Physics of Bacterial Biofilm Formation – PHYBABIFO

Most of our knowledge of bacteria comes from populations of individual, free-swimming cells. Yet, most bacteria on earth exist within biofilms, non-motile and physiologically distinct communities of cells. Biofilms provide significant protection against biological, chemical, and physical stresses. Consequently, they are responsible for many infections which are highly resistant to antibiotics and difficult to eradicate.

Under the traditional paradigm, biofilm formation begins when a motile cell adheres to the surface, triggering a drastic change in 'lifestyle'. Yet, the mechanism of this mechanochemical trigger remains largely a mystery. And, medically relevant biofilms often exist in other forms, such as a film at the liquid-air interface or cell aggregates in solution. Despite their medical relevance, the physics underlying the generation of such biofilms is nearly unexplored, and it is unknown to what extent they resemble those at the liquid-surface interface. Such mechanisms may prove crucial to bacteria’s ability to withstand the extreme conditions of evaporating aerosols during transmission.

This project seeks to uncover the physical mechanisms which trigger bacterial biofilm initiation in different microenvironments. We employ a rich combination of physics-based techniques, including digital holography, light-sheet microscopy, rheology, optical tweezers, and an electrodynamic aerosol trap, to quantitatively characterize the events prior to and immediately after biofilm nucleation. We reach beyond the traditional paradigm to explore biofilm nucleation fat the liquid-solid interface, in liquid suspension, at the liquid-air interface, and in aerosols. A deep understanding of the physics underlying biofilm formation may change the way we think about bacterial pathogen transmission and infection.