Impact of ionic strength of growth on the physiochemical properties, structure, and adhesion of Listeriamonocytogenes polyelectrolyte brushes to a silicon nitride surface in water

The adhesion energies between pathogenic Listeriamonocytogenes EGDe to a model surface of silicon nitride were quantified using atomic force microscopy (AFM) in water for cells grown in pure media (as the control) and in media of four different ionic strengths of added NaCl (IS of 0.05 M, 0.1 M, 0.3 M and 0.5 M NaCl). The physiochemical properties of L. monocytogenes EGDe surface brushes were shown to have a strong influence on the adhesion of the microbe to the silicon nitride surface. The transitions in the adhesion energies, physiochemical properties, and the structure of bacterial surface polyelectrolyte brushes were observed for the cells grown in the media of 0.1 M added NaCl. Our results suggested that the highest long-range electrostatic repulsion which was partially balanced by the Liftshitz–van der Waals attraction for the cells grown at 0.1 M was responsible for the highest energy barrier to adhesion for these cells as predicted by the soft-particle analysis of DLVO theory and the lower adhesion measured by AFM.

Figure optionsDownload high-quality image (146 K)Download as PowerPoint slideHighlights
► Ionic strength of growth media affected the structure of Listeria monocytogenes.
► Ionic strength of growth media affected the surface potential of L. monocytogenes.
► Ionic strength of growth media affected the adhesion of L. monocytogenes to Si3N4.
► Transition in all properties occurred when 0.1 M NaCl was added to growth media.
► Adhesion changes upon bacterial transport in media with variable ionic strength.