The Living Extremists
Posted February 1, 1998
Suppose a rabbit tumbled into one of the hot springs of Yellowstone National Park. Before it could scramble out of the water, it would be badly burned. Most living
things cannot survive in hot springs that reach temperatures of up to 176 degrees Fahrenheit. Some environments on Earth, such as Yellowstone's hot springs, the ice of Antarctica, and
the acid runoff from some mines, are so extreme that it hardly seems possible that anything could survive in them. However, scientists are discovering that these environments harbor
organisms that not only can survive in extreme circumstances, but that actually require such conditions to reproduce. These organisms are the archaebacteria.
It is only within the past two decades that scientists have explored some of the more extreme ecosystems. Near the Galapagos Islands in the Pacific Ocean, scientists
have discovered deep ocean hydrothermal vent ecosystems. Archaebacteria living there reproduce best at temperatures of 161 degrees Fahrenheit, and can continue to thrive even when the
temperatures reach up to 235 degrees Fahrenheit. But when the temperature falls to 194 degrees Fahrenheit, these archaebacteria stop growing because it is just too cold! On the other
hand, another group of archaebacteria have been discovered living in Antarctic sea ice. One of these species grows and reproduces best at 37 degrees Fahrenheit (just above freezing).
Other species of archaebacteria can be found in natural salt lakes and in the acidic runoff from coal mines.
Why are scientists interested in the archaebacteria? Researchers are interested in how such organisms are related to other life on Earth. Some researchers hypothesize
that archaebacteria represent the first kinds of organisms to exist on Earth. Learning more about archaebacteria might also help scientists figure out whether life exists on other planets.
Other scientists are interested in the biology of these organisms. For example, chemical reactions inside cells are governed by proteins called enzymes. Most enzymes break down at high
temperatures. But the enzymes inside the cells of some archaebacteria don't break down at high temperatures. If scientists can figure out how these enzymes work, they can reproduce them
for use in industry. The enzymes used in detergents fail in very hot water, but enzymes from archaebacteria might continue to work at such temperatures. If ordinary bacteria were "engineered"
to contain some of these enzymes, entire new industries might be developed.
References
Watanabe, Myrna E. "Hot-Vent Microbes: Looking Backward in Evolution For Future Uses." The Scientist, Vol. 8, No. 11, May 30, 1994, p. 14.
http://www.the-scientist.library.upenn.edu/
yr1994/may/hotvent_940530.html
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