Blog
About

  • Record: found
  • Abstract: found
  • Article: found
Is Open Access

Mechanism for collective cell alignment in Myxococcus xanthus bacteria

Preprint

Read this article at

Bookmark
      There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

      Abstract

      Myxococcus xanthus cells self-organize into aligned groups, clusters, at various stages of their lifecycle. Formation of these clusters is crucial for the complex dynamic multi-cellular behavior of these bacteria. However, the mechanism underlying the cell alignment and clustering is not fully understood. Motivated by studies of clustering in self-propelled rods, we hypothesized that M. xanthus cells can align and form clusters through pure mechanical interactions among cells and between cells and substrate. We test this hypothesis using an agent-based simulation framework in which each agent is based on the biophysical model of an individual M. xanthus cell. We show that model agents, under realistic cell flexibility values, can align and form cell clusters but only when periodic reversals of cell directions are suppressed. However, by extending our model to introduce the observed ability of cells to deposit and follow slime trails, we show that effective trail-following leads to clusters in reversing cells. Furthermore, we conclude that mechanical cell alignment combined with slime-trail-following is sufficient to explain the distinct clustering behaviors observed for wild-type and non-reversing M. xanthus mutants in recent experiments. Our results are robust to variation in model parameters, match the experimentally observed trends and can be applied to understand surface motility patterns of other bacterial species.

      Related collections

      Most cited references 37

      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      Dynamical clustering and phase separation in suspensions of self-propelled colloidal particles

      We study experimentally and numerically a (quasi) two dimensional colloidal suspension of self-propelled spherical particles. The particles are carbon-coated Janus particles, which are propelled due to diffusiophoresis in a near-critical water-lutidine mixture. At low densities, we find that the driving stabilizes small clusters. At higher densities, the suspension undergoes a phase separation into large clusters and a dilute gas phase. The same qualitative behavior is observed in simulations of a minimal model for repulsive self-propelled particles lacking any alignment interactions. The observed behavior is rationalized in terms of a dynamical instability due to the self-trapping of self-propelled particles.
        Bookmark
        • Record: found
        • Abstract: found
        • Article: found
        Is Open Access

        Non-equilibrium clustering of self-propelled rods

        Motivated by aggregation phenomena in gliding bacteria, we study collective motion in a twodimensional model of active, self-propelled rods interacting through volume exclusion. In simulations with individual particles, we find that particle clustering is facilitated by a sufficiently large packing fraction (eta) or length-to-width ratio (kappa). The transition to clustering in simulations is well captured by a mean-field model for the cluster size distribution, which predicts that the transition values kappa_c of the aspect ratio for a fixed packing fraction is given by kappa_c = C/eta - 1 where C is a constant.
          Bookmark
          • Record: found
          • Abstract: found
          • Article: not found

          Psl trails guide exploration and microcolony formation in early P. aeruginosa biofilms

          Bacterial biofilms are surface-associated, multicellular, morphologically complex microbial communities 1-7 . Biofilm-forming bacteria such as the opportunistic pathogen 7-10 Pseudomonas aeruginosa are phenotypically distinct from their free-swimming, planktonic counterparts. Much work has focused on factors impacting surface adhesion and it is known that P. aeruginosa secretes the Psl exopolysaccharide, which promotes surface attachment by acting as a ‘molecular glue’ 11-15 . However, how individual surface-attached bacteria self-organize into microcolonies, the first step in communal biofilm organization, is not well understood. Here, we identify a new role for Psl in early biofilm development using a massively parallel cell-tracking algorithm to extract the motility history of every cell on a newly colonized surface via a search-engine based approach 16 . By combining these techniques with fluorescent Psl staining and computer simulations, we show that P. aeruginosa deposits a trail of Psl as it moves on a surface, which influences the surface motility of subsequent cells that encounter these trails and thus generate positive feedback. Both experiments and simulations indicate that the web of secreted Psl controls the distribution of surface visit frequencies, which can be approximated by a power law. This Zipf's Law 17 indicates that the bacterial community self-organizes in a manner analogous to a capitalist economic system 18 , a ‘rich-get-richer’ mechanism of Psl accumulation that results in a small number of ‘elite’ cells extremely enriched in communally produced Psl. Using engineered strains with inducible Psl production, we show that local Psl levels determine post-division cell fates and that high local Psl levels ultimately allow ‘elite’ cells to serve as the founding population for initial microcolony development.
            Bookmark

            Author and article information

            Journal
            1506.00681
            10.1371/journal.pcbi.1004474

            Cell biology, Biophysics

            Comments

            Comment on this article