Research Highlight: Extremophiles Unite!

Extremophiles Unite!

Antarctica brings together rock-eating bacteria and the scientists who study them

Never mind New York, New York. If you can make it in Antarctica’s dry valleys, you really can make it anywhere.

These valleys are, of course, bitterly cold. There is no vegetation there. There is glacial ice at higher elevations but virtually no water. There is no shelter from the sun. There’s nothing to eat except rocks.

And somehow that’s enough for some elusive chemolithotrophic microbes that are tough enough to call this place home.

It’s unclear how the microbes — yet to be named by scientists — got here in the first place which, coincidentally, can also be said for the first life on Earth. This explains the attraction for a team of scientists that has made two trips to a region near McMurdo Sound since 2008. The scientists have set up “exposure” stations in which various forms of volcanic glass — made of microbial favorites such as iron and manganese — are made available for consumption by bacteria.

“We are hoping that formulated volcanic glasses enriched with quantities of iron or manganese will attract microbes that specialize in gaining energy from oxidizing these glasses,” said Hubert Staudigel, a geologist at Scripps Institution of Oceanography, UC San Diego.  “These microbes will help us understand who lives in the deep volcanic biosphere, or maybe even whether these microbes were amongst the earliest life on Earth”

Hubert Staudigel explains the goal of the team’s Antarctic research:

The scientists returned from Antarctica in January after a trip to check on the progress of the microbes. The team is led by Staudigel and includes Brad Tebo, a former Scripps microbiologist now at Oregon Health & Science University who has collaborated with Staudigel in the past.

The researchers believe the harsh conditions of Antarctica may have resembled in some respects the pitiless early Earth, which was pockmarked by violent volcanoes and permeated by noxious gases and liquids.  Thus one objective of the research is to make inferences about early life on the planet, some of which may have been evolving as volcanoes were going about creating land mass. There is evidence that some of those early microbes may have become enmeshed with volcanic glass that formed when molten lava was abruptly cooled down as it made contact with the water of ancient oceans.  Scientists call this tint of life deposited onto volcanic glass biofilm.  In his previous travels, Staudigel has found microscopic tubes within 3.5-billion-year-old rocks in South Africa and Australia and has concluded that living organisms drilled them as they found ways to metabolize solid minerals.

The Antarctica study is a companion to ongoing field studies Staudigel and colleagues are conducting at active volcanoes in the South Pacific Ocean. There the ocean provides plenty of food besides rocks for microbes. As a counterpoint, the dormant volcanoes of Antarctica such as Mt. Erebus, its hydrothermal vents and its dry valleys could yield much more information about the characteristics of microbes that have no other food choices. They are the ones that can tolerate extreme environments, earning admission into the category of hardcore organisms known as extremophiles.

“If we find there microbes that only rely on things like iron oxidation or chemical reactions for energy, we are one step closer to identifying the ones that are specialized to situations inside the surface of volcanoes,” said Staudigel.

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Nearly as hardy as a creature that can eat a rock is the scientist who can study the creature that can eat a rock. For its most recent trip, the team of the so-called “Golf 439” expedition required extensive training just to be able to get to the places where the microbes are without killing themselves in the process. The study sites can be under water as close to freezing point as possible or in remote caves more than 3,600 meters (12,000 feet) above sea level accessible only through the spiky crawlspace of fissures in volcanic rock.

“If you foul up, your life is in danger so you have to be very well prepared,” said Staudigel. “You have to have a basic skill set that helps you survive.”

Staudigel’s dive training began in the waters off Scripps’ La Jolla campus two years before the actual trip. The team performed several test dives in McMurdo Sound before actually trying to conduct research. Members took two-day survival courses in tents on windswept ice sheets just to train on how to function in such conditions and practiced how to operate snowmobiles in places usually considered unsafe for use.

“I’ve never been so cold in my life”, said Tebo, “but learning to drive a snowmobile and being able to drive it around on Mt. Erebus made it worth it.”

Among the gear they brought with them were airtight Gamow bags for altitude sickness for the treks they took to places beyond the ready reach of helicopters. If a team member developed symptoms during a Mt. Erebus climb, for instance, they’d climb into the bag while another member filled the bag with air to simulate air pressure at lower altitudes. The sick team member would then be carried to a lower altitude accessible by helicopter and evacuated. All this was covered in the acute mountain sickness course they were required to take by the U.S. Antarctic Program.

The team survived its month-long second leg not needing the Gamow bags. The scientists encountered no worse than a Thanksgiving week stranded on a glacier by high winds on an ice sheet and marking the holiday with its only food: crackers and hot water amid -50 degree-C (-60-degree F) temperatures. The scientists shipped some refrigerated samples home in cargo containers. Among the things they will look for in the lab is enough uncontaminated genetic material from the microbes to understand more about the traits they may share with their primordial ancestors.

Staudigel and his colleagues are planning another journey to the exposure traps next year to wrap up the experiment and hope to extend the mission further. Before then, however, the first batch may have yielded interesting knowledge about how the world’s toughest organisms manage and how their ancestors did so way back when — way, way back when.

— Robert Monroe