CORVALLIS, Ore. - Research at Oregon State University on the powerful capabilities of anaerobic microbes to digest or clean up toxic compounds has caught the attention of the United States military, which might use such microbes to tackle a $25 billion cleanup problem it faces with TNT.
In January, Morrie Craig, a professor in the OSU College of Veterinary Medicine and pioneer in the use of these unusual microbes, will assume a Senior Scientist Fellowship at Tyndall Air Force Base in Florida to bring this work closer to a working technology. The award, made to only 15 recipients in the nation, is supported by the National Research Council and U.S. Air Force Office of Scientific Research.
For Craig, this story stretches back to the mid-1980s in research to protect Oregon's cattle and horses from poisoning by tansy ragwort, a toxic plant common in the state. He discovered anaerobic microbes in the rumen of sheep that make them immune to these toxins, and developed ways to use those bacteria that can provide similar protection to other animals. He has since developed one of the nation's leading laboratories working in this field, and studied everything from the protective microbes in the bellies of Alaskan whales to new technologies that might help protect Oregon's grass seed industry.
But for the U.S. military, the problem at hand is immediate and serious. They have major military bases that are heavily contaminated with residue of the explosive trinitrotoluene, or TNT. It's an unfortunate byproduct of decades of military training, leaks, and munitions production and testing. TNT is a serious bone marrow toxin that causes aplastic anemia, liver cirrhosis and cancer, and is considered toxic at levels above 10 parts per million. Many military sites have ground contamination at levels of 700-1,000 parts per million - at 1,500 parts per million, soil residues can literally explode.
"The military would like to close some of these bases but there's just no way to do that until the land is cleaned up, and any existing technologies to do that are very difficult or expensive," Craig said. "But there are more ways to tackle a problem than an elaborate treatment plant. We think the anaerobic microbes we've discovered in sheep rumens may be able to deal with this problem effectively."
Anaerobic microbes, Craig said, are bacteria that work in the absence of oxygen. They are found throughout nature, in soils and even in the digestive system of animals. Numerous studies have confirmed that they may be a mechanism to degrade toxins - for example, protecting whales from oil and PCBs, or protecting sheep and goats from the pyrollizidine alkaloid toxins found in plants they eat.
"Nature has always had many ways to clean up the environment and break down toxins," Craig said. "We're just now finding out what some of the tricks are."
The military, Craig said, had already tried using anaerobic microbes found in soils to treat and degrade TNT, but the end result was compounds that still included toxic "amines" and were carcinogenic. They had never before considered using anaerobic microbes from the digestive systems of animals.
But preliminary research at OSU, Craig said, has already identified and applied for patents on anaerobic bacteria from sheep that may degrade TNT completely, to harmless nitrogen and amino acids. In continuing research in Florida and at OSU, Craig and other scientists will try to confirm that the end metabolites of this process are harmless to the environment. Military experts are also expected to come to OSU next summer to continue work in university laboratories.
If that is successful, Craig said, the remaining task will be to develop technologies that can be used effectively in the field to clean up the contaminated sited. And that, in turn, will draw upon almost two decades of work already done at OSU with these microbes.
In some of the earliest work, Craig's lab tackled the tansy ragwort problem, and identified just six of about 1,000 anaerobic microbe species in the stomach of sheep that can break down the toxins found in tansy. Scientists are now nearing completion of a supplement that could be given to cattle, horses or other animals to prevent pyrrolizidine toxicosis.
In another project, Craig worked with Native Americans on the North Slope of Alaska to determine how whales that were exposed to oil spills and PCBs, in addition to eating 2,000 pounds of polluted krill a day, were able to survive and thrive. Again, scientists found anaerobic microbes at work degrading the toxins.
In the late 1990s, the export of straw from Oregon's grass seed industry was threatened by concerns about toxic endophytes that are a natural component of some fescue and ryegrass varieties. Assays were quickly developed at OSU's College of Veterinary Medicine to assure foreign buyers that the level of endophytes would not be harmful to animals that ate the feed. Now, with a $1 million grant from the USDA, Craig's lab is trying to identify anaerobic microbes that could provide another mechanism of protection for animals - an advance that could be of enormous significance to the American Southeast, sometimes known as the "fescue belt," where almost $1 billion in damages is done each year to livestock that eat endophyte-contaminated grasses.
"In all of this research, we've learned more about how these anaerobic microbes work, what their protective abilities are, what types of toxins they can degrade, and how we can use them to provide solutions that work in the real world," Craig said.
"Now we're hopeful we can turn this powerful tool against the toxic TNT wastes that our military has to deal with. If we can, it should be a major step forward in the science of bioremediation."