NIAID
E. coli bacteria seen under an electron microscope
A team of scientists discovered than individual cells of Escherichia coli (E.coli) are able to carry traces of past experiences, influencing their future behavior.
In one, published last month in PRX Liferesearchers observed cells from E.coli num microfluidic devicea system of chambers that keeps bacteria immobilized while a liquid circulates around them. This technology allowed cells to alternate between nutrient-poor and nutrient-rich environments, while simultaneously monitoring their growth using microscopy.
According to , cells exposed to faster fluctuations in nutrient availability adapted more quickly than those subject to slower changes.
In some experiments, scientists tracked about 30 thousand growth histories of individual cells, gaining a detailed view of how past conditions influence subsequent behavior.
“For a long time, it was assumed that bacterial growth was determined solely by the environment in which the cell was at that time,” explained the study’s first author, Josiah Kratz.
The results suggest that this memory originates from the cell’s protein production mechanism, particularly in ribosomes.
Some processes associated with ribosomes appear to respond quickly to environmental changes, while others evolve more slowly. Together, these mechanisms may allow the cell to retain information for periods ranging from a few minutes to several hours.
However, this memory has a cost.
Although bacteria that have developed this ability adapt more quickly to changes in the environment, they show less growth in the long term. Instead of maximizing immediate growth, they seem to favor preparing for future instability.
The discovery does not mean that bacteria think, plan or remember in the same way as animals. A cell can exhibit memory without any form of consciousness. In this case, this memory appears to be stored in chemical networks, protein levels and inherited moleculeswhich can be transmitted from one bacterial generation to another.
The study’s findings could also have important implications for the investigation of bacterial infections. A bacterium’s response to an antibiotic could depend not only on present conditions, but also on its recent history, including previous periods of nutrient shortages, exposure to extreme temperatures or prior contact with low doses of medicines.
