A new mechanism for collective migration in Myxococcus xanthus

Myxobacteria exhibit a complex life cycle characterized by a sequence of cell patterns that culminate in the formation of three-dimensional fruiting bodies. This paper provides indications that the specific cell shape of myxobacteria might play an important role in the different morphogenetic processes during the life cycle. We introduce a new mechanism for collective migration that can explain the formation of aligned cell clusters in myxobacteria. This mechanism does not depend on cell cooperation, and in particular it does not depend on diffusive signals guiding cell motion. A Cellular Potts Model (CPM) that captures the rod cell shape, cell stiffness and active motion of myxobacteria is presented. By means of numerical simulations of model cell populations where cells interact via volume exclusion, we provide evidence of a purely mechanical mechanism for collective migration, which is controlled by the cells' length-to-width aspect ratio.