Studying motility to investigate the physiology of starving bacteria

Outside of the lab, bacteria spend most of their life in non-growing states; however, most of our knowledge about bacteria comes from experiments performed with model culturesgrowing exponentially in nutrient-rich conditions. Comparatively much less is known about non-growing cells, and a better understanding of bacterial physiology during starvation is likely to help tackle challenges such as antimicrobial resistance. After giving a basic introduction to bacterial metabolism for physicists, I will present our recent experiments performed to study the motility of starving suspensions of Escherichia coli. Using differential dynamic microscopy, we find that the swimming speed of the suspensions gradually decays with time, with significant variability between individual cells. I will discuss how these measurements can be used to probe the energetic state of starving cells and provide insight on the physics of dying.