Figure 3.

A designed microbial consortium. (A) The system consists of two interacting strains that produce a mutually interdependent chemotactic response. Red and green spheres represent target molecules; red and green triangles represent ligands for the chemoreceptors (Y-shaped objects). Dotted arrows represent conversion by enzymes (marked ‘E'). Solid arrows indicate rotation of the flagella (thick black lines). (B) Comparison of chemotaxis of strains SDG128, SDG275, and the SDG128+SDG275 mixture on soft-agar gradient plates, as in Figure 2A. The plates show 22 h of growth at 30°C. The leading edge of growth of the middle spot (SDG128+SDG275) on the Asn+PAG plate was collected and plated on LB agar. By counting fluorescent and non-fluorescent colonies (corresponding to SDG275 and SDG128, respectively), the mixture was found to consist of 55±5% of strain SDG275.