Getting in shape: how do bacteria control their morphology?
Professor Ariel Amir, Harvard University
Microbes such as bacteria are remarkably successful in accurately self-replicating themselves within a time-frame that can be as short as several minutes. How they reliably control their shape is an open problem. I will show how biophysical modeling, combined with experiments in which cell morphology is perturbed, can help us gain insight into the various sensory cues used for shape regulation in bacteria. After providing some background on bacterial growth, I will discuss recent work where bacterial cells are grown in curved microchannels - adapting to the shape of the channel - yet when released recover their native rod-shape upon further growth. Analysis of these results using the physics of thin shells suggests a coupling between mechanical stresses and cell wall growth. Finally, I will show how protein-membrane interactions may lead to effective sensing of one of the principal directions of curvature, which may orient cell wall growth circumferentially.