The MIT Technology Review is reporting on a group of Scottish researchers who’ve designed a form of E. coli to detect arsenic in drinking water:
The Edinburgh group found that the bacterium E. coli possesses two seemingly unrelated genetic sequences that, in combination, form an effective arsenic-detection device. First, E. coli possesses a natural arsenic detoxification system that is switched on only in the presence of arsenic. The bacterium also naturally breaks down lactose to produce acid. The researchers isolated the arsenic-switch gene and attached it to the first gene involved in the breakdown of lactose.
They hypothesized that when arsenic comes in contact with this modified E. coli, it will activate the arsenic switch, whose gene in turn will activate the breakdown of lactic acid. French says that a simple color litmus test can then pick up the resulting change in pH levels, also indicating the presence of arsenic. “It works under laboratory conditions, but we haven’t tested it with real water samples,” he says.
One drawback is the test currently takes five hours to change colors. But make no mistake — this is a strong proof-of-principle for synthetic biology applications in the real world.
Flashback: Arsenic and the Madness of King George