Populations of naturally co-occurring bacteria work together, an analysis suggests.

To test whether bacteria aggregate for reasons beyond access to resources such as food, Martin Polz at the Massachusetts Institute of Technology in Cambridge and his team created a network map of interactions between 185 strains of Vibrionaceae bacteria. They found that antagonistic interactions were much less likely between strains that are as closely related as those within naturally occurring populations.

The authors suggest that the populations act as cohesive units that can defend themselves against other groups of bacteria. The coordination seems to have arisen through horizontal gene transfer, in which population members capable of producing antibiotics passed on antibiotic-resistance genes to their neighbours.

Science 337, 1228–1231 (2012)