Bacteria as Living Circuit Boards

What if bacteria could do math? Would it be able to create algorithms to crash the global economy? Would the human species get taken over by bacteria? Well, bacteria can now do calculations, so who knows what may happen in our future.

On August 17, 2026, researchers at MIT announced their breakthroughs in turning entire bacterial colonies into biological transistors and circuit boards. The team used colonies rather than individual bacteria because individual bacteria lack the metabolic energy to host whole circuits, cell toxicity or growth failure would occur in them1. Therefore, the MIT team distributed the workload across multiple specialized bacterial colonies using quorum sensing to connect them.

Background knowledge:

To understand biological computing, it is helpful to understand traditional computing and cellular communication.

Transistor and Logic Gates:

Traditional silicon transistors are electronic switches that use voltage to flip between on and off states. Logic gates are circuits made up of two or more transistors.

Quorum Sensing and Autoinducers:

On the other hand, bacterial transistors rely on quorum sensing, which is essentially how bacteria talk to each other. Bacteria naturally emit small signaling molecules called autoinducers which change the gene expressions of other nearby bacteria, and act as the “voltage” in this specific circuit.

Methodology and setup:

In this experiment, the MIT researchers utilized acyl-homoserine lactones (AHLs), a specific family of natural autoinducer molecules. To achieve a full circuit, the team of scientists engineered five strains of the bacterium Pantoea agglomerans (a type of bacteria that resides on plant surfaces2). Two strains acted as logical switches (transistors), while three strains served as communication lines (wires).

Placement and spacing:

Using an acoustic liquid handler, the scientists printed five strains onto agar plates in different patterns to achieve different calculations3.

Layout:

Colonies were set to be about five millimeters apart. The researchers chose the distance because colonies would be close enough that signaling molecules could reach the next colony in the controlled direction while also being far enough away so they wouldn’t trigger anything else on the circuit4.

Passive Diffusion:

When a transistor colony produces the output molecule OHC-14, the molecule exits the cell without using cellular energy. This process of passive diffusion is due to the OHC-14 having a nonpolar hydrophobic acyl tail which can easily pass through the lipid membrane of the bacterium allowing for diffusion into the surrounding agar5.

Components:

Transistor Strains:

As the name suggests, these strains are the transistors of the bacterial circuit. They use three types of AHL molecules: OC-6 as the control input, OC-12 as the data input, and OHC-14 as the output1.

N-type Transistor Strain:

These strains have their DNA programmed for OC-6 to bind with receptors inside the cell called LuxR-family receptors or other variants like TraR and LasR. They are transcription factors (regulatory proteins) that have binding pockets shaped to fit the 6-carbon tail of OC-6. The activated OC-6 receptors attach to the DNA and trigger the cell to start producing either CinR or RhlR, which are proteins that catch OC-12 with binding pockets designed for grabbing the 12-carbon tails of the molecule. This is the “on” in terms of traditional transistors.

P-type Transistor Strain:

These cells are active by default, meaning they produce the output, OHC-14, whenever OC-12 is present. When OC-6 binds to its LuxR variant repressors, however, the protein physically disables the region in the cell that produces OHC-14, blocking the RNA polymerase from moving forward and stopping the entire biological assembly line that makes OHC-14. This is the “off” in terms of traditional transistors.

OC-12 and OHC-14:

OC-12 is the “target molecule,” or the data being processed. Transistors check for its presence to decide whether or not they should generate outputs, OHC-14 in this case. If the transistor is on and it detects the OC-12, the cell activates an enzyme called AHL synthase that synthesizes OHC-14 using materials in the cytoplasm. Then the OHC-14 passively diffuses into the agar and travels until it reaches a neighboring colony.

Relay Strains:

Relay strains connect the transistor cells together like wires on a traditional circuit board. They convert the OHC-14 (which cannot be read as an input by another transistor) into molecules that can be read. Each strain has receptor proteins from the LuxR family that are shaped to catch OHC-14. The DNA gets unlocked as the proteins bind with the molecule and the cell starts to manufacture a synthase enzyme that produces OC-6, OC-12, or OHC-14 depending on the strain. These molecules move out of the cell wall and travel through the gel to hit the next transistor3.

One type of relay strain translates OHC-14 to OC-6. They allow the calculations from the previous transistor to flip the switch of the second transistor. The second one translates OHC-14 to OC-12. They allow calculations from the first transistor to be the data stream of the next transistor. The third strain makes more and stronger OHC-14 after receiving OHC-14. They are amplifiers used to reduce the effects of the natural fading and diluting of chemicals as they travel through the gel.

Significance and the Future:

By combining these five strains, the MIT team connected up to 24 bacterial colonies to perform operations such as binary addition. The scope of these activities is huge, with senior author of the MIT paper and head of MIT’s Department of Biological Engineering Christopher Voigt noting that, from a logical standpoint, “there’s nothing that your iphone can do that these circuits couldn’t do.”1, “Complex calculations” section, para. 3.

While logically capable, biological computation is limited by speed. A single calculation takes around eight hours because of the time needed for protein synthesis and molecular diffusion. However, there is immense potential for expansion in environmental and medical fields.

You can be rest assured that bacteria aren’t taking over the world just yet. But as this technology advances, the boundary between living organisms and computing systems will continue to blur.