FIG. 1.
Observed force profiles for a probe on A. ferrooxidans in pH 2, 0.1 M saline solution. Steric force curves were calculated using the average (Avg), lower bound (LB), and upper bound (UB) values obtained by fitting measured force data (gray dots) to equation 1, where the tip radius is 20 nm. Lo, equilibrium thickness; Γ, polymer density. UB values are averages plus SD; LB values are averages minus SD. Also shown is the maximum electrostatic force that is expected between A. ferrooxidans (−5 mV) and the AFM tip (−5 mV) in pH 2, 0.1 M NaCl solution.