Arsenic and old lake :-)
Scientists have discovered, in California’s Mono Lake (apparently at least 760,000 years old; photo above; others here: 1, 2, 3, 4, 5, 6) a form of bacteria that can thrive on arsenic (an element that is generally considered to be toxic) and substitute arsenic for phosphorus in its DNA!
Pretty good trick, huh? 
You knew that a former microbiologist (like I am) would have to “bite” on THIS one!
The bacterium, strain GFAJ-1 of the Halmonadaceae family of Gammaproteobacteria, was isolated from sediments in Mono Lake, an alkaline (with a pH of 10) and hypersaline lake (which is “too salty” for fish, but the Mono Lake brine shrimp, Artemia monica, a tiny species that is found nowhere else on earth, loves it!) and which contains high levels of arsenic! Scientists were able to grow the bacterium with only low levels of the element phosphorus, which forms much of the “backbone” of DNA! NASA scientist Felisa Wolfe-Simon said that the bacterium not only grew but also substituted the arsenic for phosphorus normally found in DNA.
“How different can life be?” asked Arizona State University researcher Ariel Anbar in a news release
Well, those of us who live here know that life can be pretty different in California!
Needless to say, the discovery EXPANDS the definition of elements that can sustain life and likewise expands the possible environments (terrestrial and extraterrestrial) that could sustain life.
Importantly, the discovery re-emphasizes just how little we really know.
-Bill at
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