Addressable, “Packet-Based” Intercellular Communication through Plasmid Conjugation

Abstract

We develop a system for implementing "packet-based" intercellular communication in an engineered bacterial population via conjugation. Our system uses gRNA-based identification markers that allow messages to be addressed to specific strains via Cas9-mediated cleavage of messages sent to the wrong recipient, which we show reduces plasmid transfer by four orders of magnitude. Integrase-mediated editing of the address on the message plasmid allows cells to dynamically update the message's recipients in vivo. As a proof-of-concept demonstration of our system, we propose a linear path scheme that would propagate a message sequentially through the strains of a population in a defined order.

Distributed computation with continual population growth

“…While the studied model is a simplification, it represents core functions that constitute collective decision-making among biological species, and is readily adaptable for specific biological applications. If reactions are modified such that one of the two reactants not change, the model could represent one-way messaging equivalent to a conjugation event between a sender and receiver bacterial cell [36]. Similarly, if the messages A and B are coded as free species diffusible between senders and receivers, it could represent communication between bacterial cells using bacteriophage particles as messages [40].…”

“…For the amplifier, f (R, S) = ∅ and for the Nand gate f (R, S) = Y , where Y is the gate's corresponding output species. While with wildtype F plasmids, E. coli are either senders (with F plasmid) or receivers (without F plasmid), there exist engineered systems that allow the same cell (with F plasmid) to be both a sender and a receiver [18,36]. Note that a single cell still cannot act as both the sender and the receiver during a single reaction.…”