At their conference today, NASA scientist Felisa Wolfe Simon will announce that they have found a bacteria whose DNA is completely alien to what we know today. Instead of using phosphorus, the bacteria uses arsenic. All life on Earth is made of six components: carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur. Every being, from the smallest microorganism to the largest animal, share the same life stream. Their DNA blocks are the same.
The discovery of a life form that differs so completely from what we are used to opens up a huge swath of new territory in the search for extraterrestrial life.
The original source can be found here, in dutch or here translated by Google.