Thickness and surface density of extracellular polymers on Acidithiobacillus ferrooxidans.

In vivo force microscopy measurements of Acidithiobacillus ferrooxidans revealed a repulsive force that was due to the presence of extracellular polymers on the bacterium's surface. Measured force-distance profiles were fit to steric force theory to estimate the density and thickness values of these exopolymers. The polymer densities were 3.4 x 10(16) to 7.1 x 10(16) molecules m(-2), and the equilibrium thickness was 29 nm.