A year and a half ago, NASA announced that one of its scientists, Felisa Wolfe-Simon, had found a bacterium that could use arsenic instead of phosphorus in its DNA. This revelation, published in Science, had enormous implications for our understanding of what’s necessary for life—we’ve always thought phosphorus was essential and arsenic poisonous, and having that disproven might mean life could exist in environments where it had been thought impossible.
Almost immediately, though, scientists and science journalists began to pick apart this paper. DISCOVER blogger Carl Zimmer rounded up the case against in a Slate article shortly after the paper’s publication. Ever since, he’s kept track of the story’s evolution—including experiments posted by microbiologist Rosie Redfield on her blog that provided evidence against the claim—here on his blog.
All the way along, Wolfe-Simons refused to comment on Redfield’s experiments, saying she would wait until they were published by a peer-reviewed journal. Now, Redfield’s paper and one other paper finding no evidence of arsenic life have been published by Science, the same journal that published the original claim. The researchers found no evidence of arsenic being used in the bacterium’s DNA.
Autoclaves—would you cook a turkey in this?
At Popular Science is a profile of food scientists given an impossible task: make year-old mashed potatoes taste good. Food that lasts a year on the shelf needs to be sterilized, and that is a battle against extremophiles. Our most effective weapon is a very blunt one—heat. 252 degrees Fahrenheit to be exact.
Writer Paul Adams tours a food science lab and gets a taste of “retort flavor” in his sterilized mashed potatoes. The unappetizing term refers to the retort, a machine that obliterates microbes and flavor in one fell (and very hot) swoop:
The potatoes look right, once we’ve fluffed them up a bit, but the wholesome earthy taste and smell of fresh potatoes is almost gone from the dish. In its place there’s a tired, wet-paper flavor with notes of old steam pipe. This side effect of confined high-heat cooking is known in the trade as “retort flavor.” Stuckey’s theory is that it’s just underlying parts of the flavor coming through. Before food is retorted, she says, the dank base notes present in it are masked in part “by the beautiful aromatic volatile notes that we take for granted. When the retort destroys these low-molecular-weight flavors, what’s left is the ugly insides.” Read More
The only thing worse than a huge stinking pit of manure may be a huge stinking and foaming pit of manure that blows up the barn. Over the past few years, explosions have destroyed several Midwestern pig farms, killing thousands of hogs and causing millions of dollars of damage. Pig farmers and scientists have been at a loss to explain these explosions. Could the culprit be a small microbe?