How electrified bacteria get a genetic reboot from conducting plastic

Plugging living cells into a power socket

Can electricity change how a microbe behaves? For years, researchers have experimented with electrified bacteria, coaxing species like Shewanella oneidensis to eat electrical current directly from an electrode. These organisms take in electrons and use that energy to convert raw chemicals into useful products like succinate.

To speed things up, scientists usually coat the electrodes with conducting plastics called conjugated polymers. The standard assumption was simple: the polymer acted like a smooth metal wire, offering an easy physical path for electrons to jump into the microbes. But a curious team wondered if that was the whole story. What if the material was speaking directly to the cells?

More than a passive wire

To find out, the researchers coated negative electrodes with a polymer called PBFDO and settled Shewanella oneidensis onto the surface. At an applied electrical potential of -0.8 volts, the results were startling. The electric current density entering the microbes leaped up to 130-fold, reaching about 696 microamps per square centimetre compared to just over 5 on uncoated controls.

The bacteria did not just absorb extra current. They used it. Output of succinate jumped roughly 10-fold, while biomass clinging to the electrode rose 5- to 10-fold. Furthermore, the recovery of consumed raw material turned into succinate surged from 19 percent up to roughly 67 percent. Rather than simply tolerating the jolt, the microbes flourished.

The genetic instruction manual

The real surprise came when the team examined bacterial gene expression. Out of over 4,000 detected transcripts, exactly 405 genes changed their activity, alongside an elevated internal NADH/NAD+ energy ratio. This was not random cellular panic; it was a targeted adjustment.

The polymer surface prompted the cells to produce specific small non-coding RNAs, or sRNAs. These tiny genetic controllers do not make proteins themselves. Instead, they latch onto messenger RNAs to adjust membrane transport and redirect electrons into chemical assembly lines. To confirm this, researchers added just two of these sRNAs into normal bacteria on plain, uncoated electrodes. Without any polymer present, the engineered cells still increased their current uptake nearly threefold and produced up to 3.9 times more succinate.

What we still do not know

The plastic coating acts like an interactive smart road. Instead of just letting electron traffic roll over it faster, the road sends signals that prompt vehicles to upgrade their own engines and navigation systems. However, this analogy ends where biology takes over: real roads do not interact with living cell membranes.

Several questions remain open. Scientists do not yet know the exact physical trigger that prompts the envelope of the bacterium to release these sRNAs. The RNA extraction method also measured total RNA rather than adjusting per cell, meaning the thicker bacterial layers on the polymer might account for some differences. The team also only tracked part of the total carbon budget, leaving molecules like carbon dioxide unmeasured. Finally, whether this genetic reprogramming occurs when bacteria pump current outward, or in other species, remains to be seen.