Fig. 4.

Environmental influence on inter-bacterial forces. a The repulsive force (each force line represents the average of six bacterial pairs) on approach is strongest for bacteria suspended in TSB, decreases for nutrient-deprived deionized water and disappears for bacteria in NaCl solution. The shaded areas represent the standard deviation of the force at each separation distance for the six bacterial pairs. b Averaged force lines follow the same trend on approach and retreat. c–d Average force and standard deviation on approach and retreat for autoclaved bacteria in TSB and 1 μm polystyrene beads in deionized water show no repulsion, indicating that we observe a biological response in living samples