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Life in the inferno: Identifying how microorganisms can survive in hell
Even Dante would blanch at the conditions miles below the earth' s surface-temperatures climb past the boiling point of water, the weight of hundreds of atmospheres bear down, and space is so tight microorganisms can barely budge. Yet, life persists there. Subsurface microbiologists from the DOE's Idaho National Engineering and Environmental Laboratory and Princeton University are trying to determine how microorganisms survive deep underground in some places, but not others. Understanding how microbes survive and what they do in the subsurface are key to understanding how contaminants degrade there. Researchers know that microorganisms called extremophiles live embedded in rock thousands of feet below dry land, in deep ocean sediments and in fissures crisscrossing the ocean floor. "We're recognizing that microorganisms have remarkable abilities to colonize these environments. We're trying to understand the parameters that control that colonization," says INEEL microbiologist Rick Colwell, who collaborates with Princeton geochemist T.C. Onstott. The three main factors limiting the depth at which extremophiles survive are temperature, pressure and access to food and water. Between the temperature-microorganisms can't live for long at 250 degrees Fahrenheit-and the pressure-extremophiles survive at 600 times atmospheric pressure-the hardy microbes should die off at around three and a half miles below the surface of dry land. However, near geothermal hotspots such as that under Yellowstone National Park, life may survive only near the surface-unlike deep ocean sediments, where miles of cold water above keep the temperatures down below. In arid regions such as INEEL's home on the Snake River Plain, a lack of water and chemical nutrients likely prohibits deep subsurface life. However, extremophiles may flourish deep in faults and mid-ocean ridges, where fluids and nutrients flow more freely. Researchers are accumulating data from deep earth core samples. "In the early days it was 'Let's drill a hole and see what we find'," Colwell says. Now, they have better ideas of where to look for life in Dante's realm. Submitted by DOE's Idaho National Engineering and Environmental Laboratory
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