Other shoe drops on arsenic-eating bugs

It took no time in December for critics to cast doubt on the remarkable claim that a bacterium force-fed with arsenic incorporated some of the poison into its cells and even its DNA. As soon as the Science paper by Felisa Wolfe-Simon and colleagues was published, critics took to the airwaves and the blogosphere; there was even coverage of the coverage.

The debate over whether an organism could substitute a normally toxic substance, arsenic, for phosphorus, one of life’s six elemental building blocks — and whether Wolfe-Simon and her colleagues demonstrated an instance that substitution — continues with a formal octet of criticisms published online today in Science. And you can take a look for yourself at the whole thing, because the journal has made the papers freely available.

Some of the objections are with the science done (or not done) by the research team. The growth medium for example, in which the microbes known as strain GFAJ-1 were cultured, contained some phosphorous, one researcher notes. Others take issue with the math with which the data was analyzed.

Other scientists cast doubt on the claims not because of the nitty-gritty of the lab work, but because the report challenges a lot of known science, such as the chemical reactions that go into building a DNA molecule and how that might work — or not work —  if arsenic were swapped for phosphorous.

Science also published a response by Wolfe-Simon and her colleagues, in which they address the presented critiques.

And so this scientific version of Clue continues: Was it GFAJ-1, in the lab, with the arsenic? That still isn’t clear, but as Science notes in its introduction to the debate, science is proceeding as it should.