On the Verge of Attachment: The Effect of Ionic Concentration on Bacterial Adhesion

Abstract

The lipopolysaccharide layer of Pseudomonas aeruginosa is the first cell membrane layer that interacts with its surroundings. The goal of this research is to model the effects of ionic concentration by simulating the attachment of a Pseudomonas aeruginosa bacterium to a surface with hydrophilic, hydrophobic, or metallic characteristics. The Monte Carlo Metropolis algorithm was used to find the equilibrium states of the systems. Both monovalent and divalent ions were present and their effects were quantified as functions of distance between the bacterial membrane and the surface. The energies of the system comprised of hydrogen bonding, van der Waals, and electrostatic interactions. Changes in the free energy of the system decide how well the bacterium binds to the surface. It was found that the collapse of the LPS induced by calcium decreased attachment to surfaces with hydrophobic and hydrophilic characteristics and that all ions screened a metallic surface from bacterial attachment.