Embargoed Until 2 p.m. Eastern Time
August 14, 2003
Sidebar on Strain 121 (accompanies NSF feature and news release).
Deep-Sea Searchers Retrieve Finn - and Hot Microbes Within
Edifice Rex project yields steaming, stinking life from hydrothermal vents
ARLINGTON, Va.—Quite complex was Edifice Rex, a project that deployed remotely controlled submarines to recover sulfide towers from the bottom of the Pacific Ocean.
It could have been called the "Chimney Sweepstakes" as it yielded a wealth of science, including Strain 121, a microbe that has shown the greatest tolerance to heat among all of life's known forms. It inhabits a chimney called Finn, a particularly hot "black smoker" hydrothermal vent, where it survives—and thrives—at 121 degrees Celsius (250 degrees Fahrenheit).
In 1998, part of Finn was first extracted from the sea floor 7,260 beneath the surface along with chunks of three other large sulfide chimneys. University of Washington oceanographers John Delaney and Deborah Kelley led the recovery project (funded largely by the American Museum of Natural History.)
With National Science Foundation support, they and UW oceanographer John Baross are examining the diversity of microbial life amidst the four distinctly different chimney samples of Edifice Rex.
A return to the remnants of Finn in 1999 showed new mineral and microbial growth, from which Strain 121 was isolated. As soon as it reached the ship, the sample was placed in oxygen-free media and incubated at 90 C (194 F) before it was sent to the University of Massachusetts at Amherst, where collaborating microbiologists would examine it in detail.
"One of the keys to getting these novel organisms," says Baross, "is to make sure the sample is not exposed to air and is prepared for culturing in the shortest possible time."
Life in glass culture tubes was a long way from the strain's existence in Finn.
Before the 5-foot section weighing nearly 1.5 tons was taken off its top, Finn was venting 302 C (575 F) metal-enriched fluids through a chimney rising about 30 feet off the seafloor. The walls of the collected portion varied from 2 to 17 inches thick, enclosing a conduit 6 to 10 inches wide. The piece of Finn still steamed when it reached the ship after hours of rising through the cold ocean.
The three oceanographers and graduate student Matthew Schrenk, who prepared the initial microbial samples, described the life within Finn's walls in the June 2003 issue of the journal Applied and Environmental Microbiology.
Amid the steam of the chimney chunk, one of the first things they noticed was the rotten-egg stench of hydrogen sulfide, evidence that microbes had reduced sulfur in respiration. Many of them live within the interior pores of the chimney wall, some close to the extreme heat of the venting fluids and others near the coolness of the seawater that, as it abuts the chimney's outer wall, ranges from 2 to 20 C (35 to 68 F) depending on its proximity to heat-releasing fissures.
Genetic comparisons showed that some internal microbes are kin to bacteria in other hydrothermal environments, such as those in Iceland and Yellowstone National Park.
Life on the outer chimney wall, the researchers found, is relatively cool, rich with energy, and percolating with a variety of fluids. There, microbes use oxygen for cellular respiration, tubeworms flourish, and pressure-resistant fish swim by.
Beneath it all, the earth's magma roils, fueling the creation of a microbial world on—and permeating under—the sea floor evocative of earth's early eons. Baross and others believe that learning about how life developed and survived there and then, particularly by metal-respiring organisms, could someday, or some eon, help lead to discoveries of life beyond Earth.
"Strain 121 forces us to think more seriously about metabolic pathways involving iron reduction as ancient," says Baross. It also has "significant implications for our search for life on other solar bodies and particularly differentiated iron-cored hydrothermically active bodies—even if they are just in their early history."
Principal Investigator: John Baross; professor, Department of Oceanography; (206) 543-0833, firstname.lastname@example.org
Background resources, related news available on the web:
The Endeavor Observatory at the University of Washington:
The Endeavour hosts four well-known high-temperature vent fields http://www.ocean.washington.edu/hydrothermalvents/fourfields.html
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