MIT researchers have engineered bacteria to work like transistors, creating living "circuit boards" that can be printed onto growth material inside a Petri dish.
In conventional electronics, transistors act as switches that control whether electrical current can pass through a circuit. In the MIT system, engineered bacterial cells perform a similar role by regulating the movement of small signaling molecules. Those molecules then carry information to other components in the biological circuit.
The researchers created two types of bacterial transistors and three additional bacterial strains that act as relays between them. Together, these five strains provide a modular set of components that can be arranged to build nearly any kind of circuit. In the new study, the team demonstrated circuits capable of adding two or three inputs and directing a single input toward a selected destination.
"We've built some initial computer architecture components that are commonly used, but any operation can be built with these five strains," says Hamid Doosthosseini PhD '25, an MIT postdoc and the lead author of the new study.
One potential use is to place these living circuits on plant leaves or roots. There, the bacteria could process information about environmental conditions, helping plants detect and respond to stresses such as drought or pest attacks.
