----- Original Message -----
Sent: Tuesday, September 09, 2003 6:25
AM
Subject: [compost_tea] Deep Under the
Sea-New finds in Microbiology
Thought some might be interested in this article from NY
Times. Tim
September 9, 2003 Deep Under the Sea, Boiling
Founts of Life Itself By WILLIAM J. BROAD
What started as a
hunch is now illuminating the origins of life.
A few years back, Dr.
Derek R. Lovley and colleagues at the University of Massachusetts found
that a few kinds of bacteria used iron as a means of respiration (just as
humans use oxygen to burn food) and that a surprising but common byproduct
of this form of microbial breathing was magnetite, a hard black magnetic
mineral.
The scientists wondered if hidden swarms of microbes might
account for the vast deposits of magnetite that dot the earth and
sea.
So they turned to one of the strangest, most ancient of
environments — the deep sea's volcanic gashes, where mineral-rich waters
hot enough to melt lead gush forth to nourish riots of life ranging from
microbes to eight-foot-long tube worms. From the deep Pacific and other
sites, the scientists obtained many samples of hot fluids.
To their
surprise, they found that all the heat-loving microbes, known
as hyperthermophiles, could breathe iron and make magnetite. Not only that,
but one type broke the high-temperature record, thriving at an astonishing
250 degrees — far above the boiling temperatures usually associated
with sterilization. The alien organism was judged to be among the most
primitive forms of life ever discovered.
"It was a crapshoot," Dr.
Lovley said of the hunt. "The surprising thing was that all the
hyperthermophiles turned out to use iron."
That discovery, he and other
scientists say, suggests that all life on earth may have originated from a
microbe that breathed iron — potentially a key insight to learning about
the chemical pathways that eons ago led to the dawn of biologic
evolution.
In the quarter century since the discovery of the
hydrothermal ("hot water") vents, scientists have found a world's worth of
life: hundreds of unfamiliar species, new genera, new families and whole
new orders. Together, they constitute major gains in measures of global
biologic diversity, and they have gained a name: the dark
biosphere.
Today in Los Angeles, filmmakers, drawing on waves of such
excitement, are releasing a big-screen movie that celebrates the
vents.
"It has been a passion for a number of us," said Dr. Richard A.
Lutz, a Rutgers biologist who aided the film and the original discovery.
"We've been enamored by the vents ever since."
The ocean floor was
once thought to be a wasteland that possessed no light, no heat, no plants
and very little life, if any.
That image shattered in 1977, when
oceanographers working deep in the Pacific found bizarre ecosystems lush
with clams, mussels and long tube worms.
When brought to the
surface, the creatures smelled of rotten eggs, a sign of sulfur. It turned
out that the ecosystem's main energy source was sulfur compounds emitted by
the hot vents, in particular hydrogen sulfide. The primary producers (like
plants on land) were tiny microbes thriving on volcanic heats and chemical
energies rising from the earth's interior.
The dark ecosystems forced
scientists to conclude that not all life on earth depends on the sun's
energy or on photosynthesis.
As similar communities were found in the
deep, intrigued scientists theorized that the vents were perhaps windows on
a deep microbial world, a hidden biosphere extending for miles into the
earth's crust, with a total mass rivaling or exceeding that of all surface
life. Even stranger, they suggested that life on earth might have begun in
such realms, nurtured by a steady diet of hot chemicals.
Since those
frenetic early days, ocean scientists have found not only scores of such
deep oases but strong evidence that they do in fact represent the tip of a
very old, very large ecosystem. Recent papers report censuses of the
tribe's most fundamental members — microbes.
"We find bugs pretty much
everywhere we look," said Dr. John A. Baross, a biologist at the University
of Washington who studies hyperthermophiles and used a deep-sea robot to
retrieve the water sample containing superhot organism.
Much of the
exploration focuses on the West Coast — offshore from California to Canada
— because a long volcanic gash fairly close to shore makes scientific
visits there relatively easy. The National Science Foundation has financed
much of the work, along with the National Oceanic and
Atmospheric Administration.
Five years ago, in a first, scientists
off Vancouver Island raised from the depths parts of four rocky vent
chimneys, two dead and two live ones spewing hot smoke rich in chemicals
and microbes. Dark and rough, they were up to seven feet tall and weighed
up to two tons, the hot ones teeming with worms, sea spiders and
limpets.
In the June issue of Applied and Environmental Microbiology,
the scientists, including Dr. Baross as well as Matthew O. Schrenk, Dr.
Deborah S. Kelley and Dr. John R. Delaney, all of the University of
Washington, reported the dissection of a chimney that had been venting
fluids of 575 degrees. Despite the temperature, it was riddled with signs
of life.
"Direct microscopic observation indicated that micro-organisms
were attached to mineral surfaces throughout the structure," they wrote,
adding that the discovery suggested that further research would expand "the
known upper temperature limits of life."
A different census focused
on a volcanic gash off Oregon that erupted in 1998, 1999 and 2000, the
outbursts monitored by undersea microphones. Each time, the scientists took
samples more than a mile down. Such eruptions are windfalls for biologists
since not only molten rock but large volumes of hot, microbe-rich water
spew forth. The huge clouds of life — thought to originate deep within the
cracks, fissures and pores of the rocky seabed — allow experts to glimpse a
normally invisible world.
Julie A. Huber, Dr. David A. Butterfield and
Dr. Baross, all of the University of Washington, reported their census of
microbes up to third of a mile down in the April issue of Microbiology
Ecology, published by the Federation of European Microbiological
Societies.
They said that even at the greatest depths, under crushing
pressures, the rocky seabed was composed of about 30 percent open pores,
giving it plenty of living space for diminutive organisms.
The
scientists zeroed in on the raw genetic material of the collected microbes,
thus finding more than methods of culturing them with special foods could
ever discern. (The science of what hyperthermophiles like to eat and
breathe is still young.)
To the scientists' surprise, they found a huge
diversity of organisms whose composition swung wildly over time. The 1998
eruption produced 35 species of bacteria, compared with 37 and 57 from 1999
and 2000.
But the numbers of archaea — ancient organisms often found in
hot places like those thought to exist on the ancient earth — went in the
opposite direction, declining from 63 to 60 to 52, according to paper by
the same authors in the April 2002 issue of Applied and Environmental
Microbiology.
The reason behind the swings is still murky. "We're
straining to understand better how these systems work," Dr. Baross said in
an interview. "It's a very complicated puzzle. Until a couple of years ago,
we had no pieces. Now, to some extent, we're starting to put the puzzle
together."
Three years ago, scientists told of finding fossil microbes
that lived near vents formed 3.2 billion years ago, confirming that
hyperthermophiles were among earth's earliest inhabitants. That discovery
has quickened the search for descendants of primordial vent
life.
Biologists say the recent discovery of the extremely
high-temperature, iron-breathing organism by the University of
Massachusetts scientists, who included Dr. Kazem Kashefi, suggests that the
dark biosphere runs deeper and hotter than previously documented. And
sulfur, they add, may turn out to play a smaller role than previously
believed. The iron finding is reported in the Aug. 15 issue of
Science.
Dr. Lovley and Dr. Kashefi are betting that the common metal
(the earth's most abundant element) will prove important. Its
transformations, they wrote, "may have been the first form of microbial
respiration as life evolved on a hot, early earth."
Copyright
2003 The New York Times Company | Home | Privacy Policy | Search
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