Bacteria are unicellular organisms, yet they often form dense collectives such as biofilms —systems that display emergent, multicellular-like behaviors. We previously discovered genuine action potentials propagating through biofilms, coordinating nutrient sharing across millimeter scales. Surprisingly, we recently observed that a specific cell type can actively eject themselves from these collectives. The transitions between multicellular and unicellular life raise fundamental questions about how local interactions, mechanical forces, and excitable dynamics govern collective decision-making. I will present the electrochemical and mechanical mechanisms underlying these process, highlighting biofilms as a model for exploring principles of living active matter and tissue-like remodeling.
