future events

Bacterial growth: defects, elasticity and plasticity

TYPETheor./Math. Physics Seminar
Speaker:Dr. Ariel Amir
Location:Lewiner Seminar Room (412)

Bacterial cells have rigid walls, which define their shape, and enable them to hold high internal pressure.  While much is known about cell wall chemistry, the mechanisms controlling its growth remain elusive. The processes leading to the cylindrical shape of many bacteria are only now being unraveled. Recent experiments discovered that new cell wall is added by complexes running at constant velocity around the cell circumference, reminiscent of the motion of defects in crystals. By applying a condensed matter approach to this problem and modeling these complexes as edge dislocations, we find coupling between mechanical stresses and cell wall dynamics. Moreover, I will show that the cell wall deformations can be elastic (reversible) or plastic (irreversible), depending on the timescales over which the force is applied. I will corroborate these predictions experimentally by observing the growth of a single bacterium in a microfluidic device, using the flow to control the external force.