A single-celled organism with no brain or nervous system to speak of may still form memories and pass those memories on to future generations, according to new research.
Bacteria spread everywhere, Escherichia coli, He is One of the most well-studied forms of life On Earth, yet scientists are still discovering unexpected ways for it to survive and spread.
Researchers at the University of Texas and the University of Delaware have now discovered a potential memory system that allows this coli bacteria “Remember” past experiences for hours and generations later.
The team says that, to their knowledge, this type of bacterial memory has not been discovered before.
It is clear that the memory that scientists are discussing in this case is not the same as conscious human memory.
The phenomenon of bacterial memory instead Describe How information from past experiences affects current decision-making.
“Bacteria don’t have brains, but they can gather information from their environment, and if they encounter that environment repeatedly, they can store that information and quickly access it later for their own benefit.” He explains Lead researcher is molecular biologist Souvik Bhattacharya of the University of Texas.
Bhattacharyya and their team’s findings are based on strong correlations from more than 10,000 bacterial “swarming” tests.
These experiments were a test to see if… coli bacteria The cells on one plate will cluster together to form a single migratory mass that moves with the same motor. This behavior generally indicates that cells are joining to efficiently search for a suitable environment.
On the other hand when coli bacteria The cells cluster together to form a sticky biofilm, which is their way of colonizing a nutrient surface.
In preliminary experiments, researchers revealed coli bacteria The cells were exposed to several different environmental factors to find out what conditions led to them swarming more quickly.
Ultimately, the team found that intracellular iron was the strongest predictor of whether bacteria moved or stayed put.
Lower levels of iron were associated with faster and more efficient mobilization, while higher levels led to a more sedentary lifestyle.
Among the first generation coli bacteria cells, this seems to be an intuitive response. But after experiencing just one swarming event, cells that experienced lower iron levels later in life were faster and more efficient at swarming than before.
Moreover, this “iron” memory is transmitted to at least four successive generations of daughter cells, which are formed by the division of the mother cell into two new cells.
By the seventh generation of daughter cells, that iron memory is naturally lost, although it can be restored if scientists artificially enhance it.
The study authors have not yet determined the molecular mechanism behind this potential memory system or its heritability, but the strong association between intracellular iron and swarming behavior between generations suggests that there is a level of ongoing conditioning at play.
While genetics are known to play a role in… Passing “remembered” biological settings. Across generations coli bacteria By regulating the ‘on’ and ‘off’ settings of specific genes, the researchers believe that the short duration of heritability means this is not the underlying mechanism here.
Iron is associated with multiple stress responses in bacteria. That an intergenerational memory system formed around it makes a lot of evolutionary sense.
Iron-based memory system may help coli bacteria Adaptation to poor environmental conditions or antibiotics.
One coli bacteria The cell can Double within half an hourSo the ability to transfer such memory to daughter cells may also be useful in slowly changing environments.
“Before there was oxygen in Earth’s atmosphere, early cellular life used iron for many cellular processes.” He says Bhattacharya.
“Iron is not only important in the origin of life on Earth, but also in the evolution of life. It makes sense for cells to use it in this way.”
“In the end,” Bhattacharya said He concludes, “The more we know about the behavior of bacteria, the easier it is to combat them.”
The study was published in With people.
