Materials

Molecularly Engineered Bacteria Glows When It Detects Landmines

Researchers in Israel have developed a technique for mapping minefields using genetically engineered bacteria that emit a fluorescent signal when exposed to vapors from leaking, buried munitions.

Researchers in Israel have developed molecularly engineered bacteria that glow in proximity to explosives, presenting a new method for safely detecting and removing buried landmines.

Minefields often remain uncleared long after conflicts end, posing a continual threat to local residents who may never know if all planted munitions have been removed from a road or field.

The number of casualties from landmines spiked 75 percent in 2015 from the year before to 6,461, including 1,672 deaths, according to the International Campaign to Ban Landmines, a coalition of non-governmental organizations. That increase came partially as a result of armed conflicts in Libya, Syria, Ukraine, and Yemen.

Existing techniques for clearing and removing landmines can be costly, dangerous, and slow. As a result, communities recovering from armed conflict may face prolonged lack of access to mined areas, including economically important farmland or commercial roadways.

Now, scientists at Hebrew University of Jerusalem say they’ve developed a novel new system for finding and removing mines, according to results published in a paper in the journal Nature Biology.

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Central to their new method is the observation that landmines leak minuscule amounts of explosive vapors into the soil above them. These vapors accumulate and can be used as a marker: The bespoke bacteria developed by the scientists emit a fluorescent signal when they come into contact with built-up emissions from the explosives.

Once the bacteria have been spread over an area, the minefield can be scanned with lasers to determine and precisely map the location of mines, the scientists said.

Although a field test showed that their method works, the scientists cautioned that the technique requires further development.

"Several challenges need to be overcome, such as enhancing the sensitivity and stability of the sensor bacteria, improving scanning speeds to cover large areas, and making the scanning apparatus more compact so it can be used on board a light unmanned aircraft or drone," said Professor Shimshon Belkin of Hebrew University's Alexander Silberman Institute of Life Sciences, the scientist in charge of genetically engineering the bacteria.

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Historically, the top method for demining an area has been to scan the ground with a metal detector, then prod the earth to determine the source of a given signal before gingerly uncovering any mines and neutralizing them. That technique yields many false positives, however, from trash to empty bullet casings or nails, and can be thwarted by so-called minimum-metal mines constructed largely of plastic or wood.

More recently, trained dogs have been used to sniff out mines, including by the Virginia-based non-profit Marshall-Legacy Program, which has sent over 900 mine-detecting dogs to 24 countries around the world to clear thousands of acres of mined territory.

A Belgian non-governmental organization called APOPO has trained African giant pouched rats to detect landmines by getting them to associate the scent with food, and used those rats to clear hundreds of acres of mined land in Mozambique.

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