(429g) Using Synthetic Biology to Engineer Microorganisms That Make and Communicate with Materials (Invited Speaker)

Living organisms have evolved to use minerals in their environment to build protective shells, to generate energy, and as nutrients. To achieve these functions, living systems form interfaces with inorganic materials and use biomolecules to control and monitor the flow of matter across this interface. Inspired by these naturally-occurring systems, my research group seeks to engineer new organisms with tailored abilities to transfer charge and assemble matter across the microbial-material interface. In the first part of my talk, I will describe how we have engineered bi-directional electronic communication between living microbes and non-living systems using synthetic biology. By transplanting extracellular electron transfer pathways into the industrial organism Escherichia coli, we can confer upon these cells a molecularly-defined route to both accept and donate electrons to electrodes. Both current production and current consumption shift the metabolism of E. coli in well-defined ways, demonstrating that this electronic interface can control intracellular state. In the second part of my talk, I will describe how we have used surface-layer (S-layer) proteins as a programmable material. S-layer proteins form a highly ordered crystalline, yet porous, layer on the outermost cell surface of most species of bacteria and archaea. By engineering S-layers on the surface of different microorganisms, we can create patterned arrays that modulate both the binding and formation of soft and hard materials. The properties of this living hydrogel can be changed dynamically by altering the cell-hydrogel crosslinking. Taken together, this work provides a platform for creating hierarchically-assembled living materials with switchable mechanical properties.