Molecular Biology Reaches New Extremes: Scientists Conduct First DNA Field Tests on Antarctic Soil Microbes


Equipped with a portable lab kit, a generator, a small tent, and plenty of warm clothes, an international team of scientists recently conducted genetic tests of the bacteria that thrive in one of the driest, coldest places on Earth - Antarctica's "Dry Valleys." This is believed to be the first time DNA fingerprinting of soil microbes has been performed in the field on the Earth's frozen continent.

The two-week research mission, conducted in February, marked the first in a series of expeditions to assess the diversity of microorganisms that inhabit Antarctica.

The effort was led by scientists Don Cowan from the University of Western Cape Town in South Africa and Roy Daniel from the University of Waikato in New Zealand with support from Antarctica New Zealand, and by marine biologist Craig Cary from the University of Delaware in the United States. Cary's participation was made possible through a grant from the U.S. National Science Foundation. Graduate students Sarah Hawkins from the University of Waikato and Samantha Whiting from University College, London, also participated in the project.

Unlike most of Antarctica, the Dry Valleys are not covered in snow and ice. This vast region of exposed soil and rock, punctuated here and there by icy lakes, forms a frigid desert. In fact, some scientists believe that no rain has fallen in the Dry Valleys for over 4 million years.

Learning more about the microscopic life that can survive these demanding conditions appeals to Cary, Cowan, and Daniel, who typically study bacteria that live in much hotter surroundings. Previously, Cowan and Daniel had worked primarily with the bacteria that inhabit hot springs on land, while Cary's focus had been on the microbes that live at underwater hot springs called hydrothermal vents found over a mile deep in the ocean where new seafloor is being formed.

"While vent microbes set the upper end of the temperature scale in the marine environment, the polar regions set the lower limit in the terrestrial environment," says Cary, who is a marine biologist at the University of Delaware. "Past research has shown that the soils of the Dry Valleys support a diverse assemblage of microorganisms. Yet how they survive and what they are doing remains largely unknown."

Figuring out what makes polar microbes tick is important for a number of reasons, according to Cary. "Research on heat-loving vent bacteria has yielded enzymes that can be used as industrial catalysts in certain high-temperature operations like pharmaceuticals manufacturing," he says. "In examining polar microbes, scientists might identify new biotechnological tools and products for use at extremely cold temperatures, as well as shed light on the possibility of life on other planets."

To determine if they were succeeding in collecting a diversity of polar microbes in their sampling operations, the scientists needed to be able to examine the tiny life at the genetic level.

"Getting to these remote areas of Antarctica is very costly, and every effort must be made to collect the valuable samples needed for study," says Cary. "Rather than randomly collect samples, as has been done in the past, we decided to see if it was possible to run some preliminary diagnostic experiments in the field to get an idea what we were sampling before returning home to our laboratories. This had never been attempted before in Antarctica and really had to be tested before we could propose a dedicated effort in this area in the future," he notes.

To conduct the DNA tests, the scientists used the Mobile Molecular Laboratory, made by MJ Research, Inc., and donated to the expedition by Geneworks of Adelaide, Australia. They relied on a small Honda generator to power their operations. The researchers would sit cross-legged on the floor of the tent or on the First Aid box doing delicate genetic tests including DNA extractions, electrophoresis, and PCR analyses as the wind howled around them.

"It was definitely warmer inside the tent than outside of it," Cary says, "but never above 0°C unless we had some heating device. At best, we could get the tempeript.e inside the tent up to 10°C, so at least the pipettes worked and the buffers were liquid, instead of frozen."

The scientists worked in the field for nearly two weeks. Every few days, they were helicoptered to new sampling locations in the Dry Valleys, only returning to Scott Base, New Zealand's research outpost on Antarctica, to catch their flight back home. At the end of 13 days of field work, the scientists had run six successful experiments that provided valuable information on the samples they were collecting.

"The beauty of doing this testing on site is that we can be sure that we get the diversity of microbes we came for instead of collecting samples and then confirming what we got — or didn't get — weeks later back in the lab," says Cary. "Sure, this time, it was primitive, cramped, and cold," he notes smiling, "but next time, we will bring a dedicated and more spacious laboratory structure, with a table, folding chairs, a heater, and a coffee machine — a little luxury in the Dry Valleys!"

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