Sheesh, people are so gullible. It was clearly planted there by alien beings to eradicate all phosphorous based life forms on Sol 3 (that's us!) Or simply some bio-weapon they cooked up in the lab to take out commie crops or something, but I like the first idea better. In any case

Destroy it before it's too late!

NASA article:

Quote: The newly discovered microbe, strain GFAJ-1, is a member of a common group of bacteria, the Gammaproteobacteria. In the laboratory, the researchers successfully grew microbes from the lake on a diet that was very lean on phosphorus, but included generous helpings of arsenic. When researchers removed the phosphorus and replaced it with arsenic the microbes continued to grow. Subsequent analyses indicated that the arsenic was being used to produce the building blocks of new GFAJ-1 cells.
The key issue the researchers investigated was when the microbe was grown on arsenic did the arsenic actually became incorporated into the organisms' vital biochemical machinery, such as DNA, proteins and the cell membranes. A variety of sophisticated laboratory techniques was used to determine where the arsenic was incorporated.

This makes it sound like the arsenic-DNA version of the microbe was a lab creation, NOT the version found in the lake. Can someone clarify?

That's the impression I got from this article:

http://scienceblogs.com/pharyngula/2010/12/its_not_an_arsenic-based_life.php

So, I guess, the bacteria was based on phosphorus like everything else, and that they simply took in some arsenic to compensate for the dropping amounts of phosphorus in their petri dish.

NASA, did you really decide to hold a press conference for this? [headshake]

My impression was that they just used the artificial increase in arsenic concentration to bring out and culture arsenic-using bacteria, and maybe to screen out less hardy critters.

I'm still waiting for silicon-based life, and I don't mean computers.

Hold the presses! This is not life-as-we-don't-know-it folks, just NASA being more desperate for major hype (understandable, given that over the past few decades they managed to pull off the impossible--make space boring). Please note that there is still some phosphorus present, and the scientists involved have admitted they do not thus far have proof that the bacteria have actually incorporated the arsenic in their DNA and critical molecules (I'll bet big money that they're still using ATP for energy transport and not some newfangled arsenic-based analog). The slower growth rate in the low phosphorus/high arsenic concentration merely implies that the bacteria have adapted to survival with fewer of the molecules in which phosphorus is a component. Most likely only a few of these have been replaced by arsenic-based analogs.