January 29, 2024
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Bacteria choose swarms based on what happened to their great-grandparents
Even organisms without brains can remember their past: scientists discovered that Escherichia coli Bacteria form their own type of memories of nutrient exposure. They pass these memories on to future generations, which may help them evade antibiotics, the research team reported. in it Proceedings of the US National Academy of Sciences.
“We normally think of microbes as single-celled organisms (each) doing its own thing,” says Dartmouth College microbiologist George O’Toole, who studies bacterial structures called biofilms. In reality, bacteria often survive by working together. Like bees relocating their hive, colonies of bacteria in search of permanent homes often travel as collective units called swarms.
These swarms can better resist antibiotic exposure due to their high cell density, making them of particular interest to microbiologists like Souvik Bhattacharyya at the University of Texas at Austin. He was studying swarming behavior in E.coli when he observed what he calls “strange colony patterns” that he had never seen before. By isolating individual bacteria, he and his colleagues discovered that the cells behaved differently depending on their past experience. Bacterial cells in colonies that had previously swarmed were more likely to swarm again than those that had not, and their offspring did the same for at least four generations, about two hours.
When adjusting the E.coli genome, scientists discovered that behind this ability were two genes that together control the absorption and regulation of iron. Cells with low levels of this important bacterial nutrient seemed predisposed to form mobile swarms. Researchers suspect that these swarms might seek out new locations with ideal iron levels, Bhattacharyya says.
Previous research has shown that some bacteria can remember and pass on to their offspring details of their physical environment, such as the existence of a stable surface, O’Toole says, but this study suggests that bacteria can also remember the presence of nutrients. Bacteria, some of which reproduce several times an hour, use these details to determine the long-term suitability of a location and can even establish themselves together in biofilms, which are more permanent.
Microbes other than E.coli You probably also remember iron exposure, O’Toole says. “I would be very surprised if (these results) didn’t hold for other errors as well.” He hopes that future research will examine at the cellular level how bacteria translate iron sensing into different behaviors.
Because bacteria are harder to kill when they form larger structures, understanding why they do so could eventually lead to new approaches to tackling persistent infections. This research provides an opportunity to develop new treatments to fight infections, O’Toole says, something especially crucial as antibiotics become less and less effective at killing these microbes.