Engineered Microbial Communication for Population-Level Behaviour

Quorum-sensing (QS) has been extensively studied in the context of synthetic biology (Basu et al., 2005; Danino et al., 2010; Garcia-Ojalvo et al., 2004). It enables a community-level response to emerge once a certain signal concentration threshold has been reached. We use QS to design a multi-strain, engineered bacterial community with autonomous behaviour. We model our system on the familiar "client-server" architecture, with a single central server and two clients (one "red" and the other "green"). The task we define is that of oscillation (Tigges et al., 2009); by engineering feedback between three different strains, we obtain indefinite switching between "red" and "green" outputs. The system is not restricted to simple oscillation, as server cells may be introduced with much more complex behaviours.