First there was the wild speculation about the discovery of extraterrestrial life. Then came widespread, sometimes misguided, coverage of the real news: discovery of a bacterium than can substitute arsenic for phosphorus, one six elements considered essential for life (which may, perhaps, expand the scope of humanity’s search for life beyond this planet).

Now comes the third installment in the commotion-filled saga: widespread criticism of the paper detailing the discovery, published last Thursday in Science, and an apparent snubbing of the media by the paper’s authors and NASA (which helped fund the research), who rebuffed journalists’ requests for a response to the criticism.

The latest round of controversy began on Saturday when University of British Columbia microbiologist Rosie Redfield penned a scathing critique of the paper, “A Bacterium That Can Grow by Using Arsenic Instead of Phosphorous,” on her personal blog. One of the key findings of the study was that the bacterium, discovered in Mono Lake and cultured in a lab, incorporated arsenic into its DNA. But Redfield argued that the paper didn’t “present ANY convincing evidence” that that actually happened (for DNA or any of the bacterium’s other biological molecules).

Redfield criticized a number of the research team’s methodologies. For instance, she argued that scientists did not correctly purify the DNA in order to remove any arsenic that might simply have been sticking to the DNA. She also said that the bacterium was grown in an environment with enough phosphorous (even at such a depleted level) to account for the observed bacterial growth, which was attributed to arsenic. The “bottom line,” Redfield wrote, was “lots of flim-flam, but very little reliable information.”

Redfield’s post immediately caught on in the blogosphere. Science reporter David Dobbs highlighted it on his Wired Science blog, Neuron Culture, observing that although he wasn’t familiar with Redfield, “her opinion was quickly seconded in the blog’s comments and on Twitter by many sharp scientists.”

Things got even more interesting when NASA rebuffed the Canadian Broadcasting Corporation after it sought comment on Redfield’s critique. According to its article, published Monday evening:

When NASA spokesman Dwayne Brown was asked about public criticisms of the paper in the blogosphere, he noted that the article was peer-reviewed and published in one of the most prestigious scientific journals. He added that [Felisa] Wolfe-Simon [the paper’s lead author] will not be responding to individual criticisms, as the agency doesn’t feel it is appropriate to debate the science using the media and bloggers. Instead, it believes that should be done in scientific publications.

“Any discourse will have to be peer-reviewed in the same manner as our paper was, and go through a vetting process so that all discussion is properly moderated,” wrote Felisa Wolfe-Simon of the NASA Astrobiology Institute. “The items you are presenting do not represent the proper way to engage in a scientific discourse and we will not respond in this manner.”

[Update, Dec. 8: Despite her initial reluctance to respond to the criticism, Wolfe-Simon posted the following comment on her blog on Wednesday:

Curtis Brainard is the editor of The Observatory, CJR's online critique of science and environment reporting. Follow him on Twitter @cbrainard.