Arsenic-based lifeforms? Really?

First of all, a NASA astrobiologist, Felisa Wolfe-Simon, and her team found some bacteria in Lake Mono, in California.

Felisa Wolfe-Simon processing mud from Mono Lake to inoculate media to grow microbes on arsenic (click to embiggen)
Felisa Wolfe-Simon processing mud from Mono Lake to inoculate media to grow microbes on arsenic (Image by Henry Bortman, via NASA)

This lake has very high salinity, high alkalinity and high levels of arsenic. Dr Wolfe-Simon’s team extracted a strain of  Gammaproteobacteria, which they cultivated in a laboratory and called GFAJ-1 (short for “Give Felisa a job”).

When they cut off the bacteria’s supply of phosphorous – essential for DNA, cell membranes and other metabolic processes – it continued to grow. This led them to conclude that arsenic – which, although usually poisonous, is chemically similar to phosphorous – had taken its place.

Then NASA put out an announcement…

“NASA will hold a news conference at 2 p.m. EST on Thursday, Dec. 2, to discuss an astrobiology finding that will impact the search for evidence of extraterrestrial life.”

Media hype duly followed (a lot of people hoped that life had been found on one of Saturn’s moons).

The news conference, and the accompanying press release, took place the same day the research was published in the online version of a peer-reviewed journal (Wolfe-Simon F, Switzer Blum J, Kulp TR, Gordon GW, Hoeft SE, Pett-Ridge J, Stolz JF, Webb SM, Weber PK, Davies PCW, Anbar AD & Oremland RS, “A bacterium that can grow by using arsenic instead of phosphorus”, Science, 1197258, published online 2 December 201 [DOI: 10.1126/science.1197258]).

Image of GFAJ-1 grown on phosphorous (click to embiggen)Image of GFAJ-1 grown on arsenic (click to embiggen)
Image of GFAJ-1 grown on phosphorous (top) and on arsenic (bottom). (Images by Jodi Switzer Blum, via NASA)

As a result, it was already all over the news before any other scientists could have a look at it. But when they did get a chance to read the paper, the response was pretty unanimous: it didn’t make a lot of sense.

The first to comment was a Canadian biologist, Rosie Redfield, who pointed out on her blog that there were a lot of problems, such as how there was still a small amount of phosphorous in the salts they were feeding the bacteria, and how they hadn’t proved there really was arsenic in the DNA. In fact, some other biologists pointed out that there were indications that it wasn’t, because the bacteria’s DNA stayed intact in water, whereas arsenic compounds tend to fall apart very easily.

Some people even claimed that the paper should never have been published.

So far, no formal responses have been published in the traditional way, in printed journals. Instead, the discussion has been carried out online, on blogs and news websites.

We’ve had a response from the authors. And a response to the response by Dr Redfield.

This is the way science normally works. But even though it’s happening faster than usual, thanks to the internet, it’s still too slow for the news media and their attention has moved on.

As a result, apart from those like you who follow it up online, everyone will remember that in December 2010 aliens were discovered on Earth – at least, those people who read the Herald Sun will.

NASA finds 'weird life' on Earth (Herald Sun)
NASA 'weird life' discovery at the Herald Sun (Picture: AP, from the HWT Image Library)

For more on this saga, see the Lay Scientist at the Guardian.


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