Bacteria clusters use the same "percolation" method we use to make coffee – ScienceDaily

A theory known as "percolation" is now helping microbiologists at the University of California explain how communities of bacteria can effectively relay signals over long distances. Once considered a simple group of microorganisms, bacteria communities – also known as "biofilms" – use ion channels for electrochemical communication that help the community to thrive and survive threats, such as chemical attacks of antibiotics.

The results, led by Joseph Larkin and lead author Gürol Süel of UC San Diego, are published July 25 in the journal Cell Systems .

Biofilm communities inhabit places all around us, the surface of our teeth. The cells at the edge of these communities tend to grow stronger than their inland counterparts because they have access to more nutrients. To keep this growth in check and to ensure that the entire community is fit and balanced, the "hungry" members of the biofilm interior send electrochemical signals to the members on the outside. These signals stop consumption on the edge, allowing the nutrients to pbad through the inner cells to prevent starvation.

"This keeps the interior well fed and if a chemical attack comes and removes some of the outer cells, then the protection inside is able to continue and the entire population can survive," Larkin said. a postdoctoral researcher in the biological sciences of San Diego UC. "It is essential that the electrochemical signal be constantly transmitted to the edge of the biofilm because it is there that growth must be stopped for that the community can make the most of the signaling. "

In addressing their new study, researchers sought to explain how bacterial communities are able to propagate these electrochemical communication signals.In contrast to neurons that have structures designated to relaying the electrochemical signals known as axons, bacterial communities lack sophisticated structures. UC San Diego began collaborating with Andrew Mugler and Xiaoling Zhai, from Purdue University, who proposed the possibility of transferring signals over long distances into the community.

The idea that percolation theory might explain how bacterial communities can propagate cell-to-cell signals.

The theory of percolation has existed since the 1950s and has helped physicists describe how signals are transmitted. In a coffee maker, hot water seeps through the individual coffee grounds into a carafe. In the oil industry, drillers maximize their yield by extracting oil from percolated sands, where the bedrock is sufficiently porous to allow oil to flow over a large area.

In a community of bacteria, signals pbad from one cell to the other. path over a distance of hundreds of cells. Using fluorescence microscopes, researchers were able to track individual cells that were "firing" (transmitting a signal). Scientists found that the fraction of the firing cells and their spatial distribution corresponded exactly to the theoretical predictions of the onset of percolation. In other words, the bacterial community had a fraction of firing cells that was precisely at the tipping point between not having full connectivity and connectivity between cells, also known as a critical phase transition point.

We make coffee by percolation and it's an interesting twist that bacteria seem to use the same concept to accomplish the very complicated task of efficiently relaying an electrochemical signal over very long distances from cell to cell. " declared Süel

. these bacteria, which are called single-celled organisms, use a fairly sophisticated strategy to solve this problem at the community level, "said Larkin. "It's pretty sophisticated that we humans use to extract oil, for example."

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Materials Provided by University of California – San Diego . Original written by Mario Aguilera. Note: Content can be changed in style and length.