Note: Serious concerns have been raised about the conclusions of this study. I’ve written a summary of the backlash in a separate post.
Arsenic isn’t exactly something you want to eat. It has a deserved reputation as a powerful poison. It has been used as a murder weapon and it contaminates the drinking water of millions of people. It’s about as antagonistic to life as a chemical can get. But in California’s Mono Lake, Felisa Wolfe-Simon has discovered bacteria that not only shrug off arsenic’s toxic effects, but positively thrive on it. They can even incorporate the poisonous element into their proteins and DNA, using it in place of phosphorus.
Out of the hundred-plus elements in existence, life is mostly made up of just six: carbon, hydrogen, oxygen, nitrogen, sulphur and phosphorus. This elite clique is meant to be irreplaceable. But the Mono Lake bacteria may have broken their dependence on one of the group – phosphorus – by swapping it for arsenic. If that’s right, they would be the only known living things to do this.