Multi-cellular separation and patterning of fluorescence. A 1:1:1 mixture of RH32, RH37, and RH42 cells were spread evenly on plates containing Tet (30 μg/ml) and arabinose (0.1% or 0.01%). Discs of Amp or an Amp/IPTG mix were placed at the indicated locations. Three [Amp]/[IPTG] ratio were tested. Plates were incubated at 37°C. Visible light (of 0.1% arabinose plates) and merged fluorescent images are shown. The rank order of β-lactamase activity of the three strains is RH32 > RH37 > RH42. RH32 fluoresces yellow, RH37 fluoresces red, and RH42 fluoresces blue. The detailed conditions for all plates can be found in Additional file 1.