Going Deep for an Unearthly Microbe

WASHINGTON, D.C.--Even though the late Carl Sagan had his eyes on deep space, his soon-to-be namesake comes from a different deep place: beneath the sea floor. Microbiologist John Baross and his team at the University of Washington, Seattle, have recovered a cunning new microbe from the scalding fluid ejected during a submarine eruption. The bug, which Baross hopes to name Saganella, appears to be as multitalented as the famous astronomer, author, and TV star.

Typical microbes live within a relatively narrow temperature range. Not the versatile Saganella, which thrives in extreme heat (50° to 90°C) and can survive relatively frigid room temperature as well, Baross reported on 19 February at the annual meeting of the American Association for the Advancement of Science, which publishes ScienceNOW. "The fact that proteins can operate across that range of temperatures is amazing," says Peter Fields of Stanford University in Palo Alto, California, who studies protein function in Antarctic fish. He believes that Saganella or another one of the rare subsurface organisms Baross has found "might be a record breaker."

The hunt for these "extremophiles"--microbes that live in extreme environments without the light, oxygen, or other ingredients supposedly essential for life--is difficult. For the past several years, Baross and his team have chased down new sea-floor eruptions, trying to reach the cauldrons in time to collect samples from the spewing fluids. Saganella, recovered from a site off the Pacific Northwest coast, was identified when graduate student Melanie Summit grew organisms from this sample under various temperature regimes in the lab. Genetic analyses indicate that Saganella is not a bacterium but an unusual member of an ancient microbial group called the archaea. It has a metabolism unlike any Baross has seen before; he is not sure what its energy source is in the wild.

Saganella's existence has heartened those pursuing Sagan's goal of finding life in outer space. The microbe is "absolutely remarkable" and is a potential model for extraterrestrial life, says Kenneth Nealson, an astrobiologist at NASA's Jet Propulsion Laboratory in Pasadena, California. "If an organism can do this on Earth," he adds, "there's no telling what it could be doing some place else."