Fig. 3. Consortium response in different spatial structures.

A, C, and E show the predicted concentration gradient at the diagonal of the cube, for the following spatial structure: A no diffusion from beads, C diffusion from beads, 15 µm between cells within a bead, and E diffusion from beads, aggregated cells within a bead. For each condition the glucose uptake (mol/s) after 5 h of incubation was calculated, without considering growth of the cells. Bar plots show the glucose consumption rate (mol/s) in bead 1 (bead without producer cell) and bead 2 (bead with producer cell). Dashed lines indicate the glucose production rate (mol/s) of producer cells, which is equal in all conditions. Produced glucose that is not consumed in bead 1 or bead 2 is consumed by the competing glucose-consumers. In B, D, and F the experimental results are shown for these different spatial structures. Details about the gating strategy are given in Supplementary information section 3, Figs. S4 and S5. Density plots B₁, D₁, D₃, and F₁ show the populations that were gated as “growth” in the producer–receiver co-cultures (n = 3, around 3000 agarose beads measured per replicate). Density plots B₂, D₂, D₄, and F₂ show the average fluorescence of the grown cells (n = 3). This average fluorescence scales with the receiver cell fraction, as shown by the control samples that are added in the same plot: receivers only, producers only, and co-cultures of non-producers and receivers (n = 3 for each of them). The non-producers and receivers and the producers only controls are overlapping in all plots. The schematic drawing at the right summarizes the results from the presented density plots.