Novel experimental study of receptor-mediated bacterial adhesion under the influence of fluid shear

Abstract

Dynamic adhesion of cells to surfaces is a vital step in a variety of biochemical and physiological phenomena. Bacterial adhesion is responsible not only for problems associated with biofouling and biofilm formation in the biochemical industry but also in the initiation of certain infectious diseases. In this study, we report the effect of critical parameters, such as receptor and ligand densities and shear rate, on receptor‐mediated dynamic bacterial adhesion. Adhesion of a pathogenic strain of Staphylococcus aureus to immobilized collagen was studied. The receptor density on the cell surface was varied by harvesting cells at different growth times and was quantified using flow cytometry. Dynamic adhesion experiments were conducted over a range of physiologically relevant shear rates (50 to 1500 s−1) using a parallel‐plate flow chamber. Video microscopy coupled with digital image processing was employed to quantify adhesion. A semiquantitative comparison between experimental results and theoretical data obtained using a previously proposed mathematical model was also performed. The results suggest that dynamic adhesion is dependent on receptor density and shear rate, but independent of ligand density. This report demonstrates the feasibility of using bacteria to study fundamental aspects of receptor‐mediated dynamic adhesion. © 2000 John Wiley & Sons, Inc. Biotechnol Bioeng 68: 628–636, 2000.

Sex and flow: the consequences of fluid shear for sperm–egg interactions

“…Attached sperm and egg would separate if sufficient shear force breaks the bond between them (Mohamed et al, 1999;Mohamed et al, 2000;Thomas et al, 2002). Abalone sperm and egg binding force is unknown, but for mammalian sperm and the zona pullicida, it was measured as 4ϫ10 -10 -3ϫ10 -9 ·N (Baltz et al, 1988;Thaler and Cardullo, 1996).…”

Microbial Adhesion in Flow Displacement Systems

“…For instance, in aqueous suspensions, wall shear rates of 6,000 to 8,000 s Ϫ1 (equivalent to shear forces of between 6 ϫ 10 Ϫ3 and 8 ϫ 10 Ϫ3 nN) were sufficient to prevent adhesion of Pseudomonas fluorescens to stainless steel, while wall shear rates of 12,000 s Ϫ1 (or shear forces of 12 ϫ 10 Ϫ3 nN) could detach adhering organisms (78). Adhesion of Staphylococcus aureus to collagen-coated glass plates increased for shear rates between 50 and 300 s Ϫ1 due to increased mass transport and then, after exceeding the critical limit, decreased for shear rates higher than 500 s Ϫ1 , equivalent to a shear force of 0.5 ϫ 10 Ϫ3 nN (64). Note the enormous range in adhesive forces between different strains and species.…”

Surface plasmon resonance shows that type IV pili are important in surface attachment by Pseudomonas aeruginosa

“…Current techniques to monitor colonization rely on the optical detection of bacteria, either in closed or flow-cell systems, or on methods such as crystal violet staining to detect the final presence of bacterial biofilms on artificial substrates (Mohamed et al 2000;Stoodley et al 2001Stoodley et al , 2002. Staining techniques obscure the critical early stages of attachment as they rely upon the detection of the final numbers of attached bacteria; whereas the use of digital video within a flow-cell facilitates continuous real-time monitoring of bacterial attachment (Stoodley et al 2001(Stoodley et al , 2002.…”