Indiana University-Purdue University Indianapolis

In this two-part talk, I will discuss: 1) bacterial hunting strategies & 2) diffusion in crowded living cells.

Bacterial hunting: the model bacterial predator, Bdellovibrio bacteriovorus (BV), has been studied for over 50 years and has the potential to purify water, degrade biofilms and serve as a living antibiotic. However, very little is known about BV's hunting strategy for bacterial prey.

This is in because the small BV moves much faster than its typical prey and appears, by eye, to collide into it at random. We performed a more careful statistical analysis, also suggests that BV exhibits no obvious signatures of a targeted search for prey. Rather, I will present experimental and modeling work suggesting that hydrodynamics may help guide its search for prey.

Diffusion in crowded environments: Experimental methods cannot capture complex processes in living systems in their full multi-dimensional detail. At best, they provide limited snapshots of cellular processes in time and space by indirectly interrogating a few, and often just one, observable property of a dynamical process. For this reason, qualitative descriptors hinting at complexity - such as “anomalous diffusion” or “heterogeneous dynamics” - abound in the literature and suggest that a mechanistic understanding of key intracellular processes is lacking. Here I will discuss how critical information underpinning intracellular anomalous diffusion in the complex environment of living cells may be directly inferred from fluorescence correlation spectroscopy.