Bacteria outside of the lab must often navigate complex environments in search of food. A better understanding of how bacteria find their way might help researchers develop strategies to inhibit bacterial infections. To that end, we probe to what extent the common bacteria E. coli explores landscapes that have much in common with structures experienced in nature—fractals and mazes—and find that they appear to have evolved a variety of ways to navigate these puzzles.

Fractals are scale-free topologies that repeat themselves with increasing magnification. A maze is not scale free but has many possible paths, with some leading quickly to an exit and others requiring a much longer time. While our designed puzzles seem simplistic, we aim to capture the essence of how bacteria navigate and escape more complex structures and reveal the emergent collective behavior of challenges to survival. For both types of puzzles, the bacteria employ several strategies to efficiently explore the territory, escaping in less time than would be expected if the bacteria moved randomly.

We caution that there are many aspects of these experiments we do not yet understand. In microbiology research, control experiments are difficult because one often must resort to controls using different strains of bacteria, which may have their own altered (unexpected) behavior. We believe that the phenomena we see are emergent: They cannot be easily predicted from a bottoms-up approach and they might not appear if the bacteria are not presented with a similar challenge.