Microbes in ancient ice could give clues to life's origin
Riverside, California - Researchers from the University of California, Riverside and the University of Delaware have thawed ice estimated to be perhaps a million years old or more from above Lake Vostok, an ancient lake that lies hidden more than two miles beneath the frozen surface of Antarctica. Currently, the research team, led by UC Riverside’s Brian Lanoil, an assistant professor of environmental sciences, is examining the eons-old water for microorganisms. Using novel genomic techniques, the team is trying to determine how the tiny, living “time capsules” survived the ages in total darkness, in freezing cold and without food and energy from the sun.The research, which is part of the International Polar Year, is designed to provide insight into how organisms adapted to live in extreme environments. It also gives the researchers access to the genetics of organisms isolated for possibly as long as 15 million years.
“This lake may have been isolated for that long – 15 million years,” said Lanoil, the principal investigator of the research project. “After nearly a year of preparation and verifying protocols, we are now ready to process the samples, and will examine the DNA of these microorganisms to understand how they survived in such an extreme environment.”
The ice segments were cut from an 11,866-foot ice core drilled in 1998 through a joint effort involving the United States, Russia, and France. The core was taken from approximately two miles below the surface of Antarctica and 656 feet (200 meters) above the surface of Lake Vostok, and has since been stored at -35 degrees Celsius at the National Ice Core Laboratory, Denver, Colo.
During Nov. 14-15, segments of the tube-like ice core were thawed in Lanoil’s laboratory under meticulous, “clean lab” conditions to prevent accidental contamination.
Lanoil explained that the ice was once water in the lake that refroze onto the bottom of the ice sheet. His team has no direct samples of the lake itself, only the indirect sampling of the refrozen ice above it because drilling into the lake without taking extensive precautions could lead to the lake’s contamination.
The borehole made to collect the ice is filled with a mixture of jet fuel, kerosene, and chlorofluorocarbons (CFCs) to keep it from closing. “Since the lake has not had direct contact with the surface world for at least 15 million years, this would be a contamination of one of the most pristine environments on Earth,” said Craig Cary of the University of Delaware, a member of Lanoil’s research team.
Among the many measures the Nov. 14-15 decontamination procedure required were: the use of an isolation chamber for the melting; concentration of the meltwater through a special filtering system; use of bleaching solutions for the destruction of any contaminating bacteria or DNA from the outside of the core; and the wearing of dust-free jump suits for all of the laboratory personnel.
Although other scientific projects have identified the microorganisms living in the Vostok water, they have not revealed what the one-celled organisms do or how they have become adapted to an environment that is eternally dark, cold and so isolated that food and energy sources are likely rare and hard to come by.
“Our research will address these questions by directly determining the genome sequences of the microorganisms,” Lanoil said. “Because these microorganisms may have been trapped for 15 million years, this study also could help us understand the origin of life.”The Vostok water contains only between 10-100 microbes per milliliter compared to approximately 1 million microbes per milliliter for most lakes. As a result, the researchers are applying sophisticated techniques, such as whole genome amplification, to gain insight into the genetic diversity of a community of organisms when only small numbers of organisms are available.In the case of Lake Vostok, scientists speculate that it stays in a liquid state underneath miles of ice due to the very high pressures and the insulating properties of the ice.
Lanoil and Cary are being joined in the research by James Gosses of UCR; Julie Smith of the University of Delaware; and Philip Hugenholtz, Victor Kunin and Brian Rabkin of the U.S. Department of Energy's Joint Genome Institute. A grant from the National Science Foundation is funding the study.