Learning is often thought to require a brain. But learning is a broad concept that does not necessarily depend on neurons.

If an organism uses information from past experiences to shape its future decisions, it is also learning.

Research from my lab, published in the journal PRX Life, shows that even a single bacterium can learn from experience, store memories of the past and use those memories to prepare for the future.

Keeping track of nutrients

Bacteria live in environments that change constantly and on many different timescales. In the human gut, for example, nutrient levels go up and down, temperatures shift and antibiotic threats come and go.

To survive, a bacterium has to respond quickly to what is happening right now while still preserving useful information about what it recently experienced. Adapting too quickly leaves the bacterium vulnerable to changing conditions, while forgetting too readily makes it unable to anticipate a recurring threat.

How does a bacterium manage this balancing act? This question interested me as a computational biophysicist who studies how living systems process information and adapt to changing environments.

To investigate whether single-celled organisms such as bacteria can learn from past experience, my colleagues and I used what’s called a microfluidic device to track the behavior of tens of thousands of individual E. coli cells as we switched their nutrient supply on and off at different rates.

We found that........

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