(262b) Living Liquid Crystals

Living liquid crystals represent a dispersion of active rod-like bacteria (such as B. subtilis) in a lyotropic chromonic liquid crystal. We describve the effects of the liquid crystal environment on bacterial dynamics and the effects of activity on the orientational states of the system. Upon the gradual increase of activity, we observe a transition from a uniform equilibrium orientation of bacteria and liquid crystal director into a periodic bend structure and then into a state of topological turbulence with disclination defects. The bacteria move predominantly parallel to the director field and because of that demonstrate an ability to transport small particles ("cargo") along a predesigned trajectory. In special cases (such as a homeotropically aligned cells) the bacteria also move perpendicularly to the director field. Despite the fact that the effictive viscosity of the liquid crystals is many orders of magnitude higher than that of ordinary isotropic fluids, the bacterial velocity in the liquid crystal is on the same order as in the isotropic melt of the material.  We discuss the underlying mechanisms of individual and collective effects in living liquid crystals.  The work is supported by NSF DMS-1434185 and by Department of Energy, Office of Basic Energy Sciences, Division of Materials Science and Engineering,  Contract DE AC02-06CH11357.