Bacteria that secrete digestive enzymes in communities keep nutrients close at hand to avoid being exploited by cheating neighbours that do not chip in to enzyme production.

Bonnie Bassler and her colleagues at Princeton University in New Jersey studied Vibrio cholerae, which causes cholera and secretes an enzyme that digests the natural polymer chitin.

They found that cheaters do not thrive as well as enzyme producers when they are grown in communities called biofilms — probably because the thick sticky film slows the diffusion of nutrients, keeping them close to the producers. Exposing the biofilms to flowing water, which washes away nutrients before they reach the non-producers, also allowed the producers to outcompete the cheaters.

The results suggest ways in which cooperation has evolved in bacterial populations.

Curr. Biol. (2013)