A quorum sensing-controlled program of aggregation in V. cholerae

Bacteria communicate and collectively regulate gene expression using the process called quorum sensing (QS). QS relies on population-wide responses to extracellular signal molecules called autoinducers. We demonstrate that, in Vibrio cholerae, QS activates a novel program of multicellularity, which we call aggregation. Aggregation is distinct from the canonical surface-biofilm formation program, which QS represses. Specifically, aggregation is induced by autoinducers, rapidly occurs in cell suspensions, and does not require cell-division, features distinct from those characteristic of V. cholerae biofilm formation. A genetic screen identifies components required for aggregation, revealing proteins involved in V. cholerae intestinal colonization, stress response, as well as a protein that distinguishes the current V. cholerae pandemic strain from earlier pandemic strains. We propose that aggregate formation is important for V. cholerae to transit between the marine niche and the human host. Further exploration of the aggregation process may yield insight into principles that allow bacteria to rapidly build multicellular communities and collectively defend against environmental insults or withstand starvation.