MIT News breed · Wetenschap

MIT Engineers Develop Bacteria-Based Living Transistors

Researchers at MIT have engineered bacteria to function as transistors, enabling the creation of printable "living circuit boards" in Petri dishes. These biological transistors control the flow of small molecules, acting as switches to relay signals within biological circuits.

The team designed two types of transistors and three bacterial strains to relay information, providing the components for various circuit designs. These have been used to create circuits capable of adding multiple inputs or directing signals to specific locations. Lead author Hamid Doosthosseini stated that while initial computer architecture components have been built, any operation can be constructed with these five strains. The researchers envision these circuits coating plant leaves or roots to sense and respond to environmental conditions like drought or pest attacks.

Traditionally, synthetic biology circuits are built within a single cell, expressing proteins and transcription factors to perform tasks. However, this approach is limited by the finite number of usable transcription factors and the burden on cellular machinery. The MIT team's novel approach uses cells as transistors, which are then interconnected to form circuits.

The researchers utilized the bacterium Pantoea agglomerans to create two transistor types, switchable by a molecule called OC-6. One transistor activates with OC-6, the other deactivates. Both transistors detect OC-12 and produce an output molecule, OHC-14. Three additional strains of Pantoea agglomerans act as relays, translating OHC-14 signals for subsequent transistors, effectively wiring them together like an electronic circuit board.

These bacterial circuits were created by printing colonies onto agar plates, with signals propagating sequentially between adjacent colonies. The study demonstrated transistors performing logic operations like "multi-input," "or," and "imply" gates. More complex circuits were built, including those that add two signals, process multiple signals concurrently, or function as a demultiplexer. The largest demonstrated circuit, which adds two inputs, comprised 24 wired bacterial colonies.

Senior author Christopher Voigt noted that while these circuits are significantly slower than electronic computers, taking about eight hours per calculation, their speed is sufficient for biological applications. The goal is not to replace computers but to integrate computational control into biological systems, such as enabling plants to perform calculations to detect stress and trigger responses like fungicide synthesis.

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