A 'Kill Switch' for Rogue Microbes
Biologists often speak of switching genes on and off to give microbes new abilities--like producing biofuels or drugs, or gobbling up environmental toxins. For the most part, though, it's nearly impossible to turn off a gene without deleting it (which means you can't turn it on again). This limits biologists' ability to control how much of a particular protein a microbe produces. It also restricts bioengineers' ability to design new microbes.