Synthetic biology offers the prospect of engineering microbes to fight disease or produce biofuels, but designing the necessary DNA instructions is normally an arduous task. With software written by Andrew Phillips, who heads the Biological Computation Group at Microsoft Research in Cambridge, U.K., scientists can simply select the actions they want the microbe's proteins to perform and get back a corresponding DNA sequence.

The software bridges the gap between the kind of instructions biological designers would like to use—for example, "Convert protein A into protein B"--and the complicated reality inside cells, where countless reactions are taking place in parallel. It can generate multiple DNA sequences, coding for different ways a cell might produce the same desired result; users can then simulate the different possibilities. So far, the range of actions the software can handle is limited, but the Microsoft group has already used it to design live bacteria that change color when exposed to different molecules.

Phillips's software will reduce the number of time-consuming failures in real cells, says Douglas Densmore, a computer engineer and synthetic biologist at Boston University. It will enable designers to engineer biological systems that have "a greater probability of working consistently and correctly." —Giselle Weiss