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December 04, 2010

Alien Life, the GAFJ-1 Bacteria

When life gives you arsenic, make DNA
By Emily Staudenmaier

Science bloggers were atwitter this week following NASA’s announcement on Monday that a press conference would be held to discuss an “astrobiology finding that will impact the search for evidence of extraterrestrial life.” The rather cryptic press release led to rumors that perhaps NASA had discovered evidence of life on another planet.

Thursday's press conference dispelled those rumors. Instead, NASA announced that a team headed by astrobiology researcher Felisa Wolfe-Simon had discovered a remarkable new microorganism, GFAJ-1, in California's highly toxic Mono Lake.

GFAJ-1, the researchers report in a paper in Science (it's behind a paywall, unfortunately), is capable of using arsenic instead of phosphorus as one of its basic building blocks when grown in an environment abundant with the former but lacking the latter. Biologists have never before encountered an organism like this.

NASA’s press conference seems to have underwhelmed some of the bloggers and reporters who had endured days of excited speculation. Hoping to hear about the discovery of an alien life form, they felt ripped off that all NASA had on offer was a new microbe from a lake in California (xkcd captured the researchers' side of this rather hilariously).

Well, they should be excited. The fact that NASA didn’t stumble upon ALF and ET having a tea party in some distant corner of the universe does not make the implications raised by the abilities of GFAJ-1 any less profound (though, to be fair, the ALF/ET announcement would have been pretty cool).

GAFJ-1 is the ultimate optimist — instead of making lemonade from lemons, it makes DNA from arsenic. It not only can survive in the arsenic, it incorporates the normally poisonous element into all of its biomolecular structures — an adaptive strategy that is unprecedented anywhere else in the field of physiology.

The ability of GAFJ-1 to use arsenic instead of phosphorus in its DNA, proteins, and lipids will, at the bare minimum, cause biology textbooks to be rewritten.

Every such textbook notes that six elements (carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus) serve as the building blocks of life. Imagine that these elements are Legos that are capable of combining to form neat, stable, and functional structures. Replacing phosphorus with arsenic is like trying to build something out of both Legos and K'NEX — the two pieces don’t normally fit stably together. And yet this microbe provides living proof that it is possible to live and grow with DNA that, in effect, has a backbone made of K'NEX and a body made out of Legos.

This broadening of the bounds of what is physiologically possible for life forms on Earth also rewrites the search for life elsewhere. Since the mechanisms common on Earth are no longer the only game in town, a wider set of elements will now be considered capable of sustaining life.

There could be a more immediate scientific impact as well. In the past, understanding how microbes are able to survive under extreme conditions has changed the way we do research, as well as the way we practice industrial science and medicine. For example, the bacteria Thermus aquaticus lives in hot springs and can withstand great heat, which makes one of its enzymes a perfect reagent for certain molecular biology techniques that must be done at high temperatures. Understanding the molecular and physiological capabilities of this bacteria led to a revolution in research. Studying GAFJ-1 in a similarly thorough manner could yield huge practical results.

The exact mechanisms that allow GAFJ-1 to survive and the evolutionary forces which led to the development of these mechanisms remain to be seen, but there’s no doubt that new information about this organism will continue to alter, on a very fundamental level, how we think about biology.

And that, I would argue, is just as cool as extraterrestrial aliens.

Emily Staudenmaier is a Neurobiology Research Assistant and Laboratory Manager at Brandeis University. She has a B.A. in Molecular Biology from Kenyon College.


Posted by mbowang at December 4, 2010 01:49 PM


It is marvelous that depending on different models, scientists can make different predictions about the star population. I think that as we use more advanced technology to observe the universe, we will find things that will totally change our present ideas about the universe. So Astronomy is alive and fascinating. You may discover new things every day!

Posted by: hztan at December 5, 2010 08:53 PM

Before I always thought of "aliens" as something more specific so it is cool to read about how it can just mean life that does not follow the same qualifications that we put on it in general. This also makes me think that life might be easier to find than we think because we might be putting too specific qualifications for life!

Posted by: lolswang at December 6, 2010 01:27 PM

The fact is that biologists knew arsenic as a poisonous substance prior to this ground-breaking discovery. Arsenic should have killed the bacteria, not enabled the bacteria to sustain life and even grow. This certainly is ground-breaking in every sense of the word. There may be numerous other elements, some maybe not even known to man, that could be the building blocks to alien life. This realization makes an astrobiologist's life much more difficult when looking for alien life elsewhere in the universe.

Posted by: nvohra at December 6, 2010 07:02 PM

This is so interesting to read about. I have always thought of aliens as how media portrays them, but in fact they do not have to be complex life (like humans), but can be simple microbes. I wonder how long these specimens have been living in this California lake. Could it be possible that these were at one point Earthly organisms (extremophiles), but because of the dramatic levels of arsenic, and various other toxic chemicals, they mutated and therefore adapted to their surroundings?

Posted by: elizroge at December 7, 2010 09:59 PM

So if life can form under the presence of arsenic, this will definitely widen the range of locations that we could search for life on other planets. This also means that our previous theories about what elements are needed for life to be sustained are wrong. The most interesting thing to me is that it's possible for life to be sustained under other elements (aside from arsenic) that biologists first said were unable to sustain life. If we could find other elements(beside arsenic) that are able to sustain life as well, then we can continually widen the range of where life could exist on other planets. This could eventually lead to the discovery of life in other planets.

Posted by: kalajk at December 9, 2010 03:22 PM

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