martes, 21 de septiembre de 2010
Arctic Microbes Sleep for 100 Million Years
Heat-loving bugs at the bottom of the Arctic Ocean may spend a hundred million years waiting for things to warm up, according to a new study.
Casey Hubert of Newcastle University in the United Kingdom and a team of researchers analyzed bacteria populations in sediment samples from the arctic sea floor. As they surmised, microbes became very productive as samples were heated to a balmy to 20 degrees Celsius (68 degrees Fahrenheit). Then something surprising happened: as the samples were heated further, bacterial activity spiked again at 55 degrees C (131 degrees F).
In other words, the bugs were flourishing in temperatures far beyond anything they'd see in the frigid confines of the Arctic Ocean.
So what's going on? Hubert thinks the bacteria are in fact thermophilic organisms that typically thrive deep in the ocean crust, where Earth's heat provides energy for them to reproduce. Water that rises out of hydrothermal vents could deposit the bugs on the cold sea floor, where they go dormant and wait. And wait some more. From New Scientist:
Hubert's theory...proposes that rising currents thrust some cells out of their deep hot niche and into the cold Arctic seawater, where they lie dormant.
Sediment buries them until the temperature rises enough for them to germinate – but this could take up to a 100 million years. "It's like there's a seed bank in the sediment of diverse thermophiles," says Hubert. These spores can remain viable for millions of years, he says, and so might wait-out the burial period and long migration down into the warmer subsurface.
It's a crazy thought -- that microbes ejected from their habitat would just hang out for a good chunk of the planet's history until they made it back home. Bacteria are famously hardy creatures, able to survive in outer space, or for millennia locked in giant salt deposits, so it's not outside the realm of possibility. But it certainly boggles the mind.