NASA’s Mono Lake Arsenic Microbes Not Quite As Advertized

800px-Wfm_mono_lake_landsatThe announcement was exciting. The NASA media advisory, Nov. 29 that said in part: “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. Astrobiology is the study of the origin, evolution, distribution and future of life in the universe.”

Many people thought maybe NASA would announce discovery of extraterrestrial life. But, as it turned out, NASA was talking about a study at Mono Lake, California, which showed, NASA claimed, that they had discovered a microbe that could grow using arsenic rather than phosphorus which all other known life uses. If true, even this would be a great advance, but microbial use of arsenic, itself, is not news. The 2004 paper, The microbial arsenic cycle in Mono Lake, California, goes into great detail about microbial use of arsenic. But, these microbes still use phosphorus also.

After several microbiologists analyzed the NASA paper and its methodology, they concluded that laboratory errors caused NASA scientists to think the microbes did not use phosphorus.

In fact, says Harvard microbiologist Alex Bradley, the NASA scientists unknowingly demonstrated the flaws in their own experiment. They immersed the DNA in water as they analyzed it, he points out. Arsenic compounds fall apart quickly in water, so if it really was in the microbe’s genes, it should have broken into fragments, Bradley wrote Sunday in a guest post on the blog We, Beasties. But the DNA remained in large chunks—presumably because it was made of durable phosphate. Bradley got his Ph.D. under MIT professor Roger Summons, who co-authored the 2007 weird-life report. Summons backs his former student’s critique.

But how could the bacteria be using phosphate when they weren’t getting any in the lab? That was the point of the experiment, after all. It turns out the NASA scientists were feeding the bacteria salts which they freely admit were contaminated with a tiny amount of phosphate. It’s possible, the critics argue, that the bacteria eked out a living on that scarce supply. As Bradley notes, the Sargasso Sea supports plenty of microbes while containing 300 times less phosphate than was present in the lab cultures. (Source 1, Source 2)

So NASA hyped the study, but there is nothing nefarious about this incident. It’s the way science works. Researchers think they make a discovery; they write a paper; and other scientists either do experiments to replicate the work or poke holes in it. As it stands, the claimed NASA “discovery” is simply questionable and unverified. The way NASA hyped the story, however, is not good practice. And sadly, NASA has been treating climate data the same way.

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