Plants rely on microbes for delivery of nutrients and protection from stresses such as pathogens. We aim to increase the functionality of plant-associated microbes by engineering soil bacteria to sense environmental stimuli of interest. In addition, controllable and orthogonal communication between plants and microbes is being developed. In combination, our synthetic plant-microbe community will be a completely engineereable system where sensing, computation, and response can be distributed between plant and microbial cells.

Combinatorial sensing systems, like the mammalian olfactory complex, can differentiate between thousands of compounds using only a few hundred receptors. This discriminatory power is derived from the integration of many overlapping signals. In this talk, I will describe the model-driven design of a dCas9 transcriptional control system capable of integrating combinatorial inputs in Escherichia coli. By ratiometrically comparing multiple cross-talking sensors, our system can differentiate multiple ligands through a reduced sensor set.