Self-Organized Criticality Governs Dynamic Equilibrium in Bacterial Calcium

Abstract

How dynamic bacterial calcium is maintained, with kinetics faster than known mechanisms of cellular adaptation, is unknown. Herein, we discover bacterial calcium fluctuations are temporal fractals resulting from calcium dynamics self-organizing at a phase transition, a property known as self-organized criticality (SOC). SOC processes are poised at a transition between chaotic and ordered dynamics and are observed in many anthropogenic and natural systems, including neural circuits. SOC emerges due to calcium channel coupling which is mediated via membrane voltage. Environmental or genetic perturbations elicit different calcium dynamics, though always maintaining SOC, suggesting a continuum of critical attractors. We find moving along this continuum alters the collective information capacity of single-cell communities. In summary, we discover dynamic calcium equilibrium is maintained not by biological sensing, but rather by the physics of phase transitions, and our work connects ionic homeostasis in bacteria to the architecture of nervous systems in metazoans.