Characterizing the adhesion of motile and nonmotile Escherichia coli to a glass surface using a parallel‐plate flow chamber

Abstract

A parallel-plate flow chamber was used to measure the attachment and detachment rates of Escherichia coli to a glass surface at various fluid velocities. The effect of flagella on adhesion was investigated by performing experiments with several E. coli strains: AW405 (motile); HCB136 (nonmotile mutant with paralyzed flagella); and HCB137 (nonmotile mutant without flagella). We compared the total attachment rates and the fraction of bacteria retained on the surface to determine how the presence and movement of the flagella influence transport to the surface and adhesion strength in this dynamic system. At the lower fluid velocities, there was no significant difference in the total attachment rates for the three bacterial strains; nonmotile strains settled at a rate that was of the same order of magnitude as the diffusion rate of the motile strain. At the highest fluid velocity, the effect of settling was minimized to better illustrate the importance of motility, and the attachment rates of both nonmotile strains were approximately five times slower than that of the motile bacteria. Thus, different processes controlled the attachment rate depending on the parameter regime in which the experiment was performed. The fractions of motile bacteria retained on the glass surface increased with increasing velocity, whereas the opposite trend was found for the nonmotile strains. This suggests that the rotation of the flagella enables cells to detach from the surface (at the lower fluid velocities) and strengthens adhesion (at higher fluid velocities), whereas nonmotile cells detach as a result of shear. There was no significant difference in the initial attachment rates of the two nonmotile species, which suggests that merely the presence of flagella was not important in this stage of biofilm development.

Bacterial flagella explore microscale hummocks and hollows to increase adhesion

“…It has been suggested that swimming motility allows improved access to surfaces for initial attachment (22,35). In low-shear environments, however, motility has been shown to have no effect on attachment of E. coli to glass (36). It has long been known that E. coli can adhere to surfaces via flagella (37), and somewhat more recently, several pathogenic strains have been shown to adhere to epithelial tissue using flagella-mediated adhesion (38)(39)(40).…”

The effects of surface properties on Escherichia coli adhesion are modulated by shear stress

“…However, the model does not account for the fact that a higher flow rate promotes higher shear stresses that may prevent cellular attachment [42]. This hindrance may be overcome by the bacterial appendages used in adhesion [43]. Moreover, since these structures have a small size, they can help to overcome the energy barrier between the bacteria and the surface and facilitate adhesion [44].…”

“…It is however plausible that this effect is dependent on the bacteria and surface that is used for the assays. When PDMS is used as substrate, since this surface is thermodynamically more favorable for adhesion, the inhibitory effect caused by the shear stress is only noticed after 13 min possibly due to the reduction of free area available for adhesion and the lower contact time between the cells and the surface, which may hamper the adhesion assistance effect provided by the cellular appendages [43].…”

Signals, Regulatory Networks, and Materials That Build and Break Bacterial Biofilms

“…Motility itself is thought to enhance the initial interaction of the bacterium with the surface by enabling the bacterium to overcome long-range repulsive forces, thus increasing the likelihood of close approach (86). In fact, flagellar motility has been demonstrated to accelerate surface adhesion for many bacteria (169,173,192,217,224,325,344). However, under certain growth conditions, mutation of components of the flagellar structure leads to increased synthesis of the adhesive matrix that promotes interbacterial attachments and formation of a multilayer biofilm.…”