Pressorum Sensing: Growth-induced Compression Activates cAMP Signaling in Pseudomonas aeruginosa

Bacteria employ various strategies to coordinate population-level behaviors, with quorum sensing being a well-established mechanism. Here, we report a novel population-level regulatory mechanism in Pseudomonas aeruginosa, which we term pressorum sensing. This mechanism allows bacteria to modulate their collective behavior in response to growth-induced mechanical compression in confined spaces. Using a highly sensitive cAMP biosensor in combination with microfluidics, we demonstrate that when compressive forces reach approximately 30 nN, P. aeruginosa cells rapidly increases intracellular cAMP levels via the Pil-Chp chemosensory system. This response leads to up-regulation of the Type III Secretion System, a key virulence factor. Unlike quorum sensing, which relies on diffusible chemical signals, pressorum sensing utilizes mechanical cues to gauge population density and spatial confinement. In bacterial colonies, this mechanism generates striking spatial patterns of cAMP signaling, including traveling rings that coincide with step-like structures in colony morphology. Our findings reveal a previously unknown link between mechanical compression and bacterial virulence, providing new insights into how P. aeruginosa coordinates population-level responses in confined environments. This work also expands our knowledge of mechanogenetics and opens up new possibilities in synthetic biology and bioengineering applications.