Figure 3.

The frontier of the colony for three different nutrient uptake rates k = 1.8 (a), k = 2.2 (b) and k = 2.6 (c). The thickness of the growing layer (bright green) decreases only moderately (1.64×) from h = 13.5 ± 0.1 μm for k = 1.8 to h = 8.2 ± 0.1 μm for k = 2.6, but this has a large impact on the front roughness which changes from ρ = 2.1 ± 0.2 μm to ρ = 9.3 ± 0.4 μm, correspondingly. For k = 2.6, the growing layer begins to lose continuity and splits into separate branches. (Online version in colour.)