Probing the Interactive Forces Between Bacterial Biofilm Cells and Surfaces with Atomic Force Microscopy

Biofilms are complex aggregations of microbes formed at interfaces. An understanding of the initial formation, subsequent accumulation, and eventual eradication of bacterial biofilms is becoming increasingly important to a wide range of fields. In this study we use atomic force microscopy (AFM) to determine the cellular spring constants of intact, living Gram-negative and Gram-positive bacteria in simple biofilms. We also explore the mechanical characteristics of the bacterial predator Bdellovibrio bacteriovorus in comparison to that of its prey, E. coli, and the biophysical changes that take place during predation and consumption of the prey. In an effort to further understand the intra- and inter-bacterial interactions critical for biofilm formation and dynamics, we modify a force probe with live predator and prey cells. Using this “biotip,” we monitor in situ the attractive and adhesion forces between various cells, biofilms, and surfaces.