Figure 2.

Schematic representation for the main nonspecific and specific interactions between bacteria and surfaces

(A) Some physicochemical interactions include the attractive van der Waals forces; attractive or repulsive electrostatic interactions, which depend on the microenvironment conditions, where the presence of a conditioning film may contribute to reducing repulsion; and the attractive/repulsive acid-base interactions (Kimkes and Heinemann, 2020).

(B: Left side) Pili-mediated temporal attachment. Pili elongation allows attachment to the surface, whereas pili retraction may cause the bacterium to be tugged toward the surface, reach different directions, change from horizontal to vertical (and vice versa) orientations by using different types of motility, or it may be released back.

(B: Right side) Flagella-mediated temporal attachment may be caused because of their hydrophobic nature, as well as by some of the flagellar motor components. When flagella become anchored to the surface, the polarly attached cells spin around, often leading to detachment of bacteria.

(C) Specific temporal attachment may be mediated by binding of adhesins, expressed onto the bacterial surface or at the tip of certain pili appendages, to particular host receptors.