When NASA announced in December 2010 that its researchers had discovered a bacteria (GFAJ-1) that used arsenic in the backbone of its DNA instead of phosphate, the implications for alternative forms of life set the media and scientific community into a frenzy. An alternative DNA structure could mean an entirely new root for an evolutionary tree that grew up alongside the phosphate-bearing DNA structure used by every organism currently known on Earth.
But controversy over the methodology led many to challenge the result, and two papers published online today (July 9) in Science convincingly show that GFAJ-1 does in fact need phosphate to grow, and cannot survive when only arsenic is present instead. Furthermore, neither study found arsenic within or bound to the DNA of the bacteria.
One of the papers' authors, Rosie Redfield from the University of British Columbia, has been blogging about her progress in testing the claim, and released a version of her team's study in February. Watch this video of her journey, recorded February 2012.