Guide to the wildest life on Earth

Extremophiles act like alien organisms

NASA / Univ. of Alabama

A fluorescent stain renders adds a green tinge to the corkscrew-shaped Spirochaeta americana from California's Mono Lake. Green spots are spheroplasts. Reddish areas are dead cells.

By Bjorn Carey

updated 1:57 p.m. ET Feb. 7, 2005

Extremophilic microbes are a wild bunch. They can be found thriving in some of the most hostile environments imaginable — swimming in near-boiling water, eating rocks, lounging in subzero temperatures and hanging out where radiation levels rival nuclear reactors.

They’re tougher than duct tape, boldly going where humans dare not and cannot.

Extremophiles are also a multimillion-dollar-a-year business — some of them are employed to eat oil and help clean up spills. Others have important applications in medical research. But for many scientists, these hardy microbes are interesting because they suggest the potential for life on other planets.

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Recent discoveries have greatly expanded the range of these wild things. Here's a census of small creatures living in some of the worst conditions imaginable.

Needs more salt
Microbial extremophiles have recently been discovered thriving in the extremely hostile environments in the depths of the Mediterranean Sea.

At nearly 2.5 miles (4 kilometers) below sea level, with salt concentrations 10 times higher than seawater, pressure 400 times greater than atmospheric pressure, and a lack of oxygen to boot, the conditions in which these microbes thrive are some of the most hostile environments on Earth.

In the Jan. 7 issue of the journal Science, researchers working on the European Biodeep project reported the discovery of new microbes in the anoxic basins, or “brine lakes,” located off the coast of Sicily.

It is these types of conditions, particularly the high concentrations of magnesium chloride, that have scientists imagining what the environments of other planets might consist of, and whether they contain life.

"Ascertaining the nature of the subsurface on other planets is tricky, but there is growing evidence for hypersaline environments on Mars and Jupiter’s moon, Europa. Indeed, Europa is believed to have a subsurface ocean rich in magnesium salts," Terry McGenity, the lead scientist of the University of Essex group working on the Biodeep project, told LiveScience.

Since light cannot penetrate water of this depth, there are no photosynthetic bacteria in the basins. Most of the organisms the Biodeep workers have found reduce sulfates to run their metabolism.

Some of the microbes McGenity’s group found were completely unknown, including a new group of Archaea they have named MSBL-1. McGenity speculates that these microbes are methanogens because they are related to methane-producing Archaea, and no other methane-producing microbes were found in the basins, which are abundant with methane.

The European Mars Express mission detected hints of methane in Mars’ atmosphere last year, and some astrobiologists have speculated that the methane could be a by-product of extremophilic methanogens or some other form of microbial life.

CONTINUED : Some survive boiling heat or freezing cold

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