FIGURE 2 Engineered_Strain_Spikes: One of the engineered P. mirabilis strains, the “pLac-lrp” strain; when grown on a Petri dish with the molecule IPTG present in the growth medium, as shown here, the strain responds by changing its ring pattern into a pattern of spikes.

FIGURE 3 Copper_Sensing_Strain: The engineered copper sensing strain, grown with samples of water containing high copper (50 mM) which were added as drops onto the left side of the Petri dish. The copper is sensed by the bacteria, which respond by changing their swarming and thus the ring pattern, such that the invisible presence of copper becomes visible to the naked eye. The pattern on the right side of the plate, with no sample, can be used as a baseline to which the left side’s pattern can be compared.