Wednesday, May 9, 2012

A term in biology: hyperthermophile for an extremophile thriving above 60 °C

The noun hyperthermophile is composed of the Greek words hyperthermos and philos for “above,”    “hot” and “love,” respectively.  The corresponding adjective is hyperthermophilic. A hyperthermophile is a microbe that lives at temperatures we consider as hot or even more than hot.

The term hyperthermophile was coined in the 1980s by microbiologist Karl Stetter, who searched for organisms existing under extreme conditions, for example at or above boiling water [1]—conditions found at hot springs and deep-sea hydrothermal vents . Such organisms belong to the domains archaea and bacteria, which include diverse groups of extremophiles living in extreme environments. At the lower extreme of the liquid-water temperature scale are psychrophiles, which “love” frigid water and icy conditions.
Examples of hyperthermophiles can be found among bacteria species of the genus Aquifex such as Aquifex aeolicus (first obtained by K. Stetter and R. Huber) and Aquifex pyrophilus (obtained from the Kolbensey Ridge, north of Iceland) [2].

Hyperthermophiles build a subgroup of thermophiles. Some prokaryotes (cells that lack a nucleus) can grow at or above 60 °C (140 F): moderate thermophiles live between 50 and 60 °C, while hyperthermophiles typically grow at 80 °C (176 F), but also at higher temperatures [3]. The hyperthermophile Pyrolobus fumarii (a name packed with hot associations), living at 113 °C (235 F), had been the hot-temperature record holder for some time, but a tiny single-celled microbe was then discovered that survives a temperature of  121 °C—and, therefore, was named “Strain 121.” [4]. What a strange strain!

Keywords: microbiology, oceanography, astrobiology, biotechnology, archaea, tree of life, extraterrestrial life, upper temperature limit for life.

References and more to explore
[1] Tim Friend: The Third Domain. The Untold Story of Archaea and the Future of Biotechnology. Joseph Henry Press, Washington, D.C., 2007; pp. 26-27.
[2] Aquifex:
[3] Earth science > Oceanography > Thermophiles and hyperthermophiles:
[4] Microbe from depths takes life to hottest known limit (press release, August 15, 2003, source:  National Science Foundation):

No comments:

Post a Comment