Landmines left behind by past conflicts, or still fighting, pose a quiet threat to millions of people around the world. With the help of bacteria that glow in their presence, these hidden dangers may one day be discovered and safely removed or destroyed.
Researchers at the Hebrew University of Jerusalem have spent 10 years developing live mine sensors using E. coli. In recent studies, they describe their latest advances. By using genetic engineering, each bacterium can be transformed into a “miniature firefly” in the presence of explosive-related chemicals, said Simshon Belkin, a microbiologist at the Hebrew University of Jerusalem, who leads the study. It was.
In 2019, more than 5,500 people were killed or injured by land mines and the remains of explosive warfare, 80% of whom were civilians. International Campaign to Ban Landmines.. Antipersonnel mines are especially dangerous because they are only a few inches in diameter and can be easily hidden. Estimates vary by the number of buried mines in the world, but amount to 110 million.
Many strategies have been attempted to locate land mines, including the use of metal detectors and training of detector animals. Award-winning rat Helped to find 71 mines Before it retires.. Each method balances profits with risks and costs.
The idea of rewiring bacteria to detect landmines began with Robert Burlage and then at Oak Ridge National Laboratory in Tennessee. In the mid-1990s, Dr. Barrage worked on brightening bacteria in response to organic waste and mercury. Looking for a new application for this technology, he came up with the idea of targeting mine chemicals.
Dr. Barrage conducted several small field tests, but was unable to secure more funding and proceeded. “My tragic story,” said Dr. Barrage, now a professor at Concordia University in Wisconsin.
Dr. Barrage’s work has inspired Israeli researchers, who say they hope their efforts to advance the technology will work.
Bacteria are cheap and consumable and can spread to many grounds. And they report relatively quickly — within hours, or up to a day, they either glow or don’t glow.
In studies published in the last year Current research in biotechnology And Microbial biotechnology, Dr. Belkin and his team explain that they are tinkering with two important elements of the genetic code of E. coli. A piece of DNA called a “promoter” that functions as an on / off switch for a gene, and a “reporter” that promotes a luminescence reaction. To produce this effect, researchers borrowed genes from marine bacteria that naturally emit light in the ocean.
Scientists have tuned the bacteria to a chemical called 2,4-dinitrotoluene (DNT). It is a volatile by-product of trinitrotoluene (TNT). Over time, DNT vapor penetrates the soil around the mines, allowing bacteria to sniff it out.
Rather than roaming freely, the bacteria are immobilized on small gelatinous beads that nourish the bacteria during work. Each bead, about 1 to 3 millimeters in diameter, contains about 150,000 active cells.
These latest crops of genetically engineered bacteria are faster and more sensitive than the group of bacteria. Previous field testSaid Dr. Belkin. And scientists no longer need to use laser signals to activate glows.
One of the key challenges the group is trying to overcome is to safely find bioluminescent bacteria in real minefields. When they detect a land mine, their brilliance is so weak that light from the moon, stars, or nearby cities can drown it out.
To address this issue, Hebrew University bioengineer Aharon J. Agranat and other researchers said in April. Journal biosensors and bioelectronics That they have developed a device that protects bacteria and detects their brilliance. The sensor system can report the results to a nearby computer, but has not been tested outside of the laboratory settings.
Researchers recently conducted field tests in Israel and worked with the Israeli army and Israeli defense companies to ensure the safety of the experiment. The results of these tests have not been published, but Dr. Belkin called them “generally very successful.”
In the future, the team hopes to use drones to deploy bacterial sensors on minefields, eliminating the need for humans to approach them.
Dr. Barrage encountered another problem decades ago that the Hebrew University group is still working on. It’s temperature. Israeli bacterial sensors only work from about 59 to 99 degrees Fahrenheit. That is, researchers need to understand how to adapt their systems to more scorching desert conditions.
Israeli bioengineers also acknowledge that bacterial sensors can be used for both humanitarian and military purposes. DARPA, the Defense Advanced Research Projects Agency, funded their research.
Nevertheless, bacterial sensors for landmines show that the field of synthetic biology has “grown dramatically in the last few decades,” said SentiBiosciences co-founder and biology engineer at the Massachusetts Institute of Technology. Dr. Timothy K. Lu said. Technologies that were not involved in these studies.
“It’s very exciting. I’m hoping that this kind of application will start moving from the lab to the real world,” says Dr. Lu.
Shining bacteria may one day protect people from land mines
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