A matrix protein acts as a cue to preserve collective motility of B. subtilis biofilm cells

Bacteria in nature are usually found in complex multicellular communities, termed biofilms. Biofilms are generally seen as sessile structures, resulting from downregulation of motility. However, during interspecies competition and predation, biofilm cells were shown to migrate towards competitor colonies. Here, we show that a specific extracellular matrix (ECM) protein, TasA, is essential for collective migration toward potential competitors and serves as a developmental cue that increases the formation of motile offspring from sessile chains. We reveal an effective strategy to maintain migration capacities in bacterial biofilms: besides providing a three-dimensional adhesive scaffold for the cells, TasA acts as a signal within the bacterial community.