Antarctic lake bacteria discoveries

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In November 2008, an international team of distinguished scientists, educators and explorers embarked on a six week expedition to Antarctica. Their primary mission was to study the icy ecosystems of the Schirmacher Oasis and the perennially ice-covered Lake Untersee.

In this exceptionally hostile environment, the team hoped to find a new species of “extremophile” – a hardy life form that exists and flourishes in conditions inhospitable to most known organisms.

These discoveries could shed light on how life adapts to extremes on Earth – but could also shake the search for life on other planets.

From Discovery News:

Antarctic Lake Hides Bizarre Ecosystem

Bacterial colonies form cones like those on early Earth

Thu Apr 14, 2011 11:46 AM ET
Content provided by Alexandra Witze

THE GIST

East Antarctica’s Lake Untersee is home to 1.5 foot-high stromatolites that may be thousands of years old.
The mounds are similar to fossil formations of early life on Earth.

In the eerie bluish-purple depths of an Antarctic lake, scientists have discovered otherworldly mounds that tell tales of the planet’s early days.

Bacteria slowly built the mounds, known as stromatolites, layer by layer on the lake bottom. The lumps, which look like over-sized traffic cones, resemble similar structures that first appeared billions of years ago and remain in fossil form as one of the oldest widespread records of ancient life. The Antarctic discovery could thus help scientists better understand the conditions under which primitive life-forms thrived. “It’s like going back to early Earth,” says Dawn Sumner, a geobiologist at the University of California, Davis.

Sumner and her colleagues, led by Dale Andersen of the SETI Institute in Mountain View, Calif., describe the discovery in an upcoming issue of Geobiology. “These are just incredibly beautiful microbial landscapes,” she says.

Researchers have probed many Antarctic lakes to study the weird and wonderful microbes that live there; Andersen alone has dived into at least eight such lakes. But he says the discovery of the stromatolites rocketed East Antarctica’s Lake Untersee “to the top of my list.”

Researchers study fossil stromatolites, from 3 billion years ago or more, to understand how life got a foothold on Earth. Today, stromatolites actively form in only a few spots in the ocean, like off the western coast of Australia and in the Bahamas. They also grow in some freshwater environments, like super-salty lakes high in the Andes and in a few of Antarctica’s other freshwater lakes. But scientists have never seen anything like the size and shape of Untersee’s stromatolites.

Drawn by its extremely alkaline waters and high amounts of dissolved methane, Andersen and his colleagues traveled to Untersee in 2008 to drill through its permanent ice cover and collect water samples.

Andersen was used to finding mats of bacterial growth in other Antarctic lakes, but nothing like the big mounds he saw when he dived under the ice at Untersee. Up to half a meter high, these purplish piles studded the lake’s bottom like barnacles clinging to a ship hull. “It totally blew us away,” Andersen says. “We had never seen anything like that.”

Samples of one of the mounds showed that it was made mostly of long, stringy cyanobacteria, ancient photosynthetic organisms. The bacteria may take decades to build each layer in Untersee’s frigid waters, Sumner says, so the mounds may have taken thousands of years to accumulate.

Oddly, the stromatolite mounds sat next to smaller, pinnacle-shaped lumps that researchers had seen in many other lakes. And the stromatolites were made mostly of Phormidium bacteria, while the pinnacles were made of another group, Leptolyngbya.

To Sumner, that sharp distinction between bacterial composition on different shaped lumps says something significant about Untersee. “Everywhere else that we’ve looked you have a gradation between the structures,” like in bacterial mats sprawling around Yellowstone’s hot springs, she says. “There’s something very special about this particular example that’s allowing these large conical stromatolites to form.”

But scientists aren’t sure yet what that something special is. Andersen’s team has recently studied two other ice-covered Antarctic lakes, Vanda and Joyce, without finding large conical stromatolites there. Conditions vary from lake to lake, making each of them unique in their own frigid way; Lake Vanda, for instance, has a more transparent ice cover that lets more light penetrate. Lake Joyce has thicker ice, which constrains how far down photosynthesizing organisms can grow.

Understanding what makes Untersee different would help scientists better figure out the limits on life, both today and in the long-distant past. “It’s a real challenge to our understanding of how these communities developed,” says Ian Hawes, a polar limnologist at the University of Canterbury in Christchurch, New Zealand.

More answers should come this November, when Andersen’s team is scheduled to return to Untersee to scrape up more samples of the ghostly blue mounds.

Antarctica’s Don Juan Pond stays liquid in one of the unlikeliest places on Earth, the frigid McMurdo Dry Valleys. The pond is the saltiest body of water on Earth, eight times brinier than the Dead Sea. The secret to how the pond stays moist and salty suggests the possibility of water flowing on the face of Mars: here.

The first appearance and establishment of an alien vascular plant in natural habitats on the forefield of a retreating glacier in Antarctica: here.

Scientists: Ancient Microbes Found In Salty, Ice-Sealed Antarctic Lake; ‘New Boundary Conditions On The Limits For Life’: here.

April 2011: Sea stars as big as hubcaps, colourful sponges and feathery sea pens have been revealed after nearly 80 years in dark Antarctic waters: here.

Scientists believe Antarctic ozone hole on the mend (ScienceNews): here.

Greenland, Antarctic ice sheets melting faster than predicted: here.

Origin of Photosynthesis Revealed: Genome Analysis of ‘Living Fossil’ Sheds Light On the Evolution of Plants. ScienceDaily (Feb. 21, 2012) — Atmospheric oxygen really took off on our planet about 2.4 billion years ago during the Great Oxygenation Event. At this key juncture of our planet’s evolution, species had either to learn to cope with this poison that was produced by photosynthesizing cyanobacteria or they went extinct. It now seems strange to think that the gas that sustains much of modern life had such a distasteful beginning: here.

Found: Microbes From the Dinosaur Age
: here.

Related articles

• Life Found in Antarctic Lake Under 50 Feet of Ice (newser.com)
• Ancient microbes found living beneath the icy surface of Antarctic lake (eurekalert.org)
• Antarctic lake find pushes known boundaries of what life can endure (guardian.co.uk)
• Ancient microbes found in buried Antarctic lake (sott.net)
• Ancient microbes found living beneath the icy surface of Antarctic lake (esciencenews.com)
• Buried Antarctic lake microbes could shed light on ‘Alien life forms’ (rt.com)
• Ancient Microbes Found in Buried Antarctic Lake (news.discovery.com)
• Astrobiologist Dale Andersen Status: Novolazarevskaya Station, Antarctica (spaceref.com)
• UK scientists drilling in the Antarctic (bigpondnews.com)
• UK scientists begin Antarctic drilling (bigpondnews.com)