Researchers at Boston University have developed a highly tunable genetic “switch” that makes it possible to stop the production of a protein and restart it again, or act as a “dimmer switch” to finely tune how much protein a microbe would produce over time.

For years, researchers have been trying to develop these self-destruction mechanisms to allay concerns that genetically engineered microbes might prove impossible to eradicate once they’ve outlived their usefulness. But previous kill switches haven’t offered tight enough control to pass governmental regulatory muster because it was difficult to make it turn on in all the cells in a population at the same time.

Depending on how they’re designed, production of the RNA switches can be regulated by exposing the bacteria to a particular chemical. By controlling how much of the “on” and “off” RNAs are made, it’s also possible to regulate protein production over a continuum, not just turn it totally on or off.