GSE138015
The extracellular matrix protein TasA is a developmental cue that maintains a motile subpopulation within Bacillus subtilis biofilms
In nature, bacteria form biofilms – differentiated multicellular communities attached to surfaces. In the otherwise sessile biofilms, a subset of cells continues to express motility genes. Here, we demonstrate a biological role for this subpopulation, which enabled biofilms of Bacillus subtilis to expand on high-friction surfaces. Moreover, we show that the extracellular matrix (ECM) protein TasA was required for the expression of flagellar genes. In addition to its structural role as an adhesive fiber for cell attachment, TasA served as a developmental signal similar to ECM proteins of multicellular organisms. Transcriptomic analysis revealed that TasA regulated a specific subset of genes, inducing genes involved in motility and repressing ECM production. A screen for suppressor mutations that restore motility in the absence of TasA revealed activation of the biofilm-motility switch by the two-component system CssRS, that alleviated Spo0A repression by TasA. Our results suggest that although mostly sessile, biofilms retain a degree of motility by maintaining a motile subpopulation. Overall design: 8 samples. delTASA (3 biological replicates), delCSSRS (3 biological replicates), WT (2 biological replicates, control)