Crypto Zoology
Arsenic-loving bacteria may help in hunt for alien life
The bacteria slowly incorporated arsenic into their innermost workings

Arsenic-loving bacteria may help in hunt for alien life
By Jason Palmer
December 2, 2010

The first organism able to substitute one of the six chemical elements crucial to life has been found.

The bacterium, found in a California lake, uses the usually poisonous element arsenic in place of phosphorus.

The find, described in Science, gives weight to the long-standing idea that life on other planets may have a radically different chemical makeup.

It also has implications for the way life arose on Earth - and how many times it may have done so.

The "extremophile" bacteria were found in a briny lake in eastern California in the US.

While bacteria have been found in inhospitable environments and can consume what other life finds poisonous, this bacterial strain has actually taken arsenic on board in its cellular machinery.

Until now, the idea has been that life on Earth must be composed of at least the six elements carbon, hydrogen, oxygen, nitrogen, sulphur and phosphorus - no example had ever been found that violates this golden rule of biochemistry.

The bacteria were found as part of a hunt for life forms radically different from those we know.

"At the moment we have no idea if life is just a freak, bizarre accident which is confined to Earth or whether it is a natural part of a fundamentally biofriendly universe in which life pops up wherever there are Earth-like conditions," explained Paul Davies, the Arizona State University and Nasa Astrobiology Institute researcher who co-authored the research.

"Although it is fashionable to support the latter view, we have zero evidence in favour of it," he told BBC News.

"If that is the case then life should've started many times on Earth - so perhaps there's a 'shadow biosphere' all around us and we've overlooked it because it doesn't look terribly remarkable."

As unexpected

Proof of that idea could come in the form of organisms on Earth that break the "golden rules" of biochemistry - in effect, finding life that evolved separately from our own lineage.

“The take-home message is: who knows what else is there? We've only scratched the surface of the microbial realm” - Professor Paul Davies Arizona State University

Study lead author Felisa Wolfe-Simon and her colleagues Professor Davies and Ariel Anbar of Arizona State University initially suggested in a paper an alternative scheme to life as we know it.

Their idea was that there might be life in which the normally poisonous element arsenic (in particular as chemical groups known as arsenates) could work in place of phosphorus and phosphates.

Putting it to the test, the three authors teamed up with a number of collaborators and began to study the bacteria that live in Mono Lake in California, home to arsenic-rich waters.

The researchers began to grow the bacteria in a laboratory on a diet of increasing levels of arsenic, finding to their surprise that the microbes eventually fully took up the element, even incorporating it into the phosphate groups that cling to the bacteria's DNA.

Notably, the research found that the bacteria thrived best in a phosphorus environment.

That probably means that the bacteria, while a striking first for science, are not a sign of a "second genesis" of life on Earth, adapted specifically to work best with arsenic in place of phosphorus.

'Weird branch'

However, Professor Davies said, the fact that an organism that breaks such a perceived cardinal rule of life makes it is a promising step forward.

"This is just a weird branch on the known tree of life," said Professor Davies. "We're interested ultimately in finding a different tree of life... that will be the thing that will have massive implications in the search for life in the Universe.

"The take-home message is: who knows what else is there? We've only scratched the surface of the microbial realm."

John Elliott, a Leeds Metropolitan University researcher who is a veteran of the UK's search for extraterestrial life, called the find a "major discovery".

Mono Lake, California

The bacteriThe bacteria were found in the salty Mono Lake. Lakeside of the Mono Lake with Tufa columns in the Mono Lake Tufa State Reserve, California, United States. Credit: Michael Gäbler

"It starts to show life can survive outside the traditional truths and universals that we thought you have to use... this is knocking one brick out of that wall," he said.

"The general consensus is that this really could still be an evolutionary adaptation rather than a second genesis. But it's early days, within about the first year of this project; it's certainly one to think on and keep looking for that second genesis, because you've almost immediately found an example of something that's new."

Simon Conway Morris of the University of Cambridge agreed that, whatever its implications for extraterrestrial life, the find was significant for what we understand about life on Earth.

"The bacteria is effectively painted by the investigators into an 'arsenic corner', so what it certainly shows is the astonishing and perhaps under-appreciated versatility of life," he told BBC News.

"It opens some really exciting prospects as to both un-appreciated metabolic versatility... and prompting the questions as to the possible element inventory of remote Earth-like planets".

Steven Benner, an astrobiologist based at the University of Florida took a measured approach to the significance of the find at a press conference held by Nasa on Thursday.

However, he noted that although the conditions on Earth may not have particularly favoured the development of arsenic-based life, that may not be the case elsewhere in the cosmos - or even nearer to home.

"In our Solar System, there are places - Titan, a moon of Saturn, is one of them - where the temperature is much lower," Professor Benner said.

"Where very reactive species like arsenate could very well be useful because although they are too unstable to exist in many environments on Earth, they're not too unstable to exist on Titan, which is at -290F.

"You might very well want to have that increased reactivity just to get the reactions you want and make your biopolymer chains go faster."


Arsenic-using bacteria

On December 2, 2010 NASA announced the discovery of an organism that utilizes arsenic in its cellular structure.[13] This would constitute the first discovery of a life form capable of replacing one of the "big six" (carbon, hydrogen, oxygen, nitrogen, sulfur and phosphorus) elements in its biomolecules.[14] Felisa Wolfe-Simon of the US Geological Survey in Menlo Park, California, has been studying an arsenic-utilizing bacterium, named GFAJ-1, from Mono Lake. Bacteria taken to the lab showed signs of successfully incorporating arsenic into their structure after being starved of phosphorus. - Wikipedia Mono Lake

Related Links:

  • A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus - December 2, 2010
    • Life is mostly composed of the elements carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus. Although these six elements make up nucleic acids, proteins, and lipids and thus the bulk of living matter, it is theoretically possible that some other elements in the periodic table could serve the same functions. Here, we describe a bacterium, strain GFAJ-1 of the Halomonadaceae, isolated from Mono Lake, California, which substitutes arsenic for phosphorus to sustain its growth. Our data show evidence for arsenate in macromolecules that normally contain phosphate, most notably nucleic acids and proteins. Exchange of one of the major bioelements may have profound evolutionary and geochemical significance.
  • Did nature also choose arsenic? - International Journal of Astrobiology
Are Aliens Among Us? Sort of, NASA Says

Are Aliens Among Us? Sort of, NASA Says
By John Brandon
Fox News
Published December 02, 2010

Alien life has been among us all along, according to new biological findings announced by NASA Thursday.

Research conducted by biochemist Dr. Felisa Wolfe-Simon from the U.S. Geological Survey has turned the quest for alien life on its ear, suggesting that phosphorous, carbon, and the other fundamental elements found in every living thing on Earth aren't the only signs of life. Wolfe-Simon explained the findings at a hotly anticipated NASA press conference on Thursday.

After a two-year study at California's Mono Lake, near Yosemite National Park, Wolfe-Simon found that a bug will grow in the presence of the toxic chemical arsenic when only slight traces of phosphorous are present. It's a radical finding, says molecular biologist Steven Benner, who is part of NASA's "Team Titan" and an expert on astrobiology -- forcing the space agency to redefine the quest for other life in the universe.

"When we're searching for alien life, if it's not a Ferengi from Star Trek, what would it be?" Benner asked In his estimation, we've always defined life as something that has the exact same chemistry as a life-form on Earth. The new discovery will likely change that equation, because it means the basic building blocks of DNA are not quite what we thought.

Benner, said the arsenic-loving organism at Mono Lake grew without high levels of the nutrient phosphate (although some phosphates were still present). Just as important, it could change how we look for alien life on other planets, especially on Saturn and the moons of Jupiter.

"It's a paradigm shift," says Dimitar Sasselov, an astrobiologist who leads the Origins of Life Initiative at Harvard University. "The possibility that Earth-life biochemistry is not universal is a transformational concept. It fills the search [for alien life] with optimism. NASA is moving in a good overall direction. What is needed is to take alternatives for life's chemistry to heart and fund research work better."

Arsenic is poisonous to nearly all forms of life on earth. Even small amounts of the poison become embedded in living tissue, causing liver failure and ultimately death -- in nearly everything BUT these bacteria. 

However, as science fiction author Robert Sawyer told, there could be even more profound implications. We have always looked for alien life that matches our biology, but now we have found a different life-form that uses arsenic in its basic DNA structure, he said.

Sawyer explained that NASA science probes have always looked in the most likely places we thought life could exist -- on Mars or Europa, a moon of Jupiter. There is an old joke, he says, about how someone lost a quarter in their garage, then looks out in the yard for it. A neighbor asks why they are looking there instead of in the garage; the light is better, he answers.

"We tend to use the tools we know and the places we know to look for alien life," Sawyer said, explaining that humans want to find a walking, crawling alien and not one that just has different DNA.

The change, he says, is that NASA will start looking for arsenic as well, and possibly other chemicals. This could mean new missions to Titan, which is known for having traces of arsenic. Another change could be the scientific equipment we send to space – probes might be retrofitted to search for arsenic.

Benner said the finding even impacts earlier research. Several years ago, when a Martian meteorite crash-landed on Earth, scientists examined it for the presence of phosphates. Now, it may be possible to re-visit some of the earlier findings. This hints at what experts call the "shadow biosphere" -- the existence of other life-forms, even on Earth, that have a radically different DNA structure.

"It's a huge breakthrough. It changes the probabilities for their being life on other planets," Sawyer told "If there is more than one recipe that makes life, then there are chances of rolling the dice in a chemical soup of all over the universe, and the chances of that chemical soup giving rise to life is much larger."

For NASA, the scientific discovery could help the agency acquire new funding, serving as a catalyst to convince Congress to green light for new missions to Mars or Titan.

In fact, the Internet buzz about finding alien life, as Sawyer noted, is partly due to how NASA has timed the announcement. A new Congress means new opportunities for scientific missions. He says the reality of the finding is somewhat of a joykill -- we have not found E.T. -- but there are still major implications for science and the search for extra-terrestrial life in our solar system and beyond.

Benner says the findings need further review -- there are questions about how much phosphorous is needed to sustain life. 

"The next phase is to grow more of the stuff in a lab using a defined cultured, maybe cook up a broth that contains no phosphorous at all, look at this with a critical eye," he said.

However you view the announcement, the Lake Mono findings are profound, and the possibilities for finding life -- especially the primordial kind -- are now even greater.


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