WASHINGTON Researchers who were looking for organisms that eke out a living in some of the most inhospitable soils on Earth have found a hardy few. A new DNA analysis of rocky soils in the martian-like landscape on some volcanoes in South America has revealed a handful of bacteria, fungi, and other rudimentary organisms, called archaea, which seem to have a different way of converting energy than their cousins elsewhere in the world.
"We haven't formally identified or characterized the species," said Ryan Lynch, a microbiologist with the University of Colorado in Boulder who is one of the finders of the organisms, "but these are very different than anything else that has been cultured. Genetically, they're at least 5 percent different than anything else in the [DNA] database of 2.5 million sequences." The database represents a close-to comprehensive collection of microbes, he added, and researchers worldwide add to it as they publish papers about the organisms.
Life gets little encouragement on the incredibly dry slopes of the tallest volcanoes in the Atacama region, where Lynch's co-author, University of Colorado microbiologist Steven Schmidt, collected soil samples. Much of the sparse snow that falls on the terrain sublimates back to the atmosphere soon after it hits the ground, and the soil is so depleted of nutrients that nitrogen levels in the scientists' samples were below detection limits. Ultraviolet radiation in this high-altitude environment can be twice as intense as in a low-elevation desert. And, while the researchers were on site, temperatures dropped to -10 degrees Celsius (14 degrees Fahrenheit) one night, and spiked to 56 C (133 F) the next day.
How the newfound organisms survive under such circumstances remains a mystery. Although Lynch, Schmidt, and their colleagues looked for genes known to be involved in photosynthesis, and peered into the cells using fluorescent techniques to look for chlorophyll, the scienti
|Contact: Peter Weiss|
American Geophysical Union