X-treme Microbes — Text-only | Flash Special Report
Amazing Survivors


Implications
Ongoing scientific study of extremophiles is redrawing the boundaries of life and dramatically extending the known range of nature’s seemingly boundless ingenuity. (Click on pictures at left to see some ramifications of that research.)

Knowledge of organisms that subsist in extremes of cold, darkness, dryness and hostile chemistry has made it possible to imagine—and even search for—life on other worlds in our solar system and beyond. At the same time, discoveries about the structure,  biology and chemistry of extremophiles are leading to myriad practical applications, from medicine and pharmaceuticals to agriculture, nanotechnology and engineering. And the entire field is redefining the nature of life itself: how it arises, why it persists, and how far it can possibly go.

Photo 1: Space
EUROPA
Research on extremophiles is suddenly making science fiction look a lot less fictional. Now that scientists have learned that certain kinds of organisms can withstand extreme cold, survive very strong doses of radiation and adapt to exotic chemical environments, it appears much more plausible that life-forms of some sort could exist on other worlds.

One promising candidate is Europa, a satellite of Jupiter shown at left. About  seven-tenths the mass of Earth’s moon, it is covered with water ice. That surface is riddled with cracks, and may conceal a layer of liquid water. Research in Antarctica’s frozen lakes and at seafloor hydrothermal vents suggests that organisms might be able to form and even flourish in the Europan environment.
Credit: NASA

Photo 2: Medicine
MEDICINE (DNA strand)
Few people would recognize an extremophile named Thermus aquaticus, which prefers to live in water about 150 F, but it’s a biotech star. That bacterium, first found in a geyser pool in Yellowstone National Park, is the source of the key enzyme (Taq polymerase) that makes DNA analysis rapid and practical. Taq polymerase does not break down at the high temperatures involved in copying DNA, allowing scientists to amplify even small samples enough to use in molecular biology, genome sequencing and DNA fingerprinting, among other uses.

Another by-product of extremophile research is a class of compounds called antifreeze proteins (AFPs)—first identified in the study of Antarctic fish that withstand subfreezing temperatures by inhibiting ice crystallization in cells.  AFPs are now used in preserving human organs for transplant, in protecting sperm for artificial insemination, in storing food, in transporting red blood cells,  and in “cryosurgery,” in which target tissues are frozen.
Credit: Photodisc Red, Getty Images

Photo 3: Technology
VIRUS ON A CHIP
Extremophiles employ a wide range of biochemical tricks to endure tough environments, and many of those tricks have now been incorporated into commercial products and research materials. Some of the same compounds that the microbes use to protect their cells are now used in skin-care treatments and in keeping protein and cell cultures stable in the laboratory. Enzymes modeled on extremophile chemistry are employed in detergents, and researchers are testing genetically engineered radiation-tolerant microbes as a way to break down pollutants in radioactive waste.

In another application, researchers at Montana State University determined the structure of the protective coating on super-tough viruses found in boiling acid pools in Yellowstone National Park. They have artificially replicated that structure (shown at left) for use in nanotechnology, hydrogen gas production, computer chip components, and delivery of drugs for cancer treatment.
Credit: Mark Young, Montana State University (center); morgueFile (background and left)

Photo 4: Mars
MARS
As robots creep across the arid surface of Mars (shown at left), one of their goals is to identify potential signs of life, especially in areas that once had liquid water. But new research on Earth suggests that Martian life may not necessarily be visible at the surface. Many scientists now believe that the collective mass of all living things deep under the Earth—including microbes in fluids that circulate through the planet’s crust—may exceed the total biomass on the surface.

So, if evidence of life eventually shows up, as some scientists once believed it had in a Martian meteorite found in Antarctica (inset), the results may owe a great deal to extremophile hunters right here on our home planet.
Credit: NASA/JPL ­ Caltech/Cornell; NASA (inset)