Shadow Biosphere - real or NASA hype?

So the discovery that the bacteria in mono lake have switched from thriving solely on phosphorus to some arsenic have brought debate of the shadow biosphere ( [link to www.washingtonpost.com]

Others are trying to shut this down quickly - says NASA ran a "hype machine" (Update: John Sutherland from the MRC Laboratory of Molecular Biology at Cambridge adds to the skepticism. He notes that arsenic-based compounds are “not sufficiently stable in water for the phosphorus to arsenic substitution implied in this paper to be functional” and the arsenic-phosphorus swap hasn’t been demonstrated by the study’s experiments in a “chemically rigorous manner”. For Sutherland, the acid test would be actually synthesising a double helix of arsenic-based DNA and characterising its structure in detail. You could then use the data from that analysis “as a reference point” to examine the DNA from the Lake Mono bacteria. “This has not been done,” he notes, and even if it were, the existing evidence suggests that the molecule would break apart when it’s exposed to water....

[link to dx.doi.org]