Bacteria store'memories' and pass them down across generations, according to a new study. 

Scientists have revealed that bacteria can build memories about when to form strategies that might cause deadly diseases in humans, including as antibiotic resistance and bacterial swarms, which occur when millions of bacteria congregate on a single surface.  

The discovery, which has potential uses for preventing and combating bacterial infections as well as combating antibiotic-resistant bacteria, is related to a common chemical element that bacterial cells can employ to develop and pass on memories to their children throughout subsequent generations. 

The University of Texas at Austin discovered that E. coli bacteria use iron levels to store knowledge about various behaviors, which may subsequently be activated in response to certain stimuli. 

Scientists have previously discovered that bacteria with prior swarming expertise (moving across a surface as a collective via flagella) better their subsequent swarming performance. 

The University of Texas-led study team set out to find out why. Bacteria lack neurons, synapses, and nervous systems, so any memories they have are not like blowing out candles at a childhood birthday celebration. They are more like to data saved on a computer. 

"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," said lead author Souvik Bhattacharyya, a provost early career fellow in the Department of Molecular Biosciences at UT. 

It all comes down to iron, which is one of the most prevalent elements on the planet. Iron levels vary between singular and free-floating bacteria. Scientists discovered that bacterial cells with reduced iron levels were better swarmers.  

Bacteria that formed biofilms, dense, sticky mats of bacteria on solid surfaces, on the other hand, contained significant quantities of iron in their cells. Antibiotic-tolerant bacteria had iron levels that were balanced. These iron memories last at least four generations and then fade away by the seventh. 

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

According to the researchers, when iron levels are low, bacterial memories are activated, causing a fast-moving migratory swarm to seek out iron in the surroundings. When iron levels are high, memories indicate that this is an ideal setting for bacteria to stick around and develop a biofilm. 

"Iron levels are definitely a target for therapeutics because iron is an important factor in virulence," Bhattacharyya said. "Ultimately, the more we know about bacterial behavior, the easier it is to combat them." 

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