Impact of Enhanced Transport On Cell Signaling within Swimming Microorganism Communities

Motility and communication are two fundamental biological processes that are used to coordinate communities.  In bacteria, the availability of chemicals in the surroundings can be crucial in determining their ability to communicate with each other thereby causing virulence, formation of biofilms, etc. The hydrodynamic interactions between swimming organisms has been shown to lead to large scale coordination and enhanced transport. We have examined the interplay of this enhanced transport with chemical communication. We expect this interplay to have an important role in the behavior of communities.

We have performed computer simulations that track each bacterium and the flow generated by their movement. The enhanced transport is quantified using tracers as well as a continuum concentration field, which satisfies an advection diffusion equation.  We use multiple measures of mixing to distinguish convective mixing versus diffusive mixing without the limitations imposed by mean-field models. We will focus on quantifying the onset of enhanced transport by examining concentrations ranging from dilute to highly concentrated. We will also compare the enhanced transport seen for small molecules versus colloids, discuss validation with experiments, and the implications for cell-cell signaling and communication.