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Extreme Biology: A Zoo of Bizarre Organisms on Earth
We've discussed the
various ways organisms can create the energy they need to live. This diversity
is most startling when one considers the extreme environments present on
Earth and that organisms are prospering there. It redefines our view of what
is habitable?
Can you think of
an environment on Earth that is not inhabited by life?
Thermophiles and
Hyperthermophiles
Inhabit environments near deep-sea hydrothermal vents. These microbes not only
exist, but also thrive at temperatures up to 112oC, and possibly
beyond 150oC (more than 300 F), setting a new limit at which life
can exist.
Barophiles
Inhabit environments where the pressure is unusually high, for example, deep in
the ocean or far underground. Extreme barophiles live at great depths where the
pressure is at least 700 atmospheres and will not grow at all at 1 atmosphere.
Acidophiles and
Alkalinophiles
Prefer highly acidic or basic conditions. Acidophiles are found in the debris
left over from coal mining (or your stomach!). They survive by keeping the acid
out (inside their cells, acid would destroy such important molecules as DNA).
Alkalinophiles live
in soils laden with carbonate and in so-called soda lakes, such as those found
in the western U.S. Above a pH of eight or so, RNA will break down. Similar to
the acidophiles, the alkalinophiles are able to maintain neutral pH inside
their cells.
Psychrophiles
Cold environments are actually quite common on Earth. Most ocean waters are
near freezing. The most frigid places support life. Microbial communities
populate Antarctic sea ice--ocean water that remains frozen for much of the
year. These communities include photosynthetic eukaryotes and a variety of
bacteria. Their optimal temperature for growth is just 4oC, and
temperatures above 12oC are too warm for growth.
Can you think of
an environment in Cincinnati (even in your apartment) where psychrophiles can
grow?