Bacterial memory transfer across generations

Iron memory's role in decision-making in Escherichia coli.

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Scientists in Austin, Texas, found that bacteria, like E. coli, can remember when to adopt strategies that lead to harmful infections, such as antibiotic resistance. They use iron levels to store this information, passing it down to future generations. This discovery could have critical applications in preventing and treating bacterial infections, especially antibiotic-resistant ones.

The study’s results are in the Proceedings of the National Academy of Sciences. Scientists noticed that bacteria, having experienced swarming before, performed better in subsequent swarming. The research team from the University of Texas at Austin investigated why this happens. Since bacteria lack neurons and nervous systems, the ‘memories’ they form are more like computer data than childhood memories of blowing out birthday candles.”

Souvik Bhattacharyya, the lead author and a provost early career fellow in the Department of Molecular Biosciences at UT, said, “Bacteria don’t have brains, but they can gather information from their environment, and if they have encountered that environment frequently, they can store that information and quickly access it later for their benefit.”

It’s all about iron, a common element on Earth. Single bacteria have different iron levels. Researchers found that bacteria with low iron levels were better at swarming. On the other hand, those forming biofilms, dense mats of bacteria, had high iron levels. Bacteria with antibiotic tolerance had balanced iron levels. These iron ‘memories’ last for at least four generations and fade by the seventh.

Bhattacharyya said, “Before there was oxygen in the Earth’s atmosphere, early cellular life utilized iron for many cellular processes. Iron is critical not only in the origin of life on Earth but also in the evolution of life. It makes sense that cells would utilize it in this way.”

Bacteria must form a fast-moving swarm when iron is low to find more iron. They remember to stick around and create a biofilm if iron is high. Iron is a critical factor in their ability to cause harm. Understanding this behavior helps in developing treatments.

Image showing Bacterial swarm on a laboratory plate.
Bacterial swarm on a laboratory plate. Credit: The University of Texas at Austin.

This groundbreaking research, funded by the National Institutes of Health, emphasizes the role of iron in shaping bacterial memories and behavior. Rasika Harshey, a professor of molecular biosciences, served as the senior corresponding author, with contributions from Nabin Bhattarai, Dylan M. Pfannenstiel, Brady Wilkins, and Abhyudai Singh of the University of Delaware. The findings expand our understanding of bacterial behavior and open avenues for innovative therapeutic strategies.

Journal reference:

  1. Souvik Bhattacharyya, Nabin Bhattarai, et al., A heritable iron memory enables decision-making in Escherichia coli. Proceedings of the National Academy of Sciences. DOI: 10.1073/pnas.2309082120.

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