Can Bacteria learn?

ResearchBlogging Medium White Can Bacteria learn?
Higher animals are, to a more or less developed degree, able to learn how to deal with changing environmental parameters. But that an organism, as “simple” as a bacterium (Escherichia coli) could accomplish the same, is astonishing. Of course, as a Biologist, I am aware that the description “simple” should not be used fo a beeing that survived millions of years of evolution, it is more likely, that its easy organisation is an advantage and allows for fast adaptation. But in comparison to the animals usually employed for behavioural studies covering learning processes, a bacterium is “simple”, so pleas excuse this expression.
Everybody knows the story of the dogs, trained by Pavlov to couple the sound of a ringing bell to the supply of food, resulting in the production of saliva upon ringing the bell. This behavioural fixation is termed “conditioning”.
A similar process has now been described for these slimy creatures known as E. coli. Scientists already knew, that they can produce simple responses to changes in their environment, if these occur regular enough.

 Can Bacteria learn?

For example, their usual life cycle includes ingestion into the mouth, resulting in higher temperatures, which is a signal for a following change to low oxygen levels upon entering into the intestines. This temperature change results in a metabolic modulation towards downregulation of genes usually dealing with high oxygen levels. This is clearly a preparation for the new environment.
The group of Tavazoie now rendered these condition to a high oxygen level following the temperature signal and as soon as after 100 generations (E. coli devides every 20 min), the organisms had changed their response to fit the new situation. [PubMed] This suggests, that the bacteria were able to break the old association and genearte a completely new response to the “old” signal, which could be defined as “learning”.
This is the first, and astonishing description of a learned anticipation of future events due to environmental stimuli in bacteria.

Tagkopoulos, I., Liu, Y., Tavazoie, S. (2008). Anticipatory Behavior Within Microbial Genetic Networks. Science DOI: 10.1126/science.1154456

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