An illustration of a DNA spiral in green light on a black background with genetic code letters coming out of it a bit like in The Matrix

Coding for life

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Tinkering with life just got easier. A tool that lets you design DNA circuits using a simple symbolic language makes programming living cells as straightforward as writing code for computers.

The tool uses an existing language called Verilog, which is used by chip designers to design electronic circuits. The idea is to make programming cells more like programming a computer. “We take the same approach as for designing an electronic chip,” says Chris Voigt of Massachusetts Institute of Technology. “Every step in the process is the same – it’s just that instead of mapping the circuit to silicon, it’s mapped to DNA.”

Synthetic biology aims to make it possible to treat cells as machines that can be engineered and programmed. By altering a microbe’s native DNA, it can be made to perform a specific task, such as producing a drug or changing colour to detect a virus in blood. Off-the-shelf genetic parts that can be swapped in and out make this easier, but it is still a painstaking process.

That’s where Verilog comes in. Verilog is a symbolic language that lets you specify the function of an electronic circuit in shorthand – without having to worry about the underlying hardware – and then convert it into a detailed design automatically. Voigt’s team realised they could do the same with DNA circuits.


Their system, called Cello, takes a Verilog design and converts it into a DNA wiring diagram. This is fed to a machine that generates a strand of DNA that encodes the specified function. The DNA can then be inserted into a microbe.

Voigt and his colleagues have designed and tested 60 circuits – 45 worked perfectly the first time they were tried. One was the largest biological circuit ever built, with seven logic gates and strands of DNA 12,000 units long.

“Cello will allow synthetic biologists to concentrate more on what they want their microbes to do, and less on how to get them to do it,” says Matthew Bennett at Rice University in Houston, Texas. It also lowers the barrier for entry for those without expertise in biology, he says.

There is a long list of applications that synthetic biology has promised for several years. With programming cells easier than ever, Voigt is convinced many are just around the corner. “We’re on the cusp of seeing engineered cells as factories for therapeutic applications, such as bacteria engineered to be consumed like yogurt to produce health-promoting substances in the gut,” he says.

Overhead view of the oily surface of a beach, with a person clearing up

We might be able to engineer bacteria to clean up oil spills

Brian van der Brug/Los Angeles Times via Getty

Voigt and his colleagues are working with bacteria that live on plant roots. They are trying to give them genes that scavenge nitrogen from the atmosphere and make it into fertiliser for the plant (PNAS, The team hopes others will use Cello to build their own bacteria, and they have made the tool freely available on the internet. Oil companies could develop smart bugs that clean up oil spills, for example. “You could load a sensor that responds to oil by activating an enzyme that degrades the oil,” he says.

Christina Agapakis of Ginkgo BioWorks also thinks that the main beneficiaries will be businesses that do not necessarily have expertise in biology. “As the process to engineer organisms gets easier, cheaper and more reliable, more opportunities for new applications will open up in different industries,” she says.

For Drew Endy at Stanford University, the work is yet another demonstration of how synthetic biology is going to become commonplace. “I expect that programmers of biology will become more commonplace than programmers of electrical computers,” he says. “Not everyone has a computer or even a cellphone, but everyone has biology.”

Journal reference: Science, 10.1126/science.aac7341

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