IR study of self-assembly of capsular exopolymers from Pseudomonas sp. NCIMB 2021 on hydrophilic and hydrophobic surfaces.

Capsular exopolymers (EPS) of the bacterium Pseudomonas sp. NCIMB 2021 are allowed to self-assemble on hydrophilic and hydrophobic gold surfaces. Tapping mode atomic force microscopy confirms the differences in the surface topography between EPS adsorbed on both surfaces. Fourier-transform IR spectroscopy indicates that the EPS surface coverage is much greater on the hydrophobic surface. Furthermore, an increased contribution is observed from hydrophobic (i.e., methyl and tyrosyl residues) and electrostatic (i.e., carboxylate residues) groups at the hydrophobic surface, but there is relatively less neutral polymer compared to the hydrophilic surface. The behavior of this EPS is in agreement with the behavior of cells of Pseudomonas sp. NCIMB 2021 at hydrophilic and hydrophobic surfaces.