for National Geographic News
For the past 30 years scientists have scoured the most inhospitable environments on Earth searching for life. Just about everywhere researchers look, they find it thriving in microscopic form.
These organisms, known as extremophiles, snuggle up to scalding hydrothermal vents in the Pacific Ocean. They cling to ice in Antarctica. They burrow in the high deserts of Chile and wallow in salty lake beds of East Africa.
Scientists continue to search forand findextremophiles everywhere from volcanic cauldrons in Russia to alkaline waters in China's Inner Mongolia. In the process, researchers are also beginning to tease out the organisms' secrets to life.
"We know that we are only scratching the surface of what is out there. At the same time, many people are trying to decipher how these organisms function," said Kenneth Stedman, a biologist with the Center for Life in Extreme Environments at Portland State University in Oregon.
Earth's most extreme environments are thought to resemble those on distant planets. Discovering organisms that thrive in such conditions broadens our understanding of the limits to life on Earth. Organisms also provide clues on where to search for extraterrestrial life.
Learning how extremophiles thrive has led to a variety of innovations. Scientists have developed novel compounds for the development of new drugs and enzymes that make better laundry detergents, cleaner paper production, and hydrogen for fuel cells.
"Experimentally, we are coming of age," said Frank Robb, a molecular biologist at the University of Maryland Biotechnology Institute in Baltimore.
Robb is the chair of Extremophiles 2004: Fifth International Conference on Extremophiles, a five-day gathering in Cambridge, Maryland, that begins Sunday. He expects about 320 scientists from around the world to attend the meeting to discuss the latest advances in the field.
So what constitutes an extremophile? Other than the fact that all extremophiles are microbial, there is no common bond that defines an extremophile, according to Stedman, the Portland State University biologist and a conference co-chair. Rather, the differences that distinguish extremophiles from the more mundane mesophiles (organisms that live in "normal" climates and environmental conditions) are subtle.
By deciphering the genomes of extremophiles, scientists are now making their greatest advances in this field. For example, researchers have identified the subtle differences that allow the cell walls of certain microbes to hold up at temperatures above 212 degrees Fahrenheit (100 degrees Celsius).
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