Remote detection of buried explosive devices using bacterial whole-cell biosensors

Landmines and explosive remnants of war pose a global problem which claims many lives and casualties long after the conflict has ended. Current approaches for the location of landmines, such as metal detection, require physical presence at the minefield and therefore involve high risk to personnel; these methods are also costly, time-consuming, and have a high rate of false-positive results. The development of alternative technologies for efficient remote detection of buried explosive devices is thus urgently needed.

Most landmines contain 2,4,6-trinitrotoluene (TNT) as the main explosive component, as well as its production byproduct 2,4-dinitrotoluene (DNT). Over time, the more volatile DNT leaks out of the landmine casing and accumulates in the soil above it, serving as an excellent "signature molecule" for its presence.

Over the last few years, we have developed Escherichia coli-based microbial bioreporters for landmine detection. This sensor strains harbor fusions of gene promoters (yqjF and azoR) induced by the presence of DNT metabolites to the bioluminescence luxCDABE reporter gene cassette.

Several molecular biology and encapsulation techniques were applied to improve the sensitivity of these bioreporters, resulting in a ca. 100-fold reduction in the DNT detection threshold, as well as in a significant expansion of the temperature operation range. We have demonstrated the feasibility of using drones for airborne imaging of the bioluminescent signal emitted by the bacteria and detected real antipersonnel landmines buried in sandy soil.