Often dismissed as simple, solitary creatures, bacteria actually utilize complex communications mechanisms similar to the electrical signaling mechanisms used by neurons in the human brain, researchers from the University of California, San Diego have discovered.
As Gürol Süel, an associate professor of molecular biology at UCSD, and his colleagues reported in the latest edition of the journal Nature, when these microbes live together in communities, they communicate directly with each other through special proteins known as “ion channels.”
“Our discovery not only changes the way we think about bacteria, but also how we think about our brain,” Süel explained in a statement. “All of our senses, behavior and intelligence emerge from electrical communications among neurons in the brain mediated by ion channels. Now we find that bacteria use similar ion channels to communicate and resolve metabolic stress.”
The research, which builds on a previous study that determined that biofilms had the capability to resolve social conflicts within their own communities, also suggests that some neurological conditions triggered by metabolic stress could have at one point been bacterial in nature. If so, it may provide doctors with a new way to treat such disorders.
Similarities to migraine, seizure-inducing condition discovered
Previous analysis of bacterial ion channels served as the basis for much of what scientists know about the electrical signaling in our brains, Süel explained. However, exactly how microbes used those channels themselves remained unknown, so the researchers decided to study long-distance communication within organized communities of bacterial cells known as biofilms.
When biofilms comprised of hundreds of thousands of Bacillus subtilis cells grew to a specific size, they found that the protective outer edge of cells stopped growing so that nutrients such as glutamate could continue flowing to the protected center, thus ensuring those bacteria’s survival. They designed an experiment to find out how this apparent coordination was occurring.
In order to measure changes in bacterial cell membrane potential during metabolic oscillations, they found that ion channels were responsible for changes in oscillations related to the growth of the biofilm. The oscillations conducted long-range electrical signals throughout the biofilms via spatially propagating waves of charged potassium ions, thus coordinating metabolic activity.
Once the channel that allowed potassium to slow into and out of cells had been deleted from the bacteria, the biofilm could no longer transmit these electrical signals, Süel said. Not only did the bacteria communicate using electrical signals in a way similar to neurons, but the process that the microbes used was said to be similar to a “cortical spreading depression”, a condition believed to be linked to seizures and migraines in humans, the study authors discovered.
“The community of bacteria within biofilms appears to function much like a ‘microbial brain’,” Süel added. “What’s interesting is that both migraines and the electrical signaling in bacteria we discovered are triggered by metabolic stress. This suggests that many drugs originally developed for epilepsy and migraines may also be effective in attacking bacterial biofilms.”
Feature Image: Suel lab