Fluorescent bacteria enclosed in polymeric beads illuminated by a laser-based scanning system have been used by Hebrew University of Jerusalem researchers to remotely detect buried land mines.The need for safe and efficient technologies to detect unexploded ordnance is a humanitarian issue of huge global proportions. About 500,000 people around the world have been hurt by mine-inflicted injuries, and each year an additional 15,000 to 20,000 people are injured or killed by these devices. More than 100 million such devices are buried in more than 70 countries.The major technical challenge in clearing minefields is detecting the mines. The technologies used today are not much different from those used in World War II – detection teams endanger their lives by entering the minefields.Prof. Shimshon Belkin of HU’s Alexander Silberman Institute of Life Sciences reports a potential answer to this need that he has just published in the journal Nature Biotechnology. He and his team present a novel, functional system combining lasers and bacteria to remotely map the location of buried land mines and other unexploded ordnance.The system is based on the observation that all mines leak minute quantities of explosive vapors that accumulate in the soil above them and serve as markers for their presence. The researchers performed molecular engineering on live bacteria that emit a fluorescent signal when they come into contact with these vapors.This signal can be recorded and quantified from a remote location.The bacteria were encapsulated in small polymeric beads, which were scattered across the surface of a test field in which real antipersonnel land mines were buried. Using a laser-based scanning system, the test field was remotely scanned and the location of the buried mines was determined. This is apparently the first demonstration of a functional standoff land-mine detection system, Belkin said.“Our field data show that engineered biosensors may be useful in a land-mine detection system. For this to be possible, 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 Belkin, who was responsible for genetically engineering the bacterial sensors.