People tend to fear what they don't understand and cannot control, and as the public has become more removed from food and understand it less, it has become easy to make them concerned about using biology to make natural improvements they would have been happy about just a few decades ago .
Because of some consumer apprehension about genetic engineering (and movies where scientifically-engineered microbes race out of control add to that), some scientists have sought to enhance control over genetically modified organisms.
Biologists at the Massachusetts Institute of Technology may have possibly found a key to help movie goers feel more secure -- specifically, a way that scientists can effectively manage a genetic modification by creating a biologically-engineered "kill switch" for GM microbes, in this case Escherichia coli.
In case you're unfamiliar with the term, a kill switch is a mechanism used in various devices (cars, computer software, smartphones, for example) to enhance safety or security, by abruptly shutting down or disabling the device. The MIT biologists have used this concept to create synthetic gene circuits Deadman and Passcode, biocontainment initiatives engineered to keep genetically modified E. coli only where they want it.
In order to survive, any microbe containing Deadman requires the addition of a small molecule that's needed to inhibit a genetic circuit, programmed to activate toxin gene expression (leading to cell death).
Cell survival, for microbes with Passcode, are dependent on a combination of factors -- for instance, the presence of inputs "A" and "B" and the absence of input "C" -- making its regulation more complex and more robust. The biologists have also suggested that Passcode may prove beneficial in offering GMO creators some level of intellectual property protection from competitors attempting to reproduce their work.
While this work is a big milestone, it still has limitations -- after four days the study's authors noted a reduced killing efficiency over time. Further analysis revealed that inactivating mutations had occurred in the toxin genes. A possible solution it this problem, the authors suggested, is to include multiple killing systems into each circuit, which could circumvent the issue and produce an even more-robust kill switch.