Scientists alter bacteria to survive on arsenic

We didn’t find the little green men. We made them.

NASA had scheduled a press conference recently, with a panel of scientists with specialties in exobiology and weird life forms. This garnered high expectations from science buffs, and even some of the general public had to get excited. This was, indeed, a big deal.

Now, that cat’s out of the bag. Revealed was the news that researchers had created a bacteria that was arsenic based, scraped from the bottom on California’s Mono Lake and fed a diet of the poisonous arsenic.

“Bacteria that live on arsenic? Awesome,” said one student.

This announcement was met with high enthusiasm from the scientific community – but was a letdown for the people expecting aliens.

Here’s the how behind the science: Every living thing, from the tiniest protozoa to the giant blue whale, has DNA. DNA, or Deoxyribonucleic Acid, contains the instructions for all of the body’s functions, and is the reason that organisms, including humans, survive. The shape of DNA looks like a twisted ladder. The rungs are made of amino acids, and the sides of the ladder are made of phosphorus bonded to some sugars.

Generally it’s accepted that life has some basic building blocks: carbon, oxygen, nitrogen, sulfur, hydrogen, and phosphorus. When scientists look for planets that might be able to evolve alien life, that’s what they look for.

What did the scientists do? They scraped the bottom of Mono Lake for the bacteria GFAJ-1, and started to wean it off it’s diet of phosphorus – and then replace it with arsenic. Arsenic is an element known to be toxic to life, even though it’s right below phosphorus in the periodic table. So you wouldn’t expect it to work, right? Wrong. Not only did the bacteria thrive under the arsenic diet, their DNA became altered to incorporate it. The arsenic replaced some of the phosphorus in the sides of the DNA ladder.

The bacteria were also fed a glucose mixture to use synthesize as ATP – or energy. There was some phosphorus present, but the paper published by the researchers has stated that it wouldn’t have been enough for the bacteria to survive off of.

That means that these little guys are arsenic based.

“There’s this sense of surprise – it’s so unusual that it could change the way we think of everything,” scientist (and science guy) Bill Nye said in a MSNBC television segment, “See, one of the big ideas these days in astrobiology that there could have been what people like to call a second genesis…maybe life arose in multiple ways here on earth, and we’ve never gone looking in the right places and asking the right questions to discover them.”

Oh, if only Arthur C. Clarke was still alive to see this. Clarke, author of 2001: A Space Odyssey (look it up, kids – it’s a sci-fi classic) envisioned life of Saturn’s moons might be silicon based, living in the seas of Europa and in the clouds of the great planet itself.

The real excitement of all this isn’t the bacteria themselves, but of the implications for life on other planets. Up until now, when scientists looked for planets that could support life, they examine whether or not those key elements could exist on the planet.  Now we may have to reexamine our viewpoints of what life really is.

Before now, we had always assumed that life needed these key elements to survive. We were wrong.

But why should we care?

“So what?” said another student.

This discovery changes everything in the way we look for life, and how we think of life. This might cause scientists to think just a little bit harder at what they consider “alive”. There are characteristics that life has to have, according to the definition of life. Most of them are standard, like the organism needs to eat and give off waste, and needs to grow – but the key to life is that it had the essential elements, including phosphorus. Now we need to re examine what life is, and change where we look for those “little green men”.

That is, if the results are legitimate.

This announcement has also met some criticism from the scientific community, however. NASA has been accused of putting big hype on a not so big achievement, to get more funding for their programs. Several scientists also question the conclusions that the researchers made about the results obtained –  including the claim that the arsenic was present, but not replacing the phosphorus.

Bacteria had been known before to be able to survive in extreme conditions, and there are some bacteria that can live in high arsenic environments.

“I don’t know whether the authors are just bad scientists or whether they’re unscrupulously pushing NASA’s ‘There’s life in outer space!’ agenda,” wrote University of British Columbia Prof. Rosie Redfield, “Basically, it doesn’t present any convincing evidence that arsenic has been incorporated into DNA (or any other biological molecule).”

Redfield critiqued the paper in a blog post that caused some to question the legitimacy of the findings, causing a major debate about the techniques used in the study. The researchers, meanwhile, maintain that their findings and their techniques were valid and precise.

The NASA scientists have also responded to these critics: they have released several statements responding to the controversy, including this one in the New York Times: http://content.usatoday.com/communities/sciencefair/post/2010/12/arsenic-bacteria-study-authors-respond-to-critics-/1.

Life, it seems, is forever surprising us in it’s complexity and versatility.

By Gabrielle Bauman