Motion of Magnetotactic Bacteria through a Three-Dimensional Pore Space

Magnetotactic bacteria are microorganisms that align and swim along Earth's magnetic field lines. Because the geomagnetic field is not parallel to the surface of the Earth, this motion allows cells to navigate vertically through the sediment. To develop a deeper understanding of efficient navigation through microscopic pore spaces, we investigate their motion in artificial sediment under controlled magnetic fields. Previously, we examined the motion of multicellular magnetotactic bacteria in a two-dimensional chamber, where we showed that the drift velocity through a complex medium is a non-monotonic function of the applied field. Here, we extend this work to three-dimensional pore spaces. We conduct experiments by gathering bacteria into chambers filled with water and glass beads intended to replicate sand. We vary the applied magnetic field and measure the distribution of first-passage times through the sediment. The focus of this poster is on the experimental techniques that enable these measurements.