Fig. 4.

Screenshot of the spatially explicit model. The proximal end of the colon is on the left, the distal end on the right. Thus, nutrients flow from left to right. a Cells on the grid. At maximum 2 cells can be on the same grid point. Yellow:one cell present, green: 2 cells present. (b) Glucose concentration. Black: low concentrations, white: high concentrations. (c) Formate concentrations. In total, 115 extracellular metabolites are taken into account in the model