Self-organization of bacterial active matter in space and time*

Simultaneous control of spatial and temporal organization of active matter is challenging and generally requires complex interactions. Here we found that tuning the rheological properties of bacterial active fluids enables large-scale spatial and temporal self-organization. Combining experiments with an active matter model, we explain the phenomenon in terms of the interplay between active forcing and viscoelastic stress relaxation. Our findings advance the understanding of bacterial behavior in complex fluids and demonstrate experimentally that rheological properties can be harnessed to control active matter flows.