Figure 8.

Simulation 4: metabolic inhibitors can block chemotaxis towards the dedicated metabolite. The inhibitor is present evenly in the simulation box (with concentration 2 μM, not shown in the figures). (a) Exemplar bacterium showing migration from the top-left to the bottom-right in the simulation box. (b) The bacterium in (a) experiences an increase in ligand concentration. (c) The bacterium does not seek external metabolite. (d) The signal level in transmembrane sensory cluster becomes stronger as ligand concentration increases. (e) The stopping probability from the cytosolic sensory pathway remains almost zero, due to the constant inhibitory effect from the evenly distributed inhibitor. (f) The stopping probability only depends on the signal from transmembrane sensory cluster. (g–i) The distribution of 50 simulated bacteria along the x-axis shows that they seek high ligand concentrations, while being randomly distributed along the y-axis. (j) Linear metabolite gradient in x-direction. (k) Linear ligand gradient in y-direction. (Online version in colour.)