Bacteria within
a biofilm (in background and close up in right hemisphere inset)
have similar
electrical signaling mechanisms as neurons in the human brain. Credit: Suel lab
(October 21, 2015) Biologists
at UC San Diego have discovered that bacteria—often viewed as lowly, solitary
creatures—are actually quite sophisticated in their social interactions and
communicate with one another through similar electrical signaling mechanisms as
neurons in the human brain.
In a study published in this week’s advance online
publication of Nature, the scientists detail the manner by which bacteria
living in communities communicate with one another electrically through
proteins called “ion channels.
“Our discovery not only changes the way we think about
bacteria, but also how we think about our brain,” said Gürol Süel, an associate
professor of molecular biology at UC San Diego who headed the research project.
“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. Our discovery suggests that neurological disorders that are triggered
by metabolic stress may have ancient bacterial origins, and could thus provide
a new perspective on how to treat such conditions.”
“Much of our understanding of electrical signaling in our
brains is based on structural studies of bacterial ion channels” said Süel. But
how bacteria use those ion channels remained a mystery until Süel and his
colleagues embarked on an effort to examine long-range communication within
biofilms—organized communities containing millions of densely packed bacterial
cells. These communities of bacteria can form thin structures on surfaces—such
as the tartar that develops on teeth—that are highly resistant to chemicals and
antibiotics.
The scientists’ interest in studying long-range signals grew
out of a previous study, published in July in Nature, which found that biofilms
are able to resolve social conflicts within their community of bacterial cells
just like human societies. When a biofilm composed of hundreds of thousands of
Bacillus subtilis bacterial cells grows to a certain size, the researchers
discovered, the protective outer edge of cells, with unrestricted access to
nutrients, periodically stopped growing to allow nutrients—specifically
glutamate, to flow to the sheltered center of the biofilm.