Image: EPS production by ammonia oxidisers at a low rate, cells sticky
Biofilm, aged 30,000 min (3 weeks). The contour lines show the oxygen concentration in mg/l. The image was rendered with POV-Ray, showing each cell as a sphere. The ammonia oxidisers ("Nitroso") are blue, and the EPS they produce is bluish (cyan); the nitrite oxidisers ("Nitro") are red. See the reaction scheme below. 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.
The EPS producing cells usually become separated from each other with time due to the flow of EPS they create. In this simulation, the producing cells stick to each other by means of weak attractive forces of short range, modelling surface-bound adhesive molecules or pili. Larger clusters of blue cells and correspondingly larger patches of EPS devoid of cells are formed compared with the previous movie with non-sticky cells.
