Exploring viscoelastic properties of Myxococcus xanthus fruiting bodies with AFM measurements

When nutrients are scarce, the soil-dwelling bacteria Myxococcus xanthus aggregates into multicellular structures to form massive 3D clusters called fruiting bodies, where cells sporulate as a self-preservation mechanism. While our previous studies have explained the initiation of such a behavior in 2D as a motility induced phase separation process, the mechanical properties and cell dynamics within a maturing fruiting body remain unclear. In this study, we use atomic force microscopy (AFM) to explore the viscoelastic properties of a M. xanthus fruiting body. Treating M. xanthus aggregates as an active gel, our measurements provide insights on the hydrodynamic properties of such an out-of-equilibrium soft system. Mechanical measurements will also offer details about both cell-cell and cell-substrate interaction rules that can eventually lead to the understanding of the physics of long-range and self-organizing behaviors in M. xanthus.