Control of bacteria movement by using photo responsive media

Liquid crystalline materials have been shown to be an excellent host matrix enabling the easy observation of bacteria movements. In some cases, even the high sensitivity of such matrix was used to control materials’ properties by bacteria. Motivated by the key role played by bacteria in the health and food industries, our group is working on the development of dynamic micro control techniques by using photosensitivity of azobenzene or DSCG molecules. We think that the capability to control their movement may be useful for many applications, and, in the present work, we explore the possibility of such active control of the movement of flagellated bacteria (a bacterium that can swim thanks to the rotation of its helix). We demonstrate that we can dynamically change the swimming direction of bacteria by incorporating them into a liquid crystal where the phase transition is locally controlled by UV illumination. We shall also mention briefly about other types of control (magnetic, isomeriz)