Very interesting technology development...
Lab land mine detection technology gets glowing results
There’s no need to explain why land mines left over from various wars are perceived to be a problem in the world. There are plenty of pictures of maimed children to get that point across.
Technologies for getting rid of land mines and unexploded ordnance are being sought by the U.S. Department of Defense and a number of humanitarian agencies. One such technology now under study at ORNL could take advantage of the same microscopic, genetically engineered creatures that are also being used in waste management technologies.
These bacteria can be genetically engineered to glow in the presence of certain compounds—even explosives.
Bob Burlage in the Environmental Sciences Division has been working with these bacteria, Pseudomonas, for a number of years. Biotechnologies using bacteria hinge on the tiny organisms’ abilities to metabolize and break down organic compounds or transform heavy metals—if you match the right bacteria with the right meal.
“Bacteria live everywhere, and they respond to all different kinds of substances,” Burlage says.
“Luminenscence—glowing in visible light—and fluoresence—glowing in ultraviolet light—are rare in bacteria,” he says. “However, since genetic engineering began in 1975 we’ve learned that the chromosomes in bacteria can be modified to make the bacteria glow in the presence of certain chemicals. We essentially stitch together a few genes and stick them in. Then it’s no problem to produce usable quantities of them.”
Environmental microbiologists in ESD first applied the technique to environmental remediation. The bacteria, when applied to soil, would glow if the soil was contaminated with solvents like toluene or xylene.
“TNT is closely related to these solvents chemically, so it was fairly simple to modify these bacteria to fluoresce in its presence,” Burlage says.
The plan, which Burlage has described to DoD representatives and others, is to spray a solution of genetically engineered Psuedomonas over a field. Land mines and unexploded shells have a tendency, over time, to leak the explosives into the adjoining earth. When the Pseudomonas contacts the explosives and starts metabolizing it, it triggers the gene that elicits the tattletale uv glow—“Here it is.”
Although it hasn’t been tried in the field, Burlage says, “It works in the lab. Land mines leak the explosive chemicals in the parts per million range, which is just right for these bugs. Vegetation also tends to take up the chemicals, so the bacteria glowing on the vegetation could even localize the explosives more.”
Although Burlage says he’s seen mines put in some nonsensical places, they are most often placed in roadways and open fields where troops and tanks are likely to tread, and those are places that would be ideal for the bacteria.
Places they wouldn’t work, he says, would include rice paddies and other wet areas, which would disperse the bacteria, and rough jungle and snow.
Past ESD experiments have studied the effectiveness and safety of genetically engineered bacteria. In 1996 researchers at the Field Lysimeter Facility near Y-12’s west end filled large tanks with contaminated soil and treated the soil with microorganisms selected for bioremediation.
“We used simple chemicals—anthracene, naphthalene—to test the process and to make sure that everything went right. We took a lot of precautions in those experiments, but now that we are more confident on how to do the process correctly and have explored what unintentional effects might arise, further experiments should go much faster,” Burlage says.
The soil lysimeter studies, funded by the Office of Biological and Environmental Research, were the first field applications of genetically engineered microorganisms for bioremediation.
If funding agencies are sufficiently interested, the glowing bacteria might someday soon be saving innocent lives and limbs as well as cleaning up the environment.—B.C.
ornl.gov |
