Bacterial Upstream Swimming Enhanced in Non-Newtonian Fluids

Recent research has revealed significant advancements in understanding bacterial behavior in non-Newtonian fluids, which are common in biological environments. The study, titled "Enhancement of bacterial rheotaxis in non-Newtonian fluids," authored by Bryan O. Torres Maldonado and colleagues, investigates how bacteria, specifically E. coli, swim upstream in these complex fluids.

Traditionally, studies on bacterial rheotaxis have focused on Newtonian fluids, where the viscosity remains constant regardless of the flow conditions. However, most microorganisms exist in non-Newtonian fluids, such as mucus and biofilms, which exhibit varying viscosity depending on the shear rate. This research demonstrates that E. coli can enhance its upstream swimming capabilities by an order of magnitude in shear-thinning polymeric fluids compared to Newtonian fluids.

The authors conducted experiments that showed a notable increase in the bacteria's ability to swim against the flow, attributed to a torque that aligns the bacteria with the flow direction. This finding is crucial as it provides insights into how bacteria can navigate and colonize surfaces in environments where non-Newtonian fluids prevail.

The implications of this research extend beyond basic biology; understanding bacterial movement in these fluids could inform the design of medical devices and treatments for infections caused by biofilms. The study also contributes to the theoretical framework surrounding bacterial behavior in complex fluids, potentially guiding future research in microbiology and fluid dynamics.

For further details, the full paper can be accessed here.