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I was excited when I saw the press release that NASA was holding a press conference to “discuss an astrobiology finding that will impact the search for evidence of extraterrestrial life.”
NASA scientists announced that they found a form of microbe that apparently evolved the ability to use otherwise toxic arsenic in their biochemistry!
Although I thought it might have been discovered on Titan (or maybe Mars). The bacteria was found in Mono Lake, an extremely alkaline and salty lake in California near the Nevada border. That means it’s not really an alien, just very different.
Mono Lake has a pH of 10, about twice the saltiness of ocean water and a high concentration of arsenic. That’s going to kill lots of stuff. But not these little critters.
This constitutes the first discovery of a life form capable of replacing one of the “big six” (carbon, hydrogen, oxygen, nitrogen, sulfur and phosphorus) elements in its genetic makeup. If something can live on a diet of arsenic, a potent poison to us humans, then the standard definitions of “life as we know it” will need a bit of revision.
Study lead author Felisa Wolfe-Simon and her colleagues Professor Davies and Ariel Anbar of Arizona State University initially suggested in a paper an alternative scheme to life as we know it. The scientists’ idea was that there might be life in which arsenic and arsentates could work in place of phosphorus and phosphates.
Putting it to the test, they began to study the bacteria that live in Mono Lake.
They grew the bacteria in a laboratory on a diet of increasing levels of arsenic. To their surprise, the microbes eventually took up arsenic and incorporated it into the phosphate groups that cling to the bacteria’s DNA.
However, the research found that the bacteria thrived best in a phosphorus environment. That means the bacteria are not second type of life on Earth, but merely adapted to work with arsenic in place of phosphorus.
See also:
- Mono Lake bacteria build their DNA using arsenic (and no, this isn’t about aliens) in Not exactly Rocket Science
- NASA’s real news: bacterium on Earth that lives off arsenic! by Phil Plait in Bad Astronomy
- Subsisting on Arsenic, a Microbe May Redefine Life By Dennis Overbye in the New York Times
- Arsenic-loving bacteria may help in hunt for alien life
By Jason Palmer for the BBC
