As RAM crisis deepens, MIT engineers build working computer circuits using bacteria

Instead of putting circuits inside a computer, MIT researchers have figured out something interesting – how to make bacteria behave like tiny transistors and then wire those microbes together to create something that works like a living computer. Sounds like science fiction? In the future, this could allow plants to detect environmental conditions such as drought or attack by pests.

MIT revealed the research in a blog post on MIT News, explaining that the team created two types of bacterial transistors along with three bacterial strains that work as relays. Together, these five strains can be connected in different ways to build increasingly complex biological circuits.

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Bacteria that work like tiny transistors

If the word ‘transistor’ sounds too technical, think of it as a tiny switch. In an electronic device, a transistor controls the flow of electricity. MIT's biological version does something similar, except the bacteria control the movement of molecules that carry signals from one part of the circuit to another.

The researchers used a bacterium called Pantoea agglomerans, which commonly grows on surfaces, including plants. They engineered these bacteria so that certain molecules could switch their transistor-like behaviour on or off.

The bacteria can detect another molecule and, depending on whether the switch is active, produce an output molecule. That output can then be picked up by another bacterial colony.

The researchers created three additional strains that act like relays, translating one molecular signal into another that can be understood by the next transistor. In other words, the team can effectively “wire” bacterial colonies together without using traditional wires.

The researchers printed the bacterial colonies onto agar plates, placing each colony about 5 millimetres from the next one. This arrangement allows signals to move from one colony to another in a controlled direction, creating a biological circuit board.

A living computer that could one day live on plants

The team didn't stop at making bacteria switch things on and off. They used the bacterial transistors to build circuits capable of performing different logic operations and even more complicated calculations.

The largest circuit demonstrated in the study contained 24 bacterial colonies and was able to add two inputs together. The researchers also created circuits that could process multiple inputs and route one signal to different destinations.

And here's the line that makes the whole experiment sound slightly wild: MIT says that, from a computational perspective, there is nothing an iPhone can do that these circuits couldn't theoretically do.

There's an important catch, though. These bacterial circuits are not about to replace your iPhone. A conventional computer can perform calculations almost instantly, while the biological circuits take around eight hours for one calculation.

As Christopher Voigt, head of MIT’s Department of Biological Engineering, puts it, “We’re not trying to replace computers, but rather put computational control into biology. If you have bacteria on the root of a plant, or the plant itself is doing the computing, running a simple calculation overnight is fast enough relative to a growth season.” So, the idea isn't really “bacteria will become computers.” It is more interesting than that: computers could eventually become part of living biology.

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