Scientists have engineered bacteria that can work like electronic transistors, opening the door to living circuits that could one day help plants detect drought, pests, and other environmental threats.
Imagine a circuit board that is not made of silicon, wires, and metal, but from living bacteria. Researchers at the Massachusetts Institute of Technology (MIT) are working to make this idea a reality.
The team has engineered bacteria that can behave like transistors, the basic switching components used in electronic devices. In an electronic circuit, a transistor controls the flow of electrical current. In these biological circuits, bacterial transistors control the flow of chemical signals between living cells.
This approach could allow scientists to build biological "circuit boards" by arranging bacterial colonies on a growth surface.
Turning Bacteria Into Transistors
The researchers used a bacterium called Pantoea agglomerans, which commonly grows on surfaces, including plants.
They designed two different types of bacterial transistors. Both can respond to chemical signals and produce another chemical signal that can be passed to nearby bacterial cells.
One molecule, called OC-6, acts like a switch. Depending on whether OC-6 is present, a transistor can be turned on or off.
The bacterial transistors also detect another molecule called OC-12. Depending on the combination of these signals, the cells produce an output molecule called OHC-14.
This chemical output can then be passed to another group of bacteria.
In this way, the researchers created biological components that work somewhat like electronic switches.
Bacteria Can "Wire" Themselves Together
A major part of the research involved creating three additional strains of Pantoea agglomerans. These bacteria act as relays.
Their job is to receive the OHC-14 signal and convert it into another signal that can be understood by the next transistor.
This allows researchers to connect several bacterial components together.
Instead of using physical wires like those found in an electronic circuit, the scientists use chemical signals between bacterial colonies.
The result is a biological system that can process information step by step.
The researchers printed bacterial colonies onto plates containing agar, a jelly-like material commonly used to grow microorganisms in laboratories. Each colony was placed about 5 millimeters from the nearest colony.
This spacing is important because it helps signals move from one colony to the next rather than spreading randomly throughout the entire plate.
In simple terms, the researchers created a biological version of a circuit board where information moves in a controlled direction.
Building More Complex Circuits
The scientists did not stop with simple switches.
Using their bacterial transistors and relay strains, they built different types of logic circuits. These included OR gates, multi-input circuits, and IMPLY gates.
They also combined multiple components to create more advanced systems.
One example was a circuit that could add two input signals together. Another could process several signals at the same time.
The team also demonstrated a demultiplexer. In electronics, a demultiplexer takes one incoming signal and directs it toward one of several possible outputs depending on a control signal.
The largest circuit demonstrated in the study contained 24 bacterial colonies working together.
This shows that simple biological components can be connected to perform increasingly complex tasks.
Why Not Simply Put Everything Inside One Cell?
Synthetic biology researchers have already created cells that perform basic computational tasks.
Usually, scientists place several biological components inside a single cell. These components may include proteins and transcription factors that interact with one another.
However, this approach has limitations.
There are only a limited number of transcription factors that researchers can use without causing unwanted interactions, known as crosstalk. As more circuits are placed inside the same cell, the system can also put too much pressure on the cell's machinery for producing proteins.
The MIT researchers' approach solves some of these problems by dividing the circuit among different bacterial cells.
Instead of asking one cell to perform the entire calculation, each bacterial strain performs a smaller job.
These individual parts can then be connected to create larger circuits.
Lead author Hamid Doosthoshoseni, an MIT postdoctoral researcher, says the five bacterial strains provide the basic building blocks needed to create many different types of biological operations.
Senior author Christopher Voigt, head of MIT's Department of Biological Engineering, says the work demonstrates how complicated functions can be created by connecting simpler functions in individual cells.
Much Slower Than a Smartphone
There is an important difference between these biological circuits and electronic computers: speed.
The bacterial circuits currently need about eight hours to complete a calculation.
That is extremely slow compared with modern computers and smartphones, which can perform billions of operations in a short time.
However, speed is not the main goal of this research.
The scientists are not trying to replace computers with bacteria. Instead, they want to bring computation directly into biological systems.
For example, if bacteria are living on a plant, they could monitor the plant's environment and make decisions based on what they detect.
In agriculture, a calculation taking several hours may not be a serious problem because plants grow over days, weeks, and months.
Future Applications in Plants
One of the most exciting possibilities is using these bacterial circuits on plant leaves or roots.
Plants constantly experience environmental changes. They may face drought, disease, insects, temperature changes, or nutrient shortages.
A biological circuit could potentially detect combinations of these conditions and respond automatically.
For example, bacteria living around plant roots could detect chemical signals associated with plant stress.
If the circuit determines that the plant is under attack from a particular pathogen, it could trigger the production of a useful compound, such as a fungicide.
Similarly, a circuit could potentially detect signs of drought and activate a biological response.
This would essentially give plants a form of biological computing that allows them to sense their surroundings and respond accordingly.
A New Direction for Biological Computing
The MIT research represents an important step toward making biological circuits more modular.
Rather than building one complicated system inside a single cell, scientists can create simple bacterial components and connect them together.
The concept is similar to building an electronic device from individual components. Each component performs a specific task, while the complete system can perform much more complicated operations.
There is still significant work to be done before these living circuits can be safely and reliably used outside laboratory environments. Researchers will need to improve their speed, reliability, stability, and ability to operate under real-world conditions.
Nevertheless, the idea is powerful: living cells could become programmable components of biological machines.
In the future, a plant might not simply grow in its environment—it could contain microscopic biological circuits capable of sensing changes, processing information, and responding automatically.
The work published in Nature Chemical Biology shows that bacteria can do more than simply carry out biological processes. With careful engineering, they can also become tiny information-processing devices.
The next generation of biological technology may therefore not be built entirely from silicon and metal. Some of its most useful components could be alive.
Reference: Doosthosseini, H., Chen, H. & Voigt, C.A. Living circuit boards built by printing bacterial transistors. Nat Chem Biol (2026). https://doi.org/10.1038/s41589-026-02300-3
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