🦠 Bacteria Colony (2D)

Nutrient concentration 0.75 Growth rate r 0.55 Nutrient diffusion D 0.35

1colony population

0colony radius (mm)

0generations

1active front cells

Logistic growth dN/dt = rN(1−N/K) drives overall colony expansion; each front cell's chance to divide also depends on the local nutrient concentration diffusing in from the dish (Fick's second law). Low nutrient starves the front between branches, producing dendritic, diffusion-limited fractal patterns; high nutrient feeds the whole front evenly, producing a smooth, round colony disk.

Colony (bacteria)

Nutrient field