A multi-scale model of Escherichia coli chemotaxis from intracellular signaling pathway to motility and nutrient uptake in nutrient gradient and isotropic fluid environments

This paper presents a multi-scale mathematical model of Escherichia coli chemotaxis in a fluid environment that links the biochemical dynamics of intracellular signaling and flagellar dynamics to the behavior of cells and the surrounding nutrients and fluid flow. We combine the RapidCell model for the intracellular chemotaxis signaling pathway to obtain run and tumble behaviors of cells with the method of regularized Stokeslets to simulate cell motility in Stokes flow and the finite element method to solve the advection–diffusion–reaction equation of nutrients. Simulations were carried out using varying numbers of bacterial cells to ascertain the effects of cell–cell and cell–fluid interactions in isotropic environments and in fluids characterized by chemoeffector nutrient gradients. The resulting feedback between hydrodynamics and chemotaxis not only shows expected run and tumble behaviors of bacterial cells but also depicts the importance of fluid dynamical effects on the transport and consumption of chemoeffectors.