The role of motility in Myxococcus xanthus droplet formation and droplet geometries

Myxococcus xanthus, a rod-shaped soil bacterium lacking long-range interactions, collectively bead from
surfaces when starved to form 3D droplet-like aggregates known as fruiting bodies consisting of hundreds
of thousands of cells. Active self-propulsive forces of individual bacteria generate local increased
pressures that drive the dewetting process. Unlike passive fluids that form axisymmetric spherical cap-
shaped droplets, these aggregates are symmetry breaking and are often elongated in an elliptic-like
shape. To examine the role of motility in dewetting, we present here the dynamics of both stable and
unstable droplet geometries during dewetting and the formation of these fruiting bodies for cells with
different Peclet numbers. Using sparsely labelled cells, we also track emergent collective flows within
these droplets to characterize the internal hydrodynamics and cellular organization.