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Last Updated: Tuesday, 18 May, 2004, 20:59 GMT 21:59 UK
Utah microbes point to Mars
By Rachael Buchanan

Slab of salt on the edge of the Great Salt Lake, BBC
It is an extreme environment; out of this world
The Great Salt Lake in Utah has an otherworldly quality to it. It is a pink-tinged hyper-saline lake trimmed with a halo of salt that encrusts everything it touches.

With water levels at a 30-year low, the salt load has reached a saturation point of 30%, giving it 10 times the salinity of seawater.

Life just should not be able to exist here, but scientists are finding that the lake is teeming with life.

This inland sea is home to dozens of species of salt-loving micro-organisms - so called halophiles - that thrive in the sodium-chloride-rich soup.

The lake and surrounding Bonneville Salt Flats are the remnants of a much larger, ancient body of water - Lake Bonneville - which drained away thousands of years ago.

When I see this lake, I think 'why is it any different to an evaporated saline lake on Mars?'
Dr Bonnie Baxter
But despite the lake's historic existence, little is known about its curious inhabitants, and that is something Dr Bonnie Baxter, of Salt Lake City's Westminster College, plans to change.

She has teamed up with leading halophile experts, including Dr Shil DasSarma of the University of Maryland, to take the first inventory of the lake's microbes.

Cancer defence

The discovery of organisms that thrive in the conditions biological dogma once told us were impossible for life is now becoming commonplace.

Collectively known as extremophiles, these life forms selectively embrace extremes of heat, cold, acidity, pressure, radiation and of course salinity.

Map showing location of lake in Utah, BBC
Largest lake west of Mississippi
Lake covers about 4,400 sq km
Some brine shrimp and flies
Important migratory bird route
Their very toughness has attracted not only inquisitive scientists, but the biotech industry, which hopes to capitalise on the enzymes which enable these organisms to survive where nothing else can.

Dr Baxter has similar aspirations for her Salt Lake inhabitants.

They employ solar-powered salt pumps to keep their internal salt concentrations lower than the water around them. But to drive those pumps, the microbes need to be at the surface which means basking in the Sun's damaging ultraviolet light all day.

But therein lies their powerful secret. The pink colour of the lake is due, in part, to the pigments - carotenoids - that the lake's microbes produce.

These shield their DNA from damage, like an in-built sunscreen, a characteristic Dr Baxter believes could be exploited.

"We have the same pigments in our cells," she told BBC News Online.

"What if humans could express more of them, too? We could take the secrets of these organisms and prevent damage to our own DNA from the Sun - after all the Earth is only going to get sunnier."

Martian interest

But what first drew Dr Baxter to these halophiles was the lure of the unknown.

"We really don't have names for almost all of them," she explained. "Only a few have been catalogued, and nothing has been done systematically."

In Dr DasSarma, she has a partner of impeccable pedigree for the project. He was the first to sequence the genome of a halophile - Halobacterium species NRC-1 - in 2000.

Work on its Utah cousins has only just begun but Dr DasSarma says their initial results are showing just how novel these organisms are.

Bonnie Baxter (l) on Great Salt Lake, BBC
Dr Baxter (l) is making a life catalogue
When you compare the DNA of a new species to a gene bank to see if their genes resemble those of known organisms, "normally, three out of four times you find something similar," Dr DasSarma said.

"But when you do this with the Salt Lake, the majority of genes are novel - they are like nothing on Earth."

It is appropriate then that parallels are being drawn between locations like this and Meridiani Planum on Mars. This is where Nasa's Opportunity rover has discovered it is parked on top of an evaporate basin like Utah's Bonneville flats, the remnants of an ancient Martian salty sea.

As the conditions on early Mars got colder and harsher, it lost liquid water through evaporation or sequestration into permafrost.

Remaining bodies of water would have been increasingly salty places, and then finally all liquid water disappeared, and the salt deposits eventually lithified into the evaporate rocks the rover sees today.

Any early Martian microbe would have had to withstand a high salt environment and intense UV radiation. Sound familiar?

Red resurrection

Many scientists have argued for some time that if bacteria can survive such conditions here, why not on Mars? Now, Opportunity has proved bodies of open water did once exist and so shown us that the Red Planet is prime real estate after all.

Maybe it could have entertained early settlers that were a lot like the halophiles of the Great Salt Lake.

Opportunity looks back at a job well done

Nasa certainly thinks so. Suddenly, sample-return missions are back on the agenda and Meridiani Planum is being spoken of as a prime destination to go and fetch rocks for study back on Earth.

The prospect of having a chunk of Martian evaporate in an Earth lab, maybe with ancient salt crystals embedded, is an exciting one for the extremophile scientists.

In 2000, researchers actually managed to revive 250-million-year-old halo-tolerant bacteria found on Earth in underground salt crystals. Could we possibly do the same with Martian microbes?

As she sits on a salt-frosted rock looking out over the Great Salt Lake, Dr Baxter admits to fantasising about such a prospect.

"When I see this lake, I think 'why is it any different to an evaporated saline lake on Mars? What if I had a chunk of that lake bed on Mars - what kind of things could I grow from that?'"

The BBC's Fergus Walsh
"Life should not be able to exist here"

Rover finds new Mars water signs
18 May 04  |  Science/Nature
Mars rover sits on ancient beach
23 Mar 04  |  Science/Nature
Extreme bugs found in slag dump
19 Nov 03  |  Science/Nature
Microbe breaks temperature record
15 Aug 03  |  Science/Nature
First salt-loving bug sequenced
02 Oct 00  |  Science/Nature

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