Distributed bacterial computing using plasmids as wires

Abstract

Synthetic Biology aims to implement artifi cial circuits within biological systems as a promising approach to design functionalized cells able to perform complex tasks under tight control. Circuit crosstalk and metabolic burden impose a technical limit to the complexity of synthetic systems integrated in single cells. An alternative to these constraints is the use of multiple operative subpopulations, wired by artificial cell-cell communication systems. A chemical wiring strategy based on quorum-sensing systems has been adopted in Synthetic Biology in the creation of diverse gene circuits that program spatio-temporal dynamics in multiple populations. However, crosstalk between different quorum-sensing systems and the narrow dynamic range of the transcriptionally regulated circuits demand for more effi cient wiring and computing. Here we used bacterial conjugation to engineer scalable, programmable, versatile, and distributed living plasmid technology. We engineered a recombinant plasmid series able to compute complex logic circuits such as multiple-AND, Product-of-Sums and Sums-of-Products, proven that mobile plasmids can be eff ectively used for cell-cell communication as input signals, computing and reporting devices, as well as transmission wires.