You just knew that when scientists uncovered the existence of a new life form in the universe that it was going to be in California, home of new trends and bizarre lifestyles, Hollywood imaginations and philosophic creativity. And so it has come to pass.
When the NASA astrobiology announcement scheduled for Dec. 2 made news via a Nov. 29 press release, it wasn’t long before several discerning minds figured out that the scientists participating in the press conference also had recently discovered a form of bacteria in an arsenic-filled lake in California, and that that discovery could be what was meant in the NASA press release as having an ” impact” on “the search for evidence of extraterrestrial life.”
Gizmodo and the Dutch website NOS preempted NASA’s announcement by revealing that astrobiologists had found an entirely new life form not on some meteorite or in studying the spectrometry of some exoplanet, but right here on planet Earth. Scientists had found a bacteria in Mono Lake in California which had arsenic as part of its DNA structure. It wasn’t just processing arsenic in order to live (scientists have found several organisms that process toxic elements and survive), but actually made of arsenic.
As was explained live on NASA Television by astrobiologist Felisa Wolfe-Simon, who announced the discovery for NASA Thursday, the Mono Lake microbe has arsenic in its DNA chain in lieu of phosphorus. The importance of this discovery is that phosphorus is one of the common building blocks of life, and all life as had heretofore been recognized required it in its DNA linkage. By substituting arsenic for phosphorus in its DNA, the microbe not only proved itself a different type of bacteria but also a completely different life form altogether.
Wolfe-Simon said that the discovery wasn’t about Mono Lake or arsenic, but about adaptability and life finding other ways to live. It was about “cracking open the door and finding that what we think are fixed constants of life are not.”
What finding an arsenic-based life form means for the field of astrobiology — which is the study of the origin, evolution, distribution and future of life in the universe — is that it opens up the possibilities of life on extrasolar planets and satellites of stars that not only can process and metabolize toxic (and non-toxic) elements in order to survive, but that DNA is not limited to just the basic double-helix structure of elements that produces almost all life on our own planet.
In short, if life can find ways to substitute elements in its basic building blocks, it can exist perhaps anywhere in the universe in countless, myriad forms.
Although it was theorized as possible, until NASA’s astrobiologist teams studying Mono Lake found the arsenic-based bacteria and discovered its unique DNA sequence, no life forms had ever been discovered that did not fit the basic pattern of all other life forms on Earth.
Still, the bacterium didn’t start out as arsenic-based. It, too, once had phosphorus as part of its DNA. However, when grown in cultures and fed arsenic, the bacteria strain, known as strain GFAJ-1 of the Halomonadaceae family of Gammaproteobacteria, replaced the phosphorus atoms with arsenic atoms.
It seems only fitting that such a discovery was made in a place — California — known for its imagination and innovation.
“Media Avisory,” NASA.gov
Dennis Overbye, “Subsisting on Arsenic, a Microbe May Redefine Life,” NYTimes.com