Germ Killer

So, one of those unintended consequences of global warming is that things frozen in glacier ice are thawing out. Things like million-year-old bacteria.

But under the Taylor Glacier on the East Antarctic Ice Sheet, near a place called Blood Falls, scientists have discovered a time capsule of bacterial activity.

At chilling temperatures, with no oxygen or sunlight, these newly found microbes have survived for the past 1.5 million years using an "iron-breathing" technique, which may show how life could exist on other planets.

For years the reddish waterfall-like feature on the side of Taylor Glacier captured the attention of explorers and scientists. Earlier research indicates the color of Blood Falls is due to oxidized iron, but how the iron got to the surface of the glacier remained a mystery.

"When I saw iron, I thought, 'Wow -- that's an energy source for microbes. There has got to be microbes associated with that,' " said Jill Mikucki, lead author of a study about the strange bacteria, published this week in the journal Science.

Scientists found these isolated microorganisms use iron leached from the glacial bedrock in a series of energy-producing metabolic reactions. With the help of sulfate, the iron is transformed and eventually deposited on the surface of the glacier. Air oxidizes the iron, giving Blood Falls its redish hue.

"We don't fully understand the extremities of life: What cuts off life? What are the upper and lower temperatures limits? What are the parameters that life can handle?" said Mikucki, a geomicrobiologist at Dartmouth College in Hanover, New Hampshire.

"Microbes really defy those limits and can get into the extreme environments and tell us a little bit about the natural history of our earth."

As cool as this is, there's a plot for Michael Crichton or Dan Brown. Ancient iron-eating microbes thaw out from global warming and start killing people by eating all the iron in their blood!

OK, come to think of it, that would be a pretty damn cool book. And iron-munching microbes may actually be on other "lifeless" planets.