This post is also available in: heעברית (Hebrew)

Increasing soldier’s survivability is a major concern for armed forces. The US Defense Department has been making progress on genetically engineered microorganisms that can detect and even repel a host of invisible threats to US troops, from radiation to poison gas, from environmental toxins to mosquitos.

For example, sensors and defenses can be infused into soldiers’ uniforms without ever injecting a foreign substance into their bodies, by using engineered microbes which are tiny and need no electricity, instead of bulky battery-powered sensors. 

Another challenge faced by US troops deployed around the world is mosquitos. The Army’s insect-repellent program includes technologies for soaking uniforms in toxic DEET. 

According to Battelle scientist and DARPA alumnus Justin Sanchez, it is possible to use  the gene-editing enzyme CRISPR-Cas9 to alter a microorganism’s DNA so it exudes a volatile substance — i.e. an odor — that repels insects. It is possible to infuse a soldier’s uniform with that microbe instead of an artificial chemical.

The US Navy is looking at similar biotech protections, said Sarah Glaven, a Naval Research Lab biologist. Humans naturally produce the chemical melanin to protect their skin against solar radiation, and scientists have figured out ways to produce it artificially. But the best way to produce melanin, without messing with human bodies or industrial chemistry, is to get bacteria to make it, then infuse it into uniforms.

Microorganisms can also act as living sensors to protect Navy divers, Glaven told While the Navy’s increasingly investing in unmanned mini-subs, divers remain the best way to defuse floating mines or check ships’ hulls for the kind of limpet mines used by Iran in the recent tanker attacks. 

ut putting a human underwater is inherently dangerous, and there’s currently no way to quickly test the water for toxins that might harm the diver — a real concern in polluted Third World waters or war zones where damaged ships leak all sorts of poisonous substances.

So they are developing microorganisms that are sensitive to specific toxins and will rapidly react to their presence to warn the divers. If you engineer the bacteria to exude a conductive substance when they detect the threat, something that transmits electricity, that can close a circuit and trigger a warning light on a small, wearable sensor.

This biological solution could replace bulky sensors currently worn on divers’ suits or even test the water before any human got in it.

Microbes are effectively natural sensors, far more compact and precise than man-made instruments that often generate false positives. 

You could even surround a military bases with genetically engineered plants, that react to environmental contaminants — say, a chemical weapon — in ways soldiers could notice before they strayed into a danger zone.

The sentry plants, of course, would live off water, sunlight, and dirt, none of which has to be brought to them by convoys of supply trucks. The goal is a sensor that not only requires no batteries but sustains itself from the nutrients in its environment, with no need for logistical support, and can even regenerate itself when damaged.