By definition and common sense. It is a new KIND of life! It would be more obvious if it was a multi-celled critter because the two versions could not cross breed. Name another "adaptation" which was described as "revising the recipe for life" and "life as we didn't know it."
from
http://www.csmonitor.com/Science/20...ke-may-reshape-hunt-for-extraterrestrial-life
Astrobiologists have been using life on Earth as a basis for hunting for potential habitats beyond the third rock from the sun. But most of the attention has focused on what researchers offhandedly refer to as "life as we know it." Until now, biological canon has held that life on Earth is mainly built around a mix of six chemical elements: hydrogen, oxygen, carbon, sulfur, nitrogen, and phosphorus.
But a small number of scientists have been pushing the idea of "life as we don't know it," says Dirk Schulze-Makuch, an astrobiologist at Washington State University in Pullman, Wash., who counts himself as one of this small band.
"There could be different building blocks used, different types of elements, or different types of energy sources," he says.
And now, along comes a terrestrial form of life that can replace phosphorus with arsenic and thrive.
Revising the 'recipe' for life
Other bacteria in effect "breathe" arsenic or use it as a food source, converting it into something less harmful. But the newly discovered bacteria incorporate it into the very fabric of their most basic biological structures.
"It's an exciting result that basically made my day," says Dr. Schulze-Makuch of the discovery, made by a team led by US Geological Survey biochemist Felisa Wolfe-Simon.
It's as though "the recipes to make the fundamental molecules of life are open for negotiation," adds James Elser, a biologist at Arizona State University who was not part of the group making the discovery.