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Genetically Engineered Plants Eat Toxic Waste


Researchers have genetically engineered plants with an eye toward neutralizing toxic waste on military bases and mopping up industrial chemicals near manufacturing sites. As VOA's Jessica Berman reports, the scientists are using the plants as a natural solution to serious environmental hazards.

It's called phyto-remediation, the use of plants to rid soil of toxic pollutants that threaten the drinking water of communities located near military or industrial sites.

In two papers published in Proceedings of the National Academy of Sciences, researchers describe how they have genetically engineered plants to take up the toxic, chemical by products of military and manufacturing operations.

One study targets a chemical called RDX, which is a contaminant found on military training ranges.

Liz Rylott of the University of York in Great Britain is a plant molecular biologist and the lead author of that study.

Rylott says RDX is a key component of TNT that accumulates as a detonation residue or when weapons are left sitting around.

Rylott says RDX does not degrade naturally, instead seeping into the soil and threatening water supplies.

"What we did is we went to the soil on the training ranges and we collected samples and we found bacteria that were able to degrade RDX themselves and use it as their food supply," said Liz Rylott. "But they don't clean it up themselves on the training ranges because they don't a good critical mass to really deal with the problem."

Rylott and colleagues identified the gene in the bacteria, called aribidopsis, which neutralizes RDX and engineered it so that enough aribidopsis can be mass produced to degrade the military toxin.

"The next step which we are currently doing now is to transfer this technology into grass species, perennial grasses, that we can grow on the military training ranges," she said.

A likely test site for the neutralizing bacteria is the Massachusetts Military Reservation in Cape Cod where the use of RDX has been restricted because of its threat to drinking water.

But observers say there are potentially serious problems to be worked out with phyto-remediation efforts such as RDX technology.

Terry Hazen is head of the Center for Environmental Technology at the US Department of Energy's Lawrence Livermore Laboratory in Berekley, California.

Hazen says something has to be done with the plants after they take up toxins from the soil.

"The plant is exposed to then bugs and bunnies and literally deer or whatever and/or then people and can literally be carried away or disseminated," said Terry Hazen.

In the second paper published in PNAS, researchers at the University of Washington described the use of poplar trees to siphon off chemicals in the soil used in, among other things, dry cleaning and petroleum products.

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