How Microbes Use Force To Control Adhesion

Abstract

Microbial adhesion and biofilm formation are usually studied using molecular and cellular biology assays, optical and electron microscopy, or laminar flow chamber experiments. Today, atomic force microscopy (AFM) represents a valuable addition to these approaches, enabling the measurement of forces involved in microbial adhesion at the single-molecule level. In this minireview, we discuss recent discoveries made applying state-of-the-art AFM techniques to microbial specimens in order to understand the strength and dynamics of adhesive interactions. These studies shed new light on the molecular mechanisms of adhesion and demonstrate an intimate relationship between force and function in microbial adhesins.

Bacterial adhesion to biomaterials: What regulates this attachment? A review

“…Bacterial adhesion to the surface of biomaterials involves different types of physical-chemical interactions and biological processes, with mechanisms specific to the bacteria or the substrate [ 1 , 2 , 17 ]. Bacteria promote adhesion through the development of cells that detect signals, production of extracellular polysaccharides (EPS), metabolic activity, cell viability [ 3 ] charge, hydrophobicity, cell wall stiffness, receptor-ligand binding mediated by adhesins, which are protein complexes that recognize and bind to protein receptors on the host cell surface, and appendages (pili and curli) [ 13 , 14 , 24 ]. Adhesion refers to the attachment of cells to a substrate, while cohesion is the bond between cells [ 20 , 22 ].…”

“…Bacterial adhesion to abiotic surfaces is of great interest to the scientific community because it marks the beginning of biofilm formation, and in that sense, atomic force microscopy (AFM) has opened the way for a detailed understanding of biofilms [ 2 ]. In addition to being compatible with aqueous solution environments, which is an important factor for medical research, and reaching a nanoscale resolution, AFM delivers high-resolution nanometric images [ 13 , 15 , 24 , 37 , 38 ], as well as quantitative measurements of the mechanical forces involved in cell adhesion, which can vary from 5 pN to 100 nN [ 12 ], making it possible to probe interactions at the molecular level between different species [ 2 , 19 , 37 ] ( Fig. 1 ).…”

“…The AFM consists of a nanometric tip connected to the end of a highly flexible cantilever that sweeps the sample in the x and y directions, and due to the interactions between the tip and the sample, the cantilever bends vertically (z-direction) [ 2 , 13 , 15 , 24 , 39 ], thus the force required to move the bacteria attached to a surface can be registered by a laser beam focused on the cantilever and reflected on a photodiode [ 24 , 40 ]. A piezoelectric motor maintains a defined level of deflection in the cantilever ensuring that the force applied to the sample is constant and controlled to avoid sample damage [ 40 ].…”

“…The cantilever can have a sharp tip (standard), a colloidal tip (to deliver a more defined geometry), or a functionalized tip, to probe specific chemical interactions [ 13 ]. The adhesion is recorded in newtons and determined by the force exerted by the tip on the sample [ 24 , 37 , 40 ]. The scan can be performed in constant contact, intermittent contact, or without contact [ 24 , 40 ] ( Fig.…”

Staphylococcus aureus vWF-binding protein triggers a strong interaction between clumping factor A and host vWF

“…Interestingly, ClfA appeared to cluster in domains on the bacterial cell surface (Fig. 2a ) reminiscent of other S. aureus MSCRAMMs 31 . This clustering may play a role in enhancing bacterial adhesion.…”