Functional traits are attributes that influence the fitness of a species. We use microfluidic experiments, microscale visualization and mathematical modeling to study the interplay between bacterial functional traits, such as shape and motility, and flow, which is ubiquitous in bacterial habitats. For example, bacterial flagella are chiral (specifically: helical).

We discovered that the coupling of chirality and shear leads to a preferentially oriented movement, bacterial rheotaxis, akin to that in fish but of a passive nature. Bacterial rheotaxis is characterized by a drift across streamlines that originates from the reorientation of the cell body due to a lift force acting on the chiral flagellum and could hamper the quest of nutrients by bacteria. We are currently performing extensive microfluidic experiments to better understand the rich interactions among bacterial motility and flow.

Now working on this theme: Roberto Rusconi, Jeff Guasto.