extreme Water Environments. In J. E. Dasch (Ed.), Water: Science and Issues (Vol. 3, pp. 43–48). New York: Macmillian Reference.
  3. 3.0 3.1 [3], McCoy, J. F. (Ed.). (2012). Astrobiology. In Space Sciences (2nd ed., Vol. 4, pp. 10–22). Detroit: Macmillan Reference.
  4. [4], Choi, C. Q. (2013, March 17). Microbes Thrive in Deepest Spot on Earth.
  5. 5.0 5.1 [5], Rampelotto, P. H. (2013). Extremophiles and Extreme Environments. Life : Open Access Journal, 3(3), 482–485.
  6. [6], Gorman, J. (2013, February 6). Bacteria Found Deep Under Antarctic Ice, Scientists Say. The New York Times.
  7. [7], What Are Extremophiles? (2016). Retrieved September 23, 2016.
  8. [8], Lerner, B. W., & K. Lee Lerner (Eds.). (2003). Hydrothermal Vents. In World of Microbiology and Immunology (Vol. 1, pp. 282–283). Detroit: Gale.
  9. 9.0 9.1 [9], Cobb, A. B. (Ed.). (2002). Extremophile (Vol. 2, pp. 102–103). New York: Macmillian Reference.
  10. [10], Robinson, R., & Needham, C. A. (Eds.). (2006). Archaea. In Genetics (Vol. 1, pp. 36–39). New York: Macmillan Reference.

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