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News Tip


May 28, 2002

Highlights from the American Society for Microbiology General Meeting

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.

NSF Director Urges Microbiologists to 'Step Out' for Bioterrorism Protection

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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Microbes Show 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," he said.

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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Life Within 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, California.

"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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Photosynthetic 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 survive.

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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