MIT develops "passcode" and "deadman" kill switches to keep engineered bacteria in check
A team of MIT scientists has created apair of mechanisms designed to provide a fail-safe for geneticallymodified bacteria, with the aim of stopping them from escaping andproliferating outside their intended environment. The measure wouldmake the engineered bacteria much safer.
Genetically-engineered bacteria couldone day be used for all sort of things, from monitoring toxins inwater sources to moving around the human body to diagnose and treatinfections. But in order for widespread use to be viable, it's firstessential that measures are put in place to shut down the bacteria,should they start behaving in an undesirable manner.
A team of MIT researchers has beenworking on just that, developing two new solutions that can causesynthetic bacteria to die without the continued presence of certainchemicals. The team describes the solutions as "standalonecircuits" in reference to their ability to be attached to avariety of different organisms without the need to make significantadjustments to the host's genome.
The first solution, known as the"deadman" kill switch is inspired by the breaks you would find on old trains, which required the conductor to keep constant contactwith the pedal or handle for the vehicle to keep moving.
It makes use of a switchthat's able to flip between two states, turning on one of two genes.When a certain molecule is present, the switch stays in a safe state,but once the chemical is removed, it switches, activating a secondgene that releases toxins to quickly kill the host bacteria.
The second solution, known as the"passcode" switch, works a little differently. Rather thanneeding a single chemical to be present, it requires a combination ofchemicals to survive. It contains a selection of separate componentsfor sensing small molecules. If not all of the required chemicals arepresent, then the switch kills the bug immediately.
According to the researchers, thepasscode method is more versatile, as the chemical sensing componentscan be mixed and matched, allowing scientists to create bespoke killswitches. In theory, it could even be used to protecting intellectualproperty.
"Imagine that you own a certain bug,and you don't want your competitors to use it," says lead studyauthor Clement Chan. "Then you could incorporate this device sothat only people who know the passcode can use your bug."
The findings of the research werepublished in the journal Nature Chemical Biology.