The Bugs That Make Danger Glow
If you’ve heard of E. coli, you likely associate it with an illness of some sort. A type of bacteria, E. coli is usually harmless, and, in fact, is commonly found in the stomachs and intestines of healthy humans. However, there are definitely some strains of the bacteria that are worth avoiding. Per the Mayo Clinic, one such strain can “cause severe stomach cramps, bloody diarrhea and vomiting” and “young children and older adults have a greater risk of developing a life-threatening form of kidney failure.” In a typical year, E.coli infects about a quarter-million Americans and claims about 100 lives.
But E. coli has the potential to save lives, too. You just need a special type of it, some lasers, and maybe some airplanes or satellites.
Just don’t ingest it. Because it is designed to detect land mines.
In many parts of the world, we don’t have to worry about land mines. But in areas where they were used in war and similar conflicts, land mines are a persistent threat to communities. By design, land mines are munitions that you leave behind, somewhat haphazardly, in order to blow someone up at a later point. As a result, when the underlying conflict is resolved or goes dormant, the land mines are still there, putting lives at risk. And the casualty numbers are higher than you may think. the Wall Street Journal reported, “in 2015, land mines killed or injured 3,233 people in 61 countries, according to the International Campaign to Ban Landmines—and 78% of those casualties were civilians.” And the numbers aren’t necessarily going down. A more recent study found that in 2019, there were more than 5,000 land mine casualties, 80% of which were civilians and about 35% were children.
If we could reliably find land mines, the problem wouldn’t be nearly as bad — once we’re able to detect a mine’s location, disarming it isn’t typically difficult (but it is still somewhat dangerous, of course.) But that’s not an easy problem to solve. The land mines themselves — are, again, by design, intended to be hard to find. And again, that doesn’t stop when the war stops. Sending workers out with metal detectors is risky; all too often, the searcher triggers the mine by stepping on it, causing it to immediately explode. (Land mines, despite what you may have “learned” from movies, tend to detonate when you step on them, not when you step off them.) We’ve come up with all sorts of creative ways to find land mines (check out the bonus fact and the “From the Archives” story below) and while those aren’t as risky, they are also often very expensive and/or not nearly as effective. The effort to solve this problem goes on. And e.coli may be part of the solution.
The key: while land mines are very hard to see, they may be easier to find in other ways. Specifically, most land mines use TNT as their explosive chemical. Over time, the TNT breaks down and creates something called DNT. If we can detect DNT where it otherwise shouldn’t be, we can find land mines. So, as the New York Times reports, a team of researchers at the Hebrew University of Jerusalem have spent the better part of the last ten years re-engineering the bacteria, on a genetic level, to get it to eat DNT. And they’ve found success. In recent years, they’ve developed E. coli that glow green when they interact with DNT.
In the earlier stages of the research, the bioluminescence needed a push; the researchers needed to shine lasers on the E.coli to get the glow going. Further, the E.coli tended to migrate, often leaving the area where the mines were (but still producing the green light). And even when it worked, there was another problem: the light from the moon outshined that from the bacteria, But last month, per the Times, the research team was able to overcome these hurdles, at least in a laboratory setting: “these latest crops of genetically engineered bacteria are faster to react and more sensitive than bacteria in the group’s earlier field tests, [one researcher] said. And the scientists no longer need to use a laser signal to activate the glow.”
As this form of mine detection is done entirely remotely, it’s likely to save many lives (if it works). Either way, the effort to find a solution continues in creative ways.
Bonus fact: One idea that didn’t work: In 2004, Danish researchers developed a modified version of a plant (thale cress) that, per Nature, are “sensitive to nitrogen dioxide gas, which is released by underground landmines. The leaves of the plant change from green to red after three to five weeks of growth in the presence of this gas.” But unfortunately, planting the plants proved difficult and the false positive rate was too high to make for an effective solution.
From the Archives: Hero Rats: The rats that find land mines.