We develop a technique for producing synthetic microbial patterns by means of direct activation and inactivation of gene expression in an initially homogenous population of cells using a microfluidic chemical interface system. A strain of E. coli was engineered such that the presence of the membrane diffusible molecule acyl-homoserine lactone (AHL) activates the production of more AHL, thereby creating a positive feedback loop. Since the half-life of AHL decreases in high pH solutions, this feedback loop can be inhibited in a specific area by modulating the local pH using a microfluidic system. A series of microchannels beneath a permeable membrane were used to locally control the pH levels in a layer of the engineered E. coli strain. By combining a diffusible activator with a microfluidic inhibitor, we believe this type of system should be able to demonstrate controllable Turing pattern formation and contribute to the development of new classes of synthetic multi-cellular systems built from co-operating cell populations in a manner analogous to differentiation schemes in developmental biology.
Project end date: 08/11/09