Impact of Dead-End Pores on Directed Magnetotactic Bacterial Motility

Understanding the physical mechanisms regulating microorganism navigation through porous networks is critical for a wide range of biological and industrial applications. Despite their recognized importance, relatively little is known about the influence of dead-end pores on the directed motility of swimming cells, and how such micro-scale interactions impact macro-scale transport properties. Here, we precisely track the motility of magnetotactic bacteria (MC-1) directed via an external magnetic field into microfluidic model dead-end pores. The spatial distributions and escape rates of the bacteria are experimentally characterized for various pore sizes, pore shapes, and magnetic field strengths. The results are validated through simulations and supported by scaling analysis. Furthermore, we illustrate the effect of individual motility on bulk transport by measuring the transport coefficients of magnetotactic bacteria in both random porous media and arrays of engineered pores. These results may inform our understanding of physical ecology in marine sediments, as well as the design of bioremediation and targeted drug delivery processes.