“Kill Switch” Prevents Spread of Genetically Modified Bacteria

By Kari Lydersen | January 21, 2015 12:00 pm

e coli

As genetically-modified microbes take on ever more tasks – from creating new pharmaceuticals to turning out clean fuel sources – researchers have searched for a way to biologically isolate them from their wild counterparts, so that if they were ever accidentally released, they wouldn’t be able to survive.

Now, scientists releasing two separate papers in the journal Nature think they have a solution. They unveiled two different approaches to modifying a strain of E. coli to make it dependent on artificial nutrients. In a controlled environment, such as a research lab or factory, scientists would provide that sustenance. But if the bacteria break free, they wouldn’t be able to make the compounds themselves, and would die.

No Escape

Scientists have previously used similar approaches, making GMO bacteria reliant on synthetic nutrients. But in the past, the GMO bacteria have evolved the ability to live without the synthetic nutrients. Bacteria have ejected the part of their DNA that made them reliant on the nutrients, or they figured out how to cobble together an equivalent of those nutrients from the natural world.

In separate projects, teams led by Yale molecular biologist Farren Isaacs and Harvard molecular geneticist George Church have genetically modified E. coli so that it is totally dependent on synthetic amino acids. And in both cases that need is built in to multiple parts of the bacteria’s genome – 49 times in the Harvard study – so that the likelihood that the bacteria would evolve to overcome the restriction is unlikely. And both strains showed an undetectably small escape rate – the number of E. coli able to survive without being fed the synthetic amino acid.

Out in the Open

Church and Isaacs said that their work is most likely to be used in pharmaceutical or dairy operations – making cheese, yogurt or drugs. These processes happen in closed facilities and fermenters. Unlike in the fields, bees or breezes won’t spread genetically modified material around, but there is a risk of contamination if the microscopic bacteria get onto employees’ clothing or into the air.

Meanwhile the scientists hope their research lays the groundwork for larger applications of modified bacteria in open-air settings, including for bioremediation – the use of living organisms to clean up polluted sites like landfills and oil spills. In these settings a reliance on synthetic amino acids mean the genetically modified organisms could be “contained” molecularly even if they are no longer physically contained.

Future Uses

The safety features aren’t the only appealing attribute of the modified E. coli featured in the new papers. The scientists also built in resistance to a number of viruses. That means the bacteria are safe from attack by viruses that can be devastating in food or pharmaceutical manufacturing – like when viral contamination caused a Genzyme Corp. plant to halt manufacturing in 2009, temporarily cutting off the medication supply for some patients.

Church noted that the viral resistance could be an incentive to “sweeten the offer” and encourage companies to use “safe” GMOs. The technique could also provide intellectual property protection for industrial, pharmaceutical or food companies, since they could make their own GMOs dependent on specific synthetic amino acids, and other companies would have trouble replicating those modified organisms without the “key.” Such built-in IP protection could actually encourage collaboration between different companies, Isaacs said.

“This is really motivated by anticipating the impact biotechnology will have over the next several decades, recognizing the importance of endowing these GMOs with more sophisticated functions, to have more safety measures going forward,” Isaacs told reporters. “Endowing safeguards will be important to allow the field to progress.”


 Image by micronerdbox via Flickr

CATEGORIZED UNDER: Living World, top posts
MORE ABOUT: microbes & viruses
  • http://www.mazepath.com/uncleal/qz4.htm Uncle Al

    We would like to know the exact names of all the chemicals used lest they be coincidentally incorporated into perfume, hair pomade, or skin lotion. Vast swaths of fashionable people could be infected into extinction – which is forever. This is why no human-contact product may be released until all its unknown hazards are enumerated.

    • Sterling Ericsson

      I don’t think you have the slightest clue on how DNA works. They inserted codons for making certain amino acids not found in the wild into the bacteria.

      Consuming any product with them will just result in you digesting them, like you do for all other proteins and amino acids. There is no way to incorporate them into your genome.

      Take your ignorant fear-mongering elsewhere.

      • http://www.mazepath.com/uncleal/qz4.htm Uncle Al

        You eat perfume, hair pomade, and skin lotion? The “safe” synthetic life will eat its way in from the artificially nutritive surface.

        Make that “educated and informed fear-mongering.”

      • Apostasy

        …what about the RNA codes of said bacteria, RNA codes DNA and there may be autoimmune repercussions…

  • Scott Dean

    This would also be useful for biodefense research. Scientists wanting to study anthrax and others could make this change. Then if there’s ever a “release”, the bacteria won’t grow anyway… I guess this could also protect against infection by the organism being studied?

  • Sarah Levin

    A kill switch is helpful for inadvertent release, but the tech to modify will only get more capable and cheaper.
    The real question is hoe many generations do we have, with tech getting exponentially more capable and cheaper, before a small group of people or even individual have the ability to ice nine the planet biologically or by other means?

  • John Wiley

    Y’all need to watch Jurassic Park, again. Nature will find a way…

  • RW Griswold

    They should just work on a kill-switch for the human race and then flip it. That’d be the only one really worth a damn.



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