Not Just Going with the Flow : Swimming and Contamination in Complex Fluids
Microorganisms often navigate non-Newtonian fluids with suspended particles and polymers, such as mucus or soil. The heterogeneity and non-linear viscosity of these environments profoundly affect microbial swimming, though these effects are highly fluid- and organism-specific, making them difficult to study independently. In this talk, we present experiments and a hydrodynamic model designed isolate and quantify the influence of media heterogeneity on the efficiency of helical propulsion.
In the second part of the talk, we turn our attention to bacterial rheotaxis—the ability of bacteria to swim against shear flows. While upstream motility in Newtonian fluids is well-studied, much less is understood about this phenomenon in complex fluids. Our results demonstrate that shear-thinning viscosity behaviour significantly enhances bacterial upstream migration, enabling contamination at flow rates an order of magnitude larger than in water and Newtonian fluids. Our work has important consequences for the study of medical, food, or wastewater contamination, and applications in designing medical devices to prevent medical infections.
Contact Nathanaël Machicoane for more information or to schedule a discussion with the seminar speaker.