Critics raise doubts on NASA's arsenic bacteria

Dec 09, 2010 by Lin Edwards report
A microscopic image of GFAJ-1 grown on arsenic.

(PhysOrg.com) -- NASA’s announcement last week that bacteria had been discovered that appeared to replace phosphorus with arsenic and thrive even in the most poisonous environments, has now come under fire from a number of scientists.

The findings reported last week, were that some bacteria (GFAJ-1) thrived when access to phosphate was removed and the bacteria were grown in a highly toxic culture rich is arsenate. The scientists suggested the bacteria thrived because they were able to replace , which has always been thought vital to , with , which is directly under it on the periodic table and has similar chemical properties. The researchers also suggested the bacteria were replacing phosphorus with arsenic within the bases that make up DNA.

These findings, if correct, would mean the scientists had found a new form of life on Earth, and it would also re-write the guide book on the essential requirements for life to exist elsewhere.

After the findings were published in Science, other scientists began immediately to express their doubts at the conclusions of the paper, with some even expressing the opinion the paper should not have been published at all.

One of the critics was Dr. Alex Bradley, from Harvard University, who blogged that there were a number of problems with the research. Firstly, if arsenic had replaced phosphorus in the DNA the molecule would have broken into fragments when the DNA was placed in water, since the arsenic would have hydrolyzed, and yet it did not. Secondly, the paper showed there was a small amount of phosphorus in the medium and Bradley argued that even though small, this could have been enough, since bacteria metabolism is extremely efficient.

Dr. Bradley also pointed out the bacteria live in Mono Lake, which is rich in arsenic but which also contains a higher concentration of phosphate than almost anywhere else on Earth, and this means there would be no selective pressure for a life based on arsenic to evolve.

Dr. Bradley also suggested a mass spectrum of the DNA sequences would have shown whether or not the nucleotides contained arsenic in place of phosphorus, but this was not done.

Another critic was University of British Columbia biologist Rosie Redfield, who reviewed the paper on her blog, and has more recently submitted a letter to the journal. Among her conclusions are that the paper “doesn't present ANY convincing evidence that arsenic has been incorporated into DNA (or any other biological molecule).” She also writes: “If this data was presented by a PhD student at their committee meeting, I'd send them back to the bench to do more cleanup and controls.”

Dr. Redfield also points out there was phosphate in the culture and that the authors did not calculate whether the amount of growth they saw in the arsenate-only medium could be supported by the phosphate present. She calculates on the blog that the growth of the bacteria is actually limited by the amount of phosphorus.

Another point made by Redfield is that the arsenic bacteria were “like plump little corn kernels” and contain granules, which are usually produced by bacteria when they have ample supplies of carbon and energy sources but there are shortages of other nutrients needed for growth.

The authors of the arsenic bacteria paper initially refused to be drawn into the arguments, saying the discussion should be confined to peer-reviewed journals, but one of the authors, Ronald Ormeland, did answer questions on the controversy after giving a lecture on the findings at headquarters yesterday. He said the amount of phosphorus in the sample was too small to sustain growth, and a mass spectrum was not done because they did not have enough money, and wanted to get the result published quickly. He also pointed out that the are still there and other scientists could duplicate the work and carry out further experiments if they wished.

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User comments : 15

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dogbert
3 / 5 (5) Dec 09, 2010
"...a mass spectrum was not done because they did not have enough money, and wanted to get the result published quickly."

NASA can't afford the resources for the research, but can afford to publish questionable research?
SincerelyTwo
3.2 / 5 (5) Dec 09, 2010
doqbert,

Think about it. Lots of money and time to obtain and use equipment for tests. Then you have hitting the submit button to publish research. Do you think it costs more money to hit submit, or to spend a lot of money and time on tests?

I'm just surprised NASA would be so shady.
satyricon
2.8 / 5 (5) Dec 09, 2010
Just so they can publish the results quickly?!

This is unacceptable from NASA.
DarwiN100
3.2 / 5 (6) Dec 09, 2010
Yep, NASA lost some of its credibility on this one. This actually looks more like a joke than anything else.. Its 2010 and they could determine the composition of this bacteria before publishing this speculations. They decided to scream now and grab the publicity, because otherwise when all the facts are known, it is a huge possibility that the thing turns out to be not so exciting..
epsi00
5 / 5 (4) Dec 09, 2010
Well, the ball is in NASA's side now. They should respond to critics in a scientific way properly or retract the article.
otto1932
1.1 / 5 (25) Dec 09, 2010
Why are they doing this sort of research anyway? Shouldn't it be done by groups with the specific training and resources to do it? Shouldn't NASA maybe be at most identifying areas for further research by dedicated groups rather than spending money on projects directly related to space travel and exploration?
Modernmystic
2.5 / 5 (10) Dec 09, 2010
They've been a ****ing joke since after we landed on the moon and then proceeded to spend the next forty years playing patty cake in LEO and sending robots to mars that can't even dig in the soil where they were placed.

Oh and they built an idiotic erector set of a space station that doesn't even spin for artificial gravity and has NO PURPOSE at all...

They've done some good since the sixties, but nothing to justify the money they've spent.

eachus
5 / 5 (3) Dec 09, 2010
Why are they doing this sort of research anyway? Shouldn't it be done by groups with the specific training and resources to do it? Shouldn't NASA maybe be at most identifying areas for further research by dedicated groups...

Damned if you do, damned if you don't. There is nothing wrong with the paper. The hype at the press conference went a lot further than the paper does. So yes, I think NASA should do preliminary research in areas like this of interest to NASA, and hand it over to those better equipped to follow up.

Which is what NASA did... The paper identified extremophile bacteria that live in extremely high concentrations of arsenic, and have replaced some phosphorus in their structure with arsenic. Can they survive with no phosphorus at all? Probably not--for this strain--but several years more work should result in a strain which can--if it is possible.
Skeptic_Heretic
4 / 5 (11) Dec 09, 2010
They've been a ****ing joke since after we landed on the moon and then proceeded to spend the next forty years playing patty cake in LEO and sending robots to mars that can't even dig in the soil where they were placed.
So GPS, telecommunications satellites, solar powered remote radio installations, cell phone towers, etc are all junk? The metamaterials that have been used from cookware to motorvehicle safety are useless?

The Chase research group has shown that for every dollar invested in NASA the world has created 2.5 dollars of wealth in the form of new products and markets. Apollo itself as $1 to $14.

Oh and they built an idiotic erector set of a space station that doesn't even spin for artificial gravity and has NO PURPOSE at all...
You seem to not understand how difficult it would be to do anything with a wildly spinning space station, let alone docking with it.
http://www.thespa...ffs.html
barakn
5 / 5 (8) Dec 09, 2010
Firstly, if arsenic had replaced phosphorus in the DNA the molecule would have broken into fragments when the DNA was placed in water, since the arsenic would have hydrolyzed, and yet it did not.

I agree with many of the arguments, but not this one. Bradley presumes he knows how As-DNA would behave in water when it has not yet been characterized. He is instead making unwarranted extrapolations from much simpler arsenic compounds. Also I'm not sure why he would focus on the moment when the DNA was placed in water during a purification step when the interior of a cell is aqueous. If As-DNA is that susceptible, then there would have been none to extract, as it would have disintegrated within the cell. If he is right, it's only because he's guessing.
KwasniczJ
2.3 / 5 (6) Dec 09, 2010
Well, NASA can still be right (frankly, I wish it), but only more thorough research could decide it.

After all, as usually. The "first experimental confirmation" of general relativity with solar eclipse (Eddington, 1919) was not fair as well... The history belongs to the winners.
Modernmystic
1.5 / 5 (13) Dec 09, 2010
So GPS, telecommunications satellites, solar powered remote radio installations, cell phone towers, etc are all junk? The metamaterials that have been used from cookware to motorvehicle safety are useless?


Why do you ****ing leftist nut-jobs think that just because the government has done something in the past that it WOULDN'T HAVE BEEN DONE without it? Do you think that if the Europeans didn't have socialized medicine there wouldn't be an aspirin on the continent?

FFS...
Skeptic_Heretic
4.3 / 5 (9) Dec 09, 2010
Why do you ****ing leftist nut-jobs think that just because the government has done something in the past that it WOULDN'T HAVE BEEN DONE without it? Do you think that if the Europeans didn't have socialized medicine there wouldn't be an aspirin on the continent?
Aspirin existed before socialized healthcare.

These technological items came directly from NASA research money. If you're going to say NASA is a waste of money, you have to explain how all of these things are a waste. This is basic debate. If you're really that pissed over having to explain your opinions, stop sharing them.
ArcainOne
4.3 / 5 (9) Dec 09, 2010
Why do you ****ing leftist nut-jobs think that just because the government has done something in the past that it WOULDN'T HAVE BEEN DONE without it? Do you think that if the Europeans didn't have socialized medicine there wouldn't be an aspirin on the continent?


Why do you keep opening your mouth... Why are you on this site? NASA is one of the ONLY organizations in our government that actually MAKES money. Why don't you do some research into some of the other "useful" programs and organizations our government is pouring money into. At least NASA has a direct contribution to humanity and its past, present, and future.
GaryB
not rated yet Dec 11, 2010
Why are they doing this sort of research anyway? ... Shouldn't NASA ... spending money on projects directly related to space travel and exploration?


Assuming I was able to parse your last sentence which could be read in 2 opposite ways: This is exactly related to space exploration -- what life might look like and what forms life might take. Whether they did the research well or not is another question.

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