May 28, 2002
Highlights from the American Society for Microbiology
For more information on these science news and feature
story tips, contact the public information officer
listed at (703) 292-8070.
Editor: Josh Chamot
The National Science Foundation's Directorate for
Biological Sciences supports a wide array of microbiology
studies, from Bacillus anthracis genome sequencing
to the search for extremophiles. The following news
tips represent a small sample of NSF-funded projects
presented at the 102nd General Meeting
of the American Society for Microbiology held May
19 - 23 in Salt Lake City, Utah. Founded in 1899,
ASM is the oldest and largest single life science
membership organization in the world, with over 42,000
members from 25 microbiology disciplines.
Contents of this News Tip:
Urges Microbiologists to 'Step Out' for Bioterrorism
NSF Director Rita Colwell urged microbiologists to
"step up and step out" to help protect society from
bioterrorism at a speech to the American Society of
Microbiology (ASM) annual meeting this month. "We
have new and important societal responsibilities,"
Colwell said, pointing out that microbiology has always
been a dual-use science that can be used for either
benign or malevolent purposes.
"Bioterrorism is more suited than other weapons of
mass destruction to terrorist objectives," she said,
but emphasized that "the same basic science that helped
create biological weapons will also provide us with
antidotes to these scenarios." She also warned about
potential indirect threats to food and water supplies.
Colwell recommended specific actions including developing
guides, workshops, and an e-mail hotline. She also
emphasized the need to continue open scientific discourse.
"We cannot limit scientific interaction without limiting
scientific progress," she said.
Colwell is an internationally renowned microbiologist
and a former president of ASM. [Mary Hanson]
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Potential to Reduce Methane and Clean Up PCBs
Researchers have identified microbes that can detoxify
organic pollutants such as polychlorinated biphenyls
(PCBs). PCBs are listed as one of a "dirty dozen"
persistent organic pollutants that, although banned,
remain in the environment and are responsible for
a variety of health and ecological problems.
NSF-funded scientist Stephen Ragsdale of the University
of Nebraska and colleagues found that certain bacteria
"sense" the presence of such compounds as PCBs. The
organisms respond by producing a host of proteins
that enable them to turn the toxic chemicals into
electron acceptors. Many researchers consider this
process to be the first step in detoxifying PCBs and
other compounds. The researchers isolated the catalyst
for this reaction, and showed that it uses PCB-like
compounds as a substrate.
"Now we know that microbes exist that can detoxify
such compounds," said Ragsdale. "A better understanding
of how to accelerate the natural biodegradation of
such compounds would be of significant value to society,"
The same team of NSF-funded researchers has also developed
a strategy to inhibit livestock methane production.
Levels of atmospheric methane, a greenhouse gas, have
doubled in the last 200 years, a result many scientists
attribute to human and livestock activities. If the
Nebraska researchers' basic approach proves workable
in cattle, the technique could reduce methane emissions
and improve cattle feed efficiency. [Cheryl Dybas]
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Rock Salt Reveals Surprisingly Diverse Neighborhood
Researchers have extracted DNA from microorganisms
living within evaporites (minerals that crystalize
in arid environments).
Across the globe, evaporites such as halite, the ingredient
of table salt, form in tidal flats, salt ponds, dry
lakes, and other locales where water rapidly evaporates.
NSF-funded researcher John Spear of the University
of Colorado at Boulder, and colleagues, extracted
microbe DNA from colored bands in rock salt from Baja,
"We were able to characterize a diversity of life [in
the bands] using a method that is not limited by the
need to culture these organisms," said Spear. "So
an examination of what is truly there, rather than
what might grow on a dish ... is possible in the lab."
Spear and his colleagues learned that this seemingly
inhospitable environment harbors a complex, microbial
community - in effect, a whole ecosystem. The research
extends what is known about where organisms can live,
and has implications for where life is possible (such
as evaporative salts on Mars and minerals beneath
the Earth's surface).
The researchers studied large crystals of evaporative
salts weighing several pounds in high salinity, solar
evaporation ponds in North America's largest salt
works. Sunlight provides the energy for primary productivity
to this ecosystem, with salt crystals increasing light
intensity through their own reflectivity.
Scientists now use DNA, instead of complete organisms,
as markers. The methods circumvent the need to culture
microbes in a laboratory, an impossible task for some
organisms. DNA studies have opened new environments
for study, providing a new perspective on the nature
of life under various extreme conditions.
"Overall, there was a large amount of bacterial activity
in this salt which suggests a mechanism for coping
with high salt concentrations within cells," said
Spear. "This may be more widespread in the bacterial
domain than we had thought." [Cheryl Dybas]
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Bacteria Discovered in Yellowstone Hot Springs
Researchers have found green sulfur bacteria in two
of Yellowstone National Park's hot springs. The bacteria
thrive at a temperature of about 43°-52° C (110°-125°
F), growing in the complete absence of air - requiring
only light, hydrogen sulfide and carbon dioxide to
NSF-funded scientist Donna Bedard of the Rensselaer
Polytechnic Institute in Troy, New York and colleagues
found that the bacteria lead a life similar to those
that created photosynthesis roughly 3.5 billion years
ago. The more complex, more familiar, photosynthesis
that occurs in green plants ultimately evolved from
the simpler photosynthetic process that first appeared
in organisms like the green sulfur bacteria.
Before the discovery in Yellowstone, this type of photosynthetic
bacteria had been found only in New Zealand, and only
three strains had been isolated. Bedard and her colleagues
discovered the novel bacteria in the Gibbon Hills
and Mud Volcano regions of Yellowstone, where they
searched for hot springs with the appropriate conditions
(warm, mildly acidic, and sulfide rich). DNA sequences
from the bacteria indicate that there are multiple
strains of green sulfur bacteria living in at least
two hot springs in Yellowstone.
"The discovery will enable us to learn more about the
lifestyle of microorganisms that live in the harsh
climates of early Earth: warm aquatic environments
in an atmosphere devoid of oxygen but filled with
methane, carbon dioxide, ammonia and hydrogen sulfide,"
said Bedard. "They may also have practical applications
in the treatment of sulfur-polluted waste streams,
and be important for the development of novel technologies
to generate energy because they can produce hydrogen
gas." [Cheryl Dybas]
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