Movie: Individual-based model biofilm
Movie of a biofilm growing from 10 cells per species at time zero for 30,000 min (3 weeks), with one frame per 1,000 min. All frames were rendered with POV-Ray, showing each cell as a sphere. The ammonia oxidisers ("Nitroso") are green; the nitrite oxidisers ("Nitro") are red. The grey box at the bottom is the inert substratum. Note the wrapped around boundaries in the horizontal direction. Scale: total width of the system = 200 µm.
In the Individual-based model, cells are spread independently of each other. Cells are spheres rather than bricks and exist in continuous space rather than on a discrete grid. However, this leads to less mixing since the spreading mechanism is not random but deterministic.