A Novel Strategy in the War on Waste
by Charlotte Overby, Illumination, Spring 2002
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The DOE is funding basic microbial research, such as Wall's work with D. desulfuricans, to find alternatives to traditional methods of remediation. These include incinerating toxic wastes, which results in airborne pollution, or placing them in landfills, where they can leach into groundwater. Another common method is referred to as pump and treat. Contaminants are flushed from underground using water or other liquids. However, subsurface sediment and rocks hinder the flow and soils and clay often absorb the contaminants. Extraction can take decades.

"Most of the sites are a kind of witch's brew of all sorts of contaminants," says Dr. Dan Drell, biomolecular science and engineering element manager in the DOE's Office of Biological and Environmental Research. "We're not unrealistic about the promise of microorganisms' abilities to deal with some of the pollutants, but we do think it's essential to pursue fundamental research into these organisms that have undergone 3.7 billion years or so of evolution." Wall's 20-year research career and expertise made her a logical recipient for a DOE grant, says Drell, who is her project manager.

"Microbes are fastidious in terms of what conditions affect them. It can be pH, amount of oxygen, or other microbes that are present," says Drell. "Judy is a wonderful scientist because she is extremely skilled at parsing out those different factors that contribute to the local ecology, if you will, of her microbe." Wall has also, says Drell, contributed a great deal to microbiology as a whole by serving as editor of the field's premier journal, Applied and Environmental Microbiology.

Microbiologists are quick to say that there will be no stirring up of magical microbial stews to pour all over hazardous waste sites. Most field studies with toxic metals are years away. "Successes with microbes working on organic pollutants was an impetus for then turning research attention to toxic metals," says Wall. "Organic contaminants offer the advantage of being degradable. You can go all the way to CO2 and be rid of them altogether. But metals--you can't eat them and do away with them--a metal is a metal is a metal. But one of the things you can do is change its oxidation stages so that you can change the way it complexes in the environment or with the compounds that are available to it."

Future success lies in part in figuring out which proteins in D. desulfuricans are the critical uranium-reducing proteins. "Perhaps we can get the gene out, understand how it is regulated and modify it." Wall continues, "Then what might augment it? How do you apply the microbial process on a practical basis?"

There is a great deal of scientific interest--as well as some trepidation--about the promise genetically engineered microorganisms may hold for treating especially hazardous wastes. Genetically modified crops and animals tend to grab the headlines, but a number of individual researchers and organizations insist there is a need for greater regulation and debate about the use of their genetically modified microscopic cousins, too. Their concerns are varied. For example, little is known about how genetically modified microorganisms might spread, affecting natural biological cycles, evolutionary processes and biodiversity. Will the release of engineered microbes into the environment create new allergens? If so, what are the long-term health effects from exposure to them?

A researcher at Oregon State University discovered that once a bacterium that had been genetically modified to make ethanol was back in soil, it killed wheat seedlings. Wide distribution of such an organism could have devastating effects on agriculture.

"It's a socially and economically difficult situation, too, because you're talking about contaminated sites where people live," says Drell, who is also in charge of the DOE's Bioremediation and its Societal Implications and Concerns (BASIC) program, which exists to address questions and public debate about genetically modified organisms and other issues regarding bioremediation. "Once you put a microbe out in the environment, you lose the ability to call it back," he says.

The public is not ready to have recombinant microorganisms grown in large batches and put back into the environment, says Wall, and perhaps rightly so. "But what we could do is perhaps predict what will happen in the environment if we know something about the chemistry of the environment and the organism present. That's what our work is about."