Science: Bacteria Stir Debate About 'Shadow Biosphere'

All life on Earth - from microbes to elephants and us - requires the element phosphorus as one of its six components.

But now researchers have discovered a bacterium that appears to have replaced that life-enabling phosphorus with its toxic cousin arsenic, raising new and provocative questions about the origins and nature of life.

All life as we know it contains six essential elements - carbon, oxygen, hydrogen, nitrogen, sulfur and phosphorus - that have qualities that make them seemingly ideal for their tasks. A form of phosphorus, for instance, is near perfect for building the framework for the DNA molecule, and another form is crucial to the transfer of energy within cells.

These forms of phosphorus are well suited for their job because they are especially stable in the presence of water. Arsenic is not, and that fact is one that raises concerns for some researchers familiar with the Mono Lake bugs.

For more, see Bacteria Stir Debate About 'Shadow Biosphere' by Marc Kaufman, December 2, 2010 at The Washington Post.