An extremophile (from Latin extremus meaning
"extreme" and Greek philiā (φιλία) meaning "love")
is an organism that thrives in physically or
geochemically extreme conditions
that are detrimental to most life on Earth.]In
contrast, organisms that live in more moderate environments may be termed mesophiles or neutrophiles.
In the 1980s and
1990s, biologists found that microbial life has an amazing flexibility
for surviving in extreme environments—niches that are extraordinarily hot, or
acidic, for example—that would be completely inhospitable to complex organisms.
Some scientists even concluded that life may have begun on Earth in hydrothermal vents far under the ocean's
surface.According to astrophysicist Dr. Steinn Sigurdsson, "There are
viable bacterial spores that have been found that are 40 million years old on
Earth—and we know they're very hardened to radiation." On 6 February 2013,
scientists reported that bacteria were found
living in the cold and dark in a lake buried a half-mile deep under the ice in Antarctica. On 17 March 2013, researchers reported
data that suggested microbial life forms
thrive in the Mariana Trench,
the deepest spot on the Earth.Other researchers reported related studies that
microbes thrive inside rocks up to 1900 feet below the sea floor under 8500
feet of ocean off the coast of the northwestern United States.According to one
of the researchers, "You can find microbes everywhere—they're extremely
adaptable to conditions, and survive wherever they are."
Classifications
An
organism with optimal growth at pH levels of 3 or below
An
organism with optimal growth at pH levels of 9 or above
An
organism that does not require oxygen for growth such
as Spinoloricus cinzia.
Two sub-types exist: facultative
anaerobe and obligate anaerobe. A facultative anaerobe
can tolerate anaerobic and aerobic conditions; however, an obligate anaerobe
would die in the presence of even trace levels of oxygen
An
organism that lives in microscopic spaces within rocks, such as pores between
aggregate grains; these may also be called Endolith, a term that also includes
organisms populating fissures, aquifers, and faults filled with groundwater in
the deep subsurface
An
organism that can thrive at temperatures above 80 °C, such as those found
in hydrothermal systems
An
organism that lives underneath rocks in cold deserts
An
organism (usually bacteria) whose sole source of carbon is carbon dioxide and exergonic inorganic oxidation (chemolithotrophs) such as Nitrosomonas
europaea; these organisms are capable of deriving energy from
reduced mineral compounds like pyrites, and are active in geochemical cycling
and the weathering of parent bedrock to form soil
Capable
of tolerating high levels of dissolved heavy metals in solution, such as copper, cadmium, arsenic, and zinc; examples include Ferroplasma sp., Cupriavidus
metallidurans and GFAJ-1[12][13][14]
An
organism capable of growth in nutritionally limited environments
An
organism capable of growth in environments with a high sugar concentration
(Also
referred to as barophile). An
organism that lives optimally at high pressures such as those deep in the ocean
or underground;[15] common in the deep terrestrial
subsurface, as well as in oceanic trenches
Polyextremophile
A polyextremophile
(faux Ancient Latin/Greek for 'affection for many extremes') is an organism
that qualifies as an extremophile under more than one category
Psychrophile/Cryophile
An
organism capable of survival, growth or reproduction at temperatures of
-15 °C or lower for extended periods; common in cold soils, permafrost,
polar ice, cold ocean water, and in or under alpine snowpack
Organisms
resistant to high levels of ionizing radiation,
most commonly ultraviolet radiation, but also including organisms capable of
resisting nuclear radiation
An
organism that can thrive at temperatures between 45–122 °C
Combination
of thermophile and acidophile
that prefer temperatures of 70–80 °C and pH between 2 and 3
An
organism that can grow in extremely dry, desiccating conditions; this type is
exemplified by the soil microbes of the Atacama Desert
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