Mutant grasses can clean up the mess left over from bombs

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Some of the RDX-neutralizing grass(Credit: University of Washington)

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RDX is a highly-toxic explosive that has been used in munitions ever since World War II. To this day, it accumulates in the soil at locations such as bombing ranges and military training grounds, where it can ultimately leech into groundwater sources. Cleaning up these contaminated sites using conventional technology can be very expensive, so scientists at the University of Washington and the University of York have developed an alternative – they've created transgenic grass that "eats" RDX.

In a previous study, some of the researchers had isolated enzymes found in a type of bacteria that evolved to use RDX's nitrogen content as a food source. As a result of the digestion process, the RDX itself was broken down into environmentally-harmless compounds. Unfortunately, however, the bacteria wouldn't survive if simply applied to the ground, as it also requires other food sources.

So, instead, the scientists set about the eight-year-long process of inserting genes from the bacteria into two perennial grass species – switchgrass (Panicum virgatum) and creeping bentgrass (Agrostis stolonifera). In lab tests, the resulting plants were shown to be capable of drawing all of the RDX up out of simulated soil within two weeks, then digesting it and breaking it down into innocuous components.

The grasses are apparently very hardy, requiring little to no care once planted. While conventional wild grass does also take up RDX, it doesn't degrade it to a great extent. This means that the chemical is still present in the plants' stems and leaves, and is released back into the environment when the grass dies.

The scientists are now planning on field trials at a military training range, followed by an application for USDA approval of the grass. According to the University of Washington, this study marks "the first reported demonstration of genetically transforming grasses to supercharge their ability to remove contamination from the environment."

A paper on the research was recently published in the Plant Biotechnology Journal.

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